| 摘要 |
PURPOSE:To secure an automatic cut-off of the power supply at the calling time, by performing an automatic power supply through detection the call display signal sent from the MODEM at the receiver side of the telephone exchange network and then detecting the OFF of the data terminal ready signal after end of the receiving action. CONSTITUTION:In the circuit which performs the ON-OFF control by the signal sent from the center for the power supply at the calling time of the telephone exchange of the terminal equipment, the display signal called out from MODEM is detected through data terminal ready detecting circuit 10, and then contact circuit 40 to throw in the power source at the called subscriber is turned on. At the same time, the OFF is detected through circuit 10 for the data terminal ready signal after end of the receiving action of the called-side unit. Circuit 10 consists of FF11, AND circuit 12, NAND circuit 13 and INV circuit 14 and 15 respectively, And in case no transmission data is sent for a fixed time, FF11 is turned off by the signals sent from transmission data detecting circuit 20 and transmission data detecting circuit 30 to turn off the power supply of the called-side unit. |
