DC Curent and Voltage controll

[Pexy]

Hy guys. I am wondering if you could controll the curent from a DC PSU (12/15V 5/3A) just with a potenciometer (regulated resistor) or whould you need something else?
And what could you use to controll the voltage
I would prefere if the solution would not be a pre-build unit, but if it has to be one let mo know what should it be.

 

[andre_luis]

There will be very limited situations on which you could do that, but even so, the adjust would be possible in a narrow range of the output. In any case, you should necessarily to have access to the circuit schematic for analyzing and searching the resistive divider where is taken the feedback sample.

 

[Audioguru]

A potentiometer can feed an adjustable reference voltage to an opamp. The opamp can compare it to a voltage that is produced by sensing the output current in a series current sense resistor. The output of the opamp can feed a diode in series with the input of the voltage setting output amplifier. Then when the sensed current exceeds the set amount of current you want as the maximum, the output voltage of the power supply circuit is reduced until the current does not exceed the setting. The current sense resistor can be inside the feedback loop of the voltage amplifier so it does not affect the output voltage.

To limit or regulate current, the voltage must be reduced due to Ohm's Law.