A variable capacitor is not a familiar term to most. No, it's not a device that makes time travel possible. It does come in handy, however, when you want to build a radio. By following this simple set of instructions, you'll discover that building a radio is surprisingly simple!
Things You'll Need
- 1 Block of Wood
- 1 Loop Antenna Coil (with a ferrite bar inside)
- 1 Variable Capacitor
- 1 Germanium Diode
- 1 Piezoelectric Earphone
- 2 Alligator Clips
- 50 feet Stranded Insulated Wire
Obtain a ferrite loop antenna coil. The ferrite loop coil is usually made up of four colors of wire: green, red, black, and unpainted. Wind a length of black wire from the ferrite loop to the variable capacitor's middle lead, then wind a length of unpainted wire from the ferrite loop to the variable capacitor's right lead.
Hook the germanium diode to the variable capacitor's right lead (next to the unpainted wire that should already be there).
The piezoelectric earphones have two wires, often protected by a thin plastic exterior (like a looped telephone wire), so you may need to cut off some plastic at the ends to reveal the metal portion of the wires. Wrap the end of one (the actual wire part) to the center lead of the variable capacitor (next to the black wire that should already be there). Wrap the end of the other (again, the actual wire itself, not the plastic exterior) to the unused end of the germanium diode.
Connect the red wire from the ferrite loop coil to the stranded insulated wire using an alligator clip. You've just created your antenna.
Using the other alligator clip, connect the green wire to a cold water pipe in your house. The plumbing generally runs underground so this serves as suitable earth.
Put the earphone in your ear. Set the variable capacitor to the middle of its range, and slowly insert the ferrite rod into the center funnel of the coil to search for different stations.
Tips & Warnings
- Make sure to have at least 50 feet of wire for your antenna; the longer the better!
- Best-case scenario: your antenna reaches outside.
- All materials listed here are available at any decent wireless shop.
- Don't lose patience. This can take a few tries.
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...