| 摘要 |
PURPOSE:To prevent occurrence of singing caused by detouring signals and, at the same time, to enlarge the gain of the titled device, by impressing bias signals of opposite phases upon two amplifiers constituting the two-wire amplifying device and operating the amplifiers by means of opposite biases. CONSTITUTION:Signals which are inputted in a hybrid transformer 2 and amplified by an amplifier 5, flow in the direction shown by an arrow I1 and are sent to a line 3 through another hybrid transformer 1. In this case, because of the matching problem of the transformer 2, detouring signals flow in the direction toward another amplifier 6 as shown by another arrow I2 and a loop circuit of the amplifier 5-hybrid transformer 1-amplifier 6-hybrid transformer 2-amplifier 5, through which the signals flow, is formed, and then, singing tends to occur. However, the amplifier 6 is nearly set to a cut-off condition when the amplifier 5 operates and the detouring signals shown by the arrow I2 are never amplified, because bias signals B1 and B2 of opposite phases are impressed upon the amplifiers 5 and 6 from an oscillator 7. |
