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How to Solder a Resistor to a Light Bulb

A resistor is a device that limits the amount of electric current that flows through a circuit. When used in conjunction with a light bulb, a resistor can control how bright the bulb will be when a voltage differential is applied to the light bulb. One way to electrically connect a resistor to a light bulb is to solder the resistor to one of the electrical terminals on the bulb.

Things You'll Need

Light bulb
Sandpaper or steel wool
Soft cloth
Soldering iron
Electronic solder
Wet sponge
Resistor

Instructions

- 1
  Use the sandpaper or steel wool to roughen a small spot on the light bulb̵7;s outer metal sleeve. Use the soft cloth to wipe off any metal shavings or dust from the light bulb.
- 2
  Turn on the soldering iron and allow the iron to heat up for at least one minute. Place the tip of the solder wire on the tip of the hot soldering iron. Melt a small quantity, about a drop̵7;s worth, of solder to the soldering iron tip until the tip has a light coating of solder over it. Wipe the soldering iron tip against the wet sponge gently to remove any excess solder.
- 3
  Place one of the resistor leads against the roughened spot on the light bulb sleeve. Place the tip of the soldering iron against both the roughened spot on the light bulb sleeve and the resistor lead. Melt a small drop of solder from the solder wire coil to attach the resistor lead to the roughened spot on the light bulb sleeve.
- 4
  Use the tip of the soldering iron to smooth the soldered electrical joint. The soldered joint should be flat, shiny, and free of lumps.

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