Understanding solenoids

Thread Starter


Joined Feb 27, 2012
Hello all, first post..

I am pretty new to working with electronics, though I have worked through many basics. but still unsure of solenoid specifics, which is what I am interested in.

I understand that I need to use a transistor, but I am wondering how I would figure out the transistor to use based on the solenoid I am trying to use.
The specific one I am using is linked below, but I am interested in knowing how to figure it out in general.



Joined Oct 15, 2009
You didn't link anything but in general you size the transistor or mosfet or relay based on the current requirements of the solenoid (and voltage too really)
You want to find stuff like 12V @.5 Amps so your switching device must be capable of switching that 1/2 Amp current level


Joined Mar 14, 2008
Generally you like to derate the transistor for good reliability. A 50% derate for both maximum voltage and maximum current is a good value.

And remember to add a diode (or other transient device) across the solenoid coil so the inductive spike doesn't zap the transistor.