Running a small DC solenoid

Thread Starter


Joined Nov 5, 2010
I have a small solenoid (Jameco 149762 - PN SMT-1632S12A):
12 volts DC
7 watts
21 ohms coil resistance

My power supply is:
12 VDC (From an old printer or something)
1.25 Amps

I'm thinking I need to add a 15 W, 20 Ohm resistor to protect the solenoid.

Am I on the right track here, or am I over thinking it.

It's actually being used to push a doorbell acting as a switch for something else, so it won'[t be a continuous current unless someone the button gets jammed down.

Thanks in advance...


Joined Dec 19, 2007
With a 12v supply, the 12v solenoid will draw only the current it needs...~0.6A. The 1.25A rating on the supply is just the maximum that it can supply.