| 摘要 |
<p>PURPOSE:To simplify the circuit through the constitution of power supply to terminals by the increase/decrease of transmitted voltage from a telephone station only. CONSTITUTION:Normally, a station side current controller 1 is conductive, and a voltage of a main power supply 2 is supplied to terminals b, b' at terminal side via line 3. But, a detector 4 is not operated at this voltage, a terminao current controller 5 keeps nonconductivity and no power is supplied to a receiving power telephone circuit 6. To supply power to the terminal, a booster 7 is operated with a control circuit 8, a voltage at a booster power supply 9 is superimposed on the voltage of a main power supply 2, the boosted voltage is detected at a boosted voltage detector 4 at a terminal b, the terminal current controller 5 is conductive for self- hold. Thus, a temporary boosted voltage is finished by the device 7, then power is supplied to a receiving telephone set circuit 6, and the reception of a digital signal is made possible. To stop the power supply, a station side current controller 1 is made to nonconductive with the control circuit 8.</p> |
