PUSHHBUTTON DIAL TELEPHONE SET

摘要

PURPOSE:To prevent the external noise from being transmitted to the telephone circuit via the transmitter through a simple constitution by controlling the automatic dial switching device plus the automatic dial switch doubling the transmitter through electric control circuit. CONSTITUTION:Contacts 31-37 are provided to the synchronous circuit of oscillator circuit 6 in correspondence to plural units of push-buttons with automatic dial switching devices 71-77 connected in parallel. In addition, transmitter/automatic dial switch 30 are installed to switch the DC from the telephone circuit to the transmitter or circuit 6. Thus, devices 71-77 plus switch 30 are controlled by the electric control circuit, and the external noise can be prevented from being transmitted to the telephone circuit via the transmitter when switch 30 is switched toward the oscillator circuit.