Abstract: The present invention utilizes a latching relay having on and off inputs for controlling power to a load. The on and off inputs of the relay are controlled by pulse generators which are in turn controlled by an occupancy sensor circuit. These pulse generators provide pulses when movement is initially detected in a room and when no movement has been detected for a predetermined time, respectively. The outputs of the pulse generators are coupled to an isolation circuit which isolates the power supply for the occupancy sensor from the pulses during each pulse to prevent damage to the power supply.

Abstract: An improved apparatus for switching off power to an electric load in the absence of the detection of movement from the doppler shift of a transmission signal. An oscillator generates an ultrasonic transmission frequency which is transmitted via a transmission plate coupled to the oscillator. A plurality of receivers detect reflections of the ultrasonic sound signal and supply the detected signal to a bandpass filter which passes the transmission frequency. A low-pass demodulator will detect any doppler signal which modulates the transmission signal and will supply it to an amplifier for amplification. The amplified signal is then provided to a narrow band filter which will pass only a narrow band of doppler-shift signals which correspond to the frequencies of human movement. The signal is then supplied to a switching means which, when activated, will discharge a first node. The first node is charged via a resistor and a capacitor coupled to a voltage source.