Voltage stabilizer suitable for use in a telephone set

Abstract

Voltage stabilizer for use in a telephone instrument, comprising the series arrangement of the main current paths of two transistors (4, 6) and a voltage divider (8, 9) connected in parallel therewith connected between first (1) and second (2) terminals. The bases of the transistors (3, 5) are connected to the voltage divider. The transistors (3, 5) and (4, 6) are connected in the Darlington pair configuration. In addition, in order to obtain a high AC impedance, the stabilizer includes a capacitor (11) which is arranged between the bases of transistors (3, 5) and terminal (2) to which the emitter of the second transistor (6) is coupled. To reduce the switch-on time of the stabilizer, a thyristor (13, 14) is provided between the first terminal (1) and the base of the first transistor (3) and a voltage divider (17, 18) whose tap (19) is connected to the cathode gate of the thyristor circuit is connected between the first terminal (1) and the junction of the main current paths of the transistors (4, 6).