Telephone subscriber station supplied through connecting lines - has resistor connected to rectifier during speaking, which is disconnected during dialling

摘要

The telephone dialling unit has only three connection points, supplied through a full-wave rectifier. The dialling unit (K) is supplied through a double bridge rectifier (D1-D6) with two bridge arms (D1, D2) common for both bridges (D1, D4; D1, D2, D5, D6) and an additional resistor (R) is provided in one of the connections. The bridge is operated by a dialling contact (nsa) during speaking with the resistor (R), and during dialling without the resistor. The dialling contact (nsa) is in series with the terminal connector (S2) connected to the speech circuit (SS).