| 摘要 |
PURPOSE:To stabilize a call signal, by providing a circuit, which performs such control that signals to be transmitted do not collide with each other, in a circuit for transmission of the call signal to a subscriber's terminal of a telephone exchange. CONSTITUTION:Conduction or non-conduction of p-n-p-n transistors TRs 11a, 11b, 12a, and 12b constituting semiconductor switches 11 and 12 is detected by a detecting circuit 15, and the detection output is transmitted as one control information to a controlling circuit 14. Control signals T1 and T2 from the controlling circuit 14 are applied to semiconductor switches 11 and 12 through an exclusive operating circuit 13 consisting of delay circuits 21 and 38, which have delay times longer than the turn-off time of semiconductor switches 11 and 12, and gate driving circuits 13a and 13b. Consequently, the simultaneous operation of semiconductor switches 11 and 12 is prevented, and a call signal source 5 and the earth do not collide. |
