At 05:15 PM 12/22/02 -0500, you wrote:
>There are several manufacturers of load cells.  Here is one
>http://www.entran.com/ltoc.htm
>But there are others.  The real trick in application of load cells is the
>error budget.  To minimize drift, you need a highly stable excitation
>voltage.

"Stable" is about right, it does not have to be very accurate- you can get
16 or 18 bit accuracy with a 5% accurate excitation voltage.

>  In high precision you should apply a pulse and capture with a duty
>cycle such that the error introduced by self heating is eliminated.

And consider low-frequency swapping of polarity to remove unwanted
thermoelectric potentials.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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