I need a solution to control EM Lock by two card readers (both to be authenticated)

Thread Starter

Naan Manidhan Thaan

Joined Dec 9, 2020
I'm trying to figure at if and how to use relays or AND(NAND) logical gates IC Chip to control an EM Lock. This requirement due to the impact of COVID-19. Tthere are two readers. One reader takes the temperature, performs facial recognition and if all ok, it registers the temperature in its log and send a signal out to open the door : NO (Normal Open). Another reader is for checking the access rights to premises where an Weigand Card reader is used. So, this second card reader should also send siginal to open the same door ; NO. So, only when both readers sends the signal to open the door, the door should be opened; otherwise it should not open the door. So, I think if do a AND logical operation on the output from both readers, the output from the AND gate shall be used to open the door (this output from the AND gate shall be given to EM Lock).

Both readers NO (Normally Open) signal is (-ve) 12VDC and the current in it is 2.5 to 3Amps.

I am concerned about the 12V and 3Amp currrent. So, which is the best solution; using AND gate IC or or should I use industrial grade relays? how shall be the wiring? Thanks in Advance.


Joined Feb 25, 2011
Either would work,
I would suggest that this is not a secure system, more restrictive,

I'd also suggest, that if the gear you have is capable of driving relays, I'd use relays,
they are going to be much easier to debug than gates, which then need separate power supply.