Repeater circuitry for telecommunications e.g. telephone exchange - uses control and switching device with two MOSFET switch elements

摘要

The series circuit connected in parallel across the transmission line wires (1,2), comprises a control device (5) providing selection pulses and a switching device (6). The latter has a switch element receiving the selection pulses comprising a MOSFET transistor (17), controlled via a resistive voltage divider (14,15) and a capacitor (18,18a,18b) and a second series switch element with a second MOSFET (20). Pref. the gate of the MOSFET transistor (17) is coupled to the junction between the voltage divider resistors (14,15). ADVANTAGE - Prevents a.c. reflex effect along line.