The Digital Model Train Part 4

THE DIGITAL MODEL TRAIN PART 4 by T. Wigmore Universal signals and switching decoder The points (turnout) decoder described in Part 1 of this series (Ref. 1) is a circuit that provides short pulses to its output that may be used for the control of turnouts (points) and other electromagnetic elements of the model railway. That decoder does not pro- vide a momentary but a continuous con- tact. It is really a remotely controlled four- way toggle switch with change-over con- tacts. Although the decoder described in this instalment enables all kinds of element to be switched, the design is aimed primarily at (non-electromagnetic) light signals. It provides separate switched outputs to which LEDS or conventional light bulbs may be connected. If desired, it is possible to mount relays on the PCB. These would, for instance, enable switching the track voltage at the same time as the signals, in effect providing the basis for hardware- based block protection. Four sets of light signals may ...