New HV stuff, questions

Things at the limits.

Re: New HV stuff, questions

Postby Doug Coulter » Tue Mar 01, 2011 12:15 am

Nice looking job on the PCB!

Did you mean 187 uA? The CCFL only puts out 10ma at it's output -- tops.

Well, the CCFL has a 1 amp fuse on it...so if you keep the input to the lm317 down, shouldn't be much trouble. You'd rather have it heat up and shut down than blow that hard to find little fuse on the CCFL anyway.

You are going to find that you can't get as much voltage out of that stack as is implied by the ratio involved, because there will be severe corona losses -- you will have to paint it with corona dope to even get close before you get to current limit on the supply -- with no useful load applied at all. Or at least, that's what I found on mine here. I wound up painting it up to almost the tops of the caps to get it close to the theoretical voltage, no load. At that point, I could get a nice brush discharge into the air off a 1" resistor lead soldered to the HV terminal, which was just about the entire 12 watts the CCFL will put out best case. Cool, but at that multiplication ratio, there just isn't much current to drive anything else with. Good for "static electricity" type experiments, but not enough to say, make enough X rays to easily measure.

Please post things like this on their own thread! There's a new topic button on the board for that reason. This has nothing to do with the original topic at all, and as a result, no one will find it anyway.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: New HV stuff, questions

Postby William A Washburn » Tue Mar 01, 2011 5:26 am

You are correct...I misplaced a decimal point so these current is really in uA. Do you have any other suggestions for testing other than just a resistive load?
I have a few 40KV doorknob caps at 1500 pf or so. How would I charge these without having them discharge when I shutdown the stack? I'd like to see if charged
I could measure their voltage and come up with something similar to what I am getting directly off the stack.
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Re: New HV stuff, questions

Postby Doug Coulter » Tue Mar 01, 2011 10:20 am

Last warning -- this thread is for kilowatt supplies and questions about surplus parts to make them with. Start another for your project. If you think of the HV/HP forum as a book -- this is in the wrong chapter for teeny weeny supplies. Calculate the capacity of your stack capacitors in each leg -- you're already there with some stored energy, and nothing drags it down but leakage.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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