| 摘要 |
PURPOSE:To perform the stable AC branching of a two-wire circuit even when a large gain is provided by allowing a switch to connects an amplifier output in the direction of a circuit whose input is detected first and cuts off the output of an amplifier in the other direction. CONSTITUTION:When there is an input to a circuit M, a comparator CMP circuit 4a generates an output and a control circuit 6 registers its state in its internal memory and also turns on the switch SW5a to send out the output of an amplifier 2a to circuits S1 and S2. At this time, it is informed that a CMP circuit 4b also generates an output, but the circuit M is judged to be first, so an SW5b is not turned on to disconnect the path including an amplifier 2b; and there is no stray input to a hybrid circuit 1a, so that no oscillation occurs even when the gain of the amplifier 2a is large. The contents of the memory registered by the circuit 6 are reset when the input to the circuit M is ceased and input from a new circuit is held in readiness. |
