Tech Tip for Building a Test Lamp

Let there be light!

A small, homemade, 12-volt test bulb is easy to build and has myriad uses (see Tech Tip for Recharging Your Motorcycle Battery the Right Way). You can trace circuits, check charging systems, use it as a tiny spotlight and even set the timing on old points-fired crocks. Besides, it's something every shade mechanic worth his salt should build, if only as a nod toward tradition.

Constructing one takes nothing more than a light socket (I suggest using an old taillight socket; traditionalists prefer to strip them out of a wrecked bike or junked car, but you can certainly purchase one at the auto-parts store too), a few feet of wire and a couple of alligator clips. I’d recommend against soldering the wires directly to the bulb, if only because you’ll need to make a new one every time the light burns out.

test lamp, lights, motorcycle accessories, batteries
Building your test lamp is easy and useful, so follow these next steps to light the way.Photography by Mark Zimmerman

Here's the Drill:

  1. Crimp, solder, screw or otherwise fasten the wires to the socket in the appropriate spots. Use red for the positive feed and black for the ground.
  2. Attach your alligator clips in a similar manner; again, I'd suggest red for the feed.
  3. Go forth and illuminate your way!