Mains supply current frequency detector - has mains transformer coupled to period detector, and counts frequency of occurrence of period detection signal in set time

摘要

The frequency detector includes a mains transformer which converts a mains alternating current into an operating voltage for the supplied equipment. A period detector unit shapes an output waveform from the mains transformer and produces a period detection signal in each period of the shaped waveform. The frequency of generation of the period detection signal during a defined time period is counted by a further unit which also discriminates or distinguishes the frequency of the supplied mains current on the basis of the counted frequency number. USE - For detecting frequency supplied to electronic or electrical device during start-up phase after connecting supply to enable device to be switched to appropriate operating frequency, e.g. 50 or 60 Hz.