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Re: Fw: my $1.00 quasi-electrometer and more "electrostatics" experiments

At 10:17 PM 2/1/97 -0700, you wrote:
>Subscriber: harris-at-parkave-dot-net Sat Feb  1 22:13:37 1997
>Date: Sat, 1 Mar 1997 22:31:51 -0500
>From: Ed Harris <harris-at-parkave-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Fw: my $1.00 quasi-electrometer and more "electrostatics" experiments 
>
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>Hi all,
>
>	Due to Richard Hull's initial experimets on the production of
>excess mobile charge (in his case positive) during spark gap coil firing,
>I thought I'd try some experiments of my own. It's a very facinating
>subject, and I'm not sure we've really pinned the thing down completely.
>
>big snip


>Perhaps someone can repeat these experiments since they don't
>require much effort.
>
>By the way, I ordered some FET input op-amps from Burr Brown for
>$25 apiece. They have a typical  input bias cuurent of 0.040 pico-amp!
>This is getting pretty damn close to to the Keithly, eh? The number
>is OPA128LM if anyone is interested in making their own FET input
>electrometer.
>
>
>Take care,
>-Ed Harris
>
>Ed,

Good goin' guy.  I''m glad to see you did some experiments on the matter and
devised a cheapo electrometer of sorts.  I have an article which will appear
in the next ESJ Electric Spacecraft Journal where I supply a circuit diagram
for a low cost electrometer using and FET and Op Amp. I developed the little
circuit over this last summer at the request of Charles Yost.

  The Kiethley's main value is an absolute calibrated coulombmeter with the
100 teraohm input resistance (to within 2%).  This lends a true quantitative
nature to the investigations.

I note that you are using the homemade electrometer on rather sheepish
systems with none of them truely resonant and none of them consisting of
100KW peak impulse power levels like my little 30 watt system.  Thus you
should see exactly what you saw.  For simple corona, the charges sent are
always the charges collected.  Simple air ionizers do this.   Also the
ranges to my collector in my 30 watt system never were closer than 48".
There is a vast difference in the conditions of test here.  Your experiments
meet with all the conditions of tests I performed over a year and half ago.
This is why when those findings didn't extend to pulsed systems (positive
charge only), I became alarmed and curious.  Thus, the recent series of more
definitive tests.

Keep up the good work and thanks again for the input on the homemade
electrometer.


Richard Hull, TCBOR