Hello all,

I should start by saying I have only a very basic knowledge of electronics. I manage a recreation facility and am trying to increase security around a pool area in a low cost manner. My first action was going to be to pay a security company to place fob card readers and locks on both gates to the pool however the cost of modifying the gates and digging a trench for the wires alone was almost $12000 and I could not get the funds. I have an idea for a cost effective method I found online. Using the technology in this link http://www.myelectronicslab.com/tutorial/door-sensor-with-push-notification-using-esp8266-nodemcu/ I plan to wire a magnetic reed switch onto the gates that will send a text message to my cell phone if someone enters. The catch is that I would like this switch to become disabled if someone beeps a fob on a card reader and thus I will only receive the text if someone enters without a fob card. The card readers I have seen output 12v when activated but I need the magnet switch to be always on. Again, my knowledge of circuits is very basic, is there a simply device I can get that will receive the 12v signal from the card reader and will temporarily deactivate the reed switch while the person enters? I really appreciate the help and realize this is probably a very amateurish question.

 

When your keyfob detector gives out a valid signal it will activate a relay for the door catch, you could use this relay if it has two sets of voltage free contacts, one set can feed the door lock, the other can short out your reed switch,

If the relay only has one set of contacts, then parallel another relay with a set of contacts to short out the reed switch.