Infra red alarm / Koyah Embong and Normah Hussin

This circuit was designed as a multipurpose movement detector able to form the basis of all sorts of burglar alarms and automatic controllers. It will work either as a single interrupted beam alarm over substantial distances or will directly detect moving objects or persons by measuring changes in the level of reflected infra red over shorter distances. The output of the device is a set of mains-rated changeover relay contacts which operate as soon as an object is detected, arid remain operated for a pre-settable time between one second and one hour. As the relay contacts are mains voltage rated and are capable of carrying up to 6A they can be used to control a wide variety of things such as automatic garage door opening mechanisms, central heating systems, room lighting, extractor fans, alarms bells, tape-recorders and cameras. There must be hundreds of other applications in agriculture, industry and commerce for this versatile detector.