I have an arduino uno which turns on a water pump (12V, 3.6W) once every 10 hours for a few minutes (I've followed this tutorial on how to connect the water pump). To turn on the water pump I used a PN2222A transistor, and connected the base in serial with a 220 ohm resistor to the digital pin 9. A few minutes after turning on the power on my Arduino UNO the PN2222A transistor burned out (lots of smoke coming out of it).
I also used a 1N4007 diode, cathode connected to the positive pin, and anode to the negative pin of the water pump.
The power supply outputs around 12.6V
Maybe the resistor is too low/weak?
I've created a schematic here, attached it's a snapshot of it.
EDIT1: Here is a picture on how I connected my transistor. I've removed from the photo:
- the input wires (should be top-right of breadboard)
- wire to arduino digital pin (should be on h-19 on the breadboard)
- water pump from the breadboard (positive pin: c-2, negative pin: h-2)
EDIT2 (a solution that worked for me):
It looks like the input to the arduino (arduino and the pump share the same 12V input, but the arduino's goes through a step down converter to 10V) was a bit loose (to be more specific, the negative pin was loose) and randomly, the arduino would shut down and then the pump would start (maybe because the digital pin becomes HIGH, dont know why though) all while the arduino is shut off. That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested and looks like when the same problem with the power happens, nothing is burning out :)