- Find a set of headphones that has at least 6 feet of wire length. Use scissors to cut off the plug from the end of it. Peel about 4 inches of casing off the wire, starting at the edge. Find a blank CD and glue the end of the copper wire to the back of the CD. After gluing the wire to the CD, place electrical tape over the remaining couple of inches of exposed wire. Be careful to just tape over the exposed wire and not on the CD or the glued wire. Grab another blank CD and glue the other copper wire to the back of that CD. Remember, though, just glue the copper wire--not the colored wire--to the CDs. Tape that copper wire with electrical tape also. Take the blue wire and tape it to the negative side of a 9-volt battery. Take the red wire and tape it to the positive side of the 9-volt battery. Tape a battery-powered calculator to the CD right on the copper wire. Place the other CD on top of the calculator. The wire on this CD should be on the opposite side that is touching the calculator. Wrap the two CDs tightly together with electrical tape, making sure that the calculator is between them. Tape the battery to the top of the unit in the center, at the hole of the CD.
- Use your metal detector to find coins and other valuable metals. Run your metal detector over the ground, and it will make noise like static if there is something metal in the ground. The homemade detector can detect metals up to a foot below the ground. The best places to look for valuables are camps, lakes, rivers and beaches.
- The battery sends a current to the copper wire. The wire then makes a magnetic field. When the magnetic field comes to a metal object, the magnetic field generates electric currents in the metal object. The electric currents, also known as eddy currents, create their own magnetic field. This creates an opposing current in the wire, which creates a noise. That noise is what indicates to you that there is a metal object under the metal detector.
