How to Build a Radio Transmitter

Building a radio transmitter is an educational way to learn about sound waves. In addition, a radio transmitter can be useful during storms, to transmit audio from portable MP3 players to radios or to transmit a low power radio program in your neighborhood. Even better, if you are ever stranded on a desert island you may be able to build a radio to send a rescue signal.

Things You'll Need
Megahertz crystal oscillator
Audio transformer
Generic printed circuit board
Phone plug
9-volt battery clip
9volt battery
Set of alligator jumpers
Insulated wire for an antenna
Soldering gun

Instructions
Building a Radio Transmitter
1.Pull the tabs on the bottom of the transformer out so they are flat. Place glue on the bottom of the tabs. On the wooden side of the printed circuit board attach the transformer to the printed circuit board. Make sure to leave plenty of room on the right for the oscillator.

2.Insert the leads of the oscillator through the wooden side of the printed circuit board. The oscillator should be on the far right hand side of the board. Bend the leads down so the oscillator is firmly attached to the printed circuit board.

3.Solder the leads to the copper foil on the printed circuit board. Do not use too much solder.

4.Insert the stripped end of the red wire attached to the transformer into an unused hole on the printed circuit board. Insert the red wire from the battery clip into a hole near the other red wire. Connect the two wires so they are electrically connected and solder the two wires to the copper foil.

5.Insert the white transformer wire into a hole near the upper left pin of the oscillator. Gently solder the wire to the copper foil.

6.Insert the black wire of the battery clip into a hole of the printed circuit board that is near and connects to the lower right pin of the oscillator.

7.Cut the clip leads in half. You should now have two pieces of wire each with an alligator clip attached. Carefully remove half an inch of the wire insulation from the bottom of each wire.

8.Insert the stripped end of one of the alligator clip wires into a hole on the printed circuit board to the lower right pin of the oscillator. Solder the wires to the copper foil. This will be your ground.

9.Insert the stripped end of the other alligator clip into a hole on the printed circuit board near the top right pin of the oscillator. Solder the wires to the copper foil. This is your antenna.

10.Open the phone plug. Insert the blue and green wires of the transformer into the handle. In the metal part of the transformer put one of the transformer wires into one of the holes and solder it. Place the other wire in the other hole and solder it.

11.Once the metal has cooled, place the phone plug back onto the phone plug.

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