> >Hi-
> >version wets the appetite.  What we really need is a PICversion :-)
> >David
>
[]
> Of course if you want to do a PIC version, go ahead. ;-)

You know, I was trying to do this (i.e. a milliOhmmeter) a few
weeks ago. I used a temp. compensated LM334 as a current source,
and then read the (amplified) V at the A2D input of a pic. I would
send the output via RS-232 in testing, with an aim of going to
an LCD for a portable unit. I initialy used my bench supply
as the current source, and it worked nominally. As soon as I went
to the LM334, I would get screwy readings.

I suspect it was a ground loop of some kind. The pic a2d was
reading right, as I verified it with an O-scope. Something would make the
op-amp amplifier output wrong. As soon as I switched the current
source back to the bench supply, readings would be nominal again.
At first I thought it was the PC-RS232 connection, but disconnecting
that made no difference. Weird... Open to any ideas if anyone has one.
A milliOhmmeter can come in handy.

Regards,

Steve

> Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the reward"

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