Relay Help

Hello I have a school project where I need to use a solenoid electromagnetic lock and I am having trouble figuring out what kind of relay I would need or if I would need one at all. These are the specifications for the lock I will be using.

If I could be pointed in the right direction or if anyone has any suggestions on what kind of relay could be used that would be much appreciated.

Screen Shot 2020-09-24 at 4.56.50 PM
This is what the lock looks like.

Hello @marcodijamco

The relay needed would depend on what you are using to control this lock. If you are using a push button that is able to switch the 12V 2A supply needed you would likely not need a relay. If you are using a controller that is putting out a signal, you will need a relay that will switch the 12V 2A and can be controlled with the output power available from your controller.


Hi @Robert_Fay ,

I’m going to be having a power supply of 12V and I have a microcontroller that operates at about 3.6V. Would this relay be okay?

Also this is the microcontroller I will be using if you want to see it.


The relay mentioned requires 12V to drive its coil, and therefore would not be directly controllable from a 3.6v microcontroller.

I’d suggest use of an appropriate transistor for controlling such loads, in conjunction with an optoisolator if the relay’s isolation function is needed. Use of a recirculating diode for solenoid coil suppression would be suggested in such cases.

I would mention a couple of other points as well.

The MCU you mention has an absolute maximum supply voltage of 3.6V. I would not recommend operating it normally at that voltage. 3.3V would be preferable.

The relay you mention is rated for 2A maximum. You are not giving it much margin either. It would be preferable to select one rated for at least 2x that for a little margin. A relay from this group would be more suitable.