Test Light for Dummies

Howdy folks!

This has come up a couple times lately. When someone is facing an electrical issue and is forced to shoot in the dark trying to sort it out.
"Have you got a test light?"
"No."
"****!" (LOL)

I have put together a super basic test light that anyone can make with free crap they have laying around. Takes maybe 5-10 minutes and only requires you to have a soldering iron.

Materials:

-A few feet of wire, 16-18ga is fine but there's lots of wiggle room here.
-A 12v automotive light bulb. I used an 1157 taillight bulb, you may use a different one.
-Two nails, and/or alligator clips, and/or some stiff wire (your old throttle wire!), rivet shafts, whatever you have
-Electrical tape

Putting it together is easy. Clean up the contacts and base of the bulb with sandpaper, wire brush, whatever. Cut 2 lengths of wire, a couple feet each. From one wire, strip about 3" of insulation off one end, and twist the individual conductors together. Wrap it around the base of the bulb, twist, and solder. Strip 1/2" off one end of the other wire, and solder to the + contact of the bulb. Now, strip and attach the free wire ends to what you've got. For this demo, I used an old alligator clip I found, and a 3" framing nail. To attach to the nail, I stripped 1" or so of insulation, wrapped it around the nail a couple times, and soldered. Be sure to clean the solder area of the nail with sandpaper. You can use other things you have laying about as a probe. Lastly, wrap the bulb base in electrical tape to avoid unwanted short-circuits, and if you used a nail or wire as a probe, wrap most of the shaft and the head, leaving maybe 1/2" exposed.

Presto! Instant freebie test light! Now- If you can lay hands on a bulb socket and a couple crimp-on alligator clips, you can make a solderless version. Easy-peasy! If you've got better goodies laying around, you can make a really slick verion. I made one a few years ago using LED's- If you set them up opposing, you get a 3-function test light that will indicate + and - DC polarity, as well as indicating AC.

Good Thinking There.

lol, good one.

One of the simplest circuits ever!   
Although very handy to have   

Yup- and that's the point. There is NO excuse not to have a basic test light of one form or another, and I really don't understand how you can live without one. Electricity is invisible. You NEED something to see it, and that "something" can be dirt simple.

well, there's always the "Hold the sparkplug in your mouth" test for spark... You laugh... at 8 Years old my dad called me over and said "hold this wire and tell me if I'm getting spark... As he pulled the cord on our old lawnmower...

Lawren Wimberly wrote:

well, there's always the "Hold the sparkplug in your mouth" test for spark... You laugh... at 8 Years old my dad called me over and said "hold this wire and tell me if I'm getting spark... As he pulled the cord on our old lawnmower...

Explains a lot lol.

yeah... I GET that a lot LOL. This is the same man that would send me out under a tree to find nuts... Then when I didn't find any, he'd say "I see ONE from HERE!" And ya all wonder why I have such a sick sense of humor...