| 摘要 |
PURPOSE:To enable to switch from a loud speaking receiving circuit to a talking circuit using only the power source of a telephone circuit by restoring self-holding by a device that self holds the DC circuit of the telephone circuit and the off hook operation of a hand set, and at the same time, providing a combined hook switch switching the loud speaking receiving circuit and talking circuit. CONSTITUTION:When a non-lock switch for on hook transmission 21 is depressed, the anode and cathode of a thyristor 34 are conducted. The thyristor 34 self holds and supplies the DC to a dial circuit 4 and a loud speaking receiving circuit 6 and closes the circuit of the telephone circuit. When dialing is made by the dial circuit 4, A dial signal is sent out to the telephone circuit 1. When the handset is lifted after confirming the reply of a called person by a speaker, the contact 11 of a hook switch is operated, and the current between the anode and cathode of the thyristor 34 becomes off. However, the DC circuit is held by the off contact of the contact 11. At the same time, by the operation of interlocking contact 12, the loud speaking receiving circuit 6 becomes off, and the talking circuit becomes on, and the talking with the called person is changed to handset talking. |
