Digital 2 from 3 selection circuit - has four opto-couplers, with two at data channel with their transmit diodes in series

摘要

The digital selection circuit has three AND-elements, as opto-couplers, coupled to separate data channels and transmitting via an OR-element. Two opto-couplers (OK2.1,2.2) are connected to a common data channel with their transmit diodes in series. Switching transistors of the two opto-couplers are each series-connected to a switching transistor of one of the two remaining opto-couplers (OK1,3)of a set of four. They are connected to the OR-element (0). the emitter of the remaining opto-couplers switching transistor is linked to the collector of the other remaining opto-coupler switching transistor via a diode (D) polarised in the forward direction. USE/ADVANTAGE - Control in railway signalling with security despite reduced number of components.