The James River Branch Z Scale Model Railroad: Power and Wiring

Power Supply and Wiring

Like the aborted version of the layout that came before, the James River Branch was intended to be entirely battery-operated. Unlike the previous attempt, the trackwork is now a single, unbroken "block." Previously I had intended to compensate for the up- and down-grades by isolating each section of track and providing slightly different voltages to them so as to keep the train running at a constant rate of speed.

But as I came to learn when the trains ran briefly on the old layout, there was no need to compensate for the grades; the trains ran at a consistent speed regardless of the grades. This was confirmed on 6 January 2008 when the new layout had its maiden run. And so, this time around I soldered every section of track together, and attached two pairs of feeder wires, one each at the midpoint of each helix.

Feeder wires are soldered to the track on each of the hidden helixes.

Wires pass from one end of the layout to the other through a wiring channel.

Given that there would be no "operation" as such on the layout (just continuous "roundy round" running), I needed no throttle. It was then a simple matter of determining the appropriate voltage required to keep the locomotive running at the slowest speed it could reliably function. 3 volts was not quite enough, and 4.5 was a bit too much, so I used three 1.5-volt D cells plus a silicon diode to produce just the right amount of juice.

I was half-tempted to simply use an on-off switch to control the train, but I could envision occasions (hopefully few or none, actually) where I might need to reverse the engine to re-couple it to cars that might have become separated or derailed. So, I elected to use a double-pole double-throw toggle to control the train.

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