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Four aspect signal with feather at a junction fornodern image model railways


The signal controlling 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 MAS Sequencer-RI, IRDASC-4RI and IRDASC-5RI have additional terminals for operating a feather.


Contacts (accessible at terminals Y and Z) are provided for operating the feather. Provided the signal is not at red the contact closes linking Y and Z when terminal OI is connected to the 0V terminal. This connection is usually from a contact operated by the point. 2, 3 and 4 aspect versions are available which otherwise operate in the same way as the IRDASC-4 and 5. Versions are available which only allow yellow and red or double yellow, yellow and red to be displayed when the points are set for the branch line. This is to tell the engine driver to reduce speed for the curve of the junction. Terminals Y and Z have no electrical connection to the remainder of the board. Treat them as an on off switch.


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 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