| 摘要 |
PURPOSE:To stabilize shut-off action by cutting the bias of an output transistor, shutting off a push-pull amplifier, using the reverse bias of a diode, and making an input impedance into a high impedance condition. CONSTITUTION:When the output of a control circuit 9 is the condition of 1, transistors 8 and 7 for control come to be the shutting-off condition and transistors 5 and 6 come to the shutting-off condition. At such a time, a forward direction current flows at diodes 3 and 4, a suitable bias is supplied to output transistors 1 and 2 and the circuit is operated as a signal passing condition. When the output point of the control circuit 9 is the condition of 0, the transistors 8 and 7 for control come to be the conducting condition, the diodes 3 and 4 come to be the reverse bias condition, the impedance between input terminals 10 and 11 is made higher, a signal is inputted to the input terminals 10 and 11, a signal is inputted to the input terminals 10 and 11, not outputted to output terminals 12 and 13 and a line comes to be a signal shutting-off condition. Thus, the shutting-off action is stabilized.
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