Re: difference between instrumental amplifier and operational amplifier

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#883

From: William Janssen
Date: Tue, 14 Mar 2000 00:00

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Ron Dozier wrote:
> 
> In article <89smse$fkl$1@news.cz.js.cn>, peter <asdc@bigfoot.com> wrote:
> >Hi,can anyone tell me what's the general difference between
> >instrumental amplifier and operational amplifier? what kind
> >of application does each amplifier designed for?what kind of behaviors or
> >characters we could expect when using them in application
> >
> 
> I'll tak a stab at this question.  An instrumentation amp geneally
> amplifies the differnece between it's inputs in the presence of a large
> common mode signal. They may have an extremely low bandwith.
> 
> An operational amplifier on the other hand is a general purpose building
> block and is single ended.
> 
> A typical use for an IA is thermocouple signal conditioning or bridge
> amplifier and data acquisition where ground loops are a problem.
> >
> 
> Ron

Also, The op amp input impedance is not the same on the + and - 
inputs. If you are trying to use a balanced input the op amp.
won't be balanced.

You can make a instrumental amp from three op amps properly connected
so that only the + inputs of the op amps are used as inputs which
gives a balanced and high impedance input.

Bill K7NOM

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From: William Janssen <billj@calweb.com>
Subject: Re: difference between instrumental amplifier and operational amplifier
Date: 2000/03/14
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