Passive infrared detector that reacts to moving heat sources (persons, vehicles, etc.). If the motion detector detects changes in heat radiation in its detection range, it switches on the connected loads (e.g. lighting) for an adjustable duration depending on the set light value. If the heat source leaves the detection range, the motion detector switches the consumer off again after a preselected time (3 sec. to 20 min.). The short pulse function, which is set via the integrated TIME potentiometer under the cover ring of the sensor, offers an extra feature. This can be used, for example, to automatically activate staircase automats in larger buildings.