Date: Tue Oct 6 00:29:31 2009

Author: Bernard Cleyet

Subject: Re: Electroscope v. Voltmeter

Post:

Exactly!

I tried to duplicate my measurements by making the ground plane very
distant from the single trace, but the algorithm won't accept that.
I coulda plugged in to the equation the page offered, but it lost in
the triage. I found a similar phenomena -- near (a foot) my body or
a ground wire increased the cap. very much. I think I suggested a
"ground plane" to isolate the device from the ambiance. However, I
though of its being rather distant.

bc


On 2009, Oct 05, , at 06:46, George Herold wrote:

> Bernard, there is no ground plane on the back side of the board...
> Just
> the capacitance of a piece of wire with the 'reference' at infinity...
> Or in this case the inside wall of the box that the circuit lives in.
>
> (I made the mistake first time of putting on a ground plane, in which
> case the capacitance was order's of magnitude worse.)
>
> George H.
>
> -----Original Message-----
> From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-
> owner@lists.ncsu.edu] On
> Behalf Of Bernard Cleyet
> Sent: Friday, October 02, 2009 6:36 PM
> To: tap-l@lists.ncsu.edu
> Subject: Re: [tap-l] Electroscope v. Voltmeter
>
> Use very thick board?
>
> bc found a calculator for traces that included the thickness of the
> board and its relative permittivity.
>


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