Ive been asked to setup a door sensor which will detect if a door is open. The problem is I cannot run a cable to the door, so it has to be wireless, and it needs to be cheap (If this works it will be rolled out to several doors and windows).
Does anyone know of a cheap wireless switch that can be switched closed or open (Detect if a door is open of closed), and relay that signal to a reciver which replicates the closed or open circuit which can be read.
Ideally I would love the reciver to be able to recive several transmitter switch signals.
Im not sure if this is the correct place to post this question, so apoligise in advance if it is the wrong place.
Thank you in advance