This is a 12V, 2A solenoid coil, so using a FQP30N06L N-Channel MOSFET to control it from an Arduino. The 5V source and switch represent an output pin. The 1K is to keep the gate grounded when not in use. The fly-back diode is a 1N5822 Schottky. In my application this coil is part of a JF-0826B solenoid that pulls a pin to unlock a mechanism. It's pretty cool that you can see the inductor reverse current effect simulated when the switch is released (through the fly-back diode).
