Four aspect signal with feather at a junction for modern image model railways


The signal controlling a diverging junctions often has a route indicator or feather. This indicates to the engine driver when the points are set to leave the mainline. If the signal is at red the feather does not light. The IRDASC-4RI operates exactly as the IRDASC-4 with additional controls for the feather. 2 3 and 4 aspect versions are available. The full range of aspects is displayed for both the main line and diverging routes. However when the diverging route is a sharp curve the signal will only display red or yellow to warn the driver to travel at a slower speed. For the 3 and 4 aspect IRDASC-4RIs we have a version that controls the signal in this way.

extra terminals for the signals feather


Usually a point motor contact is used to tell the IRDASC-4RI that the points are set to the diverging route. The point motor contact is used to connect the 0V terminal to the OI terminal. When this connection is made the contacts at terminals Y and Z become connected together (provided the signal is not at red). These two terminals are effectively an on off switch for the feather. They are isolated from the IRDASC-4RIs supply in other words there is no electricity on them and they should be treated as an on off switch. This makes wiring the feather on any make of signal easy. Initially disregard the IRDASC-4RI and wire up the signal so the feather is permanently lit. Then simply cut either the positive or negative power wire to the feather in half. (it does not matter which). Then if these cut ends are put in terminals Y and Z (it does not matter which way round), the feather will light when the IRDAS-4RI internal switching connects Y and Z together.


The diagram shows the connections on the IRDASC-4RI. Apart from the OI, Y and Z terminals all connections and functions are identical to the IRDASC-4 and described on the IRDASC-4 page.


feather signal automatic operation when close to the point

When the train is detected by the IRDASC-4RIs the infra red detector the signal changes to red. If the signal is close to the point then there may be insufficent distance before the tracks split for the train to travel a realistic distance before the signal changes to red. If the IRDASC-4RI is located after the point it can only be on one of the two tracks the train could travel down. If the train runs down the track without infra red detection the signal will not change.

To overcome this problem the IRDASC-4RIs can be supplied with 2 sets of infra red detectors one set for each line so regardless of which line the train travels down it will reach an infra red detector and the signal will change to red. These are known as IRDASC-4RI -2EW.


Dimensions of IRDASC-4RI

Length 135 mm 5.3 inches


Width 32 mm 1.25 inches