| 摘要 |
PURPOSE:To transmit a dial signal with less distortion by quickening the start of a receiving circuit at a current being the threshold current value or below of a detector detecting the change in a current by a dial signal when a relay contact transmitting the dial signal is closed so as to interrupt the titled circuit from said receiving circuit at a current value being said threshold current value or over in terms of operating characteristic. CONSTITUTION:When a relay RL1 is operated from dial information, a contact rl1 is closed and a positive voltage from a DC power supply V is applied, then a transistor (TR) Q3 is made conductive immediately, a voltage of a capacitor C1 is risen rapidly, Trs Q2, Q1 are made conductive and the delay is decreased. When the current exceeds the threshold current of the detector 1, a voltage applied to a resistor R11 is increased from a voltage across a diode D6 by selecting the resistor R11, then the emitter voltage of the TRQ3 is decreased less than the base voltage, the TRQ3 is opened so that the quick start circuit is disconnected from the receiving circuit 2 in terms of the operating characteristics. |
