| 摘要 |
PURPOSE:To sencure the use of the non-lock key and thus to obtain a rational circuit constitution by sharing the relay contact which is inserted in parallel to the channel of the privacy circuit of the telephone set to cut off the talking as the main wire connecting contact. CONSTITUTION:When the handset is picked up, hook switch 48 and 49 are closed with transistor 59 conducting. And privacy relay 60 operates, and speech circuit network 61 is connected to extension terminal 42. To select the main wire, main wire button 46 is pushed to send the signals to control terminal 43. Then relay 60 is released, and network 61 is connected to main wire terminal 41. While to give holding, holding button 47 is pushed to actuate relay 60 again as well as to send the holding signal to terminal 43. In case the interruption is given into the talking of the main wire, the handset is picked up and button 46 is pushed. Thus, relay 60 continues its operation with network 61 kept being connected to the extension terminal. As a result, the main wire interruption becomes impossible, thus securing the privacy operation. |
