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Re: [TCML] Safety gaps

A Terry filter contains three independent circuits and you can choose to
use any or all.  I have a web page detailing the how's and why's of
protection circuits - http://www.laushaus.com/tesla/protection.htm

1) A 3-terminal safety gap.  This is the cheapest of the 3 parts and by
far, is the most important.  But to be useful, the gap width must be set to
just wider than the NST open-circuit voltage sparking voltage.  If you set
it to where it stops firing when you're running your coil, you've
accomplished nothing.

2) An R-C low-pass filter.  This filters out VHF transients resulting from
some seldom-discussed spark gap behaviors.  Read my web page above for
details.  Since the components for an R-C filter are pretty cheap, no
reason not to use it.

3) MOV voltage limiters.  The MOV's must be carefully chosen to have a
clamping voltage well in excess of the peak cap-charging voltage, but not
so high as to never conduct, even in the face of an over-voltage
(uncontrolled resonant rise) event.  If you're going to skimp, this is
probably the place to do it.

Further questions and discussion - very welcome!

Regards, Gary Lau

On Tue, Mar 16, 2021 at 7:18 PM Adam James <adamjamesarmy60@xxxxxxxxx>

> Hello all,
> Is there anything better than a simple safety gap, but less than a
> terryfilter for SG coils?
> AJ
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