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DPRG: op amp question

Subject: DPRG: op amp question
From: John Alway jalway at icsi.net
Date: Tue Aug 3 15:04:45 CDT 1999

     The best general book I know of on electronics is "The Art of
Electronics" by Horowitz and Hill.   It's a hefty text, but written in a
clear, down to earth manner, as if you were there with an expert, and it's
full of examples.  It even gives examples of bad circuits!  I love this
book!  As to OP AMPs, it has a chapter devoted to them.  If you decide to
get it get the latest addition.  I found mine at Amazon over Christmas.

      ...John

- -----Original Message-----
>From: john.r.strohm at bix.com <john.r.strohm at bix.com>
To: dprglist at dprg.org <dprglist at dprg.org>
Date: Tuesday, August 03, 1999 3:00 PM
Subject: Re: DPRG: op amp question


>>Maybe this is a dumb question, I don't know. (Are there any op-amp
>>tutorials
>>on the Internet? Something like the Encoder basics articles would be nice.
>>:) Is there any reason for V+ and V- supplies on an op amp? Can I connect
>>ground to V-? I have a RadShack TL082 "dual bifet op amp" which doesn't
>>need
>>a ground connection, only V+ and V-...  For other op amps that have gnd,
>>why
>>can't I use a voltage divider to create a level between V+ and the real
>>ground?
>
>There was a wonderful paperback book in the 1970s.  I can't remember the
>title, but the authors were Hoenig and Payne.  It spent almost the entire
>book on simple circuits involving op amps.
>
>You have V+ and V- supplies because any signal you are going to feed into
>or out of the op amp must lie between those rails.  For some applications,
>it is more convenient to have bipolar signals referenced to ground rather
>than unipolar signals referenced to 1/2 of V+.
>
>Op amps grew out of analog computers: it is EXTREMELY convenient to use
>bipolar signals to represent things like force, velocity, or acceleration.
>
>You can use the voltage divider to develop a reference ground.  Best way to
>do it is make a voltage divider and then feed a unity gain follower from
>the reference node: this gives you a zero impedance reference source.  (For
>a unity gain follower, you feed the signal into the noninverting input of
>the op amp, and tie the inverting input directly to the output.)
>
>It is an EXTREMELY worthwhile exercise to work through the equations of the
>basic op amp inverting gain amplifier circuit, using the standard
>simplifying assumptions: zero output impedance, infinite input impedance,
>infinite gain.  It is not a pleasant thing for the
>algebraically-challenged.
>

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