Automatic time setting circuit for digital clock of electronic appts. - has comparator for amplified radio signals and reference signals from generator

摘要

A microcomputer (2) normally drives the digital display (8) of a time generator (3) and produces a control signal to reset the time of the digital clock to the correct time at a certain hour of the day. A buffer amplifier (5) brings the signals from a radio receiver to a suitable level when it is powered for operating the time generator. A reference signal generator (4) continuously generates reference signals at the same frequency as the hourly time signals of a radio or t.v. station when it is powered to operate the time generator. A comparator (6) delivers signals at a high level when the amplified radio and reference signals have the same frequency. A time resetting circuit (7) uses these high level signals to deliver a resetting signal to the microcomputer (2) for correcting the displayed time. USE - Compensates for time difference arising from faulty functioning of quartz oscillator in audio or video recording or reproducing installations, in electronic appts. and computer installations.