Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!psuvm.bitnet!art100
From: ART100@PSUVM.BITNET (Andy Tefft)
Newsgroups: sci.electronics
Subject: Op amp gain control
Message-ID: <71213ART100@PSUVM>
Date: 12 Feb 89 00:05:24 GMT
Organization: Penn State University - Center for Academic Computing
Lines: 15

Probably a simple question, but:

I want to be able to control the gain of an opamp by an external control.
Normally I would just put a potentiometer in the feedback loop of the
amp but I want to be slick about this. I want the gain to be controlled
by the number stored in a register (probably converted to an analog
voltage or current in a D/A converter). How can I do this? Is there
some sort of inexpensive, small "voltage-controlled resistor" or something
that will do this for me?

Please mail responses if possible. I don't get too many chances to
read this group.

Andy Tefft

ART100@PSUVM.BITNET, a1t@ecl.psu.edu