Need Wiring Basic Help for Models!

Model Railroader Layouts and layout building
1

I’m trying to illuminate a HO Scale Bachman Bobber caboose that I’ve stripped down and detailed.

I purchased 1.2v marker lamps for the one end, and I’d like to use a grain o’ rice bulb or LED for the interior, but I have no idea how to wire these to run on my DC powered track without blowing the bulbs.

Please help!

Ignatius

2

Steve
One way to power a 1.2 volt bulb through the track is with a LM317 voltage regulator. Since you are not using it to power electronics, you don’t need the capacitors or diode shown in the diagram. You will need power pick up through metal wheels and axles.

Because of the LM317’s size and the bobber has an interior, you may have trouble finding a place to hide it. I have found and have used a smaller size regulator from Digi-Key. The part number is TK11620CT.
It’s in a TO-92 case, 2 volt and can handle up to 100 milliamp. For a 1.2 volt, 15 ma bulb, you can use a 5 ohm, 1/4 watt resistor to reduce brightness and increase bulb life.

For an LED, use the 3 volt regulator TK11630CT

With the flat side facing up (reverse of the photo) and the tabs towards you, the left tab (#1) is positive output, the center tab (#2) is negative ground and the right tab (#3) is positive input.

You will also need a small bridge rectifier, Digi-Key part # DF02MGI.
The parts are small enough be hidden under the bobber floor and can be wired together instead of using a circuit board.

3

I would consider the use of an AA battery and a small on-off switch instead of track power. No more than you would have the light on, an AA battery should last a long time before it needs to be replaced. I have 3 Bachmann Bobber cabooses and their wheels are not designed for electrical pickup from the track. Modifying them would be more expensive than a battery.

4

But that would be too simple. If there’s room for a battery and switch.
Demar Electronics sells latching reed switches, part # R-1250. Just wave a magnet past the hidden switch and it closes the circuit. Wave it over the switch again and it opens the circuit.
All Electronics have battery holders for 1/2 AA, AA and AAA. They also have rechargeable AA batteries and AAA batteries with solder tabs.

Interstate Batteries sells a rechargeable 1/2 AA, 350 mAh 1.2 volt battery (search for part # ASC0060).

I don’t know if a button would last long, but it could worth a try.