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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.analog
Subject: Re: Basic electronics -- FETs
Message-ID: <655@kitty.UUCP>
Date: Sun, 22-Dec-85 11:19:48 EST
Article-I.D.: kitty.655
Posted: Sun Dec 22 11:19:48 1985
Date-Received: Wed, 25-Dec-85 03:19:51 EST
References: <> <909@nmtvax.UUCP>
Organization: Recognition Research Corp., Clarence, NY
Lines: 22

>     Is it possible to use a FET as a solid-state potentiometer, and if
> so, what sort of driver do you need for it (AC, DC offset from ground, ...)?
> The application is digitally controlled volume, resonance of filters, etc.
> If I can use D/A converters driving some simple pot-equivalents, it would
> make life fairly easy, but I'm not familiar enough w/ analog type stuff
> to know if it'll work.  Comments?

	Your desire has been made easier to fulfill by a number of IC products
on the market.  Try an Intersil P/N VCR2N, VCR4N, VCR3P or VCR7N.  These are
JFET integrated circuits billed as "Voltaged Controlled Resistors".  A simple
DC voltage is used to control the JFET gate and hence the effective resistance.
	You may also wish to look at: (1) the National Semiconductor P/N LM1035
Dual DC Operated Tone/Volume/Balance Circuit which is an IC providing DC
control of the above named functions; (2) Motorola P/N MC3440P Electronic
Attenuator IC.

===  Larry Lippman @ Recognition Research Corp., Clarence, New York        ===
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