Signals and Block Detection in the Classification Yard


D&J RailRoad

D&J RailRoad

Professor of HO
I have a little time on my hands so I decided to expand my block detection and signal system into the classification yard.
I picked up a Digitrax BD4N module and an SE74 signal control module.
I decided where I want to plant the signal heads and then broke open the packaging to read up on how to install the two modules.
First thing I notice is the DB4N doesn't have a loconet port. Hmmmm, how does it talk to the rest of the layout then?
OK, Digitrax web page describes the DB4N and that there is a ribbon wire that connects it to the SE74. Ahhhhh, OK. I have plenty of ribbon wire and the two modules will be mounted about 6" apart.
OK, on with isolating the Arrival/Departure (A/D) tracks from the rest of the tracks. Hmmmm, lots of freight cars clogging up the yard. OK, took about 15 minutes to drag all the cuts of cars out onto the mainline to park them while I do this job.
OK, first thing is to run a common wire the length of the yard. Back rail will be the common rail as is the rest of the empire. I had to drill holes through the plywood support panels to run the common wire. Put the spool of wire on a screwdriver that was stabbed into a 2X4 so it could unroll the wire as I pulled it along through the panels. Stappled the end of the common wire to the last panel so it doesn't pull back under the yard.
Now, drillin holes down through the ballast then soldering drop wires to the rear common rail then solder each one to the common wire. About 1/3 the way down the yard and had to take a break.
 
A couple of pictures to go with the narrative.
The A/D tracks are closest to the front of the yard tower.
The yard had to be cleared of all rolling stock so I could reach the two tracks to solder drop wires to them.

20231209_162310.jpg



The electronics board is built so it lays back a bit to make it easier to work on and read the contact points.
The top item is a breaker. The top wire on the right go to the main yard. The bottom wire on the right go to the block detector.
The DB4N is next module down. The one lead coming out of it is the common wire to the back rail of each A/D track.
The bottom module is the SR74. A ribbon wire jumper will go from the block detector above it to the 10 pin connector on the right edge of the module.

20231209_162334.jpg
 
I was able to resolve the problem with the isolating the two ad tracks. Had just one wire underneath the bench work that was soldered to the wrong bus line. I should be able to finish the drop wires tomorrow.
 
When you are done I have a couple staging yards to do. I love layout building, I dislike the wiring…
 
Generally there would not be any kind of signalling within a yard - just the main tracks passing and connecting to the yard.
 
Why do you want detection and signaling in a classification yard?

As Chris mentioned that isn't done on the prototype and the signals would be red the majority of the time since in a class yard the majority of the tracks are occupied the majority of the time.
 
Finished.
The sensitivity is adjustable on the BD4N with a resistance pot.
Both tracks are completely isolated and there are surface mounted LEDs that light when the section is occupied.
I have two more occupancy sensors I can use and I[ve determined where I'll do that. I'll get the intermodal yard asphalt laid first then come back to the yard leads.
I'll hold off on installing the signal heads until I get the 10 wire strap that goes between the BD4N and the SE74.
 
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