| 摘要 |
PURPOSE:To suppress heat generated from a transistor(TR). CONSTITUTION:An incoming trunk 1 of an exchange detects a state of a line with a power supply 12 supplied to a monitor relay 3. A signal conversion circuit 2 is provided with a TR 13 operating the monitor relay 3 connecting to a line from the incoming trunk 1 and a changeover circuit of a relay contact 32 reducing the current of the TR when the monitor relay 3 is operated. |
