| 摘要 |
<p>1533929 Digital to analogue conversion WESTINGHOUSE AIR BRAKE CO 17 May 1976 [27 May 1975] 20334/76 Heading H3H A d#a converter accepts two inputs each marking one out of a plurality of lines C 0#n L 0#n , the output of a negative-feedback operational amplifier being determined by the marked line which tends to produce the lowest output. In the embodiment voltage V + is applied to one C and one L line to respective resistors and diodes, e.g. C 0 , R 1 , DLO, leading to point PO being clamped by DCO to B +. Current I, flows through RSO and RB = RSO to B-, thus the output at O = zero. If, however C 1 , R 3 , DL2 make P 1 clamp to B+ then I 3 = current at O = I 2 - I 1 = B+/ RS1 + RSO. Higher lines such as L 2 , L n have no effect since P 2 or P n will also be clamped to B +. The device is described in relation to railway control with one input being driver control, the other trackside, the device choosing the lower switched speed.</p> |
