Blog- Shelf Island (00/HO and HOn2.5) - Wiring

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The layout is wired for DCC, although at the moment all of my locos and controllers are analogue. I have put three switched track sections into the fiddle yard, but apart from these the system is very much restricted to "one engine in steam" for the time being. I think the finished layout will benefit a lot from DCC sound, and I would like to make the transfer to DCC in the next year or so.

 

The layout wiring is based on five bus bars which run the length of the baseboard. This has, I think, let me assemble a wiring system which is self-documenting and doesn’t need any schematics or wiring schedules:

 

 

The five bus bars are solid copper wires from household electric cables. The bus bars run through holes drilled in the cross members of the baseboard and are marked up with lengths of heat shrink sleeving like this:

red: track feed

blue: track return

yellow: 0V

violet: +12V regulated supply

green: -12V regulated supply

 

 

The last three of these are a split 12-0-12V supply for everything on the layout except the track power: point motors, the Bluetooth relay board (via a 5V regulator), the building lighting and so on. The 12V power supplies are built into the fiddle yard.

 

I wired up the track first - I used crocodile clip leads from each track feed to the bus bars. This let me disconnect wires as needed to find short circuits in the track. There were two problems in all, both where I had forgotten to cut a slit in copperclad sleepers. If I had soldered in all the wires before trying to test for short circuits the faults would have been almost impossible to find.

 

I chose a 12-0-12V regulated supply because it makes wiring and switching the Tortoise point motors so easy. One wire from each motor one goes to the 0V bus bar and the other wire goes to a relay on the Bluetooth relay module. There are nine motors in all, with two pairs wired in parallel as crossovers. So there are seven wires back to the relay board, leaving one relay left spare for future use.

 

The points are all wired so they are in their respective “normal” positions when the relay board in powered off. So I get a nice and predictable route when I “boot up” the layout.

 

Most of the point motors have five wires connected: two yellow wires for the motor, a green wire for the associated frog (frogs are green?) and two white wires to take track power to the frog. The wires are formed into cableforms and strapped down tightly so the wires are physically supported separately to the soldered joints:

 

 

Infuriatingly, the Bluetooth relay board needs a +5V regulated supply. So there is a 5V regulator (I used a Velleman kit, their part number K1823) to run the relay board from one of the 12V rails:

 

 

For the time being, I am controlling the relay board from my phone:

 

 

The only “difficult” thing about the wiring is the all-live flat crossing. I think I have been reasonably clever here - I have hard-wired two opposite corners to the usual track feeds (my red and blue bus bars), and used both sets of changeover contacts on the nearby point motor to route the power to the other two corners. So when the point is set for the standard gauge siding to the crossing, the standard gauge path through the crossing is powered. When the point is reversed, the narrow gauge path is powered. I’ve done the wiring in a fairly laborious sort of a way on a piece of group board so I can alter it if I decide I want something more sophisticated:

 

 

There is one luxury - a strip of LED lights along the front edge of the baseboard. These are visible in the two photos of the bus bars. The idea is to improve the look of the model when it overhangs the fronts of the book shelves underneath it at home. The LED strips are powered from one of the 12V rails. Arguably, they ought to have a completely independent power supply (so they can run when the layout is off) but again I can alter this easily enough if necessary.

 

This little lot has has consumed rather more wire than I expected, perhaps 40 metres in all. The bus bars make it very easy to extend the system, for example to add some signals or building lights. The most satisfying thing is, of course, that the wiring has turned the layout into a workable model railway. I think it is going to be a fun layout to operate - you can move wagon loads from one place to another, instead of between the usual one place and one fiddle yard.

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