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How to Build a Transistor Radio Out of Toilet Paper Rolls

Even though its uses date back to the earliest days of radio, building a simple transistor radio out of a toilet paper roll, some wire and a few other simple items is still pretty impressive. You don't need power to run it and you can build it in about an hour. That makes it a perfect father-son project or a good suggestion for any grade-school science fair.

Things You'll Need

Roll of magnet wire
Copper wire
Toilet paper roll
Package of metal thumb tacks
Small piece of lumber, at least four inches wide and six inches long
Razor blade
1 safety pin
Wire cutter or knife

Instructions

- 1
  Wrap the magnet wire around the toilet paper roll 150 times. Begin at one end of the roll and cover the entire outside of the roll with the wire. Make sure to leave a small amount of the wire loose at each end of the coil. Place a metal tack about an inch from each end of the tube. It is important the tack has a solid contact with the magnet wire.
- 2
  Attach the tube to the wood plank with several metal tacks. Attach a four-foot length of copper wire to one of the loose strands of magnet wire attached to the tube. Wrap it several times around one of the metal tacks before attaching the other end of the copper wire to a heavy metal object, such as a radiator or window frame. That will serve as the ground wire for the radio.
- 3
  Repeat the process, attaching another length of copper wire to the other loose length of magnet wire. This wire will serve as the antenna. If indoors, hang this wire out the window. If outside, simply hang it somewhere off the ground.
- 4
  Attach the razor blade to the board next to the toilet paper roll with several metal thumb tacks. Run a length of magnet wire from the roll to the blade, making sure the wire touches the blade's metal surface. Push a metal tack through the eyehole of the safety pin and attach it on the wooden board next to the razor blade. Position it so that the point of the safety pin rests at the edge of the razor blade. You will use this blade/pin combination to tune your radio.
- 5
  Run a length of wire from the safety pin to the input end of a set of headphones. Wrap that wire around the headphone end, then wrap another length of wire from the end of the headphones to the tack on the tube where the ground wire is attached. This will allow you to listen to your radio, although you won't be able to adjust the sound level.

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