Home Page.
When using relays to actuate signals the only electronic components needed are diodes. This makes the installation more acceptable to someone not familiar with electronic controls. Red aspect over-riding green and yellow depends on switching and is more limiting as to the options of signalling conditions that can be used.
A Tri-LED is the easiest to use as yellow selection only involves activating red and green together. Diodes have to be used to prevent back circuits when interlocking.
Three aspect heads in general do not need diodes and the switch points give the red over-ride that is required. Junction points need two switches to allow control of the yellow and to prevent red showing if the main block is occupied and the point is reversed to use the loop line.
Points opposing and junctions points can be signalled. The diagrams show the wiring for one block, starting with the block detector relay and going to the signals at either end of the block - one Up and one Down. There are limitations with this simple style of signalling as reverse direction is not detected so signals opposing the train direction cannot be put to red.
When using relays to actuate signals the only electronic components needed are diodes. This makes the installation more acceptable to someone not familiar with electronic controls. Red aspect over-riding green and yellow depends on switching and is more limiting as to the options of signalling conditions that can be used.
A Tri-LED is the easiest to use as yellow selection only involves activating red and green together. Diodes have to be used to prevent back circuits when interlocking.
Three aspect heads in general do not need diodes and the switch points give the red over-ride that is required. Junction points need two switches to allow control of the yellow and to prevent red showing if the main block is occupied and the point is reversed to use the loop line.
Points opposing and junctions points can be signalled. The diagrams show the wiring for one block, starting with the block detector relay and going to the signals at either end of the block - one Up and one Down. There are limitations with this simple style of signalling as reverse direction is not detected so signals opposing the train direction cannot be put to red.
LINK TO IMAGE - rly-sig-2.gif
Circuit Schematic
