Re: [TCML] Terry Filter

["Paul Brodie" <pbbrodie@xxxxxxxxxxxxx>]

Herr Zap,
Dan is getting the MOV's from me and I bought the ones Terry advised me to 
buy, way back when I was planning to use a neon sign transformer to power my 
coil in 2007. I decided to use MOT's instead and never used these. They are 
the P7215-ND, 1800 volt 2500 amp ones from Digi-Key.

I think he will be all right as far as these MOV's are concerned. I also 
went back and pulled out the Terry filter drawing I was using at the time 
and my memory is almost as bad as my vision. ;-) It does indeed specify 8 
MOV's per side and not the erroneous 9 per side I thought I remembered. Once 
again, I find myself having to apologize. I feel like a broken record. Maybe 
I will just keep my mouth shut.
Paul
Think Positive
----- Original Message ----- 
From: Quarkster
To: Tesla Coil Mailing List
Sent: Friday, November 06, 2009 14:26
Subject: Re: [TCML] Terry Filter


Dan -

You need to carefully review the manufacturer's datasheet for your specific
MOVs to verify their rated RMS voltage, and compare this to what you expect
to see in your circuit. You also need to consider if you ever intend to
"overdrive" the NST with a variac (apply more than local AC line voltage) to
achieve greater coil output. If so, you might want to "design-in" physical
space for additional MOVs, and just use  jumper wires at these locations
until you are ready to increase NST input voltage.

Some useful technical data on MOV characteristics can be found at:
www.littelfuse.co.kr/data/en/Application_Notes/an9767.pdf

Regards,
Herr Zapp
----- Original Message ----- 
From: "Dan Casaregola" <ag2z@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, November 06, 2009 9:24 AM
Subject: Re: [TCML] Terry Filter


> I have no idea.  The legend on my drawing shows 12 movs for a 9kv nst,14 
> movs for a 12kv ;nst, and 16movs for a 15kv nst.  I can only assume that 
> your drawing would provide a greater safety factor.
> ----- Original Message ----- 
> From: "Paul Brodie" <pbbrodie@xxxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Thursday, November 05, 2009 10:01 PM
> Subject: Re: [TCML] Terry Filter
>
>
> > My drawing shows 9 MOV's on each side. Why the discrepancy?
> > Paul
> > Think Positive
> >
> > ----- Original Message ----- 
> > From: "Dan Casaregola" <ag2z@xxxxxxxxxxx>
> > To: <tesla@xxxxxxxxxx>
> > Sent: Thursday, November 05, 2009 6:38 PM
> > Subject: [TCML] Terry Filter
> >
> >
> > I'm in the process of building a filter for my 15k/30ma NST, and the 
> > drawing I have shows the number of MOVs required for the stated voltage, 
> > but it only shows 6 MOV. either side of center tap ground.  I remember 
> > reading somewhere that the number of caps should be the same as the 
> > number ov MOVs.  Is this correct?  Thank you  Dan
> > _______________________________________________
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