Been wanting to add some dosers and remembered I had some L298Ns (for motor control) in the parts bin so figured it was worth giving them a shot.
I wired as shown below and added pin 4 as a doser.... to my amazement it works fantastic. The output voltage to the motor is very linear as well based on the dosing speed set to pin 4.
They're pretty cheap, about $10 for 5pcs and each is made to control 2 motors for forward/reverse/speed. For reefpi use case I think we could even control 4 pumps since each output can be set to high/low and we only want the motor to run in one direction typically.
Seems to easy to be true though. From a circuity standpoint, does anyone see any issues with using this as a long term solution?