I was trying to use a solenoid lock alongside the arduino, using a 12V 2A DC adapter, TIP120, and a diode.
The circuit looks something like this. However, the lock isn't going in automatically (it requires a push).
I've tested the circuit using a multimeter, and the output given by the transistor, is indeed 12V, however, when connected to the lock, the potential difference is around 8V. I don't know if that's normal, but the lock isn't going in on it's own.
Can anyone help me with this issue?