Public address system providing power saving function and speaker protecting function concurrently and power saving circuit used therein

摘要

And a power saving circuit used for the power saving circuit. The public address broadcasting system includes a DC / DC converter for converting a voltage of a DC power source into a driving voltage of a main amplifier and supplying the driving voltage to a main amplifier, A signal generator for generating a PWM (Pulse Width Modulation) signal required for driving the DC / DC converter, and a signal generator for generating a pulse width modulation signal from a time point at which a magnitude of a signal input from the sound source becomes equal to or greater than a threshold value corresponding to a minimum size of the audio signal And a power saving circuit for starting power supply and terminating power supply to the signal generator after a predetermined time has elapsed from the time when the magnitude of the signal input from the sound source becomes less than the threshold value.