Re: Diode Strings

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

Original poster: "Richard W." <potluckutk-at-comcast-dot-net> 

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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.

David Rieben

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Yes, I've considered that after seeing them on Ebay. At 10Kva, my target, a
pig can push almost 3/4" amp which doesn't leave much safety margin. Well,
not as much as I'd like. I could have gone with 1N5408s (1000V 3A) but I got
the 6A10s at a good price IMO. I'll be using this bridge not only for the
pig but a MOT stack and NST bank depending on the project so I'd like
something a bit on the hefty side to *help* eliminate surge current
situations.
It's just that I'm having trouble understanding the need for resistors, and
in some cases advice to even using caps across each diode. And there always
seems to be talk about recovery time. If those are issues I needn't worry
about than all the better. :)

It'll be a while before I actually build the bridge and building with
confidence is much more fun than building with doubt. I just want to be sure
I'm building something I that isn't going to give the wife support for her
argument that I'm a nutcase. :D

Rick W.