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Switching power supplies question.
Understand that inside a typical computer switching power supply there
is a higher multi kilohertz voltage (350v RMS????) produced by the switching action of the rectified 115 or 230 volt AC input? This high freq AC through various usually toroidal step down transforner windings is then rectified to provided the plus and minus 5, 12 volt outputs etc. Correct? We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt ouputs with a couple of amps in order to get the unit to work; but that's normal. Question: Is it possible to get at that higher AC voltage inside and directly rectify it as a B+ supply for tube equipment? While also possibly tiddling one or more of the 5 volt DC outputs closer to 6.3 volts for tube heaters? Rectified 10 or 20 kilohertz wouldn't need much filtering compared to 60 or 120 DC ripple of a conventiaonl power supply? Recall building a number of conventional 50 and 60 hertz power supplies many years ago with heavy chokes and large capacitors. But now have a number of slightly older ex computer power supplies of various wattages around. Or is the idea completly off base? |
Switching power supplies question.
You're pretty much on base with some some slight adjustments. The switching frequency is about ten times higher about 100KHz or so. The high voltage might be full wave rectified, doubled or boosted by a power factor corrector .... but 300V is close. The step down transformer is usually an E-E core or ETD core. The toroids are output inductors. An additional inductor is used for 3.3V in some supplies as a magnetic amplifier, which lops off some pulse width from the +5V output. It's possible to modify a PC supply and add a B+ output but you'd have to re-wind the transformer and output inductor(s). Usually the outputs are cross-regulated. That is the +5V is the regulated channel and the other outputs track due to the transformer turns ratios (sometimes with help from weighted-sum voltage sensing.) That's why the 5V output has to be loaded to get any output from the +12V. If the 6.3VDC output was most of the power it would make sense to use the 5V channel for this, strip off the other outputs and wind a new secondary for your B+ in their place. You're right, the transformer and filter components would be much, much smaller. Though you'll need room for additional EMI filtering... even so it's still much smaller. Some newer PC supplies spread the clock frequency (frequency modulate it with pseudo random noise) which can help. Understand that inside a typical computer switching power supply there is a higher multi kilohertz voltage (350v RMS????) produced by the switching action of the rectified 115 or 230 volt AC input? This high freq AC through various usually toroidal step down transforner windings is then rectified to provided the plus and minus 5, 12 volt outputs etc. Correct? We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt ouputs with a couple of amps in order to get the unit to work; but that's normal. Question: Is it possible to get at that higher AC voltage inside and directly rectify it as a B+ supply for tube equipment? While also possibly tiddling one or more of the 5 volt DC outputs closer to 6.3 volts for tube heaters? Rectified 10 or 20 kilohertz wouldn't need much filtering compared to 60 or 120 DC ripple of a conventiaonl power supply? Recall building a number of conventional 50 and 60 hertz power supplies many years ago with heavy chokes and large capacitors. But now have a number of slightly older ex computer power supplies of various wattages around. Or is the idea completly off base? |
Switching power supplies question.
terry wrote:
Understand that inside a typical computer switching power supply there is a higher multi kilohertz voltage (350v RMS????) produced by the switching action of the rectified 115 or 230 volt AC input? This high freq AC through various usually toroidal step down transforner windings is then rectified to provided the plus and minus 5, 12 volt outputs etc. Correct? We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt ouputs with a couple of amps in order to get the unit to work; but that's normal. Question: Is it possible to get at that higher AC voltage inside and directly rectify it as a B+ supply for tube equipment? While also possibly tiddling one or more of the 5 volt DC outputs closer to 6.3 volts for tube heaters? Rectified 10 or 20 kilohertz wouldn't need much filtering compared to 60 or 120 DC ripple of a conventiaonl power supply? Recall building a number of conventional 50 and 60 hertz power supplies many years ago with heavy chokes and large capacitors. But now have a number of slightly older ex computer power supplies of various wattages around. Or is the idea completly off base? The "higher voltage" is usually on the line side of the isolation transformer. You would create a safety hazard by accessing that voltage. A thought might be to use the non-rectified low voltage side to drive a small high frequency step up transformer or use a diode voltage multiplier circuit or a combination of transformer and voltage multiplier. There is a company that builds high voltage switchers for amateur radio amplifiers, and there have been construction articles to build these. (Check QEX magazine). Building from a surplus PC power supply would have a cost advantage. -- Joe Leikhim K4SAT "The RFI-EMI-GUY"© "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P |
Switching power supplies question.
"RFI-EMI-GUY" wrote in message
g.com... terry wrote: Understand that inside a typical computer switching power supply there is a higher multi kilohertz voltage (350v RMS????) produced by the switching action of the rectified 115 or 230 volt AC input? This high freq AC through various usually toroidal step down transforner windings is then rectified to provided the plus and minus 5, 12 volt outputs etc. Correct? We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt ouputs with a couple of amps in order to get the unit to work; but that's normal. Question: Is it possible to get at that higher AC voltage inside and directly rectify it as a B+ supply for tube equipment? While also possibly tiddling one or more of the 5 volt DC outputs closer to 6.3 volts for tube heaters? Rectified 10 or 20 kilohertz wouldn't need much filtering compared to 60 or 120 DC ripple of a conventiaonl power supply? Recall building a number of conventional 50 and 60 hertz power supplies many years ago with heavy chokes and large capacitors. But now have a number of slightly older ex computer power supplies of various wattages around. Or is the idea completly off base? The "higher voltage" is usually on the line side of the isolation transformer. You would create a safety hazard by accessing that voltage. A thought might be to use the non-rectified low voltage side to drive a small high frequency step up transformer or use a diode voltage multiplier circuit or a combination of transformer and voltage multiplier. There is a company that builds high voltage switchers for amateur radio amplifiers, and there have been construction articles to build these. (Check QEX magazine). Building from a surplus PC power supply would have a cost advantage. -- Joe Leikhim K4SAT "The RFI-EMI-GUY"© There's a schematic of a typical (although a bit dated) ATX power supply that shows the concept of a PC power supply design at http://www.pavouk.org/hw/en_atxps.html. Current models might use different components but the basic design will be the same. Here, you can easily see the building blocks of the supply and how the various voltages are generated. There's also a link on that page (http://www.webx.dk/oz2cpu/radios/psu-pc1.htm) that demonstrates a way to modify a power supply for high current +13.8V output. Modification for HV output would obviously involve rewinding the switching transformer to give it a HV winding. -- Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the address) Life is like a roll of toilet paper; the closer it gets to the end, the faster it goes. |
Switching power supplies question.
RFI-EMI-GUY wrote:
There is a company that builds high voltage switchers for amateur radio amplifiers, and there have been construction articles to build these. (Check QEX magazine). Regrettably the author of the key article, and owner of the company "Watts Unlimited", died a few years ago. The commercial unit followed some years after the QEX article. It contained a number of important improvements but schematics were never published. The big unanswered question is why that design had no voltage feedback, and therefore had quite poor output regulation? (We can only speculate that a feedback loop must surely have been tried, but proved unworkable... and then wonder why that should be?) An example application for the commercial unit: http://www.gare.co.uk/k5and/8877.htm Building from a surplus PC power supply would have a cost advantage. These days, tube RF amplifiers only begin to show a clear advantage over solid-state at 500-1000W RF output, ie 1-2kW DC input. That is way beyond the capabilities of PC power supplies. A small-scale project based on a PC supply would be a good way to begin to understand the problems, at relatively little cost, but it would be another big step to build (or modify) a much larger SMPS for a serious tube amplifier. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek |
Switching power supplies question.
The "higher voltage" is usually on the line side of the isolation transformer. You would create a safety hazard by accessing that voltage. Joe Leikhim K4SAT "The RFI-EMI-GUY"© , Pshaw I used to make a living fixing TV sets that ran off of the mains wit no isolation. Needless to say there were millions of these TV's back in the day, The trick was to use half wave rectification. You can do the same thing with a PC supply. Instead of using an AC input you would half wave rectify the AC and and a suitible filter capacitor to make up for the frequency change. Also you has to use the neutral as ground, and use a polarized plug in the USA, Now it's true if the wall outlet got wired the wrong way you could be in for a treat of epic proportions. So a GFI would be in there somewheres to protect you. Then your HV DC ground will be at neutral. At which point you could use a Voltage multiplier to get close to any whole number multiple of the mains voltage. Now it's true you you may not get away with this trick on 3 phase or split phase 220 mains, because then where is the neutral? 73 OM n8zu |
Switching power supplies question.
On Oct 1, 12:55*pm, terry wrote:
We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt ouputs with a couple of amps in order to get the unit to work; but that's normal. Hey terry I did that very same thing loaded the 5volt with 5ohm at 5 watt. Ran my TenTec 526 off the 12 volt side of the PC power supply. I thought it was the sweetest thing since sliced bread. Then people started telling me I had this strange background noise. They asked me what was going on in my shack. I had this strange eerie noise in my shack, so they thought. Wasn't in my shack per say but it was the PC power supply. Nobody knew I was running a PC supply to power my rig. 73 OM n7zu |
Switching power supplies question.
On Oct 2, 4:29*am, raypsi wrote:
On Oct 1, 12:55*pm, terry wrote: We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt ouputs with a couple of amps in order to get the unit to work; but that's normal. Hey terry I did that very same thing loaded the 5volt with 5ohm at 5 watt. Ran my TenTec 526 off the 12 volt side of the PC power supply. I thought it was the sweetest thing since sliced bread. Then people started telling me I had this strange background noise. They asked me what was going on in my shack. I had this strange eerie noise in my shack, so they thought. Wasn't in my shack per say but it was the PC power supply. Nobody knew I was running a PC supply to power my rig. 73 OM n7zu I also use a modified PC power supply with no problems. I did add a filter removed from a commercial computer SMPS. I dont know the values of the components but its a Pi filter and the inductor is wound on what looks like a ferrite rod. The caps are some pretty big disk that had the writing rubbed off of them a long time ago. As Grumpy put it. I like to "Frankenstien" some of my projects. I have been giving some thought as to what it would take to modify a PC power supply for HV use. I have been thinking along two lines, 1 Connect a second step-up transformer before the rectifiers. 2 Replace the transformer with one with a HV windingputting a 5volt winding on the new transformer for loading and feedback. Jimmie |
Switching power supplies question.
On Oct 2, 11:37*am, wrote:
On Oct 2, 4:29*am, raypsi wrote: On Oct 1, 12:55*pm, terry wrote: We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application. In order to do so we had to load one of the 5 volt outputs with a couple of amps in order to get the unit to work; but that's normal. Hey terry I did that very same thing loaded the 5volt with 5ohm at 5 watt. Ran my TenTec 526 off the 12 volt side of the PC power supply. I thought it was the sweetest thing since sliced bread. Then people started telling me I had this strange background noise. They asked me what was going on in my shack. I had this strange eerie noise in my shack, so they thought. Wasn't in my shack per say but it was the PC power supply. Nobody knew I was running a PC supply to power my rig. 73 OM n7zu I also use a modified PC power supply with no problems. I did add a filter removed from a commercial computer SMPS. I don't know the values of the components but its a Pi filter and the inductor is wound on what looks like a ferrite rod. The caps are some pretty big disk that had the writing rubbed off of them a long time ago. As Grumpy put it. I like to "Frankenstien" some of my projects. I have been giving some thought as to what it would take to modify a PC power supply for HV use. I have been thinking along two lines, 1 Connect a second step-up transformer before the rectifiers. 2 Replace the transformer with one with a HV winding putting a 5volt winding on the new transformer for loading and feedback. Jimmie- Hide quoted text - - Show quoted text - Great info: Thanks for all the ideas and especially about the warning that the HV would be on the line side (input) from115/230 volt mains. Unless a 60 hertz full isolation transformer were used; the weight and size of which sort of negates the idea of using a lighter weight SPS! I too used to fix TVs without power transformers, using selenium rectifiers (boy could they stink!) and voltage doubler circuits to provide B+. That was back in the mid late 1950s. I also made up a little B+ power supply in a box clipped in during house calls to show a customer that the problem was indeed inside the chassis and it had to be taken away for a 'bench job'! By that and means of never charging for a house call if I didn't fix the set in situ; built up a reputation for straightforward dealing which, despite the slightly funny accent of a British immigrant to Canada, some 15 years later, may have helped me become elected to the areas first town council? And that in a day and age when TV repairmen didn't have the best reputation in the world (well at least around here) for ethical dealings! These days customers are a lot more cynical and questioning; and rightly so! BTW first heard about SPS in the telephone industry, before PC were common; when power supplier representatives started telling us about 'rectifier/power supplies' that had efficiencies of over 80%. |
Switching power supplies question.
Ian White GM3SEK wrote:
RFI-EMI-GUY wrote: There is a company that builds high voltage switchers for amateur radio amplifiers, and there have been construction articles to build these. (Check QEX magazine). Regrettably the author of the key article, and owner of the company "Watts Unlimited", died a few years ago. The commercial unit followed some years after the QEX article. It contained a number of important improvements but schematics were never published. The big unanswered question is why that design had no voltage feedback, and therefore had quite poor output regulation? (We can only speculate that a feedback loop must surely have been tried, but proved unworkable... and then wonder why that should be?) (snip) I worked on a 13.8 Volt SMPS made by TODD for Motorola as an OEM without any documentation. There was a large stud mounted 13.8 Volt zener on the output to clamp the voltage and some op amp circuitry to sense if the output voltage fell below 13.8V it would start increasing the PWM to charge the filter caps. This PS apparently never worked right because the transformer leads were never soldered and then were plastered in conformal coating. -- Joe Leikhim K4SAT "The RFI-EMI-GUY"© "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P |
Switching power supplies question.
On Oct 3, 11:51*pm, terry wrote:
On Oct 2, 11:37*am, wrote: On Oct 2, 4:29*am, raypsi wrote: On Oct 1, 12:55*pm, terry wrote: We recently modified such a power supply to get a single 12 volt DC output at about 20 amps for a particular, amateur radio application.. In order to do so we had to load one of the 5 volt outputs with a couple of amps in order to get the unit to work; but that's normal. Hey terry I did that very same thing loaded the 5volt with 5ohm at 5 watt. Ran my TenTec 526 off the 12 volt side of the PC power supply. I thought it was the sweetest thing since sliced bread. Then people started telling me I had this strange background noise. They asked me what was going on in my shack. I had this strange eerie noise in my shack, so they thought. Wasn't in my shack per say but it was the PC power supply. Nobody knew I was running a PC supply to power my rig. 73 OM n7zu I also use a modified PC power supply with no problems. I did add a filter removed from a commercial computer SMPS. I don't know the values of the components but its a Pi filter and the inductor is wound on what looks like a ferrite rod. The caps are some pretty big disk that had the writing rubbed off of them a long time ago. As Grumpy put it. I like to "Frankenstien" some of my projects. I have been giving some thought as to what it would take to modify a PC power supply for HV use. I have been thinking along two lines, 1 Connect a second step-up transformer before the rectifiers. 2 Replace the transformer with one with a HV winding putting a 5volt winding on the new transformer for loading and feedback. Jimmie- Hide quoted text - - Show quoted text - Great info: Thanks for all the ideas and especially about the warning that the HV would be on the line side (input) from115/230 volt mains. Unless a 60 hertz full isolation transformer were used; the weight and size of which sort of negates the idea of using a lighter weight SPS! I too used to fix TVs without power transformers, using selenium rectifiers (boy could they stink!) and voltage doubler circuits to provide B+. That was back in the mid late 1950s. I also made up a little B+ power supply in a box clipped in during house calls to show a customer that the problem was indeed inside the chassis and it had to be taken away for a 'bench job'! By that and means of never charging for a house call if I didn't fix the set in situ; built up a reputation for straightforward dealing which, despite the slightly funny accent of a British immigrant to Canada, some 15 years later, may have helped me become elected to the areas first town council? And that in a day and age when TV repairmen didn't have the best reputation in the world (well at least around here) for ethical dealings! These days customers are a lot more cynical and questioning; and rightly so! BTW first heard about SPS in the telephone industry, before PC were common; when power supplier representatives started telling us about 'rectifier/power supplies' that had efficiencies of over 80%.- Hide quoted text - - Show quoted text - The 300 volts you wanted is on the input side of the power supply, not what you wanted. This does not mean that the output of the power supply is not isolated from the mains. The type of switching power supply you wanted is probably doable. Think about removing the output transformer from a PC power supply and connecting it back to back with the transformer in a working power supply. The output could be rectified and filtered and you would have a cheap to free lightweight line isolated HV power supply. I am in thr process of trying this. I not getting much work done on it due to my present work schedule but in a few weeks things should get back to normal and I will have a chance to play with my toys some more. I am just getting in to SMPSs and find it amazing what these things willl do. For example I found a a +- 15 volt unit that puts out 100 amps for each voltage. I can hold the output transformers in my hand, they couldnt weigh more than a pound each. Jimmie |
Switching power supplies question.
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Switching power supplies question.
You might find this useful Jimmie.
I had some time to cobble together a DC-DC "transformer" this weekend. It is a half-bridge running at 200KHz and fixed 96% duty cycle. The turns ratio is 1:24 and the output is full wave rectified. I'm using an EDT29 core, I think the material is 3C90. The rectified AC line was ~160V and the output was ~1800V (I'm using a Simpson 260 so the voltages are thereabout.) After running 300 watts though it for two hours the transformer wasn't near warm. If I take this further I need to build a real load. A bucket of distilled water and some magnesium sulfate (epsom salt) isn't stable when it's boiling. It's a small transformer and light. It's not regulated but I think it could replace a much larger laminated steel transformer. Takes a rainy day for me to find any motivation for stuff like this. Maybe after winter arrives I'll build it up properly and try it in the SB200. 73 wrote in : The 300 volts you wanted is on the input side of the power supply, not what you wanted. This does not mean that the output of the power supply is not isolated from the mains. The type of switching power supply you wanted is probably doable. Think about removing the output transformer from a PC power supply and connecting it back to back with the transformer in a working power supply. The output could be rectified and filtered and you would have a cheap to free lightweight line isolated HV power supply. I am in thr process of trying this. I not getting much work done on it due to my present work schedule but in a few weeks things should get back to normal and I will have a chance to play with my toys some more. I am just getting in to SMPSs and find it amazing what these things willl do. For example I found a a +- 15 volt unit that puts out 100 amps for each voltage. I can hold the output transformers in my hand, they couldnt weigh more than a pound each. Jimmie |
Switching power supplies question.
On Oct 5, 9:11*pm, Grumpy The Mule wrote:
You might find this useful Jimmie. I had some time to cobble together a DC-DC "transformer" this weekend. It is a half-bridge running at 200KHz and fixed 96% duty cycle. The turns ratio is 1:24 and the output is full wave rectified. I'm using an EDT29 core, I think the material is 3C90. The rectified AC line was ~160V and the output was ~1800V (I'm using a Simpson 260 so the voltages are thereabout.) After running 300 watts though it for two hours the transformer wasn't near warm. *If I take this further I need to build a real load. A bucket of distilled water and some magnesium sulfate (epsom salt) isn't stable when it's boiling. It's a small transformer and light. *It's not regulated but I think it could replace a much larger laminated steel transformer. Takes a rainy day for me to find any motivation for stuff like this. Maybe after winter arrives I'll build it up properly and try it in the SB200. 73 wrote : The 300 volts you wanted is on the input side of the power supply, not what you wanted. This does not mean that the output of the power supply is not isolated from the mains. The type of switching power supply you wanted is probably doable. Think about removing the output transformer from a PC power supply and connecting it back to back with the transformer in a working power supply. The output could be rectified and filtered and you would have a cheap to free lightweight line isolated HV power supply. I am in thr process of trying this. I not getting much work done on it due to my present work schedule but in a few weeks things should get back to normal and I will have a chance to play with my toys some more. I am just getting in to SMPSs and find it amazing what these things willl do. For example I found a a +- 15 volt unit that puts out 100 amps for each voltage. I can hold the output transformers in my hand, they couldnt weigh more than a pound each. Jimmie- Hide quoted text - - Show quoted text - Grumpy , when David Smith was testing out the uwave oven power supply he use a big russian made triode as a dummy load. Forgot the #, GS 35B or something like that. I was going to get one, use it for a dummy load now and later build an amp if I dont blow it up. Jimmie |
Switching power supplies question.
On Oct 5, 9:11*pm, Grumpy The Mule wrote:
You might find this useful Jimmie. I had some time to cobble together a DC-DC "transformer" this weekend. It is a half-bridge running at 200KHz and fixed 96% duty cycle. The turns ratio is 1:24 and the output is full wave rectified. I'm using an EDT29 core, I think the material is 3C90. The rectified AC line was ~160V and the output was ~1800V (I'm using a Simpson 260 so the voltages are thereabout.) After running 300 watts though it for two hours the transformer wasn't near warm. *If I take this further I need to build a real load. A bucket of distilled water and some magnesium sulfate (epsom salt) isn't stable when it's boiling. It's a small transformer and light. *It's not regulated but I think it could replace a much larger laminated steel transformer. Takes a rainy day for me to find any motivation for stuff like this. Maybe after winter arrives I'll build it up properly and try it in the SB200. 73 wrote : The 300 volts you wanted is on the input side of the power supply, not what you wanted. This does not mean that the output of the power supply is not isolated from the mains. The type of switching power supply you wanted is probably doable. Think about removing the output transformer from a PC power supply and connecting it back to back with the transformer in a working power supply. The output could be rectified and filtered and you would have a cheap to free lightweight line isolated HV power supply. I am in thr process of trying this. I not getting much work done on it due to my present work schedule but in a few weeks things should get back to normal and I will have a chance to play with my toys some more. I am just getting in to SMPSs and find it amazing what these things willl do. For example I found a a +- 15 volt unit that puts out 100 amps for each voltage. I can hold the output transformers in my hand, they couldnt weigh more than a pound each. Jimmie- Hide quoted text - - Show quoted text - I had a little time yesterday and opened up a PC power supply and brought the 3 taps off of the transformer out to binding post. The plan is to build a transformer that will step the voltage back up to about 800 volts or so, enough for my little 6146B 6M amp. Jimmie. JImmie |
Switching power supplies question.
On Oct 6, 10:40*pm, wrote:
On Oct 5, 9:11*pm, Grumpy The Mule wrote: You might find this useful Jimmie. I had some time to cobble together a DC-DC "transformer" this weekend. It is a half-bridge running at 200KHz and fixed 96% duty cycle. The turns ratio is 1:24 and the output is full wave rectified. I'm using an EDT29 core, I think the material is 3C90. The rectified AC line was ~160V and the output was ~1800V (I'm using a Simpson 260 so the voltages are thereabout.) After running 300 watts though it for two hours the transformer wasn't near warm. *If I take this further I need to build a real load. A bucket of distilled water and some magnesium sulfate (epsom salt) isn't stable when it's boiling. It's a small transformer and light. *It's not regulated but I think it could replace a much larger laminated steel transformer. Takes a rainy day for me to find any motivation for stuff like this. Maybe after winter arrives I'll build it up properly and try it in the SB200. 73 wrote : The 300 volts you wanted is on the input side of the power supply, not what you wanted. This does not mean that the output of the power supply is not isolated from the mains. The type of switching power supply you wanted is probably doable. Think about removing the output transformer from a PC power supply and connecting it back to back with the transformer in a working power supply. The output could be rectified and filtered and you would have a cheap to free lightweight line isolated HV power supply. I am in thr process of trying this. I not getting much work done on it due to my present work schedule but in a few weeks things should get back to normal and I will have a chance to play with my toys some more. I am just getting in to SMPSs and find it amazing what these things willl do. For example I found a a +- 15 volt unit that puts out 100 amps for each voltage. I can hold the output transformers in my hand, they couldnt weigh more than a pound each. Jimmie- Hide quoted text - - Show quoted text - Grumpy , when David Smith was testing out the uwave oven power supply he use a big russian made triode as a dummy load. Forgot the #, GS 35B or something like that. I was going to get one, use it for a dummy load now and later build an amp if I dont blow it up. Jimmie- Hide quoted text - - Show quoted text - should have been GU 35B |
Switching power supplies question.
What will you use for an inductor in the output filter following the second transformer? wrote in : I had a little time yesterday and opened up a PC power supply and brought the 3 taps off of the transformer out to binding post. The plan is to build a transformer that will step the voltage back up to about 800 volts or so, enough for my little 6146B 6M amp. Jimmie. |
Switching power supplies question.
On Oct 8, 7:47*pm, Grumpy The Mule wrote:
What will you use for an inductor in the output filter following the second transformer? wrote : I had a little time yesterday and opened up a PC power supply and brought the 3 taps off of the transformer out to binding post. The plan is to build a transformer that will step the voltage back up to about 800 volts or so, enough for my little 6146B 6M amp. Jimmie.- Hide quoted text - - Show quoted text - Like you said I like to Frankenstien things. I have a filter from another power supply but I am not sure how well it will work as it was designed for about 25 amps. Basically thats a bridge I will jump off of when I come to it. Right now I am having enough trouble finding an old PC power supply I can get a transformer from. Its hard to believe about a couple of months ago I tossed about a dozen of them. Last time I listen to my wife. I do have a couple of transformers from some old Lambda power supplies. Thes are some really nice ones probably capable of handling a couple of Kwatts. Im not ready to experiment with them yet. Although this is learning by destuction it's cautious destruction. I will probably take a trip down to the local computer place this weekend and do a little dumpster diving or make a run on the goodwill store and see what I can get for $10. IF you havent figured it out by now I love building things from others discards. When I was in high schooI I built a killer stereo, I thought at the time, from old stuff I found in the dump that was the envy of most of my friends. Ive enjoyed doing it ever since. Jimmie Jimmie |
Switching power supplies question.
On Oct 9, 11:11*pm, Grumpy The Mule wrote:
Cobbling stuff together is lots of fun. *From Pressman's book you can figure out the inductor value. * I'm guessing a powdered iron toroid from the output of a PC power supply would work. *Probably need quite a few turns of moderate size ~22AWG magnet wire. *Maybe 300 turns... *ugh. Makes my hands hurt just thinking about it. *I guess a bobbin wound inductor would be better. *Gapped ferrite isn't bad! Check this sitehttp://schmidt-walter.eit.h-da.de/smps_e/smps_e.html* I try to stay away from dumpsters but if I see anything electrical or electronic in one it's neigh impossible. wrote : Like you said I like to Frankenstien things. I have a filter from another power supply but I am not sure how well it will work as it was designed for about 25 amps. Basically thats a bridge I will jump off of when I come to it. Right now I am having enough trouble finding an old PC power supply I can get a transformer from. Its hard to believe about a couple of months ago I tossed about a dozen of them. Last time I listen to my wife. I do have a couple of transformers from some old Lambda power supplies. Thes are some really nice ones probably capable of handling a couple of *Kwatts. Im not ready to experiment with them yet. Although this is learning by destuction it's cautious destruction. I will probably take a trip down to the local computer place this weekend and do a little dumpster diving or make a run on the goodwill store and see what I can get for $10. IF you havent figured it out by now I love building things from others discards. When I was in high schooI *I built a killer stereo, I thought at the time, from old stuff I found in the dump that was the envy of most of my friends. Ive enjoyed doing it ever since. Jimmie- Hide quoted text - - Show quoted text - From what I gather fro mthe website there is little danger in making L to large within reason so I can expect my bits and pieces removed from old power supplies to work. If they dont its probably because its too small. Jimmie |
Switching power supplies question.
On Oct 9, 11:11*pm, Grumpy The Mule wrote:
Cobbling stuff together is lots of fun. *From Pressman's book you can figure out the inductor value. * I'm guessing a powdered iron toroid from the output of a PC power supply would work. *Probably need quite a few turns of moderate size ~22AWG magnet wire. *Maybe 300 turns... *ugh. Makes my hands hurt just thinking about it. *I guess a bobbin wound inductor would be better. *Gapped ferrite isn't bad! Check this sitehttp://schmidt-walter.eit.h-da.de/smps_e/smps_e.html* I try to stay away from dumpsters but if I see anything electrical or electronic in one it's neigh impossible. wrote : Like you said I like to Frankenstien things. I have a filter from another power supply but I am not sure how well it will work as it was designed for about 25 amps. Basically thats a bridge I will jump off of when I come to it. Right now I am having enough trouble finding an old PC power supply I can get a transformer from. Its hard to believe about a couple of months ago I tossed about a dozen of them. Last time I listen to my wife. I do have a couple of transformers from some old Lambda power supplies. Thes are some really nice ones probably capable of handling a couple of *Kwatts. Im not ready to experiment with them yet. Although this is learning by destuction it's cautious destruction. I will probably take a trip down to the local computer place this weekend and do a little dumpster diving or make a run on the goodwill store and see what I can get for $10. IF you havent figured it out by now I love building things from others discards. When I was in high schooI *I built a killer stereo, I thought at the time, from old stuff I found in the dump that was the envy of most of my friends. Ive enjoyed doing it ever since. Jimmie- Hide quoted text - - Show quoted text - The computer aided design was a big help. I figured 16mH. I think I have something about that size. I have a 20mH choke at one amp that may work. What you think Grumpy. Jimmie |
Switching power supplies question.
On Oct 10, 9:34*am, wrote:
On Oct 9, 11:11*pm, Grumpy The Mule wrote: Cobbling stuff together is lots of fun. *From Pressman's book you can figure out the inductor value. * I'm guessing a powdered iron toroid from the output of a PC power supply would work. *Probably need quite a few turns of moderate size ~22AWG magnet wire. *Maybe 300 turns... *ugh. Makes my hands hurt just thinking about it. *I guess a bobbin wound inductor would be better. *Gapped ferrite isn't bad! Check this sitehttp://schmidt-walter.eit.h-da.de/smps_e/smps_e.html* I try to stay away from dumpsters but if I see anything electrical or electronic in one it's neigh impossible. wrote : Like you said I like to Frankenstien things. I have a filter from another power supply but I am not sure how well it will work as it was designed for about 25 amps. Basically thats a bridge I will jump off of when I come to it. Right now I am having enough trouble finding an old PC power supply I can get a transformer from. Its hard to believe about a couple of months ago I tossed about a dozen of them. Last time I listen to my wife. I do have a couple of transformers from some old Lambda power supplies. Thes are some really nice ones probably capable of handling a couple of *Kwatts. Im not ready to experiment with them yet. Although this is learning by destuction it's cautious destruction. I will probably take a trip down to the local computer place this weekend and do a little dumpster diving or make a run on the goodwill store and see what I can get for $10. IF you havent figured it out by now I love building things from others discards. When I was in high schooI *I built a killer stereo, I thought at the time, from old stuff I found in the dump that was the envy of most of my friends. Ive enjoyed doing it ever since. Jimmie- Hide quoted text - - Show quoted text - The computer aided design was a big help. I figured 16mH. I think I have something about that size. I have a 20mH choke at one amp that may work. What you think Grumpy. Jimmie- Hide quoted text - - Show quoted text - This is just way to cool. I took a 500watt Lambmda 15 volt switcher I had used to power a solidstate amp and wound another secondary on the transformer. I lost count of the numer of turns, maybe 100, but after filtering and rectifying im getting about 450 volts and it has been running since about 9:30 AM 3hrs putting out 150mA. These transformers look a little wierd They seem to be two sepated coils fastened together on a frame. It looks like you could take the secondary coil off and replace it if you wanted to. Grumpy , are you familar with this. Jimmie |
Switching power supplies question.
That's great news! You could easily buck regulate the +15
down for a filament supply as well. I've seen transformers with seperate primary and secondary windings. If a company is building s standard product line with various outputs they'll sometimes do that. Although it usually increases the leakage inductance so that's the down side. Sometimes the output inductor and transformer can be combined. I hope this goes though. I keep getting error 441 so I sent you an email regarding your last post. wrote in : This is just way to cool. I took a 500watt Lambmda 15 volt switcher I had used to power a solidstate amp and wound another secondary on the transformer. I lost count of the numer of turns, maybe 100, but after filtering and rectifying im getting about 450 volts and it has been running since about 9:30 AM 3hrs putting out 150mA. These transformers look a little wierd They seem to be two sepated coils fastened together on a frame. It looks like you could take the secondary coil off and replace it if you wanted to. Grumpy , are you familar with this. Jimmie |
Switching power supplies question.
Lots of great comments and ideas in this thread; thanks. Terry |
Switching power supplies question.
On Oct 11, 1:39*pm, Grumpy The Mule wrote:
That's great news! *You could easily buck regulate the +15 down for a filament supply as well. I've seen transformers with seperate primary and secondary windings. *If a company is building s standard product line with various outputs they'll sometimes do that. *Although it usually increases the leakage inductance so that's the down side. *Sometimes the output inductor and transformer can be combined. I hope this goes though. *I keep getting error 441 so I sent you an email regarding your last post. wrote : This is just way to cool. I took a 500watt Lambmda 15 volt switcher I had used to power a solidstate amp and wound another secondary on the transformer. *I lost *count of the numer of turns, maybe 100, but after filtering and rectifying im getting about 450 volts and it has been running since about 9:30 AM 3hrs putting out 150mA. These transformers look a little wierd They seem to be two sepated coils fastened together on a frame. It looks like you could take the secondary coil off and replace it if you wanted to. Grumpy , are you familar with this. Jimmie- Hide quoted text - - Show quoted text - Well, The transformer winding doesn separate the way I thoufgt they did. there is a pretty good sized gap betwen them,1/8" and it seems one is a choke. I was confused because I have a couple of old scrap power supplies that are made as previously described. They appeared to be the same so I made a very incorrect assumption. Jimmie |
Switching power supplies question.
On Oct 10, 1:11*am, Grumpy The Mule wrote:
I try to stay away from dumpsters but if I see anything electrical or electronic in one it's neigh impossible. (Nay impossible?????) .. Hi Grumpy: Nags me too!!!!!! (OK spot the pun?) But got to go; to unload my pickup of a free load of firewood got yesterday (couldn't say no to a second free batch in a week)! Gee there were two old SPS supplies lying there too; probably all soaking wet! I didn't even look at the old 14 inch TV lying there as well in the junk pile. |
Switching power supplies question.
Wet... well, I wouldn't pass them up!
I've salvaged a few pieces of gear from floods. My most cherished HP RF sweep generator came out of the mighty Mississippi river flooding in the early 90's. First I carefully brush off the gunk while washing with tap water. Then I flush with DI or distilled water dry with a fan. Finally flush with anhydrous isopropanol and dry with gentle warming. After that a bit of lubriplate on any switch detents or gears as needed. I take some things out first for special treatment, like meter movements. The distilled water flushes off the stuff we worry about, ionic contamination and the alcohol removes the water. At least that's what I hope for. I'm trying to reform and not drag so much junk home. Sometimes I can even pass up junked hardware without flinching. With technical books of any sort I'm not having much success resisting though. Mmm! Free firewood. Which reminds me, I need to fill the wood shed yet. Oak wilt disease is killing my trees but at least I'll be warm. terry wrote in news:01a69e21-6f4f-472a-9865- : . Hi Grumpy: Nags me too!!!!!! (OK spot the pun?) But got to go; to unload my pickup of a free load of firewood got yesterday (couldn't say no to a second free batch in a week)! Gee there were two old SPS supplies lying there too; probably all soaking wet! I didn't even look at the old 14 inch TV lying there as well in the junk pile. |
Switching power supplies question.
On Oct 15, 8:13*pm, Grumpy The Mule wrote:
Wet... well, I wouldn't pass them up! I've salvaged a few pieces of gear from floods. My most cherished HP RF sweep generator came out of the mighty Mississippi river flooding in the early 90's. *First I carefully brush off the gunk while washing with tap water. *Then I flush with DI or distilled water dry with a fan. *Finally flush with anhydrous isopropanol and dry with gentle warming. After that a bit of lubriplate on any switch detents or gears as needed. *I take some things out first for special treatment, like meter movements. The distilled water flushes off the stuff we worry about, ionic contamination and the alcohol removes the water. *At least that's what I hope for. I'm trying to reform and not drag so much junk home. Sometimes I can even pass up junked hardware without flinching. *With technical books of any sort I'm not having much success resisting though. Mmm! Free firewood. *Which reminds me, I need to fill the wood shed yet. *Oak wilt disease is killing my trees but at least I'll be warm. terry wrote in news:01a69e21-6f4f-472a-9865- : . Hi Grumpy: Nags me too!!!!!! (OK spot the pun?) But got to go; to unload my pickup of a free load of firewood got yesterday (couldn't say no to a second free batch in a week)! Gee there were two old SPS supplies lying there too; probably all soaking wet! I didn't even look at the old 14 inch TV lying there as well in the junk pile.- Hide quoted text - - Show quoted text - About 6 years ago while hauling off some junk from my in-laws home near Jacksonsonville Fl some stuff caught my eye at the dump. There were 3 tektronics scopes, a singer communications monitor and an audio test set. All worked and some of the pieces had current calibratiton stickers. Up until then I had been grumbling alot about wasting days of my vaction time cleaning. Jimmie |
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