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Re: [TCML] Primary selfC



Hi Gary,

at 12/24MHz then the pf Value would only be a few pF at a guess... though as I plan to run my prrimary like 1mm gap then it could prove a bit more of a problem... I am wondering if I can just use the flat capacitor plate calaculator and treat it is a long 4 layer stack... or something along those lines... it does not have to be exact... though my caps are 570pF each which will add up to 3nF (ish) so the primary capacitance if its in the order of 100pF then its a bit of a jump....

Chris




----- Original Message ----- From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Thursday, July 24, 2008 10:05 PM
Subject: RE: [TCML] Primary selfC


Hi Chris,

The short answer is I don't know of a formula or calculator, but it's relatively easy to actually measure it.

Just as you drive the base of a secondary with a signal generator and monitor a capacitively coupled scope probe for a peak, you can do the same with a primary. With a known inductance and Fres, you can calculate the Cself. I think my Fres was about 12 MHz. I recall that for mine, it wasn't too many pF, and certainly not something that would affect primary tuning.

Regards, Gary Lau
MA, USA

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Chris Swinson
Sent: Thursday, July 24, 2008 3:59 PM
To: Tesla Coil Mailing List
Subject: [TCML] Primary selfC

Hi all,

Does anyone know how to work out , or know of an online calculator for
crunching primary Self Capacitance ?

I know its not normally needed to know these values, though my tank cap is
3nF in my High Q design, and now my primary will be 4 turns of 2" wide strap separated about 1mm apart.. the dia is about 22" so its a fair length and it could add up to a few hundred pF which is a real problem.. so I need to know
the values...

Cheers,
Chris

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