AVR-Chat

At 02:49 PM 10/21/04 -0400, you wrote:

>At 01:09 PM 10/21/04 -0500, you wrote:
> >Since I'm protecting an analog signal line here I assume optos are
> >inappropriate
> >(at least I've only seen ones suitable for digital, as opposed to analog,
> >links).  I assume that the Transorb does not effect the signal line 
> until the
> >voltage exceeds it's rating?  I also assume they conduct in the forward
> >direction like a normal diode if the surge takes the data line in the 
> reverse
> >direction (i.e.: forward polarity with respect to the Transorb)?
>
>There are analog opto-isolation devices but they are more expensive.


And there are also industrial isolation devices for analog (see for example 
http://www.dataforth.com/catalog/doc_generator.asp?doc_id=266 ).  For some 
applications these make more sense than rolling your own (already fully 
tested, Burr-Brown's analog quality, rapid assembly, available with a wide 
range of input to output scaling) but they are pricey $200-$300 US 
AFAIR.  Analog devices also makes plug compatible modules.

I've used them for test benches.  Made any questions about isolation and 
accurracy a lot easier to deal with.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III