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From: Mike Monett
X-Mailer: Mozilla 2.02 (Win16; I)
Subject: Re: Meter movements
References: <3DD47F82.14E8608@videotron.ca> <firstname.lastname@example.org> <3DD6F1BE.4F3C0ED0@earthlink.net> <email@example.com> <3DD7ADF4.2B1E@Spam.Bots> <3DD7C944.7CBC@Spam.Bots> <firstname.lastname@example.org> <3DD8E431.4D57@Spam.Bots> <email@example.com>
Date: Mon, 18 Nov 2002 05:38:50 -0800
NNTP-Posting-Date: Mon, 18 Nov 2002 05:38:50 EST
Organization: Bell Sympatico
fred bartoli wrote:
> Not at all Mike.
> The opamp will force constant current into the meter movement. So its
> driving impedance is infinite and there will be no damping at all.
> You'll have to add the parallel resistor to damp the movement or to provide
> a secondary feedback path from the top side of the meter. Don't have time to
> find what the best compensation network should be but finding it should be
> almost straightforward.
Thanks Fred. I had come to the same conclusion after posting, but you beat me
I generally find the damping resistor by trial and error. Just place different
values across the meter and rotate it, then watch how the needle settles. Pick
the one that give the most pleasing response.
The value doesn't seem very critical - changing it by +/- 10% has little
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