Abstract: A control system for determining when one or more persons exit a designated environment or location. The control system includes a magnetic cuff or anklet attached to the ankle of a person in the location or environment and an electronic detection system located in a threshold detector unit mounted in the floor of the location or environment. The electronic detector system is characterized by an amplified "Hall Effect" integrated circuit (IC) which is designed to detect movement of the magnetic cuff or anklet through a detection zone up to about 10 inches above the threshold plate. Various alarm apparatus may be connected to the "Hall Effect" IC circuit to announce movement of the person upon which the magnetic cuff or anklet is attached through the entrance way.