Monday, February 17, 2020

I used to hate wiring...


So yes, I used to really hate wiring.  I don't hate it nearly as much anymore, thanks to a wiring system that was introduced to me by Tim Eckert, fellow Marklinist, over twenty years ago...

The concept is simple: instead of having wires running around the layout with occasional distributors to feed the track and accessories, the electrical bus is made up of several runs of bare copper wire that circle the layout, allowing hook-up anywhere a wire drops from above.  The bus can be created using any number of copper wire runs.  I chose four in total, which provide the following:


Brown:  accessory and track ground
Red: track power
Yellow: accessory power
White:  feedback ground


Most of you are familiar with the first three, as they are identical to the connectors on a typical Marklin (or other train) transformer.  The last one, the white feedback ground/return, is designed to reduce the wiring to the reed switches.  You see, the way my feedbacks work is that the reed switch closes when a magnet passes over it, completing the circuit back to the S-88-style module to 'sense' the location of a train.  I'm able to tie all the wires on one side together into the bus and only need to come back with one wire.  Here is a visual representation using the feedback modules from Digikeijs:
See how the light-brown wire connects all the common terminals together?  That's why I added another bus wire.  Of course, I'm using reed switches while the image above shows using Marklin HO track to close the circuit, but the principle is the same.

Anyway, back to my bus wires.  Here is how things look from above the layout looking down through the benchwork:
I added small tabs of colored electrical tape about every three feet all the way around the layout to reduce the chance that I hook things up wrong.  The rolls of colored tape are readily available at most home stores, and even at my local Ace Hardware.

I originally considered drilling holes in the benchwork for running the bus wires, but ended up using eyelets instead:
Two things to note in the image above:  First, the eyelets are positioned on every other piece of benchwork.  I realized it was fairly pointless to put them on every single span, as long as the wire is fairly taught (but not too taught, as it is copper and will stretch over time).  The other thing you'll notice is an extra eyelet to the left (in the image above) of the eyelets with the bus wires running through them.  This eyelet appears on every span of the benchwork.  It will be used for those wires that drop down from the layout overhead and run to either a feedback module or an accessory decoder.  Each switch will have two wires, while uncouplers or reed switches will have one wire to run. 

Here's a final picture from underneath the staging yard on the lowest level.  Even in the dark it's easy to identify the bus wires by color.  Still, I plan to have lighting underneath the layout for easy troubleshooting...
A couple of comments:  First, make sure you space your wires fairly far apart, I'd say a minimum of 4 inches.  This is so you can get a wire attached to one bus wire without pushing on the one next to it.  More importantly, when you turn a corner you need to be careful to maintain the space between the wires.  In fact, it would be good to have an intermediate diagonal brace with a set of eyelets on it.  The image below shows why corners tend to be tricky:
The brown rectangles represent cross spans of benchwork with either through-holes or eyelets underneath.  The three colored lines represent three wires of the electrical bus.  See how close those wires get together when you have a sharp bend and a fair distance from the two perpendicular benchwork pieces / eyelet sets?  If the wires are insulated that's not a problem, but with bare copper wire this is just asking for an electrical short...

If you choose to solder your wires to the bus you'll also need some room for your soldering iron and the solder, another reason to space your bus wires fairly far apart.  And this buggest from personal experience: If you are soldering, have a good, hot soldering iron.  You'll probably find yourself bending over the layout or crouching underneath to solder wires to the bus, so the sooner you can get the bus and connecting wire hot enough to solder, the better it will be on your joints and back!  I'm actually going to try to not solder my wires to the bus, but rather to use liquid insulation for maintaining the connection.  But more about that in a future post...

It may be a couple of weeks before we tackle the next stage of the layout, which is the roadbed for the track to go from the bottom level of the layout to the middle level.  This will give us a very clear understanding of what challenges the grade will cause...