I want to use a transistor as a switch, allowing 12V to pass through and actuate a solenoid. The solenoid is 12V and draws about 500mA from my variable power supply.
Using some instructions I found, I came to using a 10 ohm resistor in between the 5V source and the transistor. The 24 ohm resisistor is meant to represent the solenoid. The measured voltage in Multisim is very close to what I measure on the actual circuit.
I want to use an Arduino to turn the solenoid on and off at specific intervals. The transistor gets very hot when the solenoid is connected, but does actuate when 5V is connected to the transistor base. Aside from the transistor getting quite hot in this circuit, I think that it should be fine. I found this issue when I had the same circuit, but with a pump instead of a solenoid, which draws around 80mA at 12V, but would run even when the base wasn't connected, though slower due to having less voltage. The resistor at the base of that circuit is a 4.7k ohm.
7.25V measured coming from the "solenoid" without any voltage going into the base. The 10ohms is meant for the resisor between the switch and base
I understand the importance of using a diode to reduce the chance of breaking the circuit, but I don't currently have any. If I were to get some, what type would I use for this circuit?