Voltage limiting circuit protecting telecommunications equipment - has four branches each containing two transistors in parallel with three diodes and resistor

摘要

The voltage limiter has four similar lead-off paths connected in pairs between a common rail and the two speech wires. Each lead-off path or branch has its first terminal (1) connected via the collector/emitter of a first transistor (T1) and the emitter/base of a second terminal (T2) to its second terminal (2). The second transistor's collector is connected to the first's collector. The first terminal is also connected via three series diodes (G1-G3) and a resistor (R) to the second terminal. The first transistor's base is coupled to the junction between the second and third diodes.