| 摘要 |
1. A loop current supply for a characterising signal converter comprising : a) two supply resistors, each connected to a respective pole see diagramm : EP0104581,P7,F1 of a supply voltage (US ) and to a respective wire (a, b) of a telephone line via filter means and each balanced by a series arrangement of a feeder reactance (L1, L2) and an electronic switch (SE1, SE2) ; b) a regulating device (CC) which maintains the ratio of the voltage drop across the balanced supply resistors to the loop current (IS ) constant by closing and opening electronic switches (SE1, SE2) ; and c) respective switching elements (D1, D2) are each arranged at switch-end terminals of the feeder reactances (L1, L2), via which the loop current (IS ) flows when the electronic switches (SE1, SE2) are open. |
