wiring for 3 light block signal,prototypical
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Dale H
Joined: Sep 25, 2010
Topics: 32 Replies: 39
Topics: 32
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Not much call for this but this was asked on the other forum. On a loop divided into blocks,a train immediately ahead would be a red signal. A train 2 blocks ahead would be a yellow signal. If both blocks ahead are unoccupied a green signal. If a 3pdt relay is used,shown in the diagram on each block, a complete block system can me made with a block signal for each block. For just one signal a SPDT and DPDT relay is needed. The coil circuit is not shown and is made by the insulated rail method. See my post "How to use relays for 3 rail block detection" for that wiring.
Here is the circuit in operation. Relay 3 is 2 blocks ahead,relay 2 is one block ahead of the signal on block 1. The train is moving in the direction from 1 to 2 to 3 etc.
Dale H
I think this is great, using relays seems like the old school approach to model railroading.
That in itself seems prototypical to me.
I've worked out this circuit with 2 spdt relays using some logic:
Red = Block 1 occupied.
Red = B1
Yellow = Block 1 clear and Block 2 occupied.
Yellow = -B1 & B2
Green = Block 1 clear and Block 2 clear.
Green = -B1 & -B2
Progress: