| 摘要 |
PURPOSE:To realize storage of plural number of main wires with the 4-wire wiring by using 2 wires for the time-division multiple channels and the other 2 wires as the power line and the control line respectively. CONSTITUTION:When the outgoing is given from key telephone TEL1 to main wire circuit COA, main wire button KLA1 is pushed. And control circuit CONT1 identifies the button pushing to then make switching control element P12 conduct. In main unit ME, the negative wave current flows to negative wave current detection element P01 via wirings c and d since switching element P02 conducts, thus the reception display being given to the control data. Control circuit CONT0 receives the control data and then identifies the outgoing of circuit COA of telephone TEL1 to give start to circuit COA as well as continuous circuit A00. When the reception of the control data is over, circuit CONT0 features the transmission state to send the control data to telephone TEL1 via wiring c and d. Circuit CONT1 received the control data gives start to continuous circuit A10. Thus the talking circuit is formed between main wire La and telephone circuit NW1. |
