Track Feeders & Buses


No … not that sort of bus!
In our case it’s a wire, or a collection of wires that carry an electric circuit or a data circuit.

In the underside view of this little demonstration layout, the Bus wires are the RED and WHITE pair which carry the DCC Bus along the bottom.
Tapping into it at several places are DROPPERS or FEEDERS (red and black) to carry the DCC circuit to each piece of track on the top.

In this example the bus is connected to a PCB strip in 4 places to simplify connection of the droppers to the bus.

I will have a post to cover using printed circuit board PCB for various purposes.

 

See: Making Simple PCBs

This an underside view of my layout with 4 bus wires in view.

A = DCC main bus; (heavy duty stranded copper wire) Red = rear track wire
B = 12V; (H/Duty above) Blue is Positive and White is Negative
C = DCC sub bus (in this case from the main bus to the YARD bus). This allows
me to easily isolate that section.
D = MERG Can-bus which distributes the electronic data around the layout.
Note that it is very thin as it carries low current signals.
Note also that the wires carrying a data signal A,C & D are all lightly twisted to lessen interference one to the other.

Note the colour coding – there is no fixed rule but RECORD your code.

Our problem is to get the track feeders through the baseboard, in this case FOAM, to the Bus underneath. EVERY piece of track must be fed between joiners. There is a special issue with foam.

Some sources indicate that the foam can react with the plastic on electrical wiring and cause it to break down. A wooden base board can just be drilled 6mm.

So, after we have drilled the hole in the foam (as shown here with the 6mm K&S brass tube drill still in place) we need to line the hole with an inert material.

 

Note the colour coding – there is no fixed rule but RECORD your code.
See the Post on DRILLING HOLES IN FOAM for more info.

Because this section of my track was using Expanded foam (not recommended) I had to clean the hole out with something that was a loose fit to get rid of all the little white balls of plastic.

This is not needed in Extruded Polystyrene Foam. See details on foam HERE.


The 6mm hole is an exact fit for a drinking straw. My preference is for the paper straws but they seem to have disappeared on the far South Coast so plastic ones will do.

Measure it to be 5 mm longer than the total depth of foam and underlay.

 

 

Coat the straw lightly with some PVA…

 

 

 

 

… and slip it into the hole.

 

 

 

Wipe off the excess PVA …

 

 

 

 

…and do the second one.

 

Now we come to the bit where you need to solder a wire to your track, take it down the feeder hole and connect it to your Bus wiring.
Shown below are the tools you will need for the top side. I have a colour code for the droppers – RED is the Right DCC track (or in my case, the REAR track closest to the wall in an around the walls layout). My front rail is fed with GREEN (because I had heaps of that colour).

In a module you just need to be consistent making sure that no swap-overs occur.
As can be seen at the top, I have a main DCC bus which feeds 4 sections – North (Carriage Works), South (Loco), East (Yard) & West (Station – “Bolgan Road”).

Each section is fed via a STOP LIGHT BULB in series with one feed wire. If there is a SHORT CIRCUIT, the stop light bulb will carry the load and LIGHT UP.
See THIS SITE for more info. Or THIS ONE.

Strip 1cm approx.
The wire I used was from Jaycar and is sold as
Flexible Light Duty Hook Up Wire 13 x 0.12 tinned (WH-3005 green)
Twist the strands tightly together.
A typical appropriate soldering station.
Put a tiny amount of liquid flux on the bottom flange of the rail.
Pick up a tiny amount of solder and tin the bottom flange.
This is a better photo of how the tinned flange should appear.
Use a sharp blade to cut a slit in the track bed to allow the feeder to drop straight down from the rail, as in the last photo.
Tin the end of the feeder wire – ideally only the last 2mm!
This is where the self closing tweezers are handy.
Line up the end of the wire with the flange …
…and try to solder just the tip of the wire to the flange,
Then push the wire down and into the slit made earlier.

If you are working on a timber baseboad, the feeder hole can be drilled between the sleeper (tie) ends under the connection point and there is no need to line the hole.

Once the track is painted (weathered) and ballasted the feeder should be almost invisible. The feeder is shown at the end of the toothpick.

The photo above  shows some of the kit I use when working under the layout.
There is:
1. a low level seat which can slide on the floor
2. a low level 240v light (LED) which has now been replaced by a similar size rechargeable LED work light,
3. soldering station,
4. wire strippers, knife, sidecutters (not visible) for removing the insulation from about 1cm of the Bus wire.
5. and, BEST of all – a locking clamp with a roll of solder attached so that it is easily accessible.    See the post on Strain Relief to help you work under a layout.

This is the LED battery work light. It is a 10W 6000K (cool white) unit which is also useful for colour painting.

 

 

 

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Rick Fletcher

Born in the steam era and developed an interest in railways when given a clockwork Hornby "set". Surrounded by steam when travelling to school (by train of course) and holidays were always by steam train as we had no car. How lucky was I?

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