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RE: Terry filter construction

Original poster: "Dirk Stubbs" <dirk@xxxxxxxxxxxxxx>

Thanks Terry. I just wanted to make sure before I soldered all the parts
together.


Dirk

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Tuesday, October 11, 2005 12:51 PM
To: tesla@xxxxxxxxxx
Subject: Re: Terry filter construction

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Dirk,

At 11:52 PM 10/10/2005, you wrote:
>I am now building my Terry filter but I have a couple questions. How
>much distance must be between separate the parts of different
>potential? For example, how much distance is required to prevent it
>arcing over the circuit?
>
>I have kept two things in mind while building these components.
>
>1.       Electricity follows path of least resistance.
>2.       Any distance smaller than safety gap will arc there
>first.   Approximately, how wide should the safety gap be set?

See the post Gerry just had:

""With the TC primary disconnected from the NST output, set the
safety gap spacing to "just not fire" with the NSTs maximum input
voltage (ie, 120Vac if plugged directly into the power outlet or
140Vac if using a step up variac). Once set, avoid the temptation to
widen the safety gap in order to get longer sparks.  During TC
operation, you can widen the main gap until the safety fires
occasionally (for static gaps).

Gerry R""

Here is a chart of spark gap distances vs. voltage:

http://hot-streamer.com/TeslaCoils/Misc/SGapVolt.jpg

The peak voltage on a 15kV NST is 15000 x SQRT(2) = 21000V.  The
chart says 20000V can arc 1.75cm (3/4  inch) between sharp
points.  But the filter is probably only seeing 1/2 that between
points in any places so 10kV gives about 3/8 inch.  So maybe double
that to 0.75 inch.  Try to avoid any really sharp edges since they
like to corona anyway.

>
>I have posted an image of my Terry filter template. I drew it up in
>AutoCad, then printed it up. This makes drilling the holes a lot
>easier and nicer. Do you see any errors in my template design?
>
><http://www.dirkstubbs.net/terry_filter_template.jpg>http://www.dirkstubbs.
net/terry_filter_template.jpg

Looks fine to me.

Cheers,

         Terry


>
>
>Thanks
>Dirk
>