Help. I'm building a new layout, where one of the primary goals is to have all the structures lit. I will be using LEDs for the light source. My idea is to run an appropriate power bus (much like a DCC power bus) under and benchwork and throughout the layout, with the plan to drop structure wiring leads down through the benchwork to make an easy connection to that power bus.
Question: What type of power supply, wire size would you use? What other considerations should be made? What other types of questions or issues should I be considering?
I usually build my structures (with LEDs in place and tested) on my work bench, with their own small base. After completing the weathering and details, they're moved to the layout to be permanently placed, with the LED wiring leads being pushed through benchwork. The question is, in other words, what do I connect these leads to? Will one dedicated power bus do the trick? One other thing, I have dozens of lighted structures.
Thanks.
Big George
in SLO, CA
Hi, and welcome aboard!
LEDs require very little power, and generate very little heat, so in those ways they're ideal for this application. On the other hand, most LEDs are very directional, throwing off a strong beam of light in one direction, and very little everywhere else. "Warmer" LED colors are available now, but the harse, bluish light from most white LEDs is less appealing for structure lighting.
One thing you didn't tell us was the size of your layout. When dealing with any kind of wiring bus, overall bus length is an important consideration. You can get away with smaller wires on a small layout than you can on a large one.
I would use a 12-volt bus, driven by a 1-amp power supply. That should be enough to drive all of the LEDs. Each LED should have a resistor, typically 1K, wired in series with it. The resistor limits the current through the LED, and drops the voltage to a point where the LED is happy with it. Don't wire 12 volts directly to your LED, or it will quickly become a Darkness Emitting Diode, or DED.
Because LEDs don't draw much power, you can get away with smaller wiring than you'd want for your track bus. 18 AWG should suffice for any size layout, and you can probably use 20 or 22 AWG for most home-sized setups. Your feeders can be even smaller. I'd strongly suggest color-coding the bus wires, because polarity is important. Also, consider some form of connector for the wires, rather than soldering. A simple terminal strip with screws can serve a cluster of structures, and it will be a lot easier to remove one later if needed.
It takes an iron man to play with a toy iron horse.
Wire size is small due to the fact that LED's draw very little current, and therefore generate little heat, a big plus for plastic buildings. AWG 20 or 22 should be fine without getting so small the wire is fragile.
For the power supply, following my tradition of "Don't spend when you can scrounge," I came across two sources for cheap/free power supplies for such things:
1) an old battery charger for a 9 volt rechargable drill. The drill is long dead, but I didn't discard the charger. It puts out 9 volts at 400mA, which will power quite a few LED's. Since the LED's I'm using are rated at 3 volts, I simply tie three in series, then parallel each set to the power supply.
2) an old laptop computer power supply. Since these vary in output voltage, you'll need to check the label for output, but the same formula works. For an 18 volt power supply, I'd need to tie six LED's in series.
These can usually be found for free, when someone discards an old rechargable tool or laptop. So keep your eyes open and your wallet closed.