I'm a complete beginner attempting to build a basic circuit using a MOSFET to trigger a 24V push-pull solenoid from a Raspberry Pi's 3v3 GPIO pin.
I had someone else outline a circuit that I could use using the 3v3 GPIO output to toggle the MOSFET.
This is the circuit I'm currently using that works using the following parts:
- Gikfun RFP30N06LE 30A 60V N-Channel Mosfet TO-220 ESD
- NPN Transistor (P2N2222A 741)
- 24V Push-Pull Solenoid
- 2 X 10k ohm resistors
- Raspberry Pi 3
The Problems I'm Facing
When the Raspberry Pi is turned completely off, the 24V solenoid gets switched ON causing it to heat up (not ideal that it would stay on). I'm assuming this is because there's no current coming from the GPIO pinout to pull the MOSFET gate to off. Is there a way to prevent this? Ideally when Raspberry Pi 3.3v is ON, then the solenoid gets triggered.
When the Raspberry Pi is on and outputting the 3.3v from the GPIO, then the NPN transistor heats up a lot. To keep the solenoid off with Mike's circuit, I need the GPIO set to HIGH, which causes the 12v current to run through the NPN transistor, heating it up a lot.
So my main question, is there a way to build a circuit where the solenoid is OFF by default, and only triggered ON quickly when a 3.3v GPIO signal is detected?
Also, is using a MOSFET an ideal solution for using the GPIO on the Raspberry Pi, or is there a simpler way I could be turning my 24v Solenoid on and off using Raspberry Pi? As a beginner, I can't seem to find a simple, straight-forward answer to toggling a solenoid using 3v3 GPIO pins!