An emergency exit door lock system configured to cooperate with a door hinged in a door frame for sensing when a person attempts to open the door, and for allowing the door to open after a subsequent delay. The system comprises an electromagnet affixable to a door frame for electromagnetically attracting an armature resiliently affixed at a variable armature separation distance to an armature mounting device, the device being affixable to the door. A proximity sensor including an analog Hall Effect device is mountable to the frame for detecting movement of the door away from a closed position. A controller, such as a micro-controller, receives a signal from the sensor and causes an alarm as a function of the signal. The signal is indicative of the armature separation distance, the controller being calibrate-able to provide a door alarm signal and door opening signal at any desired value of the armature separation distance.