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#15
October 8th 08, 03:09 PM
posted to rec.radio.amateur.homebrew
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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 |
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