I am looking at controlling the flow-rate of one liquid through a Solenoid Valve in a closed loop system, which takes input from another stream of liquid.

Objective is to mix the two liquids at the right concentration downstream.

I was able to source a PWM enabled valve, but how do I send the PWM signals to the valve? I have read about Controllers (a bit too expensive) and Drivers, but don't understand too much.

Any guidance would be appreciated. Thanks