REVERSIBLE DIODE DOORBELL DETECTION CIRCUIT

A doorbell detection and playback circuit for a doorbell pushbutton connecte d to an alternating current power source comprises at least one bridge rectifier circuit coupled to the power source through a diode placed in parallel with the pushbutton. The bridge rectifier circuit generates a signal at a first frequency when the pushbutton is not depressed, and generates a signal at a second frequency when the pushbutton is depressed. A frequency detection circuit is included and is coupled to the signal from the bridge rectifier. The frequency detection circuit further comprises an output responsive to the presence of a signal at the second frequency coupled to a sound generator for playing a ring tone or series thereof.