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From: rick@sesi.UUCP (Rick Lotoczky)
Newsgroups: sci.electronics
Subject: Re: Need analog opto-isolator or equiv.
Summary: Another way
Message-ID: <834@sesi.UUCP>
Date: 27 Sep 90 22:37:22 GMT
References: <222@nachos.SSESCO.com> <1990Sep25.153656.2704@zoo.toronto.edu>
Organization: Structured Electronic Systems, Inc.  Rochester, MI
Lines: 19

> In article <222@nachos.SSESCO.com> elmquist@nachos.SSESCO.com (Chris Elmquist) writes:
> >Does anyone have a nifty circuit that will replicate a 0v to 5v DC
> >signal across an opto-isolated path..??  ...
> >I've thought about serial A/D and D/A chips...  but I haven't
> >found any that use the same data format over the serial link...
> 
Another way to do it would be to send a pulse width modulated signal through
an opto-isolator to a low pass filter on the other end.  The LPF will convert
the PWM to an eqivalent analog signal.  You will most likely have to linearize
this circuit, but that can be easily done in software.  I don't know what kind
of accuracy you need, but 0.5% or so should be attainable.

rick

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