| 摘要 |
A microphone unit for incorporation in a telephone headset or the like including a low signal output transducer, and a polarity independent current control amplifier circuit for amplifying the transducer signals and having a pair of substantially identical parallel oppositely connected main current control devices, such as transistors, each having their load terminals arranged for controlling current flowing in a normal forward direction which is opposite to that of the other so that there will always be one fully conductive and one partially conductive or nonconductive path across the microphone unit terminals independently of the polarity of the D.C. current to be modulated by the microphone unit. Drive circuit means energized by the voltage on the telephone lines applied to the microphone unit terminals are provided to receive the transducer signals and amplify the same before being applied to the control terminals of the current control devices regardless of the polarity of the energizing voltage.
|
