| 摘要 |
A low pass filter is connected to a junction of a direct-coupled amplifier. The amplifier has a single-ended push-pull output stage consisting of two output transistors and series-connected two resistors. The output transistors are connected to a positive and negative d-c power sources, respectively. The series-connected two resistors are interposed between the two output transistors and defines an intermediate point therebetween at which substantially zero d-c voltage prevails when the amplifier is functioning normally. The junction of the amplifier, to which the low pass filter is connected, is between one of the output transistors and the series-connected resistors. The low pass filter is supplied with the voltage at the junction and applies its output to following isolating means. The means responds to the output of the low pass filter for isolating the intermediate point from a load device connected thereto.
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