"Ignoramus6399" wrote in message
...
I have a bunch of 1N4007 diodes (1000v rated). If I put, say, 20 of
them in series, would that be sufficient to rectify 9,000 VAC safely?

Nah- 9kVAC is 12.7kV peak, call it 15kV peak. The rectifier has to stand
off full voltage on the backswing, so you need 30kV diodes, minimum. 40 or
50kV would be even nicer.

If you make a doubler (which uses diodes of the same rating, but produces
twice the output voltage) you can test the capacitors at a bit over rated
voltage (maybe 26kVDC, 118% of ratings). All the caps I've bought are rated
for 150 or 200% of rated voltage for some time, though that doesn't mean
these are.

If you bring up the voltage slowly, through a resistor or variac perhaps,
you can monitor it (assuming you get a voltage probe) and stop right at 22kV
or so.

I have read some articles discussing that since leakage amps are not
identical, that I need to put resistors in parallel with them. If so,
these need to also be 1kV rated resistors, right?

Yeah, but conversely, I recall reading an article which stated that modern
diodes are avalanche rated, meaning that if the voltage across one diode
increases to say, rated PIV, current starts going up (it looks like a really
high voltage zener diode), pulling it back into balance.

Capacitors across the diodes were also recommended, but today's diodes are
more rugged to pulse and avalanche conditions (we've come a long way from
"top hat" diodes!) so this isn't necessary either.

If not, would anyone have a suggestion for a 30 mA rectifier for 9
kVAC?

Could rip the diodes out of a few TV sets/monitors. Or use the flybacks
themselves, LOL.

Tim

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