Hi boys. If I did the math correctly, at max output 30.5 volts the drop on the 10K DS pot would be around 6.8 Volts. As Alain stated this cannot be tolerated by the DS chip.

I believe that it would be more practicle to use PWM on an output of the PIC, filter it and then feed a Pass transistor instead of the 317. As an example please refer to Elektor December 2001 issue (Digital controlled power supply).

Ioannis