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[SOLVED] how to find very high voltage capacitor from scratch

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Hi.
One guest of mine who live far far away from me has to built 13KV power supply at 50mA output with flyback topology at 31KHz from 230VAC input. i suggested a rough estimated output filter capacitor of 0.47uF for 3V ripple. i don't work on high voltage power supplies experience due to small scale setup and lack of safety precautions. neither he can find this capacitor from his local market. he does not want to import it. so what i do for him? any suggestions. :???:
 

look for some old / bad FM radio .. or SMPS (could be computer SMPS or even mobile or laptop chargers)
a chargeable battery powered circuit will also do
 
A series circuit of "available" capacitors with respective high ohmic resistors to guarantee equal voltage share. Or implement the circuit as a cascade rectifier, which involves splitting of the total output voltage across mutiple capacitors anyway.
 
First let me point out to you that a 0.47uF capacitor at 13KV holds about 40 Joules of energy. That much energy at such a high voltage is extremely dangerous, and can easily kill people. Hell, any circuit with 13KVDC is deadly dangerous. But you should exercise extreme caution, and I recommend starting off with a much smaller capacitor value (like 10s of nF).

Anyways you'll usually want to look at industrial surplus dealers. You can sometimes find amazing stuff for very low prices. Ebay is also an option.

Microwave oven capacitors are generally ~1.0uF and are rated for >2KVrms, and are pretty easy to find (both in a junkyard, and on the market). A bank of those would probably work fine (with balancing resistors as FvM suggests).

And again, please be careful.
 
amu_cpln said:
look for some old / bad FM radio ..
Click to expand...

yes i have suggested him to use metal sheets and make his own capacitor as single capacitor. the common thing is that variable tuning capacitor is also made up of metal sheets but it can move also.

FvM said:
A series circuit of "available" capacitors with respective high ohmic resistors to guarantee equal voltage share. Or implement the circuit as a cascade rectifier, which involves splitting of the total output voltage across mutiple capacitors anyway.
Click to expand...

yes i have conveyed him both solutions. but he is insisting on that they both method does not work. i think he is not serious or he is observing himself overcompetent and is lazy in using internet research. some time simple persons take themselves too seriously. :)

mtwieg said:
First let me point out to you that a 0.47uF capacitor at 13KV holds about 40 Joules of energy. That much energy at such a high voltage is extremely dangerous, and can easily kill people. Hell, any circuit with 13KVDC is deadly dangerous. But you should exercise extreme caution, and I recommend starting off with a much smaller capacitor value (like 10s of nF).

Anyways you'll usually want to look at industrial surplus dealers. You can sometimes find amazing stuff for very low prices. Ebay is also an option.

Microwave oven capacitors are generally ~1.0uF and are rated for >2KVrms, and are pretty easy to find (both in a junkyard, and on the market). A bank of those would probably work fine (with balancing resistors as FvM suggests).

And again, please be careful.
Click to expand...

I have suggested him to start from 10nF and gradually go towards actual capacitor. and also told him to be very very careful.

well, i'm not making or neither have plan to make this level supply in near future.
 

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