I am trying to get a solenoid water valve to work with my raspberrypi pico and python. The system works with a LED but when I swap the led with the valve, add the diode and switch the power to 5v (external, not pico), the valve does not open. When I use a voltage meter, I can measure a resistance for a short moment when connect to the valve so I suppose it functions?

Below is the schematics (the triangle thing represents the solenoid valve). The diode is a 1N4007

The valve has a pulse with of 30ms at 5V so I programmed a PWM to open 30ms and then 200ms (I tried to follow this tutorial: https://learn.adafruit.com/use-dc-stepper-servo-motor-solenoid-rp2040-pico/solenoids )

Am I missing something?

  • residentoflaniakea@discuss.tchncs.deEnglish
    0·
    22 days ago

    The idea with the first valve is to drive it with an H-bridge. This allows for reversing polarity and is commonly used with motors to allow for spinning in two directions. This requires 4 MOSFETs. I’m not sure what type of MOSFET you are using but if you can find a simple dc motor to test this setup you can verify that it works with the one you have before you extend the circuit to an H-brigde configuration. This would be cheaper than buying another valve. You’d need two GPIO pins and careful design to not short circuiting the H-bridge.