Re: Diode Strings

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: tesla-at-lists.symmetric-dot-net 

On Wed, 18 Aug 2004, Tesla list wrote:

 > Original poster: "David Rieben" <drieben-at-midsouth.rr-dot-com>
 >
 > Rick,
 >
 > You may wish to consider the diode "sticks" removed from an
 > x-ray HVDC generator (x-ray transformer). These diode "sticks"
 > are amazingly small for their mammoth voltage ratings.
 > (app. 1" wide x 6" long x 1/16" thick G-10 PCB with usually
 > 15 to 25 individual diodes soldered in a series configuration).
 > There are NO balancing resistors invovled here
 > either. They are generally rated at 150 kV pk -at- appr. 1 amp.
 > Of course they are designed to operate at or near their max
 > ratings submerged in oil and usually at a low duty cycle.
 > However they can easily withstand the relatively "low" voltage
 > from a 14.4 kV pig without the need for oil-submersion and the
 > current rating may be the only issue for a really high powered
 > coil.

I suspect cooling may still be an issue, even at lower currents. The
voltage drop across those x-ray sticks is somewhere around 150 volts or
something like that. Say you run 400mA across them, that's 60 watts of
heat, or a couple watts per diode. Sounds you'd at least want a blower
across them.

KEN