> Russell, this is indeed a good introductory issue !
> However, I have seen an 1Kg kitchen scale, with 8 pF full delta-C
> variation for the whole 1Kg range, and the sensor was connected directly
> to the microcontroller !. The resolution was about 1g and precision about
> 10g. How they did this ?

Sorry - miseed this post at the time.

I think differential sysmmetric capacitance sensing would allow all this. I
would love to see the sensor though.
The key is that, even if the capacitance is small, the output range can be
almost the full driving voltage.

I wonder if Peter is willing to provide a closeup picyture of his scale's
sensor ? :-)


        Russell mcMahon

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