This is called a ratiometric conversion, and it means that you don't need a
 particularly high spec reference, you can even get away with the supply rail if
 it's well smoothed and bypassed.

TTFN Paul

>On Tue, 11 Nov 1997 18:04:58 -0400, you wrote:
>
>>Dave Celsnak wrote:
>>.....
>>> Not sure what a load cell is....
>>.....
>>
>>A load cell is a piece of steel with strain gauges in wheatstone-bridge
>>configuration in it, normally used for weighting purposes....
>>
>>As the steel (and the strain gauges glued on it) deforms, the resistance
>>values of the bridge change, and there develops an output voltage =
>between
>>two of the legs of the bridge, normally a very small voltage (in the =
>order
>>of some mV), not so easy to measure and process in an industrial
>>environment with lots of noise, induction on cables, sometimes very high
>>temperature fluctuations, and the like. Also the input voltage to the
>>bridge must be held very constant, or there must be some means to =
>measure
>>that voltage too and compensate (software !!!) for fluctuations in it I
>>think.......
>Not necessarily - if you link the ADC reference to the bridge supply
>(e.g. connect both to a stable supply rail), the errors cancel out.
>You do need to be careful, though if there are significant offsets &
>tempcos to deal with. =20
>     ____                                                           ____
>   _/ L_/  Mike Harrison / White Wing Logic / wwl@netcomuk.co.uk  _/ L_/
> _/ W_/  Hardware & Software design / PCB Design / Consultancy  _/ W_/
>/_W_/  Industrial / Computer Peripherals / Hazardous Area      /_W_/