Hi,
Subject line isn't really descriptive, but couldn't find a better one.
My bench supply has 10k ohm linear pots for setting the U and I levels, driven at 10Vdc.
Problem is, they're single turn pots, and there's to much play to set a correct value and have it stay there.
I've tried replacing them by a pic pwm output over a BC547 (to connect it to the 10Vdc), and an R/C filter behind it.
Schematic in attachment, might be a bit more clear.
It's working the way I want it to, except I can't get more than 6.23V at the output.
The 100k resistor has over 3volts over it at minimum duty cycle. If I replace it by a lower value the cap discharges to quickly.
I've tried a couple of different values but I'm can't seem to find a working solution. I realise it probably isn't possible to get the output all the way to Vdd levels, but this seems really low.
So... What am I doing wrong?