Wiring Basics, Identifying the Parts

Wiring of the circuit could not be easier. As there are only two components (three if you count the LED), there is no need for circuit boards. Simply solder the components together in a shape that suits your locomotive. Please note the orientation of the chip, as it must be wired one way only. The LED must be wired the correct way around too. To identify the correct polarity note the following points:

The resistor is not polarised and can be wired either way around. Remember to insulate the circuit from shorting against itself or anything around it. This can be as simple as wrapping the leads (once you have soldered them together) with a small tab of scotch tape. The most important note is that if the middle pin of the chip shorts to the 3rd pin (i.e. across the resistor) then the LED will most probably burn out.

Wiring Diagram

Please note that the markings on your chip may well be different than that shown above. It should say LM334Z on it somewhere though. Make sure if you are asking for (or ordering) it by name to add the Z on the end, as the other versions are too big for most model use. The Z version is the most common and commercially available version.

While the above diagram shows wire connecting the individual part, you would not typical need wire to connect in the resistor. Just solder the leads directly together, it may benefit you to cut them shorter before you do though.

The parts look like (with a pencil for scale):

Photo of the Parts Involved