How to Build an FM Radio

A radio provides signal transmission via the use of electromagnetic waves. The frequencies a radio uses are lower than those of visible light. A German scientist by the name of Heinrich Hertz was the first to detect and product radio frequencies, in 1888. Radios are still in wide use, even in this internet age.Building a simple FM radio only requires a small amount of time and materials. Although this radio is fully functioning, it isn't very pretty.

Things You'll Need

  • Fifty to 100 feet of straded insulated wire (for use as an antenna)
  • One piezoelectric earphone
  • One variable capacitor
  • One ferrite loop antenna coil
  • One base made from a block of wood
  • One Germanium diode
  • Soldering gun
  • Solder
  • Earphones
  • Two alligator clip leads

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Solder the ferrite loop to the variable capacitor. Only solder the ferrite wire that is painted black. Make sure you are soldering the ferrite loop to the center lead of the variable capacitor.

Solder the unpainted wire of the ferrite loop to the variable capacitor's right lead.

Solder the germanium diode to the same right lead of the variable capacitor as the unpainted wire of the ferrite loop. Only connect one end of the germanium diode.

Solder one end of the piezoelectric wire to the other (free) end of the germanium diode.

Solder the other end of the piezoelectric wire to the variable capacitor's center lead.

Take note of the red-painted wire of the ferrite coil. Use an alligator clip to attach it to the antenna wire.

Use the remaining alligator clip lead to attach the green-painted wire of the ferrite coil to a good ground. You can use a cold water pipe for the ground.

Tips & Warnings

  • On first listening, keep the variable capacitor in its middle setting. Then slowly move it to the right or left to tune in channels.
  • The earphones are to be connected to the piezoelectric earphone wire.
  • The radio stations in your area have to emit a strong signal in order to be picked up by this radio. For proper reception, you can't be too close to the station.
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