| 摘要 |
A device for the protection of circuits in a telephone exchange against excess voltages in the form for example of lightning transients or so-called longitudinal interference which arises on lines connected to the exchange comprises at least two non-linear electronic circuit elements T2, T3, which selectively shunt the said excess voltages to earth. The transition between the line state, conductive - non-conductive, for at least one of the said circuit elements T2, T3 is controllable. <IMAGE> |
