Many acces automation and (car) traffic control, require the detection of the vehicles in a certain position. In order to do this, we use the electromagnetic induction effect: a metalic mass in the proximity of a coil will modify it's oscillation frequency. Usually the coil / induction loop is made by installing in the floor (a few centimeters below) of an electric wire in a few spires. Then this is connected to a controller that monitors the status (inductance) of that coil / induction loop. The controller signals when a metalic mass comes in the proximity of the induction loop, giving the posibility to monitor the presence of a vehicle in a certain position. Among the usual applications we have: activation and/or safety of a barrier, garage door, gate, traffic counting, collision avoidance, and many others.
We carry in stock a range of controllers, with several functions: 24V / 220V powered, one or two output relays, one or two controlled loops, etc.