RE: disk capacitors any good ?

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

Original poster: "Ray Robidoux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <robidoux-at-basystems-dot-com>

Hi Shaun,

What I have found with ceramic caps is that they work
much better if you derate the working voltage by 4:1.
This is because with RF these caps tend to heat up and
that causes their capacitance value to drift allot and
kill any chances of tuning your TC. Not to mention
this heating can overheat and destroy the cap itself.
With a 4:1 derating you are limiting this heating to
to a tolerable level, that limits drift and keeps the
cap from self destruction. This will however bring your
max capacitance down by a factor of 4 as well.

1.5nf in_series_with 1.5nf = .75nf * 8 = 6.0nf

Ray

> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Wednesday, April 11, 2001 6:11 PM
> To: tesla-at-pupman-dot-com
> Subject: disk capacitors any good ?
>
>
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <biomed-at-miseri.winnipeg.mb.ca>
>
> Hello coilers!   Help!
>
> I need some advice from you more experienced builders.
>
> I have got my hands on a bunch(16)  of free high voltage (30kv)
> capacitors.
> They are from a power supply of an x-ray generator immersed in
> oil and in a
> large metal box.  All 16 of them are soldered to a cocroft walton (I think
> thats how it's spelled) voltage multiplier board.   They are 1 inch round
> and 3/8 inch thick with the leads comming out from each side.
>
> The labeling is  152M
>           TDK
>
> 1.5 nF  * 16 caps =  24nF        if all paralleled             and I can
> remove  any number for smaller values
>
>
> Question:   would these BIG disk caps be any good for a neon sign tesla
> coil.        I hope they are but what do you think!.
>
> also there are 20 diodes  all hv on the same board,  2 stepup
> transformers,
> 4 - 200 Mohm resistors and other stuff, cool hey!
>
> Shaun Epp
> Winnipeg, Manitoba
> Canada
>
>
>
>