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(Guest)    J&C Studios O Gauge Archive    Electronics & Wiring    wiring for 3 light block signal,prototypical
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Topic: wiring for 3 light block signal,prototypical
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Dale H
Joined: Sep 25, 2010
Topics: 32   Replies: 39
posted on Apr 29, 2011 09:09 AM:
My Archive Category  

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


Leo Hinterlang
Joined: Jan 21, 2017
Topics: 0   Replies: 1
posted on Jan 21, 2017 09:31 AM:
My Archive Category  

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



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