| 摘要 |
1,186,013. Proximity switching systems. ROBERT BOSCH G.m.b.H. 15 Sept., 1967 [17 Sept. 1966], No. 42062/67. Heading B7N. [Also in Divisions F1, G1 and H3] A proximity switch having a short response time and two or three stable states is stated to be suitable for automatic train control, by inductive operation when a train passes a halt signal, to automatically apply the train brakes. The switch comprises a transistor oscillator 10 with coils 11, 12 whose coupling is varied by a movable conducting member 34, and a positive feedback amplifier 13 normally biased to cut-off so when the oscillatory signal across coil 11 exceeds a predetermined level (U10), Fig. 2 (not shown) and Fig. 3 transistor 13 starts to amplify up to saturation level providing feedback pulses (U2), Fig. 2, which cause the level of the oscillatory signal to jump to (U12). The feedback pulses also provide signal to transistor 14 to operate relay 15. |
