Re: Chokes, Caps, and resistance (fwd)

---------- Forwarded message ----------
Date: Wed, 17 Dec 97 12:24:51 -0500
From: Adam <absmith-at-tiac-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Chokes, Caps, and resistance (fwd)

>From: Joshua Resnick <seraphim-at-WPI.EDU>:

>    While still in the hunting, gathering, and planning stage for my
>coil I think this is the perfect time to ask questions about the low
>pass filters and other components that I need to attatch to my xfmrs.
>It is my understanding that the only reson for the chokes is to "block"
>any RF coming back from the tank from getting into the xfmrs. <snip>
>so the circuit would look like this?
>                                  gnd
>                                  _|_
>                                 ----  C
>              R          L         |          C                L
>----------/\/\/\/---()()()()------------|----| |---------()()()()()--
> xfmr  |                               spg                          |
>            R           L         _|_
>                                 ----  C
>                                   |
>                                  gnd

No.  The bypass caps should come before the Resistors and chokes, not 
after.  You should also have a safety gap from each transformer HV output 
to your RF ground (a gap in parallel with each bypass cap).   Most people 
would also recommend a safety gap across the main cap, set fairly wide 
(like 1" or so) in case there are strikes to the primary coil.

I adjust my safety gaps by connecting them (alone) to the transformer, 
and setting them to just a hair's width beyond the point where the 140VAC 
input from the variac can cause the gap to breakdown.  You need the 
variac to ramp the voltage up, since just plugging the transformer into 
the wall will create a turn-on surge capable of starting the gaps arcing, 
even at excessively wide settings.


Adam Smith
Epoch, Inc. Digital Music Project

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