A SWITCHING CIRCUIT FOR CONTROLLING ELECTRICAL POWER

摘要

A two way light switching circuit comprises a first single switch (20) having a blade (20A) for making and breaking an electrical connection between a live side L and a line (23). A pair of back to back diodes (24) are connected across the switch so that there is a gap in the AC sine wave at the zero crossing point (26) when the blade breaks the connection. The line (23) connects to a second switching device (30) further connected to neutral via a line (31) and a load. A bridge rectifier and signal conditioning circuit (34) creates a positive only 100 Hz signal which is passed to a waveform detector circuit (36) to detect the small delay at the zero crossing point and provide an output representing a change in the state of the first switch (20). The output is provided to a logic circuit (38) having another input from a radio transmitter (39) which receives a signal from a remotely located further switch having an ON/OFF state and provides an output representing a change in the state of the further switch. The circuit therefore operates to make the second switch (30) toggle between an ON and OFF state (i.e. closed and open state) every time there is a change in the input to the logic circuit (38).