Time controlled light for burglar deterrent - has light sensor detecting operation of two digit- appearing in digital 24-hour clock display

摘要

The electronic clock includes a circuit which senses the displayed time to control the operation of a lamp. An LED display indicates the time, and a semiconductor light sensor is arranged to receive the light from the middle bar of the 'two' in the tens of hours display position. This is illuminated between 2000 hrs and 2400 hrs. This sensor is connected to a transistor, (T1) integrated circuit (C1) and an amplifying transistor (T2). The circuit produces a control signal fed to a triac (Tri 1) which forms the switch to control operation of the lamp. The circuit thus lights the lamp daily for a period of four hours.