0
\$\begingroup\$

I'm trying to control a 12V piezo pump (with an inbuilt driver) and I'm a bit unsure how to use it safely. I'm using an Arduino Uno to control it, with an N-channel MOSFET rated at 60V 30A (with a 10K pull down resistor). I'm powering the piezo pump with a 12V 5A power supply. Looking at the data sheet for the pump, I noticed that it amplifies the signal from 12V to 250V (but doesn't draw very much amperage... about 40mA I believe).

Will the 250V be contained within the piezo pump and not ruin anything? Or do I need a more powerful transistor? I was told it would be a good idea to place a fuse in the circuit, but I didn't really get where it should go. Or which one to use.

I know when you use a motor with a MOSFET, a diode should be used to prevent a voltage spike from coming back and frying the MOSFET, is this the same for high voltage piezos?

The whole 250V amplification thing has me a bit concerned and I'd like some advice before proceeding. So, please let me know if I should be using a higher rated transistor, a diode and/or a fuse. Don't hesitate to let me know I'm missing anything either.

Thanks,

Matthew

\$\endgroup\$
0
\$\begingroup\$

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.

\$\endgroup\$
  • \$\begingroup\$ Turns out the pump I ordered only works at 5V. I shouldn't need a transistor in this case right?.. just a resistor so the arduino doesn't get too much current. Also can I power it directly from the arduino (5v pin), or should I use a separate power supply (i.e. 5V 500mA)? Maybe I should post another question for this, so I can post an image of the circuit and the code. \$\endgroup\$ – Matty D Apr 7 '15 at 17:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.