| 摘要 |
PURPOSE:To supply power to a relay driving network of an interface panel through a connection line from the common terminal of no-voltage detecting relay contacts and transmit the strong earth through this connection line to an exchange when power to a PCM device is disconnected. CONSTITUTION:Transistors TRs 1-1, 1-2... as electronic switches in an interface part 10-2 of a PCM device 10 are controlled by a network 6 to transmit dial signals or the like corresponding to respective channels to relays RL2-1 and RL2-2 of an exchange 20. The network 6 receives power from a power supply terminal 8 of a common part 10-1 through a contact rl3' of a power-off detecting relay RL3', which is always operated, to control these transistors. When power is broken in the PCM device 10, the relay RL3' is released, and the earth from the contact rl3' is transmitted as a strong earth signal to the exchange 20 through a power supply line for the network 6 and diodes 5-1, 5-2... for insulation between channels. |
