Re: [time-nuts] Subject: Re: Working with SMT parts

[Charles Steinmetz]

Bob wrote:


So the fresh stuff, carefully refrigerated, would be expired by the time I use 
the second or third scoop of it, anyway.
What's a casual experimenter to do?


Build More Stuff !!! ;-)

Charles



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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Albert via time-nuts]

I have a Chinese hot air gun with several nozzles.  Mine are the quarter-turn 
type but that doesn't work too well due to sloppy tolerances.  I have had 
nozzles fall off in the midst of use.  With some care they can be made to stay 
on, and if necessary bend them a bit to make them more secure.
I have used my hot air device a lot but only for disassembly.  For assembly, as 
I mentioned earlier, I would want to use solder paste.  I can't control the hot 
air well enough to heat just a bit of solder from a spool, and clipping off a 
piece while trying to put it where it belongs is a poor system.  So the paste 
seems to be the way to go.
Someone needs to invent a low cost paste that doesn't spoil in a few months.  
It does seem that the Mechanics paste might be an answer to this; I would keep 
it refrigerated although that might be locking the barn door after the theft.
Again, I am not trying to meet some government soldering specification; I just 
want something to work without a lot of fuss and cost.
What do major companies do when they discover their stuff is outdated?  I need 
a connection to some of those people, maybe pick up some of it now and then at 
low cost.

Bob
 

On Thursday, August 18, 2016 7:26 PM, Bob Stewart  wrote:
 

 The stuff I use is Chipquik SMD291AX.  The first syringe of it I bought was 
from Mouser and was 15 grams.  That was back in 2014.  The second syringe I got 
was SMD291AX10, which is 35 grams.  It's dated 3/15/16, so you can see how long 
solder paste will last if you take reasonable car of it.  I pumped about 15 
grams of that into the original syringe and put them both in the fridge.  I've 
had the small one out on the workbench for several weeks now, and there doesn't 
seem to be a problem.  I fold a piece of tape around the needle when it's not 
in use to keep the air out.  When I pull the tape off, I pump out about a 1/4" 
string and throw that away.  The rest works just fine.
If you haven't switched to using a hot air gun, I strongly suggest it.  They 
take a bit of getting used to, but after that, they're a time-saver.  I have 
the cheap ebay solder station labeled 852D+.  It has solder pencil and hot air. 
 There are two things I don't like about it.  One is that you can't turn the 
air flow down enough to use narrow nozzles for anything other than blowing 
soldered components off the board.  But it's Much better than trying to use a 
pencil for that chore!  The other is that the tips are attached by tightening a 
screw.  There are units out there that have a little tool that you use to give 
the tip a 1/4 turn twist to attach.  I don't change tips much, but not having 
to wait for the hot air gun to cool down would be nice.  The first time you 
reach for the hot air gun to shrink tubing or to solder the center pin for an 
SMA connector, you know you've "arrived".

Bob
 -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

      From: Bob Albert via time-nuts 
 To: Discussion of precise time and frequency measurement  
 Sent: Thursday, August 18, 2016 8:49 PM
 Subject: Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)
  
I don't care about lead-free since I am not manufacturing, just repairing or 
building or experimenting.  But there seems to be more than one way to view 
this stuff.  Yes, it might be expired, but some say that's not a major issue.  
I can't justify the prices asked by US distributors, especially in light of the 
fact that I use very little.  So the fresh stuff, carefully refrigerated, would 
be expired by the time I use the second or third scoop of it, anyway.
What's a casual experimenter to do?
Bob
 

    On Thursday, August 18, 2016 3:33 PM, Chuck Harris  
wrote:
 

 The Chinese are certainly using a lot of solder paste, so they
are a source.  I tend to buy mine from Mouser, Digikey, TekSource,
places like that.

The last stuff I bought was made by Kester, and came from TekSource.

The only problem with using the real sources is in the summer, they
will pack your paste in an ice pack, and send it over night unless
you insist otherwise (and absolve them of any warranty).  That kind
of shipping is very expensive.

And, there is absolutely no possible way the paste you get from
China is going to make it here and follow the manufacturer's
guidelines for safe handling.  So, even if you buy new and pay
a premium price from China, you are getting paste that is expired
by the poor handling (not refrigerated).

I would bet that any paste you get on ebay is expired, for a variety
of reasons.

Also, I only buy tin/lead, though it is getting very hard to find.
It works so much better than lead free.

-Chuck Harris

Bob Albert via time-nuts wrote:
> Well I have found some Chinese sources of 42 - 50 grams on ebay for around 
> $3.  Is
> this the right stuff?  The brand is Mechanics.

Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Stewart]

The stuff I use is Chipquik SMD291AX.  The first syringe of it I bought was 
from Mouser and was 15 grams.  That was back in 2014.  The second syringe I got 
was SMD291AX10, which is 35 grams.  It's dated 3/15/16, so you can see how long 
solder paste will last if you take reasonable car of it.  I pumped about 15 
grams of that into the original syringe and put them both in the fridge.  I've 
had the small one out on the workbench for several weeks now, and there doesn't 
seem to be a problem.  I fold a piece of tape around the needle when it's not 
in use to keep the air out.  When I pull the tape off, I pump out about a 1/4" 
string and throw that away.  The rest works just fine.
If you haven't switched to using a hot air gun, I strongly suggest it.  They 
take a bit of getting used to, but after that, they're a time-saver.  I have 
the cheap ebay solder station labeled 852D+.  It has solder pencil and hot air. 
 There are two things I don't like about it.  One is that you can't turn the 
air flow down enough to use narrow nozzles for anything other than blowing 
soldered components off the board.  But it's Much better than trying to use a 
pencil for that chore!  The other is that the tips are attached by tightening a 
screw.  There are units out there that have a little tool that you use to give 
the tip a 1/4 turn twist to attach.  I don't change tips much, but not having 
to wait for the hot air gun to cool down would be nice.  The first time you 
reach for the hot air gun to shrink tubing or to solder the center pin for an 
SMA connector, you know you've "arrived".

Bob
 -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: Bob Albert via time-nuts 
 To: Discussion of precise time and frequency measurement  
 Sent: Thursday, August 18, 2016 8:49 PM
 Subject: Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)
   
I don't care about lead-free since I am not manufacturing, just repairing or 
building or experimenting.  But there seems to be more than one way to view 
this stuff.  Yes, it might be expired, but some say that's not a major issue.  
I can't justify the prices asked by US distributors, especially in light of the 
fact that I use very little.  So the fresh stuff, carefully refrigerated, would 
be expired by the time I use the second or third scoop of it, anyway.
What's a casual experimenter to do?
Bob
 

    On Thursday, August 18, 2016 3:33 PM, Chuck Harris  
wrote:
 

 The Chinese are certainly using a lot of solder paste, so they
are a source.  I tend to buy mine from Mouser, Digikey, TekSource,
places like that.

The last stuff I bought was made by Kester, and came from TekSource.

The only problem with using the real sources is in the summer, they
will pack your paste in an ice pack, and send it over night unless
you insist otherwise (and absolve them of any warranty).  That kind
of shipping is very expensive.

And, there is absolutely no possible way the paste you get from
China is going to make it here and follow the manufacturer's
guidelines for safe handling.  So, even if you buy new and pay
a premium price from China, you are getting paste that is expired
by the poor handling (not refrigerated).

I would bet that any paste you get on ebay is expired, for a variety
of reasons.

Also, I only buy tin/lead, though it is getting very hard to find.
It works so much better than lead free.

-Chuck Harris

Bob Albert via time-nuts wrote:
> Well I have found some Chinese sources of 42 - 50 grams on ebay for around 
> $3.  Is
> this the right stuff?  The brand is Mechanics.
> 
> Bob
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Oz-in-DFW]

On 8/18/2016 2:41 PM, Bob Albert via time-nuts wrote:
> Well I have found some Chinese sources of 42 - 50 grams on ebay for around 
> $3.  Is this the right stuff?  The brand is Mechanics.
>
> Bob
Best and Mechanic brand from China in small (50 gr) containers seems to
work fine.  The small containers are good because the stuff dries out
pretty fast.  I've not bothered trying to add flux to it when it does. I
keep a few containers of Best-605 on hand for home projects.  I hav a
few containers of Mechanic i bought to try, but haven't used yet. I'm
guessing it all comes from the same 55 Gallon drum ;-)

SRA Solder repackages lead based and lead free solder paste in hobby
friendly quantities (10 - 250 gr) at generally rational prices. Not
nearly as cheap as the Chinese 'brands' off eBay. Good customer service
and quick shipping though.

http://www.sra-solder.com/soldering-brazing-supplies/electronic-grade-solder-paste

I'll use chipquick or Kester paste from Mouser or Digikey for paid projects.

-- 
mailto:o...@ozindfw.net
Oz
POB 93167 
Southlake, TX 76092 (Near DFW Airport) 



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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Albert via time-nuts]

I don't care about lead-free since I am not manufacturing, just repairing or 
building or experimenting.  But there seems to be more than one way to view 
this stuff.  Yes, it might be expired, but some say that's not a major issue.  
I can't justify the prices asked by US distributors, especially in light of the 
fact that I use very little.  So the fresh stuff, carefully refrigerated, would 
be expired by the time I use the second or third scoop of it, anyway.
What's a casual experimenter to do?
Bob
 

On Thursday, August 18, 2016 3:33 PM, Chuck Harris  
wrote:
 

 The Chinese are certainly using a lot of solder paste, so they
are a source.  I tend to buy mine from Mouser, Digikey, TekSource,
places like that.

The last stuff I bought was made by Kester, and came from TekSource.

The only problem with using the real sources is in the summer, they
will pack your paste in an ice pack, and send it over night unless
you insist otherwise (and absolve them of any warranty).  That kind
of shipping is very expensive.

And, there is absolutely no possible way the paste you get from
China is going to make it here and follow the manufacturer's
guidelines for safe handling.  So, even if you buy new and pay
a premium price from China, you are getting paste that is expired
by the poor handling (not refrigerated).

I would bet that any paste you get on ebay is expired, for a variety
of reasons.

Also, I only buy tin/lead, though it is getting very hard to find.
It works so much better than lead free.

-Chuck Harris

Bob Albert via time-nuts wrote:
> Well I have found some Chinese sources of 42 - 50 grams on ebay for around 
> $3.  Is
> this the right stuff?  The brand is Mechanics.
> 
> Bob
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Chuck Harris]

The Chinese are certainly using a lot of solder paste, so they
are a source.  I tend to buy mine from Mouser, Digikey, TekSource,
places like that.

The last stuff I bought was made by Kester, and came from TekSource.

The only problem with using the real sources is in the summer, they
will pack your paste in an ice pack, and send it over night unless
you insist otherwise (and absolve them of any warranty).  That kind
of shipping is very expensive.

And, there is absolutely no possible way the paste you get from
China is going to make it here and follow the manufacturer's
guidelines for safe handling.  So, even if you buy new and pay
a premium price from China, you are getting paste that is expired
by the poor handling (not refrigerated).

I would bet that any paste you get on ebay is expired, for a variety
of reasons.

Also, I only buy tin/lead, though it is getting very hard to find.
It works so much better than lead free.

-Chuck Harris

Bob Albert via time-nuts wrote:
> Well I have found some Chinese sources of 42 - 50 grams on ebay for around 
> $3.  Is
> this the right stuff?  The brand is Mechanics.
> 
> Bob
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Chuck Harris]

Uhmmm, I buy it new, and expire it myself... blush.

-Chuck Harris

Bob Albert via time-nuts wrote:
> So where do you get this expired paste?  I have tried a few searches but no 
> luck.
> Bob
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Re: [time-nuts] Noisy Sulzer 2.5 - Suggestions?

[paul swed]

Chuck
I know those capacitors and you are right they were very high quality way
back when. Really interesting on the whiskers. I have seen them on other
parts.
What is it the tin leaching out. I guess the funny thing was that I have
seen them before and just brushed them off and continued troubleshooting.
Regards
Paul
WB8TSL

On Thu, Aug 18, 2016 at 2:46 PM, Chuck Harris  wrote:

> Hi Ed,
>
> Nope.  I just brushed off the growth, and blew the whole
> assembly down with compressed air.  The whiskers were
> huge!  I think they were capacitively coupling with the
> ground bits, and since their size and number varied in
> an uncontrolled way, they affected the frequency in an
> unstable way.
>
> These white cube shaped capacitors are something high
> quality.  The white color is a porcelain glaze that protects
> the capacitor, and the wires seemed to be connected to
> some sort of sintered silver area on the body.
>
> -Chuck Harris
>
> Ed Palmer wrote:
> > That's not something I would have expected.  Did you have to unsolder
> the capacitors
> > to clean them up?
> >
> > Ed
> >
> > On 2016-08-18 10:00 AM, time-nuts-requ...@febo.com wrote:
> >> My old 2.5A was acting up in strange drifty ways.  I opened the oven,
> and found
> >> that all of the white cube shaped ceramic capacitors in the oscillator
> were covered
> >> with fuzz on the electrode ends.  I am guessing that they were growing
> a great
> >> tin whisker beard.  I cleaned it all off, and performance improved
> greatly.
> >>
> >> -Chuck Harris
> >>
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Albert via time-nuts]

So where do you get this expired paste?  I have tried a few searches but no 
luck.
Bob
 

On Thursday, August 18, 2016 12:00 PM, Chuck Harris  
wrote:
 

 I have had similar experience with well expired paste.

I just don't worry about it.

The issue is the solder is ground to such a fine powder that
it has a huge surface area to oxidize.  As long as you keep
the air off, and refrigerate the paste, it seems to go forever.

Oh, and I only use tin/lead paste, not the RoHS stuff.

-Chuck Harris

Steve Wiseman wrote:
> On 18 August 2016 at 07:07, Bob Albert via time-nuts  
> wrote:
>> I didn't use the liquid solder because I didn't have any and it doesn't keep 
>> very long.
> 
> That's not really the case. It may change consistency so that it
> behaves a little differently and fouls up automated stencilling
> machines (which are the most finicky devices on the planet), but with
> a human in the loop, you can expect  most of a decade unless you let
> it dry out or do something daft.
> I'm still happily using stuff with a 2007 expiry code, in (big)
> plastic syringes. Still behaves fine. (and the benefit of the
> stirred-in flux and excellent wetting does make paste a joy to use
> compared to even good solder wire).
> 'Expired' solder paste can be a bargain.
> 
> Steve
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Albert via time-nuts]

Well I have found some Chinese sources of 42 - 50 grams on ebay for around $3.  
Is this the right stuff?  The brand is Mechanics.

Bob
 

On Thursday, August 18, 2016 12:11 PM, Bob Albert  
wrote:
 

 So where do you get this expired paste?  I have tried a few searches but no 
luck.
Bob
 

On Thursday, August 18, 2016 12:00 PM, Chuck Harris  
wrote:
 

 I have had similar experience with well expired paste.

I just don't worry about it.

The issue is the solder is ground to such a fine powder that
it has a huge surface area to oxidize.  As long as you keep
the air off, and refrigerate the paste, it seems to go forever.

Oh, and I only use tin/lead paste, not the RoHS stuff.

-Chuck Harris

Steve Wiseman wrote:
> On 18 August 2016 at 07:07, Bob Albert via time-nuts  
> wrote:
>> I didn't use the liquid solder because I didn't have any and it doesn't keep 
>> very long.
> 
> That's not really the case. It may change consistency so that it
> behaves a little differently and fouls up automated stencilling
> machines (which are the most finicky devices on the planet), but with
> a human in the loop, you can expect  most of a decade unless you let
> it dry out or do something daft.
> I'm still happily using stuff with a 2007 expiry code, in (big)
> plastic syringes. Still behaves fine. (and the benefit of the
> stirred-in flux and excellent wetting does make paste a joy to use
> compared to even good solder wire).
> 'Expired' solder paste can be a bargain.
> 
> Steve
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Re: [time-nuts] Noisy Sulzer 2.5 - Suggestions?

[Chuck Harris]

Hi Ed,

Nope.  I just brushed off the growth, and blew the whole
assembly down with compressed air.  The whiskers were
huge!  I think they were capacitively coupling with the
ground bits, and since their size and number varied in
an uncontrolled way, they affected the frequency in an
unstable way.

These white cube shaped capacitors are something high
quality.  The white color is a porcelain glaze that protects
the capacitor, and the wires seemed to be connected to
some sort of sintered silver area on the body.

-Chuck Harris

Ed Palmer wrote:
> That's not something I would have expected.  Did you have to unsolder the 
> capacitors
> to clean them up?
> 
> Ed
> 
> On 2016-08-18 10:00 AM, time-nuts-requ...@febo.com wrote:
>> My old 2.5A was acting up in strange drifty ways.  I opened the oven, and 
>> found
>> that all of the white cube shaped ceramic capacitors in the oscillator were 
>> covered
>> with fuzz on the electrode ends.  I am guessing that they were growing a 
>> great
>> tin whisker beard.  I cleaned it all off, and performance improved greatly.
>>
>> -Chuck Harris
>>
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Chuck Harris]

I have had similar experience with well expired paste.

I just don't worry about it.

The issue is the solder is ground to such a fine powder that
it has a huge surface area to oxidize.  As long as you keep
the air off, and refrigerate the paste, it seems to go forever.

Oh, and I only use tin/lead paste, not the RoHS stuff.

-Chuck Harris

Steve Wiseman wrote:
> On 18 August 2016 at 07:07, Bob Albert via time-nuts  
> wrote:
>> I didn't use the liquid solder because I didn't have any and it doesn't keep 
>> very long.
> 
> That's not really the case. It may change consistency so that it
> behaves a little differently and fouls up automated stencilling
> machines (which are the most finicky devices on the planet), but with
> a human in the loop, you can expect  most of a decade unless you let
> it dry out or do something daft.
> I'm still happily using stuff with a 2007 expiry code, in (big)
> plastic syringes. Still behaves fine. (and the benefit of the
> stirred-in flux and excellent wetting does make paste a joy to use
> compared to even good solder wire).
> 'Expired' solder paste can be a bargain.
> 
> Steve
> ___
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Albert via time-nuts]

Ah Steve, that's good info!  Now where does one buy expired solder paste?  And 
what's the proper name for it - solder paste searches mostly come up with just 
flux.

Bob
 

On Thursday, August 18, 2016 2:25 AM, Steve Wiseman  
wrote:
 

 On 18 August 2016 at 07:07, Bob Albert via time-nuts  
wrote:
> I didn't use the liquid solder because I didn't have any and it doesn't keep 
> very long.

That's not really the case. It may change consistency so that it
behaves a little differently and fouls up automated stencilling
machines (which are the most finicky devices on the planet), but with
a human in the loop, you can expect  most of a decade unless you let
it dry out or do something daft.
I'm still happily using stuff with a 2007 expiry code, in (big)
plastic syringes. Still behaves fine. (and the benefit of the
stirred-in flux and excellent wetting does make paste a joy to use
compared to even good solder wire).
'Expired' solder paste can be a bargain.

Steve


  
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Re: [time-nuts] Noisy Sulzer 2.5 - Suggestions?

[Ed Palmer]

On 2016-08-18 10:00 AM, paul swed  wrote:

Ed,
Thats quite the challenge and yes the carbon resistors must be about 50
years old now. So questioning them is reasonable. I have a c so take my
next comment with caution.
The oscillator is a small circuit and then it runs to buffers and
multipliers and stuff.


That's one of the differences between the 2.5 and the 2.5x models. The 
2.5 only has 2.5 MHz and lower outputs so no multipliers. Hopefully, the 
other circuit blocks are more or less the same.



Lots of parts of every type. Maybe it makes sense to isolate and measure
just the oscillator circuit to see how it behaves without all of the other
stuff. Also there were various regulators in that can.


Yes, noise on the internal voltage regulator would affect everything.  I 
might replace all the Ta capacitors 'just because', but beyond that, 
divide and conquer makes a lot of sense.


Ed


Lots of possibilities for trouble. But also worth the effort to figure it out.
Great old oscillators.
Regards
Paul
WB8TSL


On Wed, Aug 17, 2016 at 4:25 PM, Ed Palmer  wrote:


>I picked up a Sulzer 2.5 (not 2.5A or 2.5B or 2.5C) oscillator and 5P
>power supply.  It's working, but the AlDev at low tau is poor. After a few
>days of operation the AlDev @ 1sec. is only 1e-10.  It's not the power
>supply.  I'm running under 'AC fail' conditions with a lab power supply
>standing in for the batteries.  This bypasses almost everything in the
>power supply.  Eventually, I plan to replace the batteries with lead-acid
>and replace the circuit board with an improved circuit.
>
>So, I'll be opening up the oscillator to see what's what.  My first 'usual
>suspect' will be the Ta capacitors, but I'm wondering about all those
>carbon composition resistors.  Should I be looking at a wholesale
>replacement with metal film?  Maybe just in the oscillator and AVC areas?
>Are there any other known trouble spots with these oscillators?
>
>I haven't been able to find any info on the 2.5.  The manuals and
>schematics for the 5A and the 2.5B/C are some help, but the 2.5 is very
>different from the 2.5B/C.  Any info would be greatly appreciated.
>
>Thanks,
>
>Ed


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Re: [time-nuts] Noisy Sulzer 2.5 - Suggestions?

[Ed Palmer]

That's not something I would have expected.  Did you have to unsolder 
the capacitors to clean them up?


Ed

On 2016-08-18 10:00 AM, time-nuts-requ...@febo.com wrote:

My old 2.5A was acting up in strange drifty ways.  I opened the oven, and found
that all of the white cube shaped ceramic capacitors in the oscillator were 
covered
with fuzz on the electrode ends.  I am guessing that they were growing a great
tin whisker beard.  I cleaned it all off, and performance improved greatly.

-Chuck Harris

Ed Palmer wrote:

I picked up a Sulzer 2.5 (not 2.5A or 2.5B or 2.5C) oscillator and 5P power 
supply.It's working, but the AlDev at low tau is poor. After a few days of 
operation theAlDev @ 1sec. is only 1e-10.  It's not the power supply.  I'm 
running under 'AC fail'conditions with a lab power supply standing in for the 
batteries.  This bypassesalmost everything in the power supply.  Eventually, I 
plan to replace the batterieswith lead-acid and replace the circuit board with 
an improved circuit.

So, I'll be opening up the oscillator to see what's what.  My first 'usual 
suspect'will be the Ta capacitors, but I'm wondering about all those carbon 
compositionresistors.  Should I be looking at a wholesale replacement with 
metal film?  Maybejust in the oscillator and AVC areas?  Are there any other 
known trouble spots withthese oscillators?

I haven't been able to find any info on the 2.5.  The manuals and schematics 
for the5A and the 2.5B/C are some help, but the 2.5 is very different from the 
2.5B/C.  Anyinfo would be greatly appreciated.

Thanks,

Ed


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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Steve Wiseman]

On 18 August 2016 at 07:07, Bob Albert via time-nuts  wrote:
> I didn't use the liquid solder because I didn't have any and it doesn't keep 
> very long.

That's not really the case. It may change consistency so that it
behaves a little differently and fouls up automated stencilling
machines (which are the most finicky devices on the planet), but with
a human in the loop, you can expect  most of a decade unless you let
it dry out or do something daft.
I'm still happily using stuff with a 2007 expiry code, in (big)
plastic syringes. Still behaves fine. (and the benefit of the
stirred-in flux and excellent wetting does make paste a joy to use
compared to even good solder wire).
'Expired' solder paste can be a bargain.

Steve
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Re: [time-nuts] Speaking clock

[William H. Fite]

I want the voice of Forbin's megalomaniacal computer saying, "This is the
voice of world control. I bring you peace"


On Wednesday, August 17, 2016, Didier Juges  wrote:

> I would like to find an emulator of the old voice synthesizer used in the
> Atlanta airport subway. "The next stop is concourse A. The color coded maps
> in this vehicle match the station colors." "This vehicle is leaving the
> station, please hold on."
> They replaced it in 1996 for the Olympics but I remember it as if it was
> yesterday...
> (I used to travel a lot)
>
> Didier KO4BB
>
>
> On Mon, Aug 8, 2016 at 6:28 AM, Morris Odell  >
> wrote:
>
> > Hi all,
> >
> > There was a thread about this a few weeks ago and I mentioned that I was
> > working on one with a "Stephen Hawking" voice - well here's a video:
> >
> > https://youtu.be/lmg0YsHlB3g
> >
> > So far it's not GPS controlled but that will come one day.
> >
> > Cheers,
> >
> > Morris
> >
> > ___
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> >
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>


-- 
If you gaze long enough into the abyss, your coffee will get cold.
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Re: [time-nuts] GPSDO - probably a stupid question.

[Charles Steinmetz]

Bob wrote:


The point is still looking at the noise characteristics of the oscillator and 
the reference.
It is best done in the frequency domain as phase noise. We substitute ADEV, but 
that
is not an ideal proxy.


Phase noise and xDEV measure the same thing -- the stability of an 
oscillator at different time scales.  They just express the result 
differently.  Phase noise expresses it as PM in the frequency domain, 
and xDEV expresses it as "parts per" in the time domain.  (Yes, this is 
a somewhat simplified view of it, but it captures the essential point 
without undue complexity.)


Conventionally, we switch from using PN to using xDEV at a time scale 
(reciprocal frequency scale) of around 1 second, but there is no 
mathematical reason why they both cannot be extended indefinitely in 
either direction.  The convention arose largely because the equipment 
and techniques we use[ed] to quantify them have traditionally been 
different at time scales (reciprocal frequency scales) greater than and 
less than about one second.  Now that we are in the era of "digitize 
everything, and let Laplace sort it out," we needn't view it as the 
rigid convention it once was.



Either way you want the loop to cross over from one to the other
somewhere in the vicinity of the “equal noise” point if it exists. If there is 
no equal noise
point, that makes you wonder a bit about why you are locking one to the other


Not really, if one has lower noise at all time (frequency) scales, just 
lock to that one at all scales.  (It may call into question why you're 
fiddling with two oscillators, rather than just using the output of the 
quiet one, if they are both at the same frequency -- but there are a 
number of reasons one might want to do that.)


Best regards,

Charles


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Re: [time-nuts] Speaking clock

[David J Taylor]

I would like to find an emulator of the old voice synthesizer used in the
Atlanta airport subway. "The next stop is concourse A. The color coded maps
in this vehicle match the station colors." "This vehicle is leaving the
station, please hold on."
They replaced it in 1996 for the Olympics but I remember it as if it was
yesterday...
(I used to travel a lot)

Didier KO4BB


IIRC something like that is built into Windows.

 https://en.wikipedia.org/wiki/Microsoft_Speech_API
 https://msdn.microsoft.com/en-us/library/ee125077(v=vs.85).aspx

David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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Re: [time-nuts] GPSDO - probably a stupid question.

[Magnus Danielson]

I use the frequency relationship ratio as an indication of how difficult 
the design is. Divide the oscillator frequency with the comparator 
frequency, and the number gives you a ratio, how many output cycles it 
goes between each comparison. Things like smoothing becomes harder when 
this number becomes large. Lock-in etc. also becomes harder.


1-100 is relatively trivial.
1000 is a little challenging and start to need care.

By increasing the comparator frequency, I made designs more trivial and 
that has helped a lot to get the job done without too much hassle.


I bring this up since there is more to the design than just the PLL 
bandwidth and damping factor.


Cheers,
Magnus

On 08/18/2016 03:17 AM, Didier Juges wrote:

Good point, and an example of how good digital filtering (helped with 
upsampling) can make the design of the analog filter much easier :)

Reference the digital audio battles of the past century when 1 bit D/As running 
very fast started replacing the expensive 16 bit audio DACs running at 44kHz.

Didier

On August 17, 2016 5:25:39 PM CDT, Magnus Danielson 
 wrote:

Hi,

I agree.

There is however a subtle detail, how they leak out over time.

At one time we had to lock an 155,52 MHz oscillator up to 8 kHz, this
for a 2,48832 Gb/s link, which needs to pass the SDH STM-16 jitter and
wander specifications. The first attempt at that PLL was using a 4046,
and the charge-pump was being used. The charge-pump has dead-time, and
well, they thought it was good to only push the EFC here and there.
What
this meant was that they created a triangle-waved frequency modulation
of low rate, which then created phase modulations as it went through
the
integration of the oscillator. The scale-up factor made this quite
noticeable at the actual bit-rate. It made the point that you need to
update often to keep deviations limited, and when doing it at a higher
frequency, they are easier to filter out.

In essence, you need to think what each comparison or update creates as

a step response and how it is averaged out over time.

In this regard a PWM is a really bad signal, as it can push the
strongest amplitude at the lowest frequency, which becomes hardest to
filter. For one design I needed to increase the resolution, so I made
an
interpolation but with inversed spectral density to that of PWM, to
push
the highest amplitude to the highest frequency so that filtering
becomes
easier. Turned out to be quite easy and work well.

High update rates can be very useful even if the bandwidth of the loop
is low. The bandwidth only limits how low the updaterate can be, but
the
phase-noise purity makes update rates and smoothing mechanisms
interesting.

Cheers,
Magnus

On 08/17/2016 11:53 PM, Bob kb8tq wrote:

Hi

You can update the EFC a billion times a second.  Update rate and

bandwidth are not the same thing. If you want good ADEV, the loop
better not have a bandwidth greater than 0.01 Hz. GPS ADEV is pretty
awful at 1 and 10 seconds. It is starts to be good past a few thousand
seconds. Yes, older modules are a bit worse than newer ones. Also
sawtooth correction can make things a bit better.


Bob

Sent from my iPad


On Aug 17, 2016, at 2:51 PM, Nick Sayer via time-nuts

 wrote:


Updating the EFC more quickly reduces the ADEV, though. I find that

the fiddly part of tuning a GPSDO design is balancing the ADEV against
phase control. If you want keep an iron fist on the phase, you can only
do so by constantly swatting around the frequency.


I won't say that getting more frequent phase feedback is a bad

thing, but if you're trying to get the PLL time constant to be longer
rather than shorter that it won't help a lot.


Sent from my iPhone


On Aug 17, 2016, at 9:57 AM, Peter Reilley

 wrote:


You can get crystal oscillators that have a frequency control

signal and are more

stable than the run of the mill oscillators.   Changing the GPS

oscillator would

require modifying a very tightly populated circuit board.   Perhaps

not possible.


What about some of the SDR (software defined radio) projects that

aim to

implement GPS functionality?   If you used the GPS chipping rate

(1.023 MHz)

to dicipline the 10 MHz oscillator then you are less sensitive to

crystal instabilities.

You are updating the crystal one million times a second rather than

once per second.

This is assuming that the chipping rate of the transmitter is just

as good as the

1 PPS signal.   This info from here;
https://www.e-education.psu.edu/geog862/node/1753
and here;
https://en.wikipedia.org/wiki/GPS_signals

Even using the 50 bits/sec data rate of the GPS signal would allow

updating the

GPSDO faster than the 1 PPS signal.

Pete.
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Bob Albert via time-nuts]

Jim, that's the exact one I built!  I rechecked and the rise time is about 2 
ns, not longer as I previously reported.  Not only do I have a new piece of 
test gear but I have gotten some SMT experience.  Previously I have removed 
chips but this is the first time I have installed one.  I didn't use the liquid 
solder because I didn't have any and it doesn't keep very long.  I used 
ordinary solder with a small iron and it worked well, although I didn't have as 
much control as I wished.
I also have a SNA that can be used for some of the same measurements but this 
thing is simple.  I checked both with my digital HP scope and my analog Tek and 
got the same result.
I checked a three foot piece of coax, both open at the far end and shorted 
there, and got the textbook waveforms.  I love it when the basics check out.
Bob
 

On Wednesday, August 17, 2016 11:00 PM, Jim Stone  
wrote:
 

 Hi again,
The cable impedance measurement was in a different video (linked below) but
it can use the same HC14 TDR as in the first video. The concept is to just
put a pot on the end of the cable and adjust it until the reflection goes
away. Simple!

https://www.youtube.com/watch?v=Il_eju4D_TM

--Jim Stone


Hi Bob,
Take a look at this nice simple little one chip "TDR" and lesson on how to
use it to measure cable length and cable impedance. It uses a single AC14
(can use a DIP so no SMD needed) and gives a nice crisp 2 or 3 ns rise. The
AC family is nice fast logic and has been used in many Time-Nuts
application like cheap zero-cross detectors using the AC04.

https://www.youtube.com/watch?v=9cP6w2odGUc

Regards --Jim Stone

Bob Albert wrote:

 Well I got my adapter boards from China and managed to build my first SMT
project, a square wave generator for TDR use.  And it works!  The IC seems
to run hot so I used my IR temperature measurement device and it checks out
at about 37C, acceptable.  I can now drive a square wave at about 3 kHz
into 50 Ohms.  The rise time isn't very short but I must have not used the
best part for the generator.  Still, I can do some TDR experimenting as
long as the line isn't too short.
Thanks to all for the ideas and encouragement.  I didn't use a microscope,
mostly just a magnifier.  My tiniest soldering iron is a bit large but it
did the job.
Bob
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Jim Stone]

Hi again,
The cable impedance measurement was in a different video (linked below) but
it can use the same HC14 TDR as in the first video. The concept is to just
put a pot on the end of the cable and adjust it until the reflection goes
away. Simple!

https://www.youtube.com/watch?v=Il_eju4D_TM

--Jim Stone


Hi Bob,
Take a look at this nice simple little one chip "TDR" and lesson on how to
use it to measure cable length and cable impedance. It uses a single AC14
(can use a DIP so no SMD needed) and gives a nice crisp 2 or 3 ns rise. The
AC family is nice fast logic and has been used in many Time-Nuts
application like cheap zero-cross detectors using the AC04.

https://www.youtube.com/watch?v=9cP6w2odGUc

Regards --Jim Stone

Bob Albert wrote:

 Well I got my adapter boards from China and managed to build my first SMT
project, a square wave generator for TDR use.  And it works!  The IC seems
to run hot so I used my IR temperature measurement device and it checks out
at about 37C, acceptable.  I can now drive a square wave at about 3 kHz
into 50 Ohms.  The rise time isn't very short but I must have not used the
best part for the generator.  Still, I can do some TDR experimenting as
long as the line isn't too short.
Thanks to all for the ideas and encouragement.  I didn't use a microscope,
mostly just a magnifier.  My tiniest soldering iron is a bit large but it
did the job.
Bob
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Jim Stone]

Hi Bob,
Take a look at this nice simple little one chip "TDR" and lesson on how to
use it to measure cable length and cable impedance. It uses a single AC14
(can use a DIP so no SMD needed) and gives a nice crisp 2 or 3 ns rise. The
AC family is nice fast logic and has been used in many Time-Nuts
application like cheap zero-cross detectors using the AC04.

https://www.youtube.com/watch?v=9cP6w2odGUc

Regards --Jim Stone

Bob Albert wrote:

 Well I got my adapter boards from China and managed to build my first SMT
project, a square wave generator for TDR use.  And it works!  The IC seems
to run hot so I used my IR temperature measurement device and it checks out
at about 37C, acceptable.  I can now drive a square wave at about 3 kHz
into 50 Ohms.  The rise time isn't very short but I must have not used the
best part for the generator.  Still, I can do some TDR experimenting as
long as the line isn't too short.
Thanks to all for the ideas and encouragement.  I didn't use a microscope,
mostly just a magnifier.  My tiniest soldering iron is a bit large but it
did the job.
Bob
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