How to Make a Christmas Mini Lightbulb Tester. One of the wonders of Christmas time is the wonderful way people light their homes with Christmas mini-lights. They are the outdoor version of Christmas tree lights. But sometimes the string of lights goes out or partially goes out. Save money buying new ones when you can build a simple tester that will locate the bad bulb. With the tester, all you need is a supply of spares.
Things You'll Need
Old extension cord with two prong end
Pill bottle and cap
C or D cell battery
Drill and 1/16 inch drill bit
Hold the top of the pill bottle you will be using as a testing device and remove the cap. Drill two small holes in the center of the top spaced about half inch apart. This will serve as the test plug for your light bulb. Enlarge the holes to be slots by using an Xacto knife. Be very careful and use the bottle to hold the top while you cut. Test the prongs of the extension cord to make sure they fit through the slots in the top of the bottle.
Take the C or D cell battery and attach a one lead wire to the top of the battery. You can do this by electrician's tape or by soldering the wire to the top of the battery. Make sure there is two inches of wire left. Now attach a lead wire to the center of the bottom of the battery. Use the same method as you did for the top of the battery. Leave about four inches of wire on this lead. You now have a battery wired to a two-prong plug.
Insert the C or D cell battery into the pill bottle and stuff into the top of the pill bottle the two-pronged plug. Use electrician's black tape to circle the plug until it fits snuggly in the top of the pill bottle. Push the pronged plug into the bottle with the prongs facing out.
Adjust the spacing between the two prongs to be the width of one of the light sockets in the Christmas lights. Now plug the Christmas light bulb into the tester and see if it lights. If the light doesn't light, then the bulb was bad.