>
>I have a project I need 12 bit ideally, but I could settle with 8 bit. I
need
>to measure 0-12 volts.
>Any ideas or suggestions?
>
>Jon
>

You can simply do multiple 8 bits conversions of the same
voltage and add them. I used the 16C73 to build a thermometer
and I needed something like 16 bits of resolution. If you assume
the A/D converter has a white noise of 0.5 LSB, the added
precision will be proportional to the square of the number
of conversions.

example:

16 bits = 8 bits (base) + 16 bits / 2

16 bits = 65536

In this case, I did 65536 8 bits conversions over a period
of about 1.5 seconds, adding the result to a 24 bit
accumulator. After that, I simply used the 16 most significant
bits, and that`s it ! Very simple !

If you want to be absolutely sure it works under any
circumstances, just add 1/2 LSB of white noise to your
signal. The downside is the time needed to do
the conversions.

Patrick Lamontagne