At 01:55 03/19/99 -0500, Vincent Deno wrote:
>> several months ago I asked a question about bipolar A/D inputs....say,
>> -5v to +5v.  Someone suggested something using just a couple of
>> resistors to use as a voltage divider.  Could anyone say that again?
>> All of my messages were deleted....
>
>What they were probably referring to was:
>        Vin ----+
>                <
>                < R1
>                <
>                |
>                +--- Vout
>                |
>                <
>                < R2
>                <
>                |
>                GND (=0V)
>
>(Finally) => Vout=(Vin*R2)/(R1+R2)

the problem with this is that a negative input results in a negative output. in
the case of -5..5V => 0..5V, it is better to reference the divider to the 5V,
like this:

                +--- +5V
                <
                < R1
                <
                |
                +--- Vout
                |
                <
                < R2
                <
                |
        Vin -----

Now the output is (if you make R1=R2) 0..5V

ge