How to make a 12 volt DC dimmer

Written by james stevens
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How to make a 12 volt DC dimmer
Making your own 12-volt dimmer is fun and educational. (Jupiterimages/Polka Dot/Getty Images)

Dimmer units enable you to control how bright you want your light. Dimmers, also called rheostats, are made from a flat wire winding; one end of the wire connects to the power source and the other extends to the end of the wire winding. Place the end of the wire that connects to your light in different places along the winding and you find the light gets brighter or dimmer; the nearer to the power source the brighter the lights gets. The great thing about a 12-volt direct current (DC) dimmer is there's no risk of getting an electric shock, so it's a great educational item to make safely at home.

Skill level:

Things you need

  • Scissors or knife
  • Cardboard
  • Bare copper AWG 20-gauge wire
  • Battery
  • Light bulb
  • Insulating tape

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  1. 1

    Cut out a piece of cardboard about 4 inches by 2 inches. Use scissors or a knife so you get a rectangular shape to form your 12-volt DC dimmer.

  2. 2

    Start about ½ inch from one end of the cardboard and begin winding the bare copper wire around the outside of the cardboard. Leave about 6 inches of wire exposed, as you need to connect it to the power source. Take your time and do it neatly so each time you wrap wire around the card it is placed next to the previous wire.

  3. 3

    Continue winding the wire around the cardboard until you get to about ½ inch from the opposite end of where you started. Continue to wind the wire around the card, but start going back to the beginning so you make a double layer.

  4. 4

    Cut off the end of the wire once you get back to the where you started, then tuck the end under the winding so it doesn't show.

  5. 5

    Connect the end of the wire you started with to a 12-volt battery terminal; an old car battery works fine. Tape the end of the wire onto the terminal.

  6. 6

    Cut a strip of wire about 18 inches long using a knife. Tape one end of wire to the other battery terminal, then tape the opposite end to one of the terminals on the light.

  7. 7

    Cut another strip of wire about 12 inches long. Connect one end to the other terminal on the light.

  8. 8

    Place the opposite end of the second wire strip at the beginning of the winding you made earlier. The light is bright. Put the wire on the other end of the winding and the light is dim. Move the wire along the winding and the light gradually gets brighter.

Tips and warnings

  • You can change the amount of resistance in the winding by making it longer and thicker. The more wire, the greater the resistance.

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