dhenry:
You can create gain by inserting a resistor between the two 100k resistors and the output.
So if I put a 100k resistor in where you said that would give me a gain of 2.
What does the 100k resistor thats currently located between the output and ground?
I know the circuit I found does not allow for any conditioning of the PWM. I assume I will need some sort of low pass filter on the op-amp input.