At 08:07 AM 8/25/97 -0300, you wrote:
>>Hi to all.
>>
>>I was wondering if anyone out there has attempted to make an
>>electronic scale using PIC's. I have a few ideas for the PIC side
>>of things but 'What to use for a SENSOR??' I was thinking of
>>strain guages but over here in sunny South Africa, these are either
>>hard to come by or very costly. I'm considering a LVDT (Linear
>>Variable Differential Transformer) option but I wan't to keep
>>mechanics to a minimum. I was wondering if any of you out there have
>>some idea's that you would like to share on the topic.

You may want to look at the new AD7730 chips.  They are specifically
designed for use with strain gage load cells.  They interface to a PIC via
an SPI bus.

These chip are really a specialized DSP with a programmable gain
instrumentation amplifier front end.  They have lots of capability for
filtering, tare, and self calibration and test.  They are also about $12 in
small quantities.

As you can tell, I like the chip.  But, beware, there is a steep learning
curve to use them.  Its the price you pay for all the functionality.


Russ