Hi Guys.
I have a situation where a customer has some old industrial rectifiers that were controlled by a Pot.
Now i'd like to control them with the PLC but the pot circuit pulls too much current and the 0-10v outputs of the plc max at 45mA so, if i connect directly, the voltage drops on the plc output.
if i connect an external power supply and provide the 0-10v it works fine.
Now i've seen some ideas on the internet with FET+OpAmp with feedback to get linearity, i saw digital pots which could be controlled with digital plc outputs (up down steps).
An LM317, with 24v on the input and the 0-10v plc output to control the adjustment so i get 0-10 on the LM317 output. Although this uses de 24V power supply. Not ideal but it works.
this interesting one which gives me galvanic isolation too, which is important in this situation:
https://www.edn.com/use-a-photoelectric-fet-optocoupler-as-a-linear-voltage-controlled-potentiometer/What do you guys think? Any ideas?