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Re: Diode Strings
David,
Keep in mind resistors have a maximum voltage rating. For example, 1/2
watt carbon film resistors typically are rated at 350 volts maximum working
voltage. 1/4 watt are 250 volts. So you should put 3 1/2 watt resistors
in series across each of your diodes. Several sources, such as Tech
America, sell 1/2 watt resistors for 1 cent each in qualtities of 100 or
more. What value? R = (V * V)/power = (350 * 350)/.5 = about 250K minimum
per single resistor.
--Steve
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Diode Strings
> Date: Monday, March 29, 1999 9:50 PM
>
> Original Poster: David Trimmell <davidt-at-pond-dot-net>
>
> Hello,
>
> I am looking for opinions and suggestions. For my tube coil work I am in
> need of some robust, high voltage diodes. Recently in some tube coil
> experiments I have been sending back decent surges into my doubler
diodes.
> Needless to say they have not fared to well. So, I am going to order some
6
> amp 1kV diodes from Digi-Key. These will be series strung using RC
snubbers
> across each diode. Each string will have 20 diodes, giving me about 20 kV
> PIV -at- 6 amp continuos (each diode is rated for 400 amp surge for 8.3 uS).
> My plan is to use the individual strings in a doubler circuit using max
of
> 3250 VAC, and four strings arranged as a fullwave rectifier for use in a
> 6500 VAC circuit -at- 700 mA max.
>
> My questions are: For the RC resistor value would a 1/4 or 1 watt be
best?
> What about value, 300K to 500K?
<SNIP>
> Regards,
>
> David Trimmell
>