At 21:03 26.05.98 -0400, you wrote:
>I need to measure a voltage 3-30VDC using a PIC, but the PIC has a totally
>different ground reference than the voltage I'm supposed to be measuring
>(the two circuits _are_ connected, but I have no way of knowing how because
>each install will probably be different).
>

Remember that you can use a external 8 pin AD converter and isolate the
digital interface. You would need 3 of the cheapest optocouplers that you
can find. In addition you will need a isolated PSU for the AD converter. In
my application, this turned out to bee the cheapest solution. ( analog
optocouplers are expencive ) As a bonus, there's no analog mess to calibrate.

Haavard.
------------------------------------------------
HŒvard T¿rring
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Norsk Elektro Optikk A/S       Tel: +47 67974700
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