A block signal is located with one isolated outside-rail track block ahead of it and and another after it.

This example has one set of wired connections, but gives two jumpering sets: one for "prototypical" operation and one for "flashing" operation.

• With jumpers set for the "Prototypical Block Signal" feature, block signal lights are initially "off." As a train moves into the "ahead" track block, the "green" light is turned ON. When the train reaches the "after" track block, the "green" light goes OFF, and the "red" light turns ON. When the train leaves the "after" track block, both lights are OFF.
• With jumpers set for the "Flashing Block Signal" feature, the "green" light is ON when no train is in either block. As a train moves into the "ahead" track block, the "green" light flashes. When the train reaches the "after" track block, the "green" light is OFF, and the "red" light begins flashing. When the train leaves the "before" track block, the "Red" light is full on. When the train leaves the "after" track block, the "Red" light is OFF and the "green" light is ON.

This example uses one Two Relay Controller to operate a block signal: Relay-1 for the "green" light and Relay-2 for the "red" light.

The isolated outside-rail of the "ahead" track block is connected to Input-1-A. The "after" outside-rail is connected to Input-2-A.

Power for the 2RC is supplied with a 12-14 volt accessory transformer. Outside-rail input power is supplied by the train/center- rail transformer.

The 2RC jumpers are set for the Block-Signals/Train-Stopped feature set.

A series of block signals can be operated by sharing the the track blocks: the "after" track block of one signal is also the "ahead" track block of a following signal.

Click the bar for more information about Three-Rail Innovations' Two Relay Controller.