ELK Keypad + E-door w/o Relay?

[bryansera]

I have this e-door strike:

http://www.smarthome.com/5190S12/Electric-...e-5-S-12/p.aspx

I was wondering why I need an external power supply + relay...why can't I just have the output of my M1KP do it. It is rated at 12VDC right?

 

[WayneW]

The issue is with the current, not the voltage. That strike requires 400 mA and I think the keypad output can only supply 50 mA. So you need the keypad output to control a relay that draws less than 50 mA, then the relay contacts can control the 400 mA.

 

[bryansera]

The issue is with the current, not the voltage. That strike requires 400 mA and I think the keypad output can only supply 50 mA. So you need the keypad output to control a relay that draws less than 50 mA, then the relay contacts can control the 400 mA.

Thanks! That is what I figured...but the 400mA on the strike didn't jump out at me.

Man this forum is helpful!

 

[Spanky]

If you have a DC voltage door strike, make sure you put a reverse diode across the door strike coil if it does not have one. The inductive voltage spike when the power to the strike is removed can damage or at least cause eratic behavior to electronics. The reverse diode kills the inductive voltage spike.

A reverse diode is done by placing the banded side of the diode towards the + voltage side of the door strike coil and the unbanded side towards the negaive side of the door stike coil.

A one amp diode like 1N4001 works well.