Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Remember: Silly is a state of Mind, Stupid is a way of Life. -- Dave Butler ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Never eat more than you can lift. -- Miss Piggy ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- 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 For most men life is a search for the proper manila envelope in which to get themselves filed. -- Clifton Fadiman ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Thu, May 21, 2009 at 5:00 PM, Joerg joerg...@analogconsultants.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
Chris Albertson wrote: On Thu, May 21, 2009 at 5:00 PM, Joerg joerg...@analogconsultants.com 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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Life is a whim of several billion cells to be you for a while. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Complex system: One with real problems and imaginary profits. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list [4]geda-u...@moria.seul.org [5]http://www.seul.org/cgi-bin/mailman/listinfo/geda-user 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 leventel...@gmail.com 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. ... It think we are on the same side of the pond. Well, maybe the other pond (I am in California). ... 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
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Quantum Mechanics is God's version of Trust me. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Never make any mistaeks. -- Anonymous, in a mail discussion about to a kernel bug report ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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! ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, May 20, 2009 at 8:37 AM, Levente Kovacs leventel...@gmail.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Being disintegrated makes me ve-ry an-gry! huff, huff ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 -- Dave McGuire Port Charlotte, FL ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, 20 May 2009 09:26:07 -0700 Joerg joergsch-I+vV3rgtSXAS/o5rz7uibzqqe7ycj...@public.gmane.org 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, 20 May 2009 11:45:55 -0400 (EDT) der Mouse mo...@rodents-montreal.org wrote: What _is_ this driving? Ten feet of #3 copper? A current sensor. -- Levente Kovacs http://logonex.eu ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On May 20, 2009, at 12:04 PM, Ethan Swint wrote: DJ Delorie wrote: DJ Delorie d...@delorie.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, 20 May 2009 10:33:30 -0500 Mark Rages 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: 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
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) 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 d...@delorie.com 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. ___ geda-user mailing list geda-user@moria.seul.org [1]http://www.seul.org/cgi-bin/mailman/listinfo/geda-user References 1. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
DJ Delorie wrote: Levente Kovacs leventel...@gmail.com 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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ;). ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
DJ Delorie wrote: DJ Delorie d...@delorie.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
-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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
DJ Delorie d...@delorie.com 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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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? /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
Levente Kovacs leventel...@gmail.com 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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
Levente Kovacs wrote: On Wed, 20 May 2009 11:45:55 -0400 (EDT) der Mouse mo...@rodents-montreal.org 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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs leventel...@gmail.com wrote: On Wed, 20 May 2009 10:48:53 -0500 Mark Rages markra...@gmail.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 j...@ecosensory.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- Levente Kovacs http://logonex.eu ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, 20 May 2009 10:48:53 -0500 Mark Rages markra...@gmail.com 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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- 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 A formal parsing algorithm should not always be used. -- D. Gries ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wednesday 20 May 2009, Joerg wrote: DJ Delorie wrote: Levente Kovacs leventel...@gmail.com 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. https://www.nrahq.org/nrabonus/accept-membership.asp Stray Alpha Particles from memory packaging caused Hard Memory Error on Server. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wed, 2009-05-20 at 11:27 -0500, Mark Rages wrote: On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs leventel...@gmail.com wrote: On Wed, 20 May 2009 10:48:53 -0500 Mark Rages markra...@gmail.com 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!) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ j...@noqsi.com ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
~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. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 \ / Ribbon Campaign X Against HTML mo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ j...@noqsi.com ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 markrages-re5jqeeqqe8avxtiumw...@public.gmane.org wrote: On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs leventelist-re5jqeeqqe8avxtiumw...@public.gmane.org wrote: On Wed, 20 May 2009 10:48:53 -0500 Mark Rages markrages-re5jqeeqqe8avxtiumw...@public.gmane.org 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 ___ geda-user mailing list geda-user-3olirty5fqqavzljymc...@public.gmane.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- Levente Kovacs http://logonex.eu ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 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 River: Also, I can kill you with my brain. --Episode #11, Trash ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
Is this data obtained from a Kill-a-watt? No, from the prototype powermeter board. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 markrages-re5jqeeqqe8avxtiumw...@public.gmane.org wrote: On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs leventelist-re5jqeeqqe8avxtiumw...@public.gmane.org wrote: On Wed, 20 May 2009 10:48:53 -0500 Mark Rages markrages-re5jqeeqqe8avxtiumw...@public.gmane.org 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 ___ geda-user mailing list geda-user-3olirty5fqqavzljymc...@public.gmane.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
Levente Kovacs wrote: On Wed, 20 May 2009 09:26:07 -0700 Joerg joerg...@analogconsultants.com 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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
DJ Delorie wrote: DJ Delorie d...@delorie.com 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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
Gene Heskett wrote: On Wednesday 20 May 2009, Joerg wrote: DJ Delorie wrote: Levente Kovacs leventel...@gmail.com 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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 \ / Ribbon Campaign X Against HTML mo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ j...@noqsi.com ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- 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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
On Wednesday 20 May 2009, Joerg wrote: Gene Heskett wrote: On Wednesday 20 May 2009, Joerg wrote: DJ Delorie wrote: Levente Kovacs leventel...@gmail.com 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. https://www.nrahq.org/nrabonus/accept-membership.asp Oh no, not again. - A bowl of petunias on it's way to certain death. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp If that makes any sense to you, you have a big problem. -- C. Durance, Computer Science 234 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 markrages-re5jqeeqqe8avxtiumw...@public.gmane.org wrote: On Wed, May 20, 2009 at 11:16 AM, Levente Kovacs leventelist-re5jqeeqqe8avxtiumw...@public.gmane.org wrote: On Wed, 20 May 2009 10:48:53 -0500 Mark Rages markrages-re5jqeeqqe8avxtiumw...@public.gmane.org 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 ___ geda-user mailing list geda-user-3olirty5fqqavzljymc...@public.gmane.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- 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 Now KEN and BARBIE are PERMANENTLY ADDICTED to MIND-ALTERING DRUGS ... ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp Now KEN and BARBIE are PERMANENTLY ADDICTED to MIND-ALTERING DRUGS ... ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 leventel...@gmail.com 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 ;-) -- Regards, Joerg http://www.analogconsultants.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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). ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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 leventel...@gmail.com 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 was on the wall I may have a 1 pound can in the basement yet that hasn't been tapped. 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
Re: gEDA-user: [OFF] high current amplifier
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. https://www.nrahq.org/nrabonus/accept-membership.asp You can't hold a man down without staying down with him. -- Booker T. Washington ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: [OFF] high current amplifier
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. :) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- 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 Time is the most valuable thing a man can spend. -- Theophrastus ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
