DIY: Air Variable Capacitors

A capacitor is a basic circuit element that stores electric energy.

Electrical circuits are comprised of three basic components: resistors, inductors and capacitors. A resistor is a material that opposes electrical current passed through it. An inductor is a coil of wire that stores energy in a magnetic field. A capacitor is composed of two parallel conductive plates separated by a dielectric medium, such as air. Capacitors store energy in an electric field. You can make a capacitor at home with some basic material. By varying the overlapping area of the two plates and the distance between them, you can create a capacitor that stores a variable amount of electric energy.

Things You'll Need

• Two copper sheets, approximately 6 inches square
• Spool of copper wire
• Wire cutters
• Spool of solder
• Soldering Iron
• 9-volt battery

Instructions

1. Cut two lengths of wire from the spool of copper wire. These lengths will form the leads of the capacitor. Each wire should be about 6 inches in length.

2. Plug in the soldering iron and allow it to heat up. Soldering irons are used to join two pieces of metal. Solder has a low melting point compared to other metals, which allows the solder to melt without damaging the components being joined. The soldering iron may take a minute to warm up completely.

3. Unwind a short length of solder from the spool.

4. Touch the tip of the solder to an end of one length of wire. Touch the tip of the soldering iron to the solder, which causes the solder to melt onto the wire. The wire now has a thin coat of solder on one end.

5. Repeat the previous step for the second length of wire.

6. Place the soldered end of the wire onto the copper plate. Place the wire in the approximate middle of the plate. Touch the tip of the soldering iron to the wire and melt the solder. The solder joins the wire to the plate.

7. Repeat the previous step for the second copper plate and wire.

8. Connect the free ends of the wires to an electric circuit. This circuit can be as simple as a single 9-volt battery. By placing the plates close to each other, you can vary the capacitance of the circuit. This circuit is called a RC circuit. You can also vary the capacitance by moving the plates so that the area of overlap increases or decreases.

Resources

• Encyclobeamia: Capacitor