Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Saturday 23 May 2009, John Doty wrote:
>On May 23, 2009, at 7:56 PM, Gene Heskett wrote:
>> To me, a 6AU6 is a newer
>> tube.  6SJ/K7's are middle aged, and the 4X's were popular for
>> small signal &
>> 2A3's for audio output's about the time I was born.  And all are
>> transconductance pikers compared to a 7788. :)  And my spell
>> checker does not
>> even recognize the word!
>
>Not much excuse for a spell checker that doesn't know
>transconductance. Now, if it didn't know perveance I might be
>inclined to cut it some slack... ;-)

Chuckle, tell that to the Aspell folks, John.  And I'm not so sure I wouldn't 
fuss just as loud over perveance, and darned if it isn't fussing about that 
too.  Sigh...

>John Doty  Noqsi Aerospace, Ltd.
>http://www.noqsi.com/
>j...@noqsi.com
>
>
>
>
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 23, 2009, at 7:56 PM, Gene Heskett wrote:

> To me, a 6AU6 is a newer
> tube.  6SJ/K7's are middle aged, and the 4X's were popular for  
> small signal &
> 2A3's for audio output's about the time I was born.  And all are
> transconductance pikers compared to a 7788. :)  And my spell  
> checker does not
> even recognize the word!

Not much excuse for a spell checker that doesn't know  
transconductance. Now, if it didn't know perveance I might be  
inclined to cut it some slack... ;-)

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Saturday 23 May 2009, Joerg wrote:
>Gene Heskett wrote:
>> On Friday 22 May 2009, Joerg wrote:
>>> I'll second that. Did it in Spain but the track owner from whom I also
>>> rented the go-kart didn't want me on there anymore after my power-slides
>>> blew out the 2nd tire (including some smoke plumes). They must be rather
>>> expensive.
>>
>> 40 years ago, those slicks were about a $30 bill ea.  So today, probably
>> $75, 90 maybe?  I haven't kept up.  Shame on me.  But I never blew one. 
>> My only failures were related to spinning the wheel in them, peeling the
>> valve core out of the innertube.
>
>I don't know much about tires but what happened was that while the
>surface seemed to smoke the blow-outs happened on the sides of the
>tires. Both times it was the right rear. And in Spain $30 back then was
>a whole lotta dough.

Probably was.  ISTR I was making about $90/week back then.  So I made those 2 
tires run for 3 seasons worth of some dirt, some blacktop racing, never for 
more than a case of pop to the winners.  But it was the ultimate fun for me at 
the time.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Never eat more than you can lift.
-- Miss Piggy



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Saturday 23 May 2009, Joerg wrote:
>Gene Heskett wrote:
>> On Friday 22 May 2009, Joerg wrote:
>>> John Doty wrote:
 On May 21, 2009, at 6:00 PM, Joerg wrote:
> Chris Albertson wrote:
>
> [...]
>
>> I'm thinking about tube amps that had an output impedance of about 1M
>> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
>> to 1 ratio.
>
> 1M? What kind of tube was that?

 Well, that's a typical plate resistance for a small signal pentode, but

 Power pentodes have lower plate resistance.
>>>
>>> Small signal, yes. But a 12AX7 won't be enough for a rock concert ;-)
>>
>> And its not even a pentode, its a dual triode, designed for phono preamps
>> and such.
>
>Sorry, I meant something like the 6AU6.

Which fits the general thread idea a lot better.  To me, a 6AU6 is a newer 
tube.  6SJ/K7's are middle aged, and the 4X's were popular for small signal & 
2A3's for audio output's about the time I was born.  And all are 
transconductance pikers compared to a 7788. :)  And my spell checker does not  
even recognize the word!

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Remember:  Silly is a state of Mind, Stupid is a way of Life.
-- Dave Butler



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Friday 22 May 2009, Joerg wrote:
> 
>> I'll second that. Did it in Spain but the track owner from whom I also
>> rented the go-kart didn't want me on there anymore after my power-slides
>> blew out the 2nd tire (including some smoke plumes). They must be rather
>> expensive.
> 
> 40 years ago, those slicks were about a $30 bill ea.  So today, probably $75, 
> 90 maybe?  I haven't kept up.  Shame on me.  But I never blew one.  My only 
> failures were related to spinning the wheel in them, peeling the valve core 
> out of the innertube.
> 

I don't know much about tires but what happened was that while the 
surface seemed to smoke the blow-outs happened on the sides of the 
tires. Both times it was the right rear. And in Spain $30 back then was 
a whole lotta dough.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Friday 22 May 2009, Joerg wrote:
>> John Doty wrote:
>>> On May 21, 2009, at 6:00 PM, Joerg wrote:
 Chris Albertson wrote:

 [...]

> I'm thinking about tube amps that had an output impedance of about 1M
> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
> to 1 ratio.
 1M? What kind of tube was that?
>>> Well, that's a typical plate resistance for a small signal pentode, but
>>>
>>> Power pentodes have lower plate resistance.
>> Small signal, yes. But a 12AX7 won't be enough for a rock concert ;-)
>>
> And its not even a pentode, its a dual triode, designed for phono preamps and 
> such.
> 

Sorry, I meant something like the 6AU6.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Matthew Sager]

   I have not made it to Akihabara, but if you are around the Nagoya area
   you can try Osu it has the same kind of stuff.  I always have to plan
   for a side trip and a little extra spending money.

   On Fri, May 22, 2009 at 2:49 PM, John Doty <[1]...@noqsi.com> wrote:

   On May 22, 2009, at 12:35 PM, Joerg wrote:
   >
   >> In Japan, Tokyu Hands (a division of the Tokyu department store
   >> chain) sells tube amplifier kits.
   >>
   >
   > The dream of any electronics engineer, one whole day for an extended
   > stroll through Akihabara,

 Hai, shimashita. Been there, done that. But I don't recall a Tokyu
 Hands there. Plenty of them around, though. I'm often in Machida in
 December, and there's a Tokyu Hands right by the train station.
 Good
 place for Christmas shopping. It's arts, crafts, tools, and
 housewares, not primarily electronics.
 > and no budget limits :-)
 >
 Sadly, no.

   John Doty  Noqsi Aerospace, Ltd.
   [2]http://www.noqsi.com/

 [3]...@noqsi.com

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References

   1. mailto:j...@noqsi.com
   2. http://www.noqsi.com/
   3. mailto:j...@noqsi.com
   4. mailto:geda-user@moria.seul.org
   5. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Friday 22 May 2009, Joerg wrote:

>I'll second that. Did it in Spain but the track owner from whom I also
>rented the go-kart didn't want me on there anymore after my power-slides
>blew out the 2nd tire (including some smoke plumes). They must be rather
>expensive.

40 years ago, those slicks were about a $30 bill ea.  So today, probably $75, 
90 maybe?  I haven't kept up.  Shame on me.  But I never blew one.  My only 
failures were related to spinning the wheel in them, peeling the valve core 
out of the innertube.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Complex system:
One with real problems and imaginary profits.



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Friday 22 May 2009, Joerg wrote:
>John Doty wrote:
>> On May 21, 2009, at 6:00 PM, Joerg wrote:
>>> Chris Albertson wrote:
>>>
>>> [...]
>>>
 I'm thinking about tube amps that had an output impedance of about 1M
 ohm that used transformers to drive 8 ohm speakers.  About a 100,000
 to 1 ratio.
>>>
>>> 1M? What kind of tube was that?
>>
>> Well, that's a typical plate resistance for a small signal pentode, but
>>
>> Power pentodes have lower plate resistance.
>
>Small signal, yes. But a 12AX7 won't be enough for a rock concert ;-)
>
And its not even a pentode, its a dual triode, designed for phono preamps and 
such.

>> For a large signal amplifier, the load generally isn't matched to the
>> output resistance. Instead, it's roughly (peak output voltage)/(peak
>> output current), which is different. If you match the output
>> resistance, in most cases you'll clip at an output power well below
>> the capacity of the amplifier.
>>
>> And finally, the real issue here is the current required. 100 amps
>> will melt the wire in any audio transformer I've ever seen.
>>
>> Everybody seems to think Mark's soldering gun suggestion is a joke,
>> but I don't know. I think I'd get one, pull the transformer, measure
>> its characteristics, see if it might work (maybe a couple of them in
>> series/parallel or something). They're light, cheap, and the closest
>> thing to the requirement here I can think of. I'm sure they won't run
>> at full power all day without overheating, but for a test set that
>> might be OK.

Full power? A minute thirty maybe then needs at least a 5 minute cooldown.

>It's not a joke, quite viable maybe. But the solder guns I have used
>can't quite get to 100 amps. Maybe the 100W Weller I got for a client
>does, it cost around $30 at a hardware store. Another option is to use a
>regular (fat) mains transformer that has a bit of clearance between the
>packet and core. Run a wide sheet of thick copper through there, only
>one turn and leave its usual secondary winding alone. Or if to be driven
>from a generator drive that other secondary and leave the primary alone
>(and don't touch it ...). This results in a huge current capability.
>Another option may be welding transformers. Even my cheap one can
>deliver 160 amps for quite some time. But those are huge.
>
>As usual, Levente needs to take every piece of metal off. Wedding band,
>wrist watch, etc. Best not to have credit cards close by either because
>their magnetic strip might later be stripped of its information. BTDT,
>quite embarrassing when you take the guys out for lunch and the waitress
>comes back with "Your credit card doesn't work".

:-)

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Life is a whim of several billion cells to be you for a while.



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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 22, 2009, at 12:35 PM, Joerg wrote:

>
>> In Japan, Tokyu Hands (a division of the Tokyu department store
>> chain) sells tube amplifier kits.
>>
>
> The dream of any electronics engineer, one whole day for an extended
> stroll through Akihabara,

Hai, shimashita. Been there, done that. But I don't recall a Tokyu  
Hands there. Plenty of them around, though. I'm often in Machida in  
December, and there's a Tokyu Hands right by the train station. Good  
place for Christmas shopping. It's arts, crafts, tools, and  
housewares, not primarily electronics.

> and no budget limits :-)
>

Sadly, no.

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

John Doty wrote:
> On May 22, 2009, at 10:47 AM, Joerg wrote:
> 
>> As for tubes I found that HV-driver tubes for color TVs were the best
>> deal. But this was decades ago, today you'd have to take a look at  
>> which
>> current production tubes are available and at what cost. Sovtek,
>> Svetlana and so on.
> 
> Still lots of old TV tubes around: repair shops kept large stocks  
> around, and dealers grabbed them for pennies on the dollar as the  
> shops closed up when the tube era ended. If you want to build tube  
> stuff from scratch http://tubesandmore.com/ has lots of stuff: old  
> tubes, current tubes, sockets, transformers, ...
> 

Thanks. There are many tube places and prices (or the mark-ups) seem to 
vary widely. One shop has a certain tube for cheap, but another is a lot 
better in price for a different tube.

These guys even have Chinese 6146 for 20 bucks:

http://www.tubedepot.com/index.html

But I haven't shopped there yet and also I prefer the mil version with 
graphite plates, with some luck those can be had for around $30.

Then there is stuff you'd be hard-pressed to do with semiconductors, 
like HV-switching. The GP-5 triode can avoid the white-knuckle ride of a 
FET-stack and I've seen it for $5 at a few places:

http://tubes-store.com/product_info.php?products_id=58


> In Japan, Tokyu Hands (a division of the Tokyu department store  
> chain) sells tube amplifier kits.
> 

The dream of any electronics engineer, one whole day for an extended 
stroll through Akihabara, and no budget limits :-)

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 22, 2009, at 10:47 AM, Joerg wrote:

> As for tubes I found that HV-driver tubes for color TVs were the best
> deal. But this was decades ago, today you'd have to take a look at  
> which
> current production tubes are available and at what cost. Sovtek,
> Svetlana and so on.

Still lots of old TV tubes around: repair shops kept large stocks  
around, and dealers grabbed them for pennies on the dollar as the  
shops closed up when the tube era ended. If you want to build tube  
stuff from scratch http://tubesandmore.com/ has lots of stuff: old  
tubes, current tubes, sockets, transformers, ...

In Japan, Tokyu Hands (a division of the Tokyu department store  
chain) sells tube amplifier kits.

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Thursday 21 May 2009, Joerg wrote:
> [...]
>> Wow, I've never been in a close call like that one. Only once in a small
>> Dornier aircraft when the (otherwise totally quiet) bush pilot kind of
>> guy let off a lot of cuss words, the stall horn was blaring, pine tree
>> tops came at us and it was of course not high enough to do a parachute
>> bail. A burly mtorcycle guy next to me who usually isn't afraid of
>> anything mumbled "Well, I guess this is it". We made it but could see
>> the snow flying off the trees as we inched up in altitude. Maybe the
>> newly "found" ground effect or something saved us. For a while there the
>> tree tops looked like the road does from the low seats of a Porsche.
> 
> Humm, similar I suppose to a go-kart I once had.  Quite a rush when the 
> blacktop is going by your hip joints at 120+mph, an only an inch below them.  
> That of course was back in the 60's when go-kart engines were 2 strokers and 
> some could make 4 to 5 horse per cubic inch.  Mine was an old outboard, 14ci, 
> but a deflector head design so even on booze it was only maybe 2hp/ci, and 
> about 1 on straight gas.  But that was enough to get the job done for me. :)
> 
> I highly recommend that everyone who really wants to learn to drive, do it on 
> an old go-kart, the new 4 strokers aren't fast enough by any means.  On a go-
> kart you can play with the envelope and find out what the machine can do, 
> generally without collecting any broken momentos.  Lose it in the corner and 
> spin it out?  Go do it again, till you can hit that corner 30mph faster than 
> when you spun out, steer it with the throttle while sliding at a 10 degree 
> angle to the direction you are going, using every inch of the track just like 
> the indy cars do.  Spend a summer or 3 doing that and I guarantee you will 
> never, ever drive a cage in such a manner that you can't handle whatever the 
> road or weather throws at you.  Even at my age, 74, I still have one corner I 
> use as a gauge to see how I'm doing.
> 

I'll second that. Did it in Spain but the track owner from whom I also 
rented the go-kart didn't want me on there anymore after my power-slides 
blew out the 2nd tire (including some smoke plumes). They must be rather 
expensive.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Chris Albertson wrote:
> On Thu, May 21, 2009 at 5:00 PM, Joerg  wrote:
>> Chris Albertson wrote:
>>
>> [...]
>>
>>> I'm thinking about tube amps that had an output impedance of about 1M
>>> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
>>> to 1 ratio.
>>>
>> 1M? What kind of tube was that? I think the highest I had was about 5K.
>> At 5000 volts on the plates ...
> 
> OK off by "just one decimal point".  My point still is that tube amps
> have to deal with a huge impedance mis-match and they handle it with a
> transformer.Then you ask "what transformers can handle a load that
> is well under 1 ohm.  So I thought about arc welders.
> 

Point-contact welders may also be an option.


> While on the subject, I'm wanting to build a tube amp.  But my goal is
> not to re-create an old design.  Mostly for entertainment and
> education I want to design and build the transformers too.  Anyone
> have any leads or links to places to buy the parts?  I know you can
> buy frames and the metal plates used to stack a transformer core but
> where?.  I'd start by building something small and easy, like a low
> power 12V power supply but the goal is to learn the art of high power
> transformer building
> 

Hammond makes tube-stage transformers, even quite large ones. But those 
cost a pretty penny and I couldn't bring myself to chop up some of those 
beauties to stack the cores. Paralleling, yes. You might want to ask in 
a hardcore audio-freak group.

As for tubes I found that HV-driver tubes for color TVs were the best 
deal. But this was decades ago, today you'd have to take a look at which 
current production tubes are available and at what cost. Sovtek, 
Svetlana and so on.

The biggest tube amp I ever built was with two of these and you almost 
had to call the utility before turning it on:

http://www.pll.gr/qb5-1750.pdf

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Chris Albertson]

On Thu, May 21, 2009 at 5:00 PM, Joerg  wrote:
> Chris Albertson wrote:
>
> [...]
>
>> I'm thinking about tube amps that had an output impedance of about 1M
>> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
>> to 1 ratio.
>>
>
> 1M? What kind of tube was that? I think the highest I had was about 5K.
> At 5000 volts on the plates ...

OK off by "just one decimal point".  My point still is that tube amps
have to deal with a huge impedance mis-match and they handle it with a
transformer.Then you ask "what transformers can handle a load that
is well under 1 ohm.  So I thought about arc welders.

While on the subject, I'm wanting to build a tube amp.  But my goal is
not to re-create an old design.  Mostly for entertainment and
education I want to design and build the transformers too.  Anyone
have any leads or links to places to buy the parts?  I know you can
buy frames and the metal plates used to stack a transformer core but
where?.  I'd start by building something small and easy, like a low
power 12V power supply but the goal is to learn the art of high power
transformer building

-- 
=
Chris Albertson
Redondo Beach, California


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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

John Doty wrote:
> On May 21, 2009, at 6:00 PM, Joerg wrote:
> 
>> Chris Albertson wrote:
>>
>> [...]
>>
>>> I'm thinking about tube amps that had an output impedance of about 1M
>>> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
>>> to 1 ratio.
>>>
>> 1M? What kind of tube was that?
> 
> Well, that's a typical plate resistance for a small signal pentode, but
> 
> Power pentodes have lower plate resistance.
> 

Small signal, yes. But a 12AX7 won't be enough for a rock concert ;-)


> For a large signal amplifier, the load generally isn't matched to the  
> output resistance. Instead, it's roughly (peak output voltage)/(peak  
> output current), which is different. If you match the output  
> resistance, in most cases you'll clip at an output power well below  
> the capacity of the amplifier.
> 
> And finally, the real issue here is the current required. 100 amps  
> will melt the wire in any audio transformer I've ever seen.
> 
> Everybody seems to think Mark's soldering gun suggestion is a joke,  
> but I don't know. I think I'd get one, pull the transformer, measure  
> its characteristics, see if it might work (maybe a couple of them in  
> series/parallel or something). They're light, cheap, and the closest  
> thing to the requirement here I can think of. I'm sure they won't run  
> at full power all day without overheating, but for a test set that  
> might be OK.
> 

It's not a joke, quite viable maybe. But the solder guns I have used 
can't quite get to 100 amps. Maybe the 100W Weller I got for a client 
does, it cost around $30 at a hardware store. Another option is to use a 
regular (fat) mains transformer that has a bit of clearance between the 
packet and core. Run a wide sheet of thick copper through there, only 
one turn and leave its usual secondary winding alone. Or if to be driven 
from a generator drive that other secondary and leave the primary alone 
(and don't touch it ...). This results in a huge current capability. 
Another option may be welding transformers. Even my cheap one can 
deliver 160 amps for quite some time. But those are huge.

As usual, Levente needs to take every piece of metal off. Wedding band, 
wrist watch, etc. Best not to have credit cards close by either because 
their magnetic strip might later be stripped of its information. BTDT, 
quite embarrassing when you take the guys out for lunch and the waitress 
comes back with "Your credit card doesn't work".

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[John Griessen]

John Doty wrote:

> And finally, the real issue here is the current required. 100 amps  
> will melt the wire in any audio transformer I've ever seen.
> 
> Everybody seems to think Mark's soldering gun suggestion is a joke,  
> but I don't know. I think I'd get one, pull the transformer, measure  
> its characteristics, see if it might work (maybe a couple of them in  
> series/parallel or something). They're light, cheap, and the closest  
> thing to the requirement here I can think of. I'm sure they won't run  
> at full power all day without overheating, but for a test set that  
> might be OK.

The classic 10kW spot welder by Miller is now cloned and available
at Harbor Freight cheap.  It's a similar, beefier transformer as
a quick hot or weller solder gun.

John
-- 
Ecosensory   Austin TX


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Thursday 21 May 2009, Joerg wrote:
[...]
>Wow, I've never been in a close call like that one. Only once in a small
>Dornier aircraft when the (otherwise totally quiet) bush pilot kind of
>guy let off a lot of cuss words, the stall horn was blaring, pine tree
>tops came at us and it was of course not high enough to do a parachute
>bail. A burly mtorcycle guy next to me who usually isn't afraid of
>anything mumbled "Well, I guess this is it". We made it but could see
>the snow flying off the trees as we inched up in altitude. Maybe the
>newly "found" ground effect or something saved us. For a while there the
>tree tops looked like the road does from the low seats of a Porsche.

Humm, similar I suppose to a go-kart I once had.  Quite a rush when the 
blacktop is going by your hip joints at 120+mph, an only an inch below them.  
That of course was back in the 60's when go-kart engines were 2 strokers and 
some could make 4 to 5 horse per cubic inch.  Mine was an old outboard, 14ci, 
but a deflector head design so even on booze it was only maybe 2hp/ci, and 
about 1 on straight gas.  But that was enough to get the job done for me. :)

I highly recommend that everyone who really wants to learn to drive, do it on 
an old go-kart, the new 4 strokers aren't fast enough by any means.  On a go-
kart you can play with the envelope and find out what the machine can do, 
generally without collecting any broken momentos.  Lose it in the corner and 
spin it out?  Go do it again, till you can hit that corner 30mph faster than 
when you spun out, steer it with the throttle while sliding at a 10 degree 
angle to the direction you are going, using every inch of the track just like 
the indy cars do.  Spend a summer or 3 doing that and I guarantee you will 
never, ever drive a cage in such a manner that you can't handle whatever the 
road or weather throws at you.  Even at my age, 74, I still have one corner I 
use as a gauge to see how I'm doing.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


"Being disintegrated makes me ve-ry an-gry!" 



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Re: gEDA-user: [OFF] high current amplifier

[al davis]

On Thursday 21 May 2009, John Doty wrote:
> Everybody seems to think Mark's soldering gun suggestion is a
> joke,   but I don't know. I think I'd get one, pull the
> transformer, measure its characteristics,

Maybe someone has a broken one laying around.  I recall those 
plastic (Bakelite??) housings were rather fragile.  I think my 
Sears soldering gun was a superior product.




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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 21, 2009, at 6:00 PM, Joerg wrote:

> Chris Albertson wrote:
>
> [...]
>
>> I'm thinking about tube amps that had an output impedance of about 1M
>> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
>> to 1 ratio.
>>
>
> 1M? What kind of tube was that?

Well, that's a typical plate resistance for a small signal pentode, but

Power pentodes have lower plate resistance.

For a large signal amplifier, the load generally isn't matched to the  
output resistance. Instead, it's roughly (peak output voltage)/(peak  
output current), which is different. If you match the output  
resistance, in most cases you'll clip at an output power well below  
the capacity of the amplifier.

And finally, the real issue here is the current required. 100 amps  
will melt the wire in any audio transformer I've ever seen.

Everybody seems to think Mark's soldering gun suggestion is a joke,  
but I don't know. I think I'd get one, pull the transformer, measure  
its characteristics, see if it might work (maybe a couple of them in  
series/parallel or something). They're light, cheap, and the closest  
thing to the requirement here I can think of. I'm sure they won't run  
at full power all day without overheating, but for a test set that  
might be OK.

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Chris Albertson wrote:

[...]

> I'm thinking about tube amps that had an output impedance of about 1M
> ohm that used transformers to drive 8 ohm speakers.  About a 100,000
> to 1 ratio.
> 

1M? What kind of tube was that? I think the highest I had was about 5K. 
At 5000 volts on the plates ...

The other was a few hundred ohms, well, forced down to there, and we 
rewound the speaker. Then someone strapped on his E-guitar and shortly 
thereafter the cops came.

[...]

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Chris Albertson]

On Wed, May 20, 2009 at 8:37 AM, Levente Kovacs  wrote:
> Ok,
>
>
> I guess I wasn't clear, so I have to add that it won't be used to drive a
> speaker, I used the word "audio" to refer the frequency range. 500W audio
> amplifier that designed to drive 4-8 Ohms is easy. But 100A, is something you
> won't get in a pro audio store.

First off, your requet caught my eye as I'm looking for an audio amp
that goes down
to about 40Hz and hasthat kind of power.  I'd use it for my bass
guitar.  They are
easy to find.  Any music store will sell you a 500W bass amp.

What about using a very large 500W output transformer to impedence
match a "normal" amp to the load.

I'm thinking about tube amps that had an output impedance of about 1M
ohm that used transformers to drive 8 ohm speakers.  About a 100,000
to 1 ratio.

You could salvage the transformer from an arc welder to re-purpose as
your output transformer.  These are designed for close to the specs
youd need


What are you driving?



-- 
=
Chris Albertson
Redondo Beach, California


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Re: gEDA-user: [OFF] high current amplifier

[der Mouse]

>> [...] I'm having trouble seeing the error.
> [...various people...]

Ah, yes, if you compute the number of pounds you have and then think -
or inadvertently tell your aircraft - that number is how many kilograms
you have...yes, I can see the problem now.  It's not clear from the
article whether they fed the aircraft what they knew were pound
figures, not realizing it was expecting kg, or whether they computed
pound numbers but thought they'd computed kg numbers, but the only
difference lies in where the mistake was made - the effect is the same.

In principle this could have been caught at the stop in Ottawa, since
the fuel consumed would not jibe with the amount apparently needed to
refill.  I rather suspect that any discrepancy here would have been
treated as "that's odd, well, let's check out how much we really have
now..." and a repetition of the mistake.  I'm reminded of some stuff I
did for a billing system where I saw a discrepancy of three thousandths
of a cent.  This totally was an ignorably small amount, but it bothered
me enough that I dug until I knew where it came from; after reading
this story, I'm glad I have that tendency.  (It turned out to be
nothing important, in this case, but still.)

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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Thursday 21 May 2009, Joerg wrote:
>> der Mouse wrote:
 Or it produces nailbiters like this one:

 http://www.wadenelson.com/gimli.html
>>> It's a very interesting story, to be sure, but I'm having trouble
>>> seeing the error.  It says
>>>
>>> [...] each time using 1.77 pounds/liter as the specific gravity
>>> factor.  [...]  The factor the refuelers and the crew should
>>> have used on the brand new, all-metric 767 was .8 kg/liter of
>>> kerosene.
>>>
>>> But 1.77 pounds/liter is the same as .8 kg/liter, to within something
>>> like a third of a percent.  Perhaps it's just bad reporting and/or
>>> writing, but I'm having trouble seeing the error.
>> They calculated alright but then entered the pound number into the fuel
>> clocking system of the aircraft. Since Canada had (officially) converted
>> to metric the new aircraft was delivered with metric firmware so the 767
>> assumed this to be kilograms. But a pound ain't a kilogram, so ...
>>
>> I guess the fuel clock showed plenty of fuel when things went phut ...
>> shh. AFAIU the make-shift system in the 767 calculates the fuel flow
>>from engine sensors and keeps subtracting that from the entered total.
>> Assuming this entered total was kilograms.
>>
>> Probably they should have never taken off with a non-functional FQI
>> system. An added circumstance was most likely that nearly all the other
>> (older) aircraft were non-metric.
> 
> I agree, the FAA $hould have cited the airline for $uch poor practice$.
> 
>> I've been on one flight on a 767 when an engine went phut about an hour
>> before reaching the Belgian coast, something had gone kaputt in there.
>> That left only on engine to fly on. Even some of the stewardesses turned
>> pale, the whole Frankfurt airspace was cleared for us (that alone is no
>> small feat) and all the ambulances and firetrucks they could muster
>> could be seen on the ground. Just as a precaution they said. But the
>> pilot greased her on very professionally, right on the numbers. Had to,
>> because he could not use the thrust reverser to slow down.
> 
> I've been in on one that was sorta the opposite.  A Convair 580 being flown 
> by 
> Frontier, in the 70's.  Afternoon flight from Scottsdale AZ to Gallup NM, 
> Farmington NM, and Durango CO where it would be parked for the night.  Wind 
> came up, as the pilot said about 4 garbage can lids worth as he was looking 
> at 
> the Gallup strip.  We had a passenger for Gallup, and I saw an expert pilot 
> put it down in a 60 mph crosswind carrying quite a bit of sand, and they 
> almost threw that squaw out the door so he could get back up out of it.  
> Probably less than a minute from door open & ramp down to ramp up & door 
> latched again.  On arrival at Farmington, the wind was up to the middle 70's, 
> again across the runway and the sand looked like snow on a mountaintop, 
> except 
> it was 30 to 50 feet up.  He announced he was gonna figure 8 and burn fuel 
> before he tried to land, which he did till it was well dusk & fading fast.  
> Then he brought it down into the sand and both engines looked like 4th of 
> july 
> sparklers gone ballistic.  He had the trips on the flaps cocked, and both 
> wings turned straight up the instant it kissed, and about 8 secs of full 
> reverse props and all buckets out between that and shutdown.  We lit up the 
> sky all around us.  He let it roll dead off the runway into the grass and a 
> bus came out to get us, it wasn't going anyplace without a pull till those 2 
> engines had new spools in them & probably new props, they were scrubbed as 
> clean as could be.  New windshields too as the view wasn't very good when I 
> stopped to praise the pilot & he said they had had several classes based on 
> that scenario at the Frontier school.
> 

Wow, I've never been in a close call like that one. Only once in a small 
Dornier aircraft when the (otherwise totally quiet) bush pilot kind of 
guy let off a lot of cuss words, the stall horn was blaring, pine tree 
tops came at us and it was of course not high enough to do a parachute 
bail. A burly mtorcycle guy next to me who usually isn't afraid of 
anything mumbled "Well, I guess this is it". We made it but could see 
the snow flying off the trees as we inched up in altitude. Maybe the 
newly "found" ground effect or something saved us. For a while there the 
tree tops looked like the road does from the low seats of a Porsche.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Thursday 21 May 2009, Joerg wrote:
>der Mouse wrote:
>>> Or it produces nailbiters like this one:
>>>
>>> http://www.wadenelson.com/gimli.html
>>
>> It's a very interesting story, to be sure, but I'm having trouble
>> seeing the error.  It says
>>
>>  [...] each time using 1.77 pounds/liter as the specific gravity
>>  factor.  [...]  The factor the refuelers and the crew should
>>  have used on the brand new, all-metric 767 was .8 kg/liter of
>>  kerosene.
>>
>> But 1.77 pounds/liter is the same as .8 kg/liter, to within something
>> like a third of a percent.  Perhaps it's just bad reporting and/or
>> writing, but I'm having trouble seeing the error.
>
>They calculated alright but then entered the pound number into the fuel
>clocking system of the aircraft. Since Canada had (officially) converted
>to metric the new aircraft was delivered with metric firmware so the 767
>assumed this to be kilograms. But a pound ain't a kilogram, so ...
>
>I guess the fuel clock showed plenty of fuel when things went phut ...
>shh. AFAIU the make-shift system in the 767 calculates the fuel flow
>from engine sensors and keeps subtracting that from the entered total.
>Assuming this entered total was kilograms.
>
>Probably they should have never taken off with a non-functional FQI
>system. An added circumstance was most likely that nearly all the other
>(older) aircraft were non-metric.

I agree, the FAA $hould have cited the airline for $uch poor practice$.

>I've been on one flight on a 767 when an engine went phut about an hour
>before reaching the Belgian coast, something had gone kaputt in there.
>That left only on engine to fly on. Even some of the stewardesses turned
>pale, the whole Frankfurt airspace was cleared for us (that alone is no
>small feat) and all the ambulances and firetrucks they could muster
>could be seen on the ground. Just as a precaution they said. But the
>pilot greased her on very professionally, right on the numbers. Had to,
>because he could not use the thrust reverser to slow down.

I've been in on one that was sorta the opposite.  A Convair 580 being flown by 
Frontier, in the 70's.  Afternoon flight from Scottsdale AZ to Gallup NM, 
Farmington NM, and Durango CO where it would be parked for the night.  Wind 
came up, as the pilot said about 4 garbage can lids worth as he was looking at 
the Gallup strip.  We had a passenger for Gallup, and I saw an expert pilot 
put it down in a 60 mph crosswind carrying quite a bit of sand, and they 
almost threw that squaw out the door so he could get back up out of it.  
Probably less than a minute from door open & ramp down to ramp up & door 
latched again.  On arrival at Farmington, the wind was up to the middle 70's, 
again across the runway and the sand looked like snow on a mountaintop, except 
it was 30 to 50 feet up.  He announced he was gonna figure 8 and burn fuel 
before he tried to land, which he did till it was well dusk & fading fast.  
Then he brought it down into the sand and both engines looked like 4th of july 
sparklers gone ballistic.  He had the trips on the flaps cocked, and both 
wings turned straight up the instant it kissed, and about 8 secs of full 
reverse props and all buckets out between that and shutdown.  We lit up the 
sky all around us.  He let it roll dead off the runway into the grass and a 
bus came out to get us, it wasn't going anyplace without a pull till those 2 
engines had new spools in them & probably new props, they were scrubbed as 
clean as could be.  New windshields too as the view wasn't very good when I 
stopped to praise the pilot & he said they had had several classes based on 
that scenario at the Frontier school.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

der Mouse wrote:
>> Or it produces nailbiters like this one:
> 
>> http://www.wadenelson.com/gimli.html
> 
> It's a very interesting story, to be sure, but I'm having trouble
> seeing the error.  It says
> 
>   [...] each time using 1.77 pounds/liter as the specific gravity
>   factor.  [...]  The factor the refuelers and the crew should
>   have used on the brand new, all-metric 767 was .8 kg/liter of
>   kerosene.
> 
> But 1.77 pounds/liter is the same as .8 kg/liter, to within something
> like a third of a percent.  Perhaps it's just bad reporting and/or
> writing, but I'm having trouble seeing the error.
> 

They calculated alright but then entered the pound number into the fuel 
clocking system of the aircraft. Since Canada had (officially) converted 
to metric the new aircraft was delivered with metric firmware so the 767 
assumed this to be kilograms. But a pound ain't a kilogram, so ...

I guess the fuel clock showed plenty of fuel when things went phut ... 
shh. AFAIU the make-shift system in the 767 calculates the fuel flow 
from engine sensors and keeps subtracting that from the entered total. 
Assuming this entered total was kilograms.

Probably they should have never taken off with a non-functional FQI 
system. An added circumstance was most likely that nearly all the other 
(older) aircraft were non-metric.

I've been on one flight on a 767 when an engine went phut about an hour 
before reaching the Belgian coast, something had gone kaputt in there. 
That left only on engine to fly on. Even some of the stewardesses turned 
pale, the whole Frankfurt airspace was cleared for us (that alone is no 
small feat) and all the ambulances and firetrucks they could muster 
could be seen on the ground. Just as a precaution they said. But the 
pilot greased her on very professionally, right on the numbers. Had to, 
because he could not use the thrust reverser to slow down.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> It's a very interesting story, to be sure, but I'm having trouble
> seeing the error.

The error was in using 1.77 kg/liter.  Keep track of your units!


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Re: gEDA-user: [OFF] high current amplifier

[der Mouse]

> Or it produces nailbiters like this one:

> http://www.wadenelson.com/gimli.html

It's a very interesting story, to be sure, but I'm having trouble
seeing the error.  It says

[...] each time using 1.77 pounds/liter as the specific gravity
factor.  [...]  The factor the refuelers and the crew should
have used on the brand new, all-metric 767 was .8 kg/liter of
kerosene.

But 1.77 pounds/liter is the same as .8 kg/liter, to within something
like a third of a percent.  Perhaps it's just bad reporting and/or
writing, but I'm having trouble seeing the error.

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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Thursday 21 May 2009, Joerg wrote:
>Gene Heskett wrote:
[...]
>>> But I can't really bleed off freon. Plus AFAIK they don't sell that
>>> stuff to ordinary folk anymore unless you have a contractor's license. I
>>> mean, I could get one, but that would go a bit far ;-)
>>
>> Its no better on this side of the pond either, Joerg. ...
>
>It think we are on the same side of the pond. Well, maybe the other pond
>(I am in California).

Oh, my mistake, I'm back here in the hills & hollers of West (by God) 
Virginia.
>>   ... I stocked up on the
>> auto stuff 20 years ago when the handwriting was on the wall & I may have
>> a 1 pound can in the basement yet that hasn't been tapped. ...
>
>That can could be worth a whole lot of money these days.

To me maybe.  I don't think I could legally sell it.

>>   ... My AC gages have R-134
>> scales on them, but the hoses can't take the R-134 pressures.  I'm not
>> sure, but I think my oldest vehicle (a 99 GMC 3 door, 4wd) now has R-134
>> in it, and its working poorly, so I'll have to bite the bullet and get it
>> serviced before warm weather sets in for the summer.  Ditto for the wifes
>> VW Jetta, a 2002, but I have come to expect that, that Jetta was a lemon
>> from the gitgo, costing the dealer I bought it from almost $2500 in body
>> electrics within the 90 day warranty he gave me.  Both front door window
>> motors failed ($400 ea) and the motorized skylight ($1600) fell out!  And
>> I still have a laundry list of things that don't work right, like the
>> passenger side seat heat, the radio, and the inability to aim the OEM but
>> aftermarket Helia headlights in it, they are too low by about 5 degrees
>> when cranked as high as I can get them.  The OEM's were the usual
>> sandblasted yellow sitting on the lot, and new ones, one of which has
>> already burned up its internal wiring & been replaced for gratis, were
>> part of the purchase deal.  And it still has only 20% of the lights my GMC
>> has, that thing can see through a 2 course brick wall with its 10 year
>> old, stock, original headlights yet!  Fresh lamps of course, but still,
>> they haven't yellowed a bit.  Whatever kind of plastic they are made of,
>> its the Right Stuff(TM).
>>
>> Ya win some, and ya lose some. :)
>
>Ouch. Sad actually. I've had an Audi station wagon in Europe, same mfg
>family. But I always try to buy the vehicle with the least amount of
>electrics/electronics because automotive guys don't seem to master this
>field all that well. The Audi still runs just fine over there, 21 years
>old, no issues in all those years.

Yeah, I have a friend that drives them. Did have a black one when I met him in 
the early 80's, finally got a new one a couple of years ago that was light 
tan.  I ribbed him about how much the paint job cost cuz there wasn't that 
much diff in the cars appearance.  He said about 30 large. :)

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Thursday 21 May 2009, DJ Delorie wrote:
>> I'd kill 2 birds then, and grab a lawn chair and a beer, and sit
>> beside it while its running long enough to run out of beer. :)
>
>Or just ask Pat to listen for it.  She sits out there a lot - the A/C
>is next to the screen porch.
>
Chuckle, passing the buck. :)  Love it. But that would work if she can 
separate the sound of the compressor from the sound of the fan.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Quantum Mechanics is God's version of "Trust me."



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Wednesday 20 May 2009, Joerg wrote:
>> Gene Heskett wrote:
>>> On Wednesday 20 May 2009, Joerg wrote:
 Gene Heskett wrote:
> On Wednesday 20 May 2009, Joerg wrote:
>> DJ Delorie wrote:
>>> Levente Kovacs  writes:
 230V times 100A is something I dont want to even calculate.
>>> It's 23000 :-)
>>>
>>> My air conditioner draws 123 amps at 240 volts for the first few
>>> seconds.  That's almost 30kW.
>> Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton
>> unit that doesn't sound normal. Did you find some of the power hogs
>> with your new board by now?
> Off topic reply, but could be germain too.
>
> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox
> will draw that much for that long.  Its startup was a peak in the 250
> amps/phase area, and the reason I say area is that a std 400 amp scale
> on an amp-probe on any phase line swung up to 250 and back down to its
> running of about 39 amps/phase in a purely ballistic fashion as the
> startup surge was only 6 or 7 cycles of the 208/3 phase line.
>
> Now it really gets off-topic.
>
> That was one of those _must_ _work_ units else a tv station was off the
> air 10 (or less) minutes after it failed.  It was also probably
> responsible for some of the early ozone holes over the antarctic as it
> was severely under fanned on the condensor side, and I had to add 20
> pounds of freon in the fall to keep it working right until it wasn't
> needed, and bleed that 20 pounds back off as spring turned into summer. 
> This went on for 8 years on my watch, back in the 70's, and long before
> they started regulating all that stuff.
>
> 2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it.  I
> got tired of that one spring and fixed _some_ of it by taking a failed
> motor to town, having the brackets stretched to carry 2 horse 1800 rpm
> motors, replacing the motor with a 2 horse 1800 and repeating it the
> next week with the second one.  2 horse wasn't quite enough as they ran
> a couple of amps over nameplate when the condensor was relatively clean.
>  When those blades failed (fatigue cracks, caught before they made
> shrapnel), I replaced them with blades with an inch less pitch.  That
> allowed it to continue to work until the ambient went over 80 degrees
> without bleeding freon to keep the high side under 400 psi and the
> compressor currents under 43 amps/phase else the overcurrents in the
> compressor would trip. Based on those results, I would have said that a
> single 20hp motor, running at full load pulling a quad torrington wheel
> with each half about 16" wide & 14" diameter, would have been about
> right.  That could have been throttled with a 4' square louver driven by
> a M-H proportional control Modutrol to regulate the high side
> pressures/temps and made it work all year.  Some of the crappy designs
> foisted off on the industry by supposedly reputable, old line makers are
> amazingly loaded with excrement. I even called Lennox and they swore on
> a stack of bibles that those 2, 1/2 horse motors were enough.  I asked
> what was the expected operating temperature range and he said 75-90F
> outside.  I said "and what happens when you have enough heat load to
> need it, but the outside temp is 33F?" "Its not designed to run at those
> temps."  Why did you sell it to the State of Nebraska then, you did have
> the specs, I've seen them?  Mumble.
>
> Obviously I wasn't talking to a real engineer so I asked him where he
> got his sheepskin.  More mumbling.
>
> Being a tv engineer for the state NETV commission, when the nearest help
> is 200 miles away in Star City, (Lincoln NE) means you truly are a Jack
> Of All Trades. :)  Those 8 years were _very_ educational, but I left
> because I was still not the lead dog, so the scenery never changed. :)
 Thanks for sharing, that was a real story from the trenches.

 Not looking forward to the 105F days that are coming. I don't need A/C
 even when it gets to 95F in the office but when visitors come I have to.
 And then the compressor often goes into bypass mode making that awful
 rar noise. Then it's waiting 5-10 mins, crossing fingers, make sure
 no black cat crosses street from right to left, turn switch to the old
 Lennox back on, hold breath.
>>> Then it needs help like I've described.  That sort of a locked rotor
>>> shutdown is pure hell on the compressors.  No other nice way to describe
>>> it unforch.
>> But I can't really bleed off freon. Plus AFAIK they don't sell that
>> stuff to ordinary folk anymore unless you have a contractor's license. I
>> mean, I could get one, but that would go a bit far ;-)
> 
> Its no better on this side of the pond

Re: gEDA-user: [OFF] high current amplifier

[Joerg]

John Doty wrote:
> On May 20, 2009, at 6:05 PM, Joerg wrote:
> 
>> John Doty wrote:
>>> On May 20, 2009, at 2:36 PM, der Mouse wrote:
>>>
>> A ton of cooling is 12 Kbtu, about the heat of crystallization of
>> one ton of water, per hour.
>>> Why do engineers use so many whacky units?
>> [...], tradition and convenience.
> Good excuses for the masses.  Not so good for engineering, which
> depends on precise communication.
 Which measuring air conditioning capacities in tons provides.  Just
 because it's disorienting to those who are acquainted with only  
 other
 meanings of the word doesn't make it any less precise.
>>> It's poor communication. Specialized jargon. Language should
>>> illuminate the issue to the widest possible audience. But here, even
>>> to specialists, the language obfuscates, since using the same units
>>> for heat and electrical energy would reveal the thermodynamic
>>> efficiency of the technology.
>>>
>> Depends on who you are dealing with.
> 
> Of course. You have to be prepared to deal with this problem.
> 
>> When I spec'd out a catheter
>> manufacturing plant the construction guys as well as the architact
>> looked at me with wrinkled foreheads when I started with kilowatts.  
>> "So
>> what size unit goes where, then?" ... "Well, two five-ton units over
>> here and we'll need another one over yonder." ... "Ah, ok, I think we
>> can work that into the budget."
> 
> And *you* did exactly right. But the other guys would find energy  
> efficiency issues much easier to comprehend if they used consistent  
> units.
> 

Well, I am trying. In some areas you just have to stick to the old 
conventions or nobody will understand. But I recently did (partially, 
for data storage) move to the ISO date format after a few overseas 
engineers "convinced" me ;-)

The topper was when someone at a Scottish heliport asked me how many 
stones I weigh.


>> Same in other professions. Taking it back four inches doesn't mean
>> altitude in an aircraft ;-)
>>
> 
> The first space mission I worked on did mass properties in slugs and  
> feet, and magnetic properties in CGS units (pole-cm et al.). Since we  
> were using magnetics to orient the spacecraft, that produced a  
> collection of magic constants, both in the computer code and written  
> on a crib sheet in the ops room. You can deal with it, but it's  
> stupid to have to. And sometimes it produces catastrophic confusion  
> (Mars Climate Orbiter).
> 

Or it produces nailbiters like this one:

http://www.wadenelson.com/gimli.html

-- 
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.



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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> I'd kill 2 birds then, and grab a lawn chair and a beer, and sit
> beside it while its running long enough to run out of beer. :)

Or just ask Pat to listen for it.  She sits out there a lot - the A/C
is next to the screen porch.


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, DJ Delorie wrote:
>> It is _your_ AC, right?
>
>Well yeah, but I don't want to fiddle with it *that* much.  Besides, I
>don't know that they don't already do what you've suggested.  IIRC the
>fan and compressor turn on separately, they might turn off separately
>too.  I've never paid that much attention to them.

I'd kill 2 birds then, and grab a lawn chair and a beer, and sit beside it 
while its running long enough to run out of beer. :)
>
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-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> It is _your_ AC, right?

Well yeah, but I don't want to fiddle with it *that* much.  Besides, I
don't know that they don't already do what you've suggested.  IIRC the
fan and compressor turn on separately, they might turn off separately
too.  I've never paid that much attention to them.


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, DJ Delorie wrote:
>> Then put a time delay to off of at least 3 to 5 minutes into the
>> condensor fan circuit only,
>
>I don't have that kind of control over it.  I have one low-voltage
>control loop to tell it on/off, and that's it.

It is _your_ AC, right?  You have every right to re-engineer the controls that 
were probably speced by some bean counter who wouldn't know what the high side 
pressure meant if his life depended on it.  I am not the least bit allergic to 
fixing what is plainly poorly engineered because they perceive that the extra 
50 bucks it would take to do it right costs them their competitive edge.

Scroooem, that what we do, the _real_ engineering, or we wouldn't be on this 
list.  It may take a while to decipher the drawing inside the outdoor unit to 
figure out where to add what, but it can be done.

>> By the same token, if the evaporator fan in the furnace is being
>> stopped at the same time as the compressor,
>
>It's not, it stays on for a while after that, until the air it's
>moving warms up.

That at least is correct.

>> On a long run cycle, long enough to reach steady state conditions,
>> gas charge can be somewhat judged by inspecting the big line where
>> it comes back out of the furnace.
>
>I have a thermocouple in the plenum right after the A/C exchanger, the
>air in there is nearly freezing.  It reads 41F but I think the
>software is bottoming out because it drops fast and just flat-lines at
>41F (that thermocouple system is designed for the woodstove - 0C to
>1023C).  I'm pretty sure it's OK.

I'd want to dbl check with a decent thermometer.  Even a $20 dial type for 
photo darkroom use may be more accurate than the thermocouple in those ranges.
But the outlet pipes condition is the better clue IMO.

>It did have a leak at one point,
>and we had an A/C specialist come and redo the joints and recharge it,
>it hasn't degraded since then.

Then the after run on the condenser fan should really make a diff.  The 
biggest concern for TD relays, when they are air bleed & bellows designs, is 
that being outside, they don't function well for long term use as they will 
corrode.  There is an electronic TD relay, with a knob on top of the case to 
adjust the delay, that I have used as replacements for the mercury based TD 
relays in older Harris transmitters that would appear capable of doing the 
job, but I don't have the catalog handy as its 1000 miles away in Upstate MI 
from me.  I actually got 3 of them from a local heating/ac place in Iron 
Mountain MI, IIRC I paid around $50 a copy.  Keep those dry and they should 
work for quite a while.

>> 25kVA, still small.  How many houses are they running from it?
>
>Just mine :-)
>
>I have 7200 VAC coming up the driveway (it's 0.3 miles to the road).

Ahh.  That explains a lot.  I _think_ its 14.4kv on the street here, but don't 
quote me in court. :)

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.

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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, Joerg wrote:
>Gene Heskett wrote:
>> On Wednesday 20 May 2009, Joerg wrote:
>>> Gene Heskett wrote:
 On Wednesday 20 May 2009, Joerg wrote:
> DJ Delorie wrote:
>> Levente Kovacs  writes:
>>> 230V times 100A is something I dont want to even calculate.
>>
>> It's 23000 :-)
>>
>> My air conditioner draws 123 amps at 240 volts for the first few
>> seconds.  That's almost 30kW.
>
> Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton
> unit that doesn't sound normal. Did you find some of the power hogs
> with your new board by now?

 Off topic reply, but could be germain too.

 Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox
 will draw that much for that long.  Its startup was a peak in the 250
 amps/phase area, and the reason I say area is that a std 400 amp scale
 on an amp-probe on any phase line swung up to 250 and back down to its
 running of about 39 amps/phase in a purely ballistic fashion as the
 startup surge was only 6 or 7 cycles of the 208/3 phase line.

 Now it really gets off-topic.

 That was one of those _must_ _work_ units else a tv station was off the
 air 10 (or less) minutes after it failed.  It was also probably
 responsible for some of the early ozone holes over the antarctic as it
 was severely under fanned on the condensor side, and I had to add 20
 pounds of freon in the fall to keep it working right until it wasn't
 needed, and bleed that 20 pounds back off as spring turned into summer. 
 This went on for 8 years on my watch, back in the 70's, and long before
 they started regulating all that stuff.

 2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it.  I
 got tired of that one spring and fixed _some_ of it by taking a failed
 motor to town, having the brackets stretched to carry 2 horse 1800 rpm
 motors, replacing the motor with a 2 horse 1800 and repeating it the
 next week with the second one.  2 horse wasn't quite enough as they ran
 a couple of amps over nameplate when the condensor was relatively clean.
  When those blades failed (fatigue cracks, caught before they made
 shrapnel), I replaced them with blades with an inch less pitch.  That
 allowed it to continue to work until the ambient went over 80 degrees
 without bleeding freon to keep the high side under 400 psi and the
 compressor currents under 43 amps/phase else the overcurrents in the
 compressor would trip. Based on those results, I would have said that a
 single 20hp motor, running at full load pulling a quad torrington wheel
 with each half about 16" wide & 14" diameter, would have been about
 right.  That could have been throttled with a 4' square louver driven by
 a M-H proportional control Modutrol to regulate the high side
 pressures/temps and made it work all year.  Some of the crappy designs
 foisted off on the industry by supposedly reputable, old line makers are
 amazingly loaded with excrement. I even called Lennox and they swore on
 a stack of bibles that those 2, 1/2 horse motors were enough.  I asked
 what was the expected operating temperature range and he said 75-90F
 outside.  I said "and what happens when you have enough heat load to
 need it, but the outside temp is 33F?" "Its not designed to run at those
 temps."  Why did you sell it to the State of Nebraska then, you did have
 the specs, I've seen them?  Mumble.

 Obviously I wasn't talking to a real engineer so I asked him where he
 got his sheepskin.  More mumbling.

 Being a tv engineer for the state NETV commission, when the nearest help
 is 200 miles away in Star City, (Lincoln NE) means you truly are a Jack
 Of All Trades. :)  Those 8 years were _very_ educational, but I left
 because I was still not the lead dog, so the scenery never changed. :)
>>>
>>> Thanks for sharing, that was a real story from the trenches.
>>>
>>> Not looking forward to the 105F days that are coming. I don't need A/C
>>> even when it gets to 95F in the office but when visitors come I have to.
>>> And then the compressor often goes into bypass mode making that awful
>>> rar noise. Then it's waiting 5-10 mins, crossing fingers, make sure
>>> no black cat crosses street from right to left, turn switch to the old
>>> Lennox back on, hold breath.
>>
>> Then it needs help like I've described.  That sort of a locked rotor
>> shutdown is pure hell on the compressors.  No other nice way to describe
>> it unforch.
>
>But I can't really bleed off freon. Plus AFAIK they don't sell that
>stuff to ordinary folk anymore unless you have a contractor's license. I
>mean, I could get one, but that would go a bit far ;-)

Its no better on this side of the pond either, Joerg.  I stocked up on the 
auto stuff 20 years ago when the handwriting w

Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 20, 2009, at 6:05 PM, Joerg wrote:

> John Doty wrote:
>> On May 20, 2009, at 2:36 PM, der Mouse wrote:
>>
> A ton of cooling is 12 Kbtu, about the heat of crystallization of
> one ton of water, per hour.
>> Why do engineers use so many whacky units?
> [...], tradition and convenience.
 Good excuses for the masses.  Not so good for engineering, which
 depends on precise communication.
>>> Which measuring air conditioning capacities in tons provides.  Just
>>> because it's disorienting to those who are acquainted with only  
>>> other
>>> meanings of the word doesn't make it any less precise.
>>
>> It's poor communication. Specialized jargon. Language should
>> illuminate the issue to the widest possible audience. But here, even
>> to specialists, the language obfuscates, since using the same units
>> for heat and electrical energy would reveal the thermodynamic
>> efficiency of the technology.
>>
>
> Depends on who you are dealing with.

Of course. You have to be prepared to deal with this problem.

> When I spec'd out a catheter
> manufacturing plant the construction guys as well as the architact
> looked at me with wrinkled foreheads when I started with kilowatts.  
> "So
> what size unit goes where, then?" ... "Well, two five-ton units over
> here and we'll need another one over yonder." ... "Ah, ok, I think we
> can work that into the budget."

And *you* did exactly right. But the other guys would find energy  
efficiency issues much easier to comprehend if they used consistent  
units.

>
> Same in other professions. Taking it back four inches doesn't mean
> altitude in an aircraft ;-)
>

The first space mission I worked on did mass properties in slugs and  
feet, and magnetic properties in CGS units (pole-cm et al.). Since we  
were using magnetics to orient the spacecraft, that produced a  
collection of magic constants, both in the computer code and written  
on a crib sheet in the ops room. You can deal with it, but it's  
stupid to have to. And sometimes it produces catastrophic confusion  
(Mars Climate Orbiter).

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> Then put a time delay to off of at least 3 to 5 minutes into the
> condensor fan circuit only,

I don't have that kind of control over it.  I have one low-voltage
control loop to tell it on/off, and that's it.

> By the same token, if the evaporator fan in the furnace is being
> stopped at the same time as the compressor,

It's not, it stays on for a while after that, until the air it's
moving warms up.

> On a long run cycle, long enough to reach steady state conditions,
> gas charge can be somewhat judged by inspecting the big line where
> it comes back out of the furnace.

I have a thermocouple in the plenum right after the A/C exchanger, the
air in there is nearly freezing.  It reads 41F but I think the
software is bottoming out because it drops fast and just flat-lines at
41F (that thermocouple system is designed for the woodstove - 0C to
1023C).  I'm pretty sure it's OK.  It did have a leak at one point,
and we had an A/C specialist come and redo the joints and recharge it,
it hasn't degraded since then.

> 25kVA, still small.  How many houses are they running from it?

Just mine :-)

I have 7200 VAC coming up the driveway (it's 0.3 miles to the road).


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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

John Doty wrote:
> On May 20, 2009, at 2:36 PM, der Mouse wrote:
> 
 A ton of cooling is 12 Kbtu, about the heat of crystallization of
 one ton of water, per hour.
> Why do engineers use so many whacky units?
 [...], tradition and convenience.
>>> Good excuses for the masses.  Not so good for engineering, which
>>> depends on precise communication.
>> Which measuring air conditioning capacities in tons provides.  Just
>> because it's disorienting to those who are acquainted with only other
>> meanings of the word doesn't make it any less precise.
> 
> It's poor communication. Specialized jargon. Language should  
> illuminate the issue to the widest possible audience. But here, even  
> to specialists, the language obfuscates, since using the same units  
> for heat and electrical energy would reveal the thermodynamic  
> efficiency of the technology.
> 

Depends on who you are dealing with. When I spec'd out a catheter 
manufacturing plant the construction guys as well as the architact 
looked at me with wrinkled foreheads when I started with kilowatts. "So 
what size unit goes where, then?" ... "Well, two five-ton units over 
here and we'll need another one over yonder." ... "Ah, ok, I think we 
can work that into the budget."

Same in other professions. Taking it back four inches doesn't mean 
altitude in an aircraft ;-)

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Wednesday 20 May 2009, Joerg wrote:
>> Gene Heskett wrote:
>>> On Wednesday 20 May 2009, Joerg wrote:
 DJ Delorie wrote:
> Levente Kovacs  writes:
>> 230V times 100A is something I dont want to even calculate.
> It's 23000 :-)
>
> My air conditioner draws 123 amps at 240 volts for the first few
> seconds.  That's almost 30kW.
 Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton
 unit that doesn't sound normal. Did you find some of the power hogs with
 your new board by now?
>>> Off topic reply, but could be germain too.
>>>
>>> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox will
>>> draw that much for that long.  Its startup was a peak in the 250
>>> amps/phase area, and the reason I say area is that a std 400 amp scale on
>>> an amp-probe on any phase line swung up to 250 and back down to its
>>> running of about 39 amps/phase in a purely ballistic fashion as the
>>> startup surge was only 6 or 7 cycles of the 208/3 phase line.
>>>
>>> Now it really gets off-topic.
>>>
>>> That was one of those _must_ _work_ units else a tv station was off the
>>> air 10 (or less) minutes after it failed.  It was also probably
>>> responsible for some of the early ozone holes over the antarctic as it was
>>> severely under fanned on the condensor side, and I had to add 20 pounds of
>>> freon in the fall to keep it working right until it wasn't needed, and
>>> bleed that 20 pounds back off as spring turned into summer.  This went on
>>> for 8 years on my watch, back in the 70's, and long before they started
>>> regulating all that stuff.
>>>
>>> 2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it.  I got
>>> tired of that one spring and fixed _some_ of it by taking a failed motor
>>> to town, having the brackets stretched to carry 2 horse 1800 rpm motors,
>>> replacing the motor with a 2 horse 1800 and repeating it the next week
>>> with the second one.  2 horse wasn't quite enough as they ran a couple of
>>> amps over nameplate when the condensor was relatively clean.  When those
>>> blades failed (fatigue cracks, caught before they made shrapnel), I
>>> replaced them with blades with an inch less pitch.  That allowed it to
>>> continue to work until the ambient went over 80 degrees without bleeding
>>> freon to keep the high side under 400 psi and the compressor currents
>>> under 43 amps/phase else the overcurrents in the compressor would trip. 
>>> Based on those results, I would have said that a single 20hp motor,
>>> running at full load pulling a quad torrington wheel with each half about
>>> 16" wide & 14" diameter, would have been about right.  That could have
>>> been throttled with a 4' square louver driven by a M-H proportional
>>> control Modutrol to regulate the high side pressures/temps and made it
>>> work all year.  Some of the crappy designs foisted off on the industry by
>>> supposedly reputable, old line makers are amazingly loaded with excrement.
>>>  I even called Lennox and they swore on a stack of bibles that those 2,
>>> 1/2 horse motors were enough.  I asked what was the expected operating
>>> temperature range and he said 75-90F outside.  I said "and what happens
>>> when you have enough heat load to need it, but the outside temp is 33F?" 
>>> "Its not designed to run at those temps."  Why did you sell it to the
>>> State of Nebraska then, you did have the specs, I've seen them?  Mumble.
>>>
>>> Obviously I wasn't talking to a real engineer so I asked him where he got
>>> his sheepskin.  More mumbling.
>>>
>>> Being a tv engineer for the state NETV commission, when the nearest help
>>> is 200 miles away in Star City, (Lincoln NE) means you truly are a Jack Of
>>> All Trades. :)  Those 8 years were _very_ educational, but I left because
>>> I was still not the lead dog, so the scenery never changed. :)
>> Thanks for sharing, that was a real story from the trenches.
>>
>> Not looking forward to the 105F days that are coming. I don't need A/C
>> even when it gets to 95F in the office but when visitors come I have to.
>> And then the compressor often goes into bypass mode making that awful
>> rar noise. Then it's waiting 5-10 mins, crossing fingers, make sure
>> no black cat crosses street from right to left, turn switch to the old
>> Lennox back on, hold breath.
> 
> Then it needs help like I've described.  That sort of a locked rotor shutdown 
> is pure hell on the compressors.  No other nice way to describe it unforch.
> 

But I can't really bleed off freon. Plus AFAIK they don't sell that 
stuff to ordinary folk anymore unless you have a contractor's license. I 
mean, I could get one, but that would go a bit far ;-)

-- 
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http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, der Mouse wrote:
>>> A ton of cooling is 12 Kbtu, about the heat of crystallization of
>>> one ton of water, per hour.
>>>
 Why do engineers use so many whacky units?
>>>
>>> [...], tradition and convenience.
>>
>> Good excuses for the masses.  Not so good for engineering, which
>> depends on precise communication.
>
>Which measuring air conditioning capacities in tons provides.  Just
>because it's disorienting to those who are acquainted with only other
>meanings of the word doesn't make it any less precise.  It's not even
>ambiguous, since air conditioning capacity doesn't have units of
>weight.  You might as well ask why motor power is measured in
>horsepower - that's another historical unit that's cryptic and baffling
>to the uninitiated, but is perfectly good to those in the industry.

And the unit called a horsepower is a complete unit also, as I believe its 
defined as lifting 550 pounds 1 foot in 1 second.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Now KEN and BARBIE are PERMANENTLY ADDICTED to MIND-ALTERING DRUGS ...



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, Levente Kovacs wrote:
>We want to avoid transformers. The older version of this equippment had the
>good old Quad-405 power amplifiers, and transformers at the end. It is so
>heave, that one man can hardly lift the unit.
>
>Btw... the same unit must also provide a voltage output up to 300V, but only
>100Watts. For that, we'll go for transformer.
>
>And a plus... multiply everything by 3, hence it must be 3 phase...
>
>:-)

Loverly.  Next I suppose they like a side of Moose Tracks ice cream to go with 
their single malt scotch? :)

>
>On Wed, 20 May 2009 11:27:48 -0500
>
>Mark Rages  wrote:
>> On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs
>>
>>  wrote:
>> > On Wed, 20 May 2009 10:48:53 -0500
>> > Mark Rages 
>> >
>> > wrote:
>> >> What kind of transient are you trying to simulate?  Maybe it would
>> >> be easier to make a circuit to add the transient to mains power,
>> >> instead of recreating mains power with an amplifier.
>> >
>> > 230V times 100A is something I dont want to even calculate.
>> >
>> > --
>>
>> You need a high-current, low-voltage transformer:
>>
>> http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103
>>079480
>>
>> Regards,
>> Mark
>> markra...@gmail
>> --
>> Mark Rages, Engineer
>> Midwest Telecine LLC
>> markrages-oYGxGvcBBqUZk/wt9ibm20eocmrvl...@public.gmane.org
>>
>>
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, DJ Delorie wrote:
>> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox
>> will draw that much for that long.
>
>Gee, you guys are making me feel bad.  Now I have to go out and
>research air conditioners :-P
>
>Anyway, I know I have a 60 amp circuit for it, and it hits 123 amps
>long enough for my DVM to stabilize at 123 amps.  How long it stays
>there depends on when it last ran (the first unit broke because it ran
>too often, and would lock - 123 amps until it overheated and shut down
>- hence the furnace controller).  When it's in a good mood the surge
>lasts just under a second or so.  During hot days it could be longer
>because it cycles more (minimum 30 minutes "off" time or it has a hard
>time restarting).
>
Then put a time delay to off of at least 3 to 5 minutes into the condensor fan 
circuit only, its killing them both simultainiously, leaving a severe overtemp 
condition that is falsely holding up the head pressure, or even running it up 
over 400 psi.  There must be enough fan running to liquify the remaining gas, 
bringing the head pressure down to something the compressor can get restarted 
against in a timely manner, which should be under 1 second.

By the same token, if the evaporator fan in the furnace is being stopped at 
the same time as the compressor, you have a virtual guarantee that the 
evaporator will turn into a solid block of ice on a warm muggy day when you 
will really notice it.  It must have enough after-run to vaporize all the 
refrigerant in the evaporator coils so that they will warm up, thawing any ice 
that formed when it was running, and running with what may be a borderline low 
charge, often the case even for new installs.

On a long run cycle, long enough to reach steady state conditions, gas charge 
can be somewhat judged by inspecting the big line where it comes back out of 
the furnace.  It should have a coat of sweat on it, not frost.  If no sweat 
and no frost, (and the air is moving 100% normally) its quite likely down to 
half charge or less.  As you add refrigerant, it will first frost, then 
eventually clear to sweat, and this is pretty close to the ideal charge level 
for the conditions that exist that day.  Low side pressure/temp should be held 
not lower than 34F (for whatever gas is in it), and high side pressures/temps 
to 275F or so maximum.  This high side is for older F12 systems of course, I 
believe that R-134 will run a high side somewhat above that.  R-134 is also a 
much smaller gas molecule and will leak from systems that can hold an F12 
charge for decades.  That higher high side temps for R-134 also translates to 
failure of the lube oil that circulates with the refrigerant at a higher rate.  
This can lead to plugging of the capillary tube used as the expansion 
restriction in the entry to the A coil in the furnace with flakes of varnish 
from the overcooked oil too.  The tech will generally want to replace the 
whole coil because of the leak possibilities with even well done silver solder 
repairs on site.

>Note that I do *not* have the "hard start" (aka "soft start") kit for
>this, although I've been thinking about getting it.

Those can be very hard on the compressors, prolonging the startup overcurrent 
phase.  Giving it a good stiff supply so it gets started as quickly as 
possible is actually the easiest on them, far less of an instant overtemp 
surge.  Again I'm referring to multiphase motors of course.  Single phase 
stuff can sometimes be optimized for the starter coil efficiency with a minor 
change to the quality and size of the starting capacitor.  The keyword there 
is often ESR, and the usual non-polarized electrolytics can be quite poor.  
Not knowing the phase angle the starter coils are inserted into the stator can 
make that approach a cuss and cry method though.

>The 10 kVA transformer wasn't enough for this.  At startup, the mains
>voltage would brown-out to 190 vac.  They swapped it for a 25 kVA
>transformer, and upped my wiring from 00 to  coming in to the
>house.

25kVA, still small.  How many houses are they running from it?  I think the 
can on the pole I'm fed from is now a 50kVA, but its feeding 4 or 5 houses.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


"If that makes any sense to you, you have a big problem."
-- C. Durance, Computer Science 234



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

DJ Delorie wrote:
>> But if your computer and network gear uses anywhere close to half of 
>> your grand total I think that stuff needs some "greenification" 
>> attention. Even if it was 1/4 that's huge.
> 
> Agreed, but keep in mind I work from home, so this is all high power
> equipment that gets used all day.  Not a lot of fiddle room.
> 

Same here but since I do hardware there's lots of boat anchors such as 
HP analyzers to be fed with power. Still I don't even come close to your 
numbers.

WRT to computers I've economized quite a bit. Mainly one quite 
power-savvy desktop, a laptop, plus a netbook that gets a whooping 8h 
out of one battery charge. Plus we usually don't run the A/C until it 
gets above 95F in the house, and even then mostly because our Rottweiler 
gets older and can't take it too well anymore.

Lighting is all CFL plus halogen task lights, LAN server is turned off 
when my wife calls for dinner, etc. I try to be diligent about power, 
like turning off the scope when I found a serious bug and it looks like 
it'll be more than 20 minutes to come up with a solution. Heck, even the 
new Weller iron has the green touch, if you don't move its handle for a 
certain time because you forgot about it in the heat to a lab bench 
battle it turns itself off.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> But if your computer and network gear uses anywhere close to half of 
> your grand total I think that stuff needs some "greenification" 
> attention. Even if it was 1/4 that's huge.

Agreed, but keep in mind I work from home, so this is all high power
equipment that gets used all day.  Not a lot of fiddle room.


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, Joerg wrote:
>Gene Heskett wrote:
>> On Wednesday 20 May 2009, Joerg wrote:
>>> DJ Delorie wrote:
 Levente Kovacs  writes:
> 230V times 100A is something I dont want to even calculate.

 It's 23000 :-)

 My air conditioner draws 123 amps at 240 volts for the first few
 seconds.  That's almost 30kW.
>>>
>>> Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton
>>> unit that doesn't sound normal. Did you find some of the power hogs with
>>> your new board by now?
>>
>> Off topic reply, but could be germain too.
>>
>> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox will
>> draw that much for that long.  Its startup was a peak in the 250
>> amps/phase area, and the reason I say area is that a std 400 amp scale on
>> an amp-probe on any phase line swung up to 250 and back down to its
>> running of about 39 amps/phase in a purely ballistic fashion as the
>> startup surge was only 6 or 7 cycles of the 208/3 phase line.
>>
>> Now it really gets off-topic.
>>
>> That was one of those _must_ _work_ units else a tv station was off the
>> air 10 (or less) minutes after it failed.  It was also probably
>> responsible for some of the early ozone holes over the antarctic as it was
>> severely under fanned on the condensor side, and I had to add 20 pounds of
>> freon in the fall to keep it working right until it wasn't needed, and
>> bleed that 20 pounds back off as spring turned into summer.  This went on
>> for 8 years on my watch, back in the 70's, and long before they started
>> regulating all that stuff.
>>
>> 2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it.  I got
>> tired of that one spring and fixed _some_ of it by taking a failed motor
>> to town, having the brackets stretched to carry 2 horse 1800 rpm motors,
>> replacing the motor with a 2 horse 1800 and repeating it the next week
>> with the second one.  2 horse wasn't quite enough as they ran a couple of
>> amps over nameplate when the condensor was relatively clean.  When those
>> blades failed (fatigue cracks, caught before they made shrapnel), I
>> replaced them with blades with an inch less pitch.  That allowed it to
>> continue to work until the ambient went over 80 degrees without bleeding
>> freon to keep the high side under 400 psi and the compressor currents
>> under 43 amps/phase else the overcurrents in the compressor would trip. 
>> Based on those results, I would have said that a single 20hp motor,
>> running at full load pulling a quad torrington wheel with each half about
>> 16" wide & 14" diameter, would have been about right.  That could have
>> been throttled with a 4' square louver driven by a M-H proportional
>> control Modutrol to regulate the high side pressures/temps and made it
>> work all year.  Some of the crappy designs foisted off on the industry by
>> supposedly reputable, old line makers are amazingly loaded with excrement.
>>  I even called Lennox and they swore on a stack of bibles that those 2,
>> 1/2 horse motors were enough.  I asked what was the expected operating
>> temperature range and he said 75-90F outside.  I said "and what happens
>> when you have enough heat load to need it, but the outside temp is 33F?" 
>> "Its not designed to run at those temps."  Why did you sell it to the
>> State of Nebraska then, you did have the specs, I've seen them?  Mumble.
>>
>> Obviously I wasn't talking to a real engineer so I asked him where he got
>> his sheepskin.  More mumbling.
>>
>> Being a tv engineer for the state NETV commission, when the nearest help
>> is 200 miles away in Star City, (Lincoln NE) means you truly are a Jack Of
>> All Trades. :)  Those 8 years were _very_ educational, but I left because
>> I was still not the lead dog, so the scenery never changed. :)
>
>Thanks for sharing, that was a real story from the trenches.
>
>Not looking forward to the 105F days that are coming. I don't need A/C
>even when it gets to 95F in the office but when visitors come I have to.
>And then the compressor often goes into bypass mode making that awful
>rar noise. Then it's waiting 5-10 mins, crossing fingers, make sure
>no black cat crosses street from right to left, turn switch to the old
>Lennox back on, hold breath.

Then it needs help like I've described.  That sort of a locked rotor shutdown 
is pure hell on the compressors.  No other nice way to describe it unforch.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


"Oh no, not again." 

- A bowl of petunias on it's way to certain death. 



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, David C. Kerber wrote:
>Are Kill-a-watt meters any good?  I just got one for my company to check
> loading on UPSs and racks of equipment.  Seems ok when I plugged it in and
> compared its reading to the 5-light load indicator on the UPS.
>
>> -Original Message-
>> From: geda-user-boun...@moria.seul.org
>> [mailto:geda-user-boun...@moria.seul.org] On Behalf Of Gene Heskett
>> Sent: Wednesday, May 20, 2009 3:12 PM
>> To: gEDA user mailing list
>> Subject: Re: gEDA-user: [OFF] high current amplifier
>
>...
>
>> Is this data obtained from a Kill-a-watt?
>
>
>
>D
I have heard they are fairly decently accurate as long as the power factor is 
above 80%.  Sadly, many modern electronic loads are below that.
>
>
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.
<https://www.nrahq.org/nrabonus/accept-membership.asp>

"Oh no, not again." 

- A bowl of petunias on it's way to certain death. 



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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 20, 2009, at 2:36 PM, der Mouse wrote:

>>> A ton of cooling is 12 Kbtu, about the heat of crystallization of
>>> one ton of water, per hour.
 Why do engineers use so many whacky units?
>>> [...], tradition and convenience.
>> Good excuses for the masses.  Not so good for engineering, which
>> depends on precise communication.
>
> Which measuring air conditioning capacities in tons provides.  Just
> because it's disorienting to those who are acquainted with only other
> meanings of the word doesn't make it any less precise.

It's poor communication. Specialized jargon. Language should  
illuminate the issue to the widest possible audience. But here, even  
to specialists, the language obfuscates, since using the same units  
for heat and electrical energy would reveal the thermodynamic  
efficiency of the technology.

>   It's not even
> ambiguous, since air conditioning capacity doesn't have units of
> weight.  You might as well ask why motor power is measured in
> horsepower - that's another historical unit that's cryptic and  
> baffling
> to the uninitiated, but is perfectly good to those in the industry.
>
> /~\ The ASCII   Mouse
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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Gene Heskett wrote:
> On Wednesday 20 May 2009, Joerg wrote:
>> DJ Delorie wrote:
>>> Levente Kovacs  writes:
 230V times 100A is something I dont want to even calculate.
>>> It's 23000 :-)
>>>
>>> My air conditioner draws 123 amps at 240 volts for the first few
>>> seconds.  That's almost 30kW.
>> Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton
>> unit that doesn't sound normal. Did you find some of the power hogs with
>> your new board by now?
> 
> Off topic reply, but could be germain too.
> 
> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox will 
> draw 
> that much for that long.  Its startup was a peak in the 250 amps/phase area, 
> and the reason I say area is that a std 400 amp scale on an amp-probe on any 
> phase line swung up to 250 and back down to its running of about 39 
> amps/phase 
> in a purely ballistic fashion as the startup surge was only 6 or 7 cycles of 
> the 208/3 phase line.
> 
> Now it really gets off-topic.
> 
> That was one of those _must_ _work_ units else a tv station was off the air 
> 10 
> (or less) minutes after it failed.  It was also probably responsible for some 
> of the early ozone holes over the antarctic as it was severely under fanned 
> on 
> the condensor side, and I had to add 20 pounds of freon in the fall to keep 
> it 
> working right until it wasn't needed, and bleed that 20 pounds back off as 
> spring turned into summer.  This went on for 8 years on my watch, back in the 
> 70's, and long before they started regulating all that stuff.
> 
> 2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it.  I got 
> tired of that one spring and fixed _some_ of it by taking a failed motor to 
> town, having the brackets stretched to carry 2 horse 1800 rpm motors, 
> replacing the motor with a 2 horse 1800 and repeating it the next week with 
> the second one.  2 horse wasn't quite enough as they ran a couple of amps 
> over 
> nameplate when the condensor was relatively clean.  When those blades failed 
> (fatigue cracks, caught before they made shrapnel), I replaced them with 
> blades with an inch less pitch.  That allowed it to continue to work until 
> the 
> ambient went over 80 degrees without bleeding freon to keep the high side 
> under 400 psi and the compressor currents under 43 amps/phase else the 
> overcurrents in the compressor would trip.  Based on those results, I would 
> have said that a single 20hp motor, running at full load pulling a quad 
> torrington wheel with each half about 16" wide & 14" diameter, would have 
> been 
> about right.  That could have been throttled with a 4' square louver driven 
> by 
> a M-H proportional control Modutrol to regulate the high side pressures/temps 
> and made it work all year.  Some of the crappy designs foisted off on the 
> industry by supposedly reputable, old line makers are amazingly loaded with 
> excrement.  I even called Lennox and they swore on a stack of bibles that 
> those 2, 1/2 horse motors were enough.  I asked what was the expected 
> operating temperature range and he said 75-90F outside.  I said "and what 
> happens when you have enough heat load to need it, but the outside temp is 
> 33F?"  "Its not designed to run at those temps."  Why did you sell it to the 
> State of Nebraska then, you did have the specs, I've seen them?  Mumble.
> 
> Obviously I wasn't talking to a real engineer so I asked him where he got his 
> sheepskin.  More mumbling.
> 
> Being a tv engineer for the state NETV commission, when the nearest help is 
> 200 miles away in Star City, (Lincoln NE) means you truly are a Jack Of All 
> Trades. :)  Those 8 years were _very_ educational, but I left because I was 
> still not the lead dog, so the scenery never changed. :)
> 

Thanks for sharing, that was a real story from the trenches.

Not looking forward to the 105F days that are coming. I don't need A/C 
even when it gets to 95F in the office but when visitors come I have to. 
And then the compressor often goes into bypass mode making that awful 
rar noise. Then it's waiting 5-10 mins, crossing fingers, make sure 
no black cat crosses street from right to left, turn switch to the old 
Lennox back on, hold breath.

-- 
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

DJ Delorie wrote:
> DJ Delorie  writes:
>> I think it's a 60 ton.
> 
> Or it's a 60 kbtu, I don't recall - it's got "60" in the model number.
> 

Ok, that sounds more reasonable. I thought you guys lived in a structure 
similar to Hearst Castle.

But if your computer and network gear uses anywhere close to half of 
your grand total I think that stuff needs some "greenification" 
attention. Even if it was 1/4 that's huge.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Levente Kovacs wrote:
> On Wed, 20 May 2009 09:26:07 -0700
> Joerg 
> wrote:
> 
>> I'd wear eye protection :-)
>>
>> I can already picture it, on day a connection comes loose, we all
>> hear a muffled *BOOM* and see an orange glow over Budapest ...
> 
> Well... I will do it in Budakalász. :-) But yes, I know it is a crazy toy! :-)
> 

That's less than 10 miles, you could still level the city when it goes 
wrong ;-)

If it's any comfort I just had a 70kV thing going on the lab bench here. 
It gave me the occasional hiss.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[David C. Kerber]

Are Kill-a-watt meters any good?  I just got one for my company to check 
loading on UPSs and racks of equipment.  Seems ok when I plugged it in and 
compared its reading to the 5-light load indicator on the UPS.
 

> -Original Message-
> From: geda-user-boun...@moria.seul.org 
> [mailto:geda-user-boun...@moria.seul.org] On Behalf Of Gene Heskett
> Sent: Wednesday, May 20, 2009 3:12 PM
> To: gEDA user mailing list
> Subject: Re: gEDA-user: [OFF] high current amplifier
> 

...

> Is this data obtained from a Kill-a-watt?



D


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Re: gEDA-user: [OFF] high current amplifier

[Bert Timmerman]

Hi Levente,

On Wed, 2009-05-20 at 22:02 +0200, Levente Kovacs wrote:
> 
> We want to avoid transformers. The older version of this equippment had the
> good old Quad-405 power amplifiers, and transformers at the end. It is so
> heave, that one man can hardly lift the unit.
> 
> Btw... the same unit must also provide a voltage output up to 300V, but only
> 100Watts. For that, we'll go for transformer.
> 
> And a plus... multiply everything by 3, hence it must be 3 phase...
> 
> :-)
> 
> On Wed, 20 May 2009 11:27:48 -0500
> Mark Rages  wrote:
> 
> > On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs
> >  wrote:
> > > On Wed, 20 May 2009 10:48:53 -0500
> > > Mark Rages 
> > > wrote:
> > >
> > >> What kind of transient are you trying to simulate?  Maybe it would
> > >> be easier to make a circuit to add the transient to mains power,
> > >> instead of recreating mains power with an amplifier.
> > >
> > > 230V times 100A is something I dont want to even calculate.
> > >
> > > --
> > 
> > You need a high-current, low-voltage transformer:

Being a mechanical oriented guy, electric arc welding comes to mind.

Very rugged equipment, being able to withstand rough handling in worst
conditions possible.

Also available with low voltage (50 V) between electrode and mass
connector for electric conductive areas like large steel vessels and
equipment.

Kind regards,

Bert Timmerman.


> > 
> > http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103079480
> > 
> > Regards,
> > Mark
> > markra...@gmail
> > -- 
> > Mark Rages, Engineer
> > Midwest Telecine LLC
> > markrages-oYGxGvcBBqUZk/wt9ibm20eocmrvl...@public.gmane.org
> > 
> > 
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> > 
> 
> 



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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> You might as well ask why motor power is measured in horsepower -
> that's another historical unit that's cryptic and baffling to the
> uninitiated, but is perfectly good to those in the industry.

Bad example, though - motor horsepower is not a regulated measurement
like amps is, so marketing folks "fiddle" with the number.  The HP
numbers on most power tools, for example, are pure fiction.  My air
compressor, for example, says "5 HP" in big letters, but the motor
plate says it draws 15 amps - a max of 2.4 HP.  It runs on a 20 amp
120v circuit, too, which can't possibly power a 5 HP motor.

Perhaps in higher industry they specify *which* horsepower they're
referring to, to make the numbers meaningful.


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Re: gEDA-user: [OFF] high current amplifier

[der Mouse]

>> A ton of cooling is 12 Kbtu, about the heat of crystallization of
>> one ton of water, per hour.
>>> Why do engineers use so many whacky units?
>> [...], tradition and convenience.
> Good excuses for the masses.  Not so good for engineering, which
> depends on precise communication.

Which measuring air conditioning capacities in tons provides.  Just
because it's disorienting to those who are acquainted with only other
meanings of the word doesn't make it any less precise.  It's not even
ambiguous, since air conditioning capacity doesn't have units of
weight.  You might as well ask why motor power is measured in
horsepower - that's another historical unit that's cryptic and baffling
to the uninitiated, but is perfectly good to those in the industry.

/~\ The ASCII Mouse
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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> Is this data obtained from a Kill-a-watt?

No, from the prototype powermeter board.


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, DJ Delorie wrote:
>> Seconds and not fractions or a second? Yikes! Unless it's a 10-15
>> ton unit that doesn't sound normal.
>
>I think it's a 60 ton.  It draws 30 amps once it's running.  Yeah,
>seconds, not fractions.  They had to upgrade the transformer on the
>pole to supply enough juice.
>
>> Did you find some of the power hogs with your new board by now?
>
>Not really.  I did discover that the "off" button on the remote for
>the receiver in the living room just shuts off the speakers, not the
>amp, if you used the button on the amp to turn it on.

Interesting.  My big Kenwood also kills the VF display, but haven't checked 
the 'off' draw.  And I know the tv's all draw at least 20 watts turned off.

Is this data obtained from a Kill-a-watt?

>I measured that
>all my computer and networking stuff is less than half my bill.
>Haven't populated the new boards yet, so I can't yet measure the dryer
>or oven.  I have all the stuff I need to populate them, just need some
>free time (and have to clean my work table ;).

Same here.  I build additional work area, and its soon buried in work debris.

-- 
Cheers, Gene
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: gEDA-user: [OFF] high current amplifier

[Levente Kovacs]

We want to avoid transformers. The older version of this equippment had the
good old Quad-405 power amplifiers, and transformers at the end. It is so
heave, that one man can hardly lift the unit.

Btw... the same unit must also provide a voltage output up to 300V, but only
100Watts. For that, we'll go for transformer.

And a plus... multiply everything by 3, hence it must be 3 phase...

:-)

On Wed, 20 May 2009 11:27:48 -0500
Mark Rages  wrote:

> On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs
>  wrote:
> > On Wed, 20 May 2009 10:48:53 -0500
> > Mark Rages 
> > wrote:
> >
> >> What kind of transient are you trying to simulate?  Maybe it would
> >> be easier to make a circuit to add the transient to mains power,
> >> instead of recreating mains power with an amplifier.
> >
> > 230V times 100A is something I dont want to even calculate.
> >
> > --
> 
> You need a high-current, low-voltage transformer:
> 
> http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103079480
> 
> Regards,
> Mark
> markra...@gmail
> -- 
> Mark Rages, Engineer
> Midwest Telecine LLC
> markrages-oYGxGvcBBqUZk/wt9ibm20eocmrvl...@public.gmane.org
> 
> 
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-- 
Levente Kovacs
http://logonex.eu


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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 20, 2009, at 1:31 PM, der Mouse wrote:

> ~5 tons, enough for a 3000 sq ft house.
 And neither makes dimensional sense ;-)
>>> 1 ton refers to the equivalent cooling power as melting 1 ton of  
>>> ice -
>> Still not dimensionally right.  Need time in the denominator.
>
> Yes - "per hour".  A ton of cooling is 12 Kbtu, about the heat of
> crystallization of one ton of water, per hour.
>
>> Why do engineers use so many whacky units?  Why pretend Rumford and
>> Joule never existed?  What's wrong with watts?
>
> The same reason people will say "a bulb shedding about 40 watts of
> light" when they really mean "about the light given off by a
> bog-standard 40-watt light bulb" (meaning maybe as much as 6 watts of
> light).  The same reason people still occasionally cite weight in
> stones.  The reason people say thing like "weighs about two kilos"  
> even
> though "two kilos" is a mass, not weight, measurement.  The same  
> reason
> machine screws are still sized with small integers (as in the 6 in
> "6-32") rather than overt measurements.
>
> That is to say, tradition and convenience.

Good excuses for the masses. Not so good for engineering, which  
depends on precise communication. Crashing a spacecraft into Mars is  
pretty inconvenient, and we'd prefer not to make a tradition of it.

>
> /~\ The ASCII   Mouse
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John Doty  Noqsi Aerospace, Ltd.
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Re: gEDA-user: [OFF] high current amplifier

[der Mouse]

 ~5 tons, enough for a 3000 sq ft house.
>>> And neither makes dimensional sense ;-)
>> 1 ton refers to the equivalent cooling power as melting 1 ton of ice -
> Still not dimensionally right.  Need time in the denominator.

Yes - "per hour".  A ton of cooling is 12 Kbtu, about the heat of
crystallization of one ton of water, per hour.

> Why do engineers use so many whacky units?  Why pretend Rumford and
> Joule never existed?  What's wrong with watts?

The same reason people will say "a bulb shedding about 40 watts of
light" when they really mean "about the light given off by a
bog-standard 40-watt light bulb" (meaning maybe as much as 6 watts of
light).  The same reason people still occasionally cite weight in
stones.  The reason people say thing like "weighs about two kilos" even
though "two kilos" is a mass, not weight, measurement.  The same reason
machine screws are still sized with small integers (as in the 6 in
"6-32") rather than overt measurements.

That is to say, tradition and convenience.

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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox
> will draw that much for that long.

Gee, you guys are making me feel bad.  Now I have to go out and
research air conditioners :-P

Anyway, I know I have a 60 amp circuit for it, and it hits 123 amps
long enough for my DVM to stabilize at 123 amps.  How long it stays
there depends on when it last ran (the first unit broke because it ran
too often, and would lock - 123 amps until it overheated and shut down
- hence the furnace controller).  When it's in a good mood the surge
lasts just under a second or so.  During hot days it could be longer
because it cycles more (minimum 30 minutes "off" time or it has a hard
time restarting).

Note that I do *not* have the "hard start" (aka "soft start") kit for
this, although I've been thinking about getting it.

The 10 kVA transformer wasn't enough for this.  At startup, the mains
voltage would brown-out to 190 vac.  They swapped it for a 25 kVA
transformer, and upped my wiring from 00 to  coming in to the
house.


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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 20, 2009, at 1:10 PM, Ethan Swint wrote:

>
> I think it's a 60 ton.
 Or it's a 60 kbtu, I don't recall - it's got "60" in the model
 number
>>> 60 tons would be almost enough for a big-box store!  60kbtu sounds
>>> more
>>> like it, ~5 tons, enough for a 3000 sq ft house.
>>>
>>
>> And neither makes dimensional sense ;-)
>>
> 1 ton refers to the equivalent cooling power as melting 1 ton of ice -

Still not dimensionally right. Need time in the denominator.

Why do engineers use so many whacky units? Why pretend Rumford and  
Joule never existed? What's wrong with watts?

> back when A/C units would freeze ice at night and let it melt  
> during the
> day.  Not a bad way to level the electrical load, really.  I've  
> thought
> about putting a couple of 500 gal tanks in my crawl space to do
> something similar...

I use these:

http://www.thenaturalhome.com/heatstorage.htm

in my sunroom.

>
> -Ethan
>
>
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John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Ethan Swint]

 I think it's a 60 ton.
>>> Or it's a 60 kbtu, I don't recall - it's got "60" in the model  
>>> number
>> 60 tons would be almost enough for a big-box store!  60kbtu sounds  
>> more
>> like it, ~5 tons, enough for a 3000 sq ft house.
>> 
>
> And neither makes dimensional sense ;-)
>   
1 ton refers to the equivalent cooling power as melting 1 ton of ice - 
back when A/C units would freeze ice at night and let it melt during the 
day.  Not a bad way to level the electrical load, really.  I've thought 
about putting a couple of 500 gal tanks in my crawl space to do 
something similar...

-Ethan


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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, Joerg wrote:
>DJ Delorie wrote:
>> Levente Kovacs  writes:
>>> 230V times 100A is something I dont want to even calculate.
>>
>> It's 23000 :-)
>>
>> My air conditioner draws 123 amps at 240 volts for the first few
>> seconds.  That's almost 30kW.
>
>Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton
>unit that doesn't sound normal. Did you find some of the power hogs with
>your new board by now?

Off topic reply, but could be germain too.

Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox will draw 
that much for that long.  Its startup was a peak in the 250 amps/phase area, 
and the reason I say area is that a std 400 amp scale on an amp-probe on any 
phase line swung up to 250 and back down to its running of about 39 amps/phase 
in a purely ballistic fashion as the startup surge was only 6 or 7 cycles of 
the 208/3 phase line.

Now it really gets off-topic.

That was one of those _must_ _work_ units else a tv station was off the air 10 
(or less) minutes after it failed.  It was also probably responsible for some 
of the early ozone holes over the antarctic as it was severely under fanned on 
the condensor side, and I had to add 20 pounds of freon in the fall to keep it 
working right until it wasn't needed, and bleed that 20 pounds back off as 
spring turned into summer.  This went on for 8 years on my watch, back in the 
70's, and long before they started regulating all that stuff.

2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it.  I got 
tired of that one spring and fixed _some_ of it by taking a failed motor to 
town, having the brackets stretched to carry 2 horse 1800 rpm motors, 
replacing the motor with a 2 horse 1800 and repeating it the next week with 
the second one.  2 horse wasn't quite enough as they ran a couple of amps over 
nameplate when the condensor was relatively clean.  When those blades failed 
(fatigue cracks, caught before they made shrapnel), I replaced them with 
blades with an inch less pitch.  That allowed it to continue to work until the 
ambient went over 80 degrees without bleeding freon to keep the high side 
under 400 psi and the compressor currents under 43 amps/phase else the 
overcurrents in the compressor would trip.  Based on those results, I would 
have said that a single 20hp motor, running at full load pulling a quad 
torrington wheel with each half about 16" wide & 14" diameter, would have been 
about right.  That could have been throttled with a 4' square louver driven by 
a M-H proportional control Modutrol to regulate the high side pressures/temps 
and made it work all year.  Some of the crappy designs foisted off on the 
industry by supposedly reputable, old line makers are amazingly loaded with 
excrement.  I even called Lennox and they swore on a stack of bibles that 
those 2, 1/2 horse motors were enough.  I asked what was the expected 
operating temperature range and he said 75-90F outside.  I said "and what 
happens when you have enough heat load to need it, but the outside temp is 
33F?"  "Its not designed to run at those temps."  Why did you sell it to the 
State of Nebraska then, you did have the specs, I've seen them?  Mumble.

Obviously I wasn't talking to a real engineer so I asked him where he got his 
sheepskin.  More mumbling.

Being a tv engineer for the state NETV commission, when the nearest help is 
200 miles away in Star City, (Lincoln NE) means you truly are a Jack Of All 
Trades. :)  Those 8 years were _very_ educational, but I left because I was 
still not the lead dog, so the scenery never changed. :)

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Stray Alpha Particles from memory packaging caused Hard Memory Error on 
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Re: gEDA-user: [OFF] high current amplifier

[Mark Cianfaglione]

   True... But I think they use tons once you reach about 1 ton of
   cooling. (12000BTU/Hr)
   Mark
   > Most window air-conditioners I see in stores are rated in BTU's.
   >
   > D
   >


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Re: gEDA-user: [OFF] high current amplifier

[David C. Kerber]

 

> -Original Message-
> From: geda-user-boun...@moria.seul.org 
> [mailto:geda-user-boun...@moria.seul.org] On Behalf Of Mark 
> Cianfaglione
> Sent: Wednesday, May 20, 2009 2:12 PM
> To: gEDA user mailing list
> Subject: Re: gEDA-user: [OFF] high current amplifier
> 
> DJ
> 
> Knowing that you live in the North-East I'd say it's a 6.0 
> ton unit. A 60 Kbtu unit (btus are normally only for heating) 

Most window air-conditioners I see in stores are rated in BTU's.

D


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Re: gEDA-user: [OFF] high current amplifier

[Mark Cianfaglione]

   DJ
   Knowing that you live in the North-East I'd say it's a 6.0 ton unit. A
   60 Kbtu unit (btus are normally only for heating) would be too small
   and a 60 ton would imply that you are running Antartic winter
   simulations in your house in the summer... ;-)
   Mark
   geda-user-boun...@moria.seul.org wrote on 20/05/2009 01:51:22 PM:
   >
   > DJ Delorie  writes:
   > > I think it's a 60 ton.
   >
   > Or it's a 60 kbtu, I don't recall - it's got "60" in the model
   number.
   >
   >
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References

   1. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user


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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 20, 2009, at 12:04 PM, Ethan Swint wrote:

>
> DJ Delorie wrote:
>> DJ Delorie  writes:
>>
>>> I think it's a 60 ton.
>>>
>>
>> Or it's a 60 kbtu, I don't recall - it's got "60" in the model  
>> number.
>>
> 60 tons would be almost enough for a big-box store!  60kbtu sounds  
> more
> like it, ~5 tons, enough for a 3000 sq ft house.
>

And neither makes dimensional sense ;-)

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Levente Kovacs]

On Wed, 20 May 2009 09:26:07 -0700
Joerg 
wrote:

> I'd wear eye protection :-)
> 
> I can already picture it, on day a connection comes loose, we all
> hear a muffled *BOOM* and see an orange glow over Budapest ...

Well... I will do it in Budakalász. :-) But yes, I know it is a crazy toy! :-)

-- 
Levente Kovacs
http://logonex.eu


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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> 60 tons would be almost enough for a big-box store!  60kbtu sounds
> more like it, ~5 tons, enough for a 3000 sq ft house.

It's 4000 sq ft.


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Re: gEDA-user: [OFF] high current amplifier

[Ethan Swint]

DJ Delorie wrote:
> DJ Delorie  writes:
>   
>> I think it's a 60 ton.
>> 
>
> Or it's a 60 kbtu, I don't recall - it's got "60" in the model number.
>   
60 tons would be almost enough for a big-box store!  60kbtu sounds more 
like it, ~5 tons, enough for a 3000 sq ft house.

-Ethan


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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

DJ Delorie  writes:
> I think it's a 60 ton.

Or it's a 60 kbtu, I don't recall - it's got "60" in the model number.


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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

> Seconds and not fractions or a second? Yikes! Unless it's a 10-15
> ton unit that doesn't sound normal.

I think it's a 60 ton.  It draws 30 amps once it's running.  Yeah,
seconds, not fractions.  They had to upgrade the transformer on the
pole to supply enough juice.

> Did you find some of the power hogs with your new board by now?

Not really.  I did discover that the "off" button on the remote for
the receiver in the living room just shuts off the speakers, not the
amp, if you used the button on the amp to turn it on.  I measured that
all my computer and networking stuff is less than half my bill.
Haven't populated the new boards yet, so I can't yet measure the dryer
or oven.  I have all the stuff I need to populate them, just need some
free time (and have to clean my work table ;).


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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

DJ Delorie wrote:
> Levente Kovacs  writes:
>> 230V times 100A is something I dont want to even calculate.
> 
> It's 23000 :-)
> 
> My air conditioner draws 123 amps at 240 volts for the first few
> seconds.  That's almost 30kW.
> 

Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton 
unit that doesn't sound normal. Did you find some of the power hogs with 
your new board by now?

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Dave McGuire]

On May 20, 2009, at 12:27 PM, Mark Rages wrote:
> You need a high-current, low-voltage transformer:
>
> http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm? 
> upc=037103079480

   ROFL!!

-- 
Dave McGuire
Port Charlotte, FL



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Re: gEDA-user: [OFF] high current amplifier

[John Griessen]

John Doty wrote:
> On May 20, 2009, at 9:43 AM, Levente Kovacs wrote:
> 
>> we want to test a current sensor with mains' frequency. However  
>> there are
>> transient once in a while on the line, so we must simulate them too.
> 
> Why not just use the mains, then? Step down volts to get current,  
> make your transients by switching loads.


Yeah, the loads switched by SCRs and/or big FETs will give you more of
a HF transient than any other way.  That would be a
high performance tester for your sensor.

John
-- 
Ecosensory   Austin TX


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Re: gEDA-user: [OFF] high current amplifier

[John Doty]

On May 20, 2009, at 9:43 AM, Levente Kovacs wrote:

> we want to test a current sensor with mains' frequency. However  
> there are
> transient once in a while on the line, so we must simulate them too.

Why not just use the mains, then? Step down volts to get current,  
make your transients by switching loads.

John Doty  Noqsi Aerospace, Ltd.
http://www.noqsi.com/
j...@noqsi.com




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Re: gEDA-user: [OFF] high current amplifier

[Peter Clifton]

On Wed, 2009-05-20 at 11:27 -0500, Mark Rages wrote:
> On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs  
> wrote:
> > On Wed, 20 May 2009 10:48:53 -0500
> > Mark Rages  wrote:
> >
> >> What kind of transient are you trying to simulate?  Maybe it would be
> >> easier to make a circuit to add the transient to mains power, instead
> >> of recreating mains power with an amplifier.
> >
> > 230V times 100A is something I dont want to even calculate.
> >
> > --
> 
> You need a high-current, low-voltage transformer:
> 
> http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103079480

I'd second the idea of using a transformer, although you'd have to check
the resistance of the filaments on those soldering guns to be sure what
currents they would actually deliver.

You might consider how to get wider bandwidth than the 50/60Hz that
these transformers are probably designed for... One option might be to
deliberately choose a transformer with a higher voltage rating than you
need. (E.g. feed a 240V transformer from 110V). The lower voltage should
keep the flux levels in the core down, and (hopefully) help with the
bandwidth of the system.

It isn't too hard to obtain the required currents from a chunky H-bridge
and a suitable PWM generator. It doesn't need a significant power level
to achieve, and in my case, I used the resistance + inductance of about
10metres of fat cable as the load.

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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Re: gEDA-user: [OFF] high current amplifier

[Mark Rages]

On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs  wrote:
> On Wed, 20 May 2009 10:48:53 -0500
> Mark Rages  wrote:
>
>> What kind of transient are you trying to simulate?  Maybe it would be
>> easier to make a circuit to add the transient to mains power, instead
>> of recreating mains power with an amplifier.
>
> 230V times 100A is something I dont want to even calculate.
>
> --

You need a high-current, low-voltage transformer:

http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103079480

Regards,
Mark
markra...@gmail
-- 
Mark Rages, Engineer
Midwest Telecine LLC
markra...@midwesttelecine.com


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Re: gEDA-user: [OFF] high current amplifier

[DJ Delorie]

Levente Kovacs  writes:
> 230V times 100A is something I dont want to even calculate.

It's 23000 :-)

My air conditioner draws 123 amps at 240 volts for the first few
seconds.  That's almost 30kW.


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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Levente Kovacs wrote:
> On Wed, 20 May 2009 11:45:55 -0400 (EDT)
> der Mouse 
> wrote:
> 
>> What _is_ this driving?  Ten feet of #3 copper?
> 
> A current sensor.
> 

I'd wear eye protection :-)

I can already picture it, on day a connection comes loose, we all hear a 
muffled *BOOM* and see an orange glow over Budapest ...

-- 
Regards, Joerg

http://www.analogconsultants.com/



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Re: gEDA-user: [OFF] high current amplifier

[Gene Heskett]

On Wednesday 20 May 2009, Steve Underwood wrote:
>Levente wrote:
>> Hi,
>>
>>
>> I have to design an audio amplifier that can deliver 100Amps. It should
>> work around 50Hz, and the maximum output power shall be 500W. I am
>> currently reading articles about this topic, but it is very hard to find
>> things like this. If someone has some experience with, or some
>> documentation of high current amplifiers, please share it.
>
>If you search the class-D power amp modules available for the audio
>market I think you may find what you need off the shelf.
>
>Steve

Yeah, I did a quick google search, and 500 watts can be had for less than a C 
note from several places.  The class D chip business has converted what was a 
$3000 amp into the sub $100 category in the last couple of years.  I don't 
believe it would pay one to do a design from scratch today, its already done.

Think car audio, where speaker impedance choices are 4, 2 and 1 ohm.  And they 
wire everything with 4/0 cabling.
>
>
>
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
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Re: gEDA-user: [OFF] high current amplifier

[Levente Kovacs]

On Wed, 20 May 2009 10:48:53 -0500
Mark Rages  wrote:

> What kind of transient are you trying to simulate?  Maybe it would be
> easier to make a circuit to add the transient to mains power, instead
> of recreating mains power with an amplifier.

230V times 100A is something I dont want to even calculate.

-- 
Levente Kovacs
http://logonex.eu



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Re: gEDA-user: [OFF] high current amplifier

[Levente Kovacs]

On Wed, 20 May 2009 11:45:55 -0400 (EDT)
der Mouse 
wrote:

> What _is_ this driving?  Ten feet of #3 copper?

A current sensor.

-- 
Levente Kovacs
http://logonex.eu



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Re: gEDA-user: [OFF] high current amplifier

[Joerg]

Levente Kovacs wrote:
> Ok,
> 
> 
> I guess I wasn't clear, so I have to add that it won't be used to drive a
> speaker, I used the word "audio" to refer the frequency range. 500W audio
> amplifier that designed to drive 4-8 Ohms is easy. But 100A, is something you
> won't get in a pro audio store. The coldamp design provides 25Amps. So the
> easy solution would be to convince my manager that 25Amps is quite enough for
> us... :-)
> 
> I think I can connect power MOSFETs parallel, and they might put that current
> out. The important thing is to charge and discharge the gate capacitances. I
> too thinking in class-D solution.
> 

If your favored class-D chip can't drive that many FETs consider 
employing one or more MIC4422 per side:

http://www.micrel.com/_PDF/mic4421.pdf

That way you could drive just about anything. I wouldn't go much past 
2pF per MIC4422 but they are cheap, just add some more.

And be careful not to drop anything onto the output rail, take off your 
wrist watch, wedding band etc. I know a guy who almost lost a finger 
that way.

-- 
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.



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Re: gEDA-user: [OFF] high current amplifier

[der Mouse]

> I guess I wasn't clear, so I have to add that it won't be used to
> drive a speaker, I used the word "audio" to refer the frequency
> range.  500W audio amplifier that designed to drive 4-8 Ohms is easy.
> But 100A, is something you won't get in a pro audio store.

100A 500W...5V...that's .05 ohms load.  Now you've got me curious.
What _is_ this driving?  Ten feet of #3 copper?

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Re: gEDA-user: [OFF] high current amplifier

[Mark Rages]

   On Wed, May 20, 2009 at 10:43 AM, Levente Kovacs
   <[1]leventel...@gmail.com> wrote:

   On Wed, 20 May 2009 10:33:30 -0500
   Mark Rages <[2]markra...@gmail.com> wrote:
   > 100 amps and 500 watts implies a load impedance of 0.05 ohms.  Some
   > professional audio amplifiers may handle this, but I think most will
   > go into self-protect mode.
   >
   > Best bet might be a car amp:
   > [3]http://www.sonicelectronix.com/item_11796_Kenwood+KAC-8104D.html

 Looks nice.

   > If Levente is just looking for a sine wave, he should check out
   > variable frequency drive motor controllers.   Search ebay for "VFD".

 No, we want to test a current sensor with mains' frequency. However
 there are
 transient once in a while on the line, so we must simulate them
 too.

   OK, so this amp:
   [4]http://www.sonicelectronix.com/item_11682_MA+Audio+HK10KA.html
   is rated to deliver 10kw into 1 ohm, if you feed it 17.5 V.  That's
   100A.  The protection circuitry may still be a problem with your load,
   however.
   Also, I am not endorsing that vendor, it's just a random website I ran
   across.
   What kind of transient are you trying to simulate?  Maybe it would be
   easier to make a circuit to add the transient to mains power, instead
   of recreating mains power with an amplifier.
   Regards,
   Mark
   markra...@gmail
   --
   Mark Rages, Engineer
   Midwest Telecine LLC
   [5]markra...@midwesttelecine.com

References

   1. mailto:leventel...@gmail.com
   2. mailto:markra...@gmail.com
   3. http://www.sonicelectronix.com/item_11796_Kenwood+KAC-8104D.html
   4. http://www.sonicelectronix.com/item_11682_MA+Audio+HK10KA.html
   5. mailto:markra...@midwesttelecine.com


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Re: gEDA-user: [OFF] high current amplifier

[Levente Kovacs]

On Wed, 20 May 2009 10:33:30 -0500
Mark Rages  wrote:

> 100 amps and 500 watts implies a load impedance of 0.05 ohms.  Some
> professional audio amplifiers may handle this, but I think most will
> go into self-protect mode.
> 
> Best bet might be a car amp:
> http://www.sonicelectronix.com/item_11796_Kenwood+KAC-8104D.html

Looks nice.
 
> If Levente is just looking for a sine wave, he should check out
> variable frequency drive motor controllers.   Search ebay for "VFD".

No, we want to test a current sensor with mains' frequency. However there are
transient once in a while on the line, so we must simulate them too.

-- 
Levente Kovacs
http://logonex.eu



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Re: gEDA-user: [OFF] high current amplifier

[Levente Kovacs]

Ok,


I guess I wasn't clear, so I have to add that it won't be used to drive a
speaker, I used the word "audio" to refer the frequency range. 500W audio
amplifier that designed to drive 4-8 Ohms is easy. But 100A, is something you
won't get in a pro audio store. The coldamp design provides 25Amps. So the
easy solution would be to convince my manager that 25Amps is quite enough for
us... :-)

I think I can connect power MOSFETs parallel, and they might put that current
out. The important thing is to charge and discharge the gate capacitances. I
too thinking in class-D solution.

I think your digital amp is not what one calls class-D amplifier. Or do I get
something wrong?

I think the problem is not that it should provide 500W, rather 100Amps.

Anyways, thanks for your thoughts.

On Wed, 20 May 2009 09:19:43 -0500
John Griessen  wrote:

> Levente wrote:
> > Hi,
> > 
> > 
> > I have to design an audio amplifier that can deliver 100Amps. It
> > should work around 50Hz, and the maximum output power shall be
> > 500W. I am currently reading articles about this topic, but it is
> > very hard to find things like this. If someone has some experience
> > with, or some documentation of high current amplifiers, please
> > share it.
> 
> Sounds like a fog horn driver.  Your best bet will be a "digital amp",
> or in other words a sigma delta DAC with the speaker coil and some
> capacitance in the feedback loop.  An example would be: a train of
> 2-bit plus sign data is converted into analog levels 0 +1 +2 -1 -2
> Volts and the analog level on the speaker coil and cap. is fed back
> into the DAC to a fast ADC stage so it can combine with the
> datastream inside the sigma delta converter.  The low pass filter
> that loses all the choppy back and forth of the drive data levels is
> the cap. and speaker coil itself.
> 
> This is the highest efficiency type of driver since it's driving
> transistors are never in active region -- always full on or off. High
> efficiency is what you need to put out 500W.
> 
> John
> -- 
> Ecosensory   Austin TX
> 
> 
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> 


-- 
Levente Kovacs
http://logonex.eu



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Re: gEDA-user: [OFF] high current amplifier

[Mark Rages]

   On Wed, May 20, 2009 at 10:14 AM, Steve Underwood
   <[1]ste...@coppice.org> wrote:

   Levente wrote:
   > Hi,
   >
   >
   > I have to design an audio amplifier that can deliver 100Amps. It
   should
   > work around 50Hz, and the maximum output power shall be 500W. I am
   > currently reading articles about this topic, but it is very hard to
   find
   > things like this. If someone has some experience with, or some
   > documentation of high current amplifiers, please share it.
   >

 If you search the class-D power amp modules available for the audio
 market I think you may find what you need off the shelf.
 Steve

   100 amps and 500 watts implies a load impedance of 0.05 ohms.  Some
   professional audio amplifiers may handle this, but I think most will
   go into self-protect mode.
   Best bet might be a car amp:
   [2]http://www.sonicelectronix.com/item_11796_Kenwood+KAC-8104D.html
   If Levente is just looking for a sine wave, he should check out
   variable frequency drive motor controllers.   Search ebay for "VFD".
   Regards,
   Mark
   markra...@gmail
   --
   Mark Rages, Engineer
   Midwest Telecine LLC
   [3]markra...@midwesttelecine.com

References

   1. mailto:ste...@coppice.org
   2. http://www.sonicelectronix.com/item_11796_Kenwood+KAC-8104D.html
   3. mailto:markra...@midwesttelecine.com


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Re: gEDA-user: [OFF] high current amplifier

[Dave McGuire]

On May 20, 2009, at 11:17 AM, John Griessen wrote:
>>I believe this is commonly referred to as a "Class D" amplifier.
>> It is basically a switching regulator with a loop response time that
>> is fast enough to handle audio frequencies.
>
> Sure.  and he says to operate "around 50 Hz", which I take as 35 to  
> 65 Hz...fog horn.

   Sounds plausible.  And fun. :)

> With a limited required response the digital amp version can be
> simplified.  To simplify to meet a spec is good design.

   Agree 100%.

 -Dave

-- 
Dave McGuire
Port Charlotte, FL



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Re: gEDA-user: [OFF] high current amplifier

[Steve Underwood]

Levente wrote:
> Hi,
>
>
> I have to design an audio amplifier that can deliver 100Amps. It should 
> work around 50Hz, and the maximum output power shall be 500W. I am 
> currently reading articles about this topic, but it is very hard to find 
> things like this. If someone has some experience with, or some 
> documentation of high current amplifiers, please share it.
>   
If you search the class-D power amp modules available for the audio 
market I think you may find what you need off the shelf.

Steve



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Re: gEDA-user: [OFF] high current amplifier

[John Griessen]

Dave McGuire wrote:

>I believe this is commonly referred to as a "Class D" amplifier.   
> It is basically a switching regulator with a loop response time that  
> is fast enough to handle audio frequencies.


Sure.  and he says to operate "around 50 Hz", which I take as 35 to 65 Hz...fog 
horn.

With a limited required response the digital amp version can be
simplified.  To simplify to meet a spec is good design.

John
-- 
Ecosensory   Austin TX


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Re: gEDA-user: [OFF] high current amplifier

[Dave McGuire]

On May 20, 2009, at 10:33 AM, der Mouse wrote:
>>> I have to design an audio amplifier that can deliver 100Amps.
>>> [...50Hz...500W...]
>> [...sketch...]
>> This is the highest efficiency type of driver since [its] driving
>> transistors are never in active region -- always full on or off.
>> High efficiency is what you need to put out 500W.
>
> It occurs to me that this could also be viewed as a switching power
> supply whose regulation target voltage varies at audio-signal rates.
> You might find useful literature by looking for switching power supply
> design info.

   I believe this is commonly referred to as a "Class D" amplifier.   
It is basically a switching regulator with a loop response time that  
is fast enough to handle audio frequencies.

-Dave

-- 
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Port Charlotte, FL



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Re: gEDA-user: [OFF] high current amplifier

[der Mouse]

>> I have to design an audio amplifier that can deliver 100Amps.
>> [...50Hz...500W...]
> [...sketch...]
> This is the highest efficiency type of driver since [its] driving
> transistors are never in active region -- always full on or off.
> High efficiency is what you need to put out 500W.

It occurs to me that this could also be viewed as a switching power
supply whose regulation target voltage varies at audio-signal rates.
You might find useful literature by looking for switching power supply
design info.

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Re: gEDA-user: [OFF] high current amplifier

[John Griessen]

Levente wrote:
> Hi,
> 
> 
> I have to design an audio amplifier that can deliver 100Amps. It should 
> work around 50Hz, and the maximum output power shall be 500W. I am 
> currently reading articles about this topic, but it is very hard to find 
> things like this. If someone has some experience with, or some 
> documentation of high current amplifiers, please share it.

Sounds like a fog horn driver.  Your best bet will be a "digital amp",
or in other words a sigma delta DAC with the speaker coil and some capacitance
in the feedback loop.  An example would be: a train of 2-bit plus sign data is 
converted into
analog levels 0 +1 +2 -1 -2 Volts and the analog level on the speaker coil and 
cap. is
fed back into the DAC to a fast ADC stage so it can combine with the datastream
inside the sigma delta converter.  The low pass filter that loses all the choppy
back and forth of the drive data levels is the cap. and speaker coil itself.

This is the highest efficiency type of driver since it's driving transistors are
never in active region -- always full on or off. High efficiency is what you 
need
to put out 500W.

John
-- 
Ecosensory   Austin TX


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gEDA-user: [OFF] high current amplifier

[Levente]

Hi,


I have to design an audio amplifier that can deliver 100Amps. It should 
work around 50Hz, and the maximum output power shall be 500W. I am 
currently reading articles about this topic, but it is very hard to find 
things like this. If someone has some experience with, or some 
documentation of high current amplifiers, please share it.

Thank you,
Levente



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