| 摘要 |
<p>1,130,017. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORP. 17 June, 1966 [19 June, 1965], No. 27098/66. Heading H4K. A loop current detector, shown as a transistor, is connected in the diagonal a b of a bridge, one arm of which is the exchange line represented by components RL, CL and the other arms being the resistors R1, R2 and RS2, R1 being shunted by a capacitor CA and the line being fed from exchange battery U over resistors RS1, RS2. The detector being so connected is not affected by longitudinal disturbances on the line or by fluctuations of exchange battery. When the loop opens CA discharges and line capacitance CL charges, the transistor detector consequently switching on with a fast response time. When the line loop is reclosed the detector is slow to cut off. Rectifier D limits the load on the transistor.</p> |
