Electrical – Controlling a 5W 12V DC water pump

fluid-pumpmotor controllerpwm

I have just bought this pump to circulate coolant through an experiment. I would like to control the pump output as it doesn't have any control on it.

It is being powered from a 12V 0.5A power supply.

How would be best to go about this? Voltage control or PWM?

Best Answer

My reccomendation for this would be using 'Current control' not voltage control using a MOSFET, and POTENTIOMETER: See: How to build the simplest DC Motor Speed Controller(Using Potentiometer and MOSFET)Updated
Alternatively You could use an adjustable DC-to-DC control module to set the voltage, however this will have a small dropout voltage which may not be desirable du to the reduction in maximum voltage output.
You could use a large, high-power potentiometer, but this is expensive.
If you are using a uController, then PWM control of the Motor will be an easy task. You would likely just need a MOSFET, uController (eg arduino) and a diode.

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Setting up piezo pump with arduino

I think that it's pretty safe to say that the 250V driving voltage used in the piezo pump won't affect your circuit. It's likely that the driving voltage is already isolated from the input, and even if you had a diode between the output of your FET, it'd have to be rated for > 250V in order to prevent it from breaking down. If the 250V coming back were a real concern, however, you'd want some kind of fuse that would trip at your MOSFET's rating of 60V so that it's physically isolated from any high voltages.

Lastly, the flyback diode isn't needed here. You're simply driving the pump with a PWM/analog signal. Assuming this thing is well designed, it would have any necessary protection already inside the box. I'd imagine some decoupling caps with the supply lines would be very beneficial, however.

Electronic – arduino – 5v piezo (micropump) with arduino

Default pin state on reset for the ATMega328P is input tri-state. Therefore, adding an external pull-up resistor to the signal line will keep it HIGH at startup. Connect a 10K - 100K resistor from the yellow wire pin to 5V.

Update:

pinMode(9,OUTPUT); enables the output, however startup config is LOW. Try:

digitalWrite(9,HIGH);
pinMode(9, OUTPUT);

Alternative

N-Channel MOSFET between black wire and ground. Connect gate to digital IO pin on board. Pull down pin using 10K resistor to ground. Now setting pin HIGH will turn on MOSFET and allow current to flow through pump. Problem with this approach is there is another current path through the signal wire so even if the MOSFET is off it could still run.

Best Answer

Related Solutions

Setting up piezo pump with arduino

Electronic – arduino – 5v piezo (micropump) with arduino

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