UTC1240A Electronic Dual-Tone Ringer

The UTC1240A is a monolithic integrated circuit that works with an electro-acoustic converter to replace the mechanical bell in telephone sets. Both devices can drive a piezoceramic converter directly (buzzer). A decoupling capacitor is required for the UTC1240A output. On the output stage of the UTC1240A, there is no current limit. As a result, a minimum DC load of 50 ohms is recommended. Both the tone frequencies and the switching frequency may be modified externally, and the two-tone frequencies are switched in a quick sequence by an internal oscillator and made audible through an output amplifier in the loudspeaker.

The signal and circuit are built such that noise on the line or changes in the ringing signal do not interfere with the device’s proper operation. An internal oscillator altered the two-tone frequencies in a rapid succession. And made audible by a loudspeaker’s output amplifier. Both the tone and switching frequencies can be changed externally. The AC ring signal provides the supply voltage. And the circuit is constructed such that noise on the line or changes in the ringing signal do not interfere with the device’s proper operation.