I need to speed control a 12 amp 24 voltDC compressor using an Uno, PWM pin. I have been looking for something akin to the TIP120 but capable of 15 or more amps.
There are several webpages that go into the maths but the mists decend and I'm not qualified for this sort of analysis.
The application is to alternate between running an air compressor supply line into a 30 liter water tank. The air pushes water out of the bottom of the tank out to our farm 5000 gal tank. After 5 min, the air line vents to ambient and the 30 liter water tank fills by syphon 12 minutes.
The problem is the PV supplied compressor needlessly draws the full 12 amps from the battery/PV supply. I need to use PWM to back off on the supplied current. I need to experiment with this until I can balance the drain from the air pump motor with the input from the PV.
The pressure at full noise goes up to 38 PSI. I only need a fraction of that to move the water through the lines. IOW there is virtually no head, just 700 meters of 20 mm plastic pipe.
But I dont know what would be a good transistor for this design. I think a mosfet but the 510/520 data sheets say 10 amp absolute max drain-source continuous current...from there I just get more confused.
the need is getting urgent, we are at a summer long drought.
RECAP: I need a PWM control-able power transistor to vary the current to a 12 amp 24 volt DC motor
sorry for the novel :)