# [TCML] Terry filters

Lau, Gary Gary.Lau at hp.com
Sun Dec 30 22:29:55 MST 2007

```Absolutely correct!  But note that the "C" is the one in the TF, not the primary cap.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> Behalf Of bartb
> Sent: Sunday, December 30, 2007 10:53 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Terry filters
>
> A Terry Filter can dissipate about 100 to 200 watts easily.
>
> Each gap conduction must be added. For a Terry Filter or similar,
> consider the following:
>
> P = 2 x 0.5 x C x V^2 x BPS
>
> Now do the math.
>
> You'll find it is still be low comparatively, but not quite as low as you are thinking.
>
> Take care,
> Bart
>
>
>
>
> Bill Lemieux wrote:
> >
> > On Dec 30, 2007, at 12:15 AM, Neal Namowicz wrote:
> >
> >> Hello everyone,
> >> Just a question about terry filters, since the topic seems to be
> >> cropping up a lot lately. How much loss is there when using them? I'm
> >> no EE, but any time I see the main power coming in going through
> >> resistors, there must be some loss.
> >
> > power dissipated in a resistor = the square of the current X resistance
> >
> > So, for a TF with 1kΩ resistors, and a 15kV / 30 ma NST
> > short-circuited by the spark gap, we dissipate 0.9 watts in the
> > resistors, or 0.2% of the transformer's power.
> >
> > With a 15kV / 120mA NST driving a short through the filter, we
> > dissipate 14 watts, or 0.8% of the transformer's maximum power.
> >
> > (somebody check my math, I'm still waking up this morning)
> >
> >> Also, are the TF's "one size fits all", or can the components be
> >> sized to correspond with how much potential power you have coming in?
> >> It seems that we endeavor to eliminate "lossy" components. "Using
> >> beer bottle caps? Replace them with an MMC." Don't use a dimmer
> >> switch, too "lossy", etc. Ultimately, is using a TF a trade-off
> >> between loss and protection? Kind of like driving a newer car that
> >> comes with a mandatory explosive device (air bag) in the steering
> >> wheel. "But it's for your protection!" Just one of a number of
> >> reasons my two vehicles are 1964 and 1980 Chevys. The k.i.s.s.
> >> principle, and no bombs staring me in the face. But I digress, sorry.
> >> So, what do you think about the terry filters?
> >>
> >> Neal.
> >>
> >> _______________________________________________
> >> Tesla mailing list
> >> Tesla at www.pupman.com
> >> http://www.pupman.com/mailman/listinfo/tesla
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla at www.pupman.com
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> >
> >
> >
>
>
> _______________________________________________
> Tesla mailing list
> Tesla at www.pupman.com
> http://www.pupman.com/mailman/listinfo/tesla

```