Would it be possible for me to control the level at which the water pump operates if I use this method? Ie full power, low power, etc.
I'm not sure what you mean by "level." I think you mean motor speed, seehttp://arduino.cc/en/Main/ArduinoMotorShieldR3
Yes logic level, means that the gate will respond when at 5V.Yes, I believe a MOSFET is the most effective method, I do not like relays and if the motor for the pump is DC, you can use a MOSFET with PWM to adjust the power of the motor (but it is not a linear relationship), which you can't do with a relay.
There Might be an issue here as 'most' water pumps are BIG 50 or 60 Hz devices that really don't like to be turned off and on at a high rate or speed. Variable flow pumps have a VFD controller (variable Frequency Drive) controller that controls the rate of speed of an induction motor. Switching an induction motor off and on at PWM speeds is likely to have a lot of Magic Blue Smoke associated with it's use... Not really a great Idea... A relay controlled by a mosfet is called for here and this relay controls the pump control relay which is typically controlled by a 24VAC contactor or controller relay. There are Very high voltages and Currents associated with pumps....Even 110VAC is Extremely dangerous to associate directly with an Arduino... Always use an intermediate 24 VAC control link. I've commercially make 50 HP pump controllers that operate from 3 Phase 440V AC Mains sources. All work well and safely with the intermediate control link.Doc
This is a small 12V pump though. Not sure if that will still apply or how much in this case but please do let me know what you think!http://www.ebay.com/itm/6-5L-12V-CPU-Cooling-CAR-HHO-DC-submersible-Water-Pump-/350251953553?pt=BI_Pumps&hash=item518ca4ad91#ht_1321wt_1035
You can certainly use a mosfet (or even a bipolar transistor, if you choose it carefully) to turn that pump on and off. You can try using PWM to vary the speed, however it uses a brushless motor, so it may not work very well with PWM. You will have to try it and see.
Quote from: dc42 on Aug 15, 2012, 10:32 pmYou can certainly use a mosfet (or even a bipolar transistor, if you choose it carefully) to turn that pump on and off. You can try using PWM to vary the speed, however it uses a brushless motor, so it may not work very well with PWM. You will have to try it and see.Oh okay. Anything else I can do? Maybe something that will read the PWM signal and use it to supply steady power (the level of which would be based on the level indicated by the PWM pulses) to the motor?
I'm looking at motor drivers now, but not sure if there's much benefit over just a mosfet.
You can use and inductor and capacitor to smooth the power to the motor. If you go this route, it's best to increase the PWM frequency, so that you can use a smaller inductor and capacitor.
The benefit of a motor driver is that is can reverse the direction of the motor - if it is a standard brushed type.