John wrote:

> Does anyone have an idea of how i can increase the sensitivity of
> a 10 bit A/D
> on a 12f675 ?


If you draw a straight line graph, the formula is Y=MX+C where M is the
gradient and C is the offset.  What you are asking for (I think) is to get a
14 bit number out of a voltage from 0-5V.  This could be done with some very
careful opamp signal conditioning.  You need to raise the gradient of the
line, but at +5v input, this would give you too many volts at your A-D....
Ok, so you could have a comparator checking the voltage at the A-D and when
it reaches +5v, it could put an offset back into the amp section bringing it
back to 0v.  With that same comparator, you could then tell the PIC there is
another MSB to add.  You could then calibrate the device to compensate for
ant offset.

Brian.

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