Reference frequency timing circuit - derives clock pulses from three-phase network giving fifty hZ frequency using phase shifters and OR=gates

摘要

The timing circuit is used for deriving clock pulses from a 3-phase network (10) for use as a 50 Hz reference. It has RC circuits connected to each phase line to convert their voltages into rectangular waves and to shift them in time until they are roughly coincident. These coincident signals are they applied to the inputs of an OR-gate. The RC circuits are used as phase shifters which also eliminate noise. The OR-gate may consist of three discrete diodes.