The most challenging part of this layout was the design and execution of the electrical system. This required extensive planning before doing much of anything with wires and terminal strips. So I had to think hard about what I wanted to accomplish. I wanted the following features

• I like the "old school" way of running trains using simple 12‑V DC (direct current) with variable resistance transformers. I would like to use 4 transformers (power packs).
• I would like to retain the option for conversion to DCC. But indeed that is easily accommodated.
• I want reliable remote-controlled turnouts that are operated from a single intuitive control panel. If possible, I'd like the control panel to somehow blend in with the layout itself.
• I wish to take advantage of recent developments in light-emitting diodes (LEDs) for various status indicators.

I would like to take a moment here to mention a source of many of the electrical components in this layout: The Black Hole, a surplus store that had a great deal of equipment from Los Alamos National Laboratory.

The Black Hole was run by Ed Grothus, RIP. I took full advantage of what the place had to offer: remainders of spools of wire in many colors, flip switches, and even what was called a "submarine switch", which was a 12-position dual channel switch that I'll mention later. I really miss The Black Hole.

The entire layout has a single plug for an extension cord to household 110-V electrical main power. This is the socket with the single black fat wire on the right, in this photograph of all power penetrations through the frame:

In order to maximize flexibility for operators, I built these two power pack consoles that hang on the side of the layout frame. Each has a special wire spooler to handle excess cable, depending on where the console is hung. Here is what they look like with the compartment/coffee cup holder closed:

The compartment is handy for storing decouplers and other small stuff. Here the compartment/coffee cup holder is open:

On the inside of the frame, the incoming 110‑VAC power (the small black "can" to the lower left of the photo below) is run to two places: One is through the big ON/OFF switch to a power strip that feeds both the household receptable used by the power packs and two 12‑VDC power adapters, also used for accessories. The other wire from the "can" goes left in the photo, feeding an additional 12‑V adapter (through a switch) for the string of LEDs that run around the layout, turning the entire layout into a large hanging light fixture.

So, let's continue by following the current from the power packs to the track. This layout is wired as simple DC (direct current, as opposed to DCC, which is direct command control), with the speed of the locomotives determined by the track power, which is controlled by the 4 transformers. In a very simple DC layout, you would use only a single transformer and it would power the entire track. But you could run only a single locomotive at a time. I wanted a bit more of a challenge.

That comes with "block wiring". All the track in the layout is divided into a set number of "blocks", or electrically isolated sections. That set number happens to be 11 for this layout. There is one block for the yard, one for the turntable, one for the intermodal yard, and three each for the two main loops. Two more blocks are used for the yard lead. Each block is powered through a selector switch (the blue-capped knobs on the control panel whown in the photo below), which provides power to that block from one of the 4 power packs. Each block is independent, so that all the blocks could be set to run on any one of the transformers (like the simple layout described earlier), or the inner loop could be one one controller, the outer loop on another, and yard and turntable on another, and the intermodal yard on the fourth. Four operators could have fun with this. And, if you are quick-thinking, you can do fancy maneuvers like switching trains between inner and outer loops without switching transformers—all through timely block selection. It can get surprisingly complicated!

Recall that each transformer, blue, yellow, green, or red, is sending power to the wires that go through the mil-spec connectors. From there, each of the four power pack wires is input to each of the 11 block power selectors. The block power selectors connect one of the four power sources to the block of track to which it is assigned. So, four inputs to one output. Times 11. Actually, there is also a second set of inputs and outputs on the selectors to power associated indicator LEDs, but more on those later. A closer view of the block power selectors and other controls follows. In this example, the outer loop (consisting of 3 blocks) is running on the red transformer, the inner loop (also 3 blocks), yard lead (2 blocks), and the intermodeal yard are on yellow, the yard is on green, and the turntable and surrounding tracks are on blue.

Power to each block is provided by dedicated wires running from the assigned block power selector to the track(s) making up the block. This could be a short length of track (like a yard lead), to a complex array of tracks (like the yard itself). The turntable tracks are unique in that their power is run from the block power selector for the turntable through a 12‑position switch (the large silver knob on the control panel) hooked up to 11 different tracks leading from the turntable itself, plus one null location.

This layout also takes advantage of the "common rail" concept, where the power from the various block power selectors is directed only to the powered rail in any section of track. The other rail, in all cases, is the "common rail". All these common rails are wired together, which vastly simplifies the wiring, especially under the control panel. In these photos, the hot conductors are all in white wire, and the common conductors are whie with black stripes (or at least Sharpie marks trying to look like stripes). The following photo shows the underside of some of the turntable tracks. The hot wires (of which only one will carry power at a time, since it is run through the turntable track selector switch) come through the wooden bit of benchwork and fan out to feed up into holes below each track. The commons for each track are bundled together and leave the photo at the upper right, where they are all connected together electrically using a terminal strip. Somilar common-gathering terminal strips are around the layout. Ultimately, all the common wires are connected and fed back to the transformers.

In the photo above of the control panel, you no doubt also noticed several metal flip switches. Note that these each correspond to turnouts on the layout. These turnout control switches on the control panel are powered by a 12‑VDC source, and are used simply to provide power to the Tortiose switch machines at each turnout. They do not consume much power, and more than a couple are not run simultaneously, so there is little power demand and they are all attached to a single power source. These are simple SPDT (single pole, dual throw ON-ON) switches, diverting power to either one terminal or another. The output from each is connected directly to the corresponding switch machine. Flipping the switch one way makes the switch machine flip the turnout one way, and the other is opposite. Dead simple. To start the wiring, each switch machine was provided a pair of leads. This was a bit easier to do before installing them.

After installation, wires were run from the turnout control switches to each of the switch machines.

The turnouts require an additional bit of wiring, facilitated by the Tortoise switch machines: wiring the frogs. The frog of the turnout is that small wedge-shaped piece that lies right at the juncture of rails. If the turnout is thrown one way, the frog needs to have the hot power for the adjoining block. If it thrown the other way, it needs to be part of the common rail. So, the wiring to the frog has to be switchable in coordination with the position of the turnout. The Tortoise switch machines, in addition to throwing the wire that physically operates the turnout above, has two internal SPDT switches, so that frog power can be connected to either the local block or to common. The other SPDT internal Tortoise switch is used for indicator LEDs as described at the end of this section.

Let's take another look at the control panel. One nifty feature is that this corner mounted panel, made from an old speed limit sign (that the County gave me—I did not steal it) on a piano hinge.

In the following photo, taken early on in the wiring process, you can see that many of the switches are installed. The block power DP6T rotary selectors are the brownish ones, and the turntable track selector is the big tan DP12T one. Some of the turnout switches are installed here, and in other places, only the hole is drilled. The two switches in the E of SPEED are to be attached to turnouts.

This also shows another application, this time for some simple SPST (single pole single throw) ON-OFF switches: isolating bits of track power. For example, see the row of four red SPDT switches along the right edge. Each of these will be connected to a track power wire for a tail end of a yard track. This will allow a locomotive to enter the tail of the yard track and then have its power isolated, so that multiple locomotives may be stored in the yard without them all sharing power.

The gray box at the left corner is the control box for the turntable. This box was later replaced with the blue one that came with the new turntable, but fortunately the replacement is the same size and wiring. The only other as‑yet unexplained bit of the control panel is the light-emitting diodes (LEDs), which have several uses...

As mentioned above, each block power selector connects one of four power sources to each block of track. These selectors are actually DP6T rotary switches, Only 4 of the positions are used, with a dead one at each extreme, which is handy for killing power to a block if desired. These are dual throw, meaning that they control two things at the same time. One thing obviusly is the track power. The other thing is the LEDs that indicate which transformer is connected to the track. As each transformer is switched to, a 12‑VDC power source is also switched to the corresponding blue, yellow, red, or green LED. Each block power selector has a bank of four LEDs next to it, so that the operator can readily see which block has power from which transformer.

Note that each LED, operating on 12 VDC, requires a resistor in order to moderate power. This is something that you will have to figure out on your own (there are calculators available on line), and for me each color required a different resistor. Fortunately, resistors in a variety of values were available from–where else?–The Black Hole. I made resistor/LED bundles for each turnout selector switch.

So, what's up with the orange ones? I had a great brain wave one night. The switch machines, now wired in, have a set of pinouts on them that are electrically switched inside the Tortoise to match the position of the turnout above. I could therefore connect a series of wires through the switch machines in the yard (and also in the intermodal yard) so that an orange LED at the end of the track (under the track bumper) would light up only if that yard track was selected by arrangement of the turnouts. Not only that, I could add a second LED on the control panel to also show which yard track was "selected". I was very happy to make this discovery.

And yet another use of the orange track selection LEDs: identifying the turntable tracks. Recall that the big turntable track selector DP12T "submarine switch" sends power to only one turntable track at a time. Using the second pole, an LED is wired in parallel with each of the track power leads to show which track is "active". In the case of these indicators, no corresponding orange LED is provided on the control panel. The operator has only to glance at the turntable to see which is the powered track.