RE: [TCML] Terry Filter

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

Hi Chip,

You're correct - the capacitance in the Terry filter is not extremely critical.  It's not like we're shooting for a specific cutoff frequency.

The published Terry filter schematic has six .0033uF (3300pF) caps per side, resulting in 550pF.  But your seven 820pF caps will only give you 117pF - more than slightly off.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: chipford@xxxxxxxxxxxxxx [mailto:chipford@xxxxxxxxxxxxxx]
> Sent: Monday, December 21, 2009 8:51 AM
> To: Tesla Coil Mailing List
> Cc: Lau, Gary
> Subject: RE: [TCML] Terry Filter
> 
> Really. I asked the question before I started building this thing and was told the cap
> pf value wasn't that important. My filter has (7) 820pf 2000volt caps/bank. This is off
> slightly from the .0033uf caps I see in most drawings. Please advise.
> 
> Chip
> 
> 
> ---- "Lau wrote:
> The capacitor configuration need not and should not be altered as a function of
> NST voltage.  Only the number of MOV's must be changed.
> 
> Someone once suggested that the capacitor string could be changed to a lower
> voltage when using a lower voltage NST to perhaps save a few pennies, but the
> string capacitance should always stay the same pF value regardless of voltage.
> 
> Regards, Gary Lau
> MA, USA
> 
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of Thomas Ryckmans
> > Sent: Monday, December 21, 2009 2:44 AM
> > To: 'Tesla Coil Mailing List'
> > Subject: RE: [TCML] Terry Filter
> >
> > Hi Chip,
> >
> > I used a few taps (banana plugs) on my filter - allowing me to select the
> > number of MOVs/caps that are seried
> >
> >
> http://picasaweb.google.co.uk/Thomas.Ryckmans/TeslaStuff#51914351748720649
> > 62
> >
> >
> >
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf
> > Of chipford@xxxxxxxxxxxxxx
> > Sent: 21 December 2009 01:31
> > To: tesla@xxxxxxxxxx
> > Subject: [TCML] Terry Filter
> >
> > I have my terry filter about 50% done. While building it, I asked myself a
> > question. Why would a person build anything but a Terry Filter capable of
> > protecting a NST of 15,000 volts? I ordered 14 MOV's from dig-key. For 4 or
> > 5 dollars more, I could have had 16. Now if i want enough for a 15k trany, I
> > gotta pay shipping again.Correct me if I am wrong. If I build a Terry filter
> > capable of protecting a 15K volt trany, I can use it to protect my 9000 volt
> > NST without any modifications. I bring this up because, as we all know,
> > parts get swapped from coil to coil and if I decide to built a larger coil
> > with my 15k trany later on, I could've just moved it over without worry. Am
> > I wrong?

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