RE: [TCML] Terry filters

["Lau, Gary" <Gary.Lau@xxxxxx>]

I'm sorry Dr, but anecdotal evidence like this is going to set us back to using leeches and bloodletting.

No one has ever performed a study on failure rates, ON EQUIVALENT HARDWARE, comparing R-C filters and L or L-R filter networks.  But there is overwhelming theoretical and simulation-based evidence that show that R-C filters are the superior topology.

Adding just a series inductor with or without a series resistor does nothing to form a low pass filter.  You need a capacitor; this is elementary circuit analysis.  On what basis do you conclude that this would "catch especially the very nasty high freq transients "?

I maintain that the use of chokes in NST/PT/pig protection networks should be abandoned.

Regards, Gary Lau
MA, USA



> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of resonance@xxxxxxxxxxxx
> Sent: Sunday, December 30, 2007 9:21 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Terry filters
>
> If you are really on a tight budget using used NSTs and can't afford a
> full Terry filter, there is an alternative.
>
> For almost 20 years I used a simple pair of air core RF choke made of 2"
> ID x 12 inch long PVC tube.  I wound it for 10 inches with #26 AWG PVC
> covered wire.  It seemed to catch especially the very nasty high freq
> transients that could break down the NSTs HV coils as these transients can
> form a "spider-web" like effect, essentially "crawling" over the windings
> until they connect and then the main power flows causes failure.
>
> Using a pair of these simple air core chokes I had only one failure in
> nearly 30 years.  Some of these coils with NSTs and these simple chokes
> are still in daily operation at museums for over 15 years.
>
> The failure I had was also a used NST so that could have entered into the
> factor --- the xmfr might have been ready for a failure from prior neon
> service.
>
> Food for thought anyway.
>
> Dr. Resonance

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