Here is the innards of the signal switching - all simple with a mechanical micro-switch.
The 12V supply to the point motor is picked off and rectified as it is reversed to move the actuator. The -ve are the two common rails - black pins.
The +ve is changed by the actuator tripping the micro-switch and taken to the red or green pins, to which the LEDs are connected.
The top aspect of the signal head (normally green) is a red and green common cathode (-ve) LED so that both colours can be illuminated together - giving orange/yellow colour.
By picking off the 12V at the red of the next signal, bringing it back and adding to the top LED on the red pin, a yellow distant caution will be shown when green is also on. Thus indicating the next signal may be at STOP.
The relay switch inhibits the top red being lit when the bottom, red, aspect is lit. Don't want TWO reds at the same time...
There are six wires connecting the point motor boxes, which are also the signal base. Blue and White carry the constant. but reversing, 12V to the actuators. Yellow then carries the 12VDC back one signal for the Caution signal. Leaving Red, Green and Black for other functions.
The bottom pix are the prototype boards for the bi-colour LEDs. Same size as the original Ron Light, Right Track signals.
SRR convention is that the continuous oval is the mainline. Normal running is clockwise. All top signal heads refer to the mainline. No block control so all top signals are green. For mainline running all point motors are retracted or 'in'. Any relays are 'off'.
SRR convention is that the continuous oval is the mainline. Normal running is clockwise. All top signal heads refer to the mainline. No block control so all top signals are green. For mainline running all point motors are retracted or 'in'. Any relays are 'off'.
