Hi Cory,

The single transistor PWM/DAC circuit that I have sent you is working very well in an applications. I in fact have copied the circuit from there.

Using an op-amp shall raise the cost which I have to avoid.

Can you kindly tell me how can I maintain the linearity in the out put or at least decrease the curvature that is causing large voltage changes at the out put with same amount of change in the pulse width.

Regards

Simon