| 摘要 |
The invention relates to a circuit arrangement for a telephone station powered via the subscriber line with a microphone amplifier and with a logic system which controls the dialling procedure and the loop interruption. The DC voltage supply is made polarity-independent by a Graetz rectifier bridge. The intended object of the invention is to activate the microphone amplifier in such a way that it requires minimal power. This is achieved by activating the microphone amplifier via an MOS component in such a way that it is disconnected from the power supply, even during the short periods in which it is not required. This also concerns in particular the periods of loop interruptions by the dial pulse contact. The circuit arrangement according to the invention is suitable for every subscriber station with remotely powered amplifiers. |
