| 摘要 |
PURPOSE:To prevent the excessive generation of input signals when the input signal is cut off by switching the input signal to be applied to an output amplifier to a constant potential output amplifier from the output of an input signal amplifier when the input signal is cut off and then stopping the actuation of the output amplifier. CONSTITUTION:When a control input terminal 28 is set at H level, the control signals S1 and S2 given from a switching control circuit 26 are set at L levels with no actuation of switches 22 and 24. Thus contacts 22a and 22b are closed and opened respectively, and contacts 24a and 24b are closed. In this case, the input signal supplied from a terminal 10 is amplified by an output amplifier 6 after passing through an amplifier 2 and delivered through a terminal 20. When the signal to be applied to the terminal 28 is set at L level, the switch 22 is actuated by the signal S1 from the circuit 26. Thus the actuation of the amplifier 2 is stopped, and a constant potential output amplifier 4 is actuated to switch the input of the amplifier 6 to the output of the amplifier 4. Then the switch 24 is actuated by the signal S2 after a prescribed period of time decided by a resistance 32 and a capacitor 34 of the circuit 26. Then the contacts 24a and 24b are opened to stop the actuation of the amplifier 6. |
