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From: zimmer@calvin.stanford.edu (Andrew Zimmerman)
Newsgroups: sci.electronics
Subject: Re: Good Clamping Circuit
Message-ID: <1991Mar11.083343.26065@neon.Stanford.EDU>
Date: 11 Mar 91 08:33:43 GMT
References: <1041@eplunix.UUCP> <1991Mar10.093752.18289@neon.Stanford.EDU> <1542@tekig7.MAP.TEK.COM>
Sender: news@neon.Stanford.EDU (USENET News System)
Organization: Stanford University
Lines: 41

>
>                   D1
>         r------------|>|---------,
>         |                        |
>To Point |               D2       |
> "C" <---*---R2---*---------|<|---*
>                  |  |\           |
>                  ---|- \         |
>                     |    \       |
>                     |      \_____|
>  +5V --R2----,      |      /
>              *------|+   /
>     r--R2----'      |  /
>     |               |/
>    ---
>     -
>
>
>Brian Rhodefer

    In an earlier messge, Brian mentioned what was wrong with a circuit
I proposed.  He of course was right that it would be hard on the op-amp,
and therefore you should not use it.  
    His other point was that the original posting wanted it accurate
to 9 mV.  I wasn't aware of this.  (oops)
    I was also under the wrong assumption that the circuit was not to 
use an additional op-amp.  If that was wrong, I agree with the change
of Brian's which is putting a precsion diode where it should have
been in my circuit, at the input, with the clamp voltage either 
bing 2.5 (1.8) or with a 2.5 zener.  
    Sorry about the previous post.  

Brian:  Thanks for correcting my circuit.

Andrew
zimmer@calvin.stanford.edu

PS.  In my original post, I did say it was a while since I had done op-amps.
:-)