I need to create a circuit that will enable my 8051 to digital change an output voltage. A digital pot would be prefect however, my maxium voltage is above all the digital pots available. My maxium voltages varies from 30VDC-50VDC. I would like to develop a circuit that will incorporate an OP-amp to control my output voltage. So, If i set the digital pot to 50% ie2.5Vdc of my board voltage. I would get 50% of the maxium voltage which would be 50% of x's Vdc. Where x can vary from 30-50vdc.

Can some recommend which type of OP-amp configuration would be best for this application.