In electronics, an oscillator is a circuit that generates a signal at a certain frequency. You can make a simple oscillator with an inductor (a coil) and a capacitor (two parallel plates). The circuit will alternately store energy in the capacitors (electrical energy) and in the inductor (magnetic energy). The electrons coming off one plate will pass through the inductor. As the charge on the plates becomes equal, the current dies. The drop in current creates an electromotive force in the inductor that propels electrons to continue in the same direction, thus charging the other capacitor plate.
Things You'll Need
- 2 rolls of Saran Wrap
- Roll of aluminum foil
- 2 bare wires
- Thin insulated copper wire
- Cardboard tube
Create a capacitor as follows, if you don’t have one handy. Unroll two rolls of Saran Wrap a few feet. Place a few feet square of aluminum foil on each unrolled area so that the Saran Wrap extends out farther (covers more area) than the aluminum sheets. This extra extension will provide electrical insulation between the “plates” when the two sheets of Saran Wrap and aluminum are rolled up together again. Now cut the Saran Wrap at the edge of one of the Saran Wrap rolls and place the newly cut-off Saran Wrap-aluminum sandwich squarely onto the other Saran Wrap-aluminum sandwich. This makes a Saran-Wrap-foil-Saran-Wrap-foil sandwich. The bottom Saran Wrap layer is still connected to its roll of Saran Wrap. Insert two bare wires into the sandwich at different layers to contact the two aluminum sheets. Then roll up the whole thing into the Saran Wrap roll that is still attached to the bottom Saran Wrap layer. The Saran Wrap layer between the two foil layers keeps them insulated from each other like an air gap in a conventional capacitor.
Tape the capacitor wires to opposite ends of a battery with electrical tape. This will charge up the capacitor. Let it charge for an hour, just like you’d charge a battery.
Remove the battery and replace it with an inductor. To make an inductor on your own, if you don’t have one, just coil thin insulated copper wire around the cardboard core or tube of a roll of paper towels or toilet paper a few hundred times. Scrape the ends of the wire bare with scissors or a knife, and hold them in contact with the bare wires of the capacitor. The electrons are now oscillating back and forth between the two sheets of foil.
Tips & Warnings
- For evidence that a current is actually oscillating between the capacitor and inductor, you can insert an ammeter or small light bulb into the circuit to see how fast it flickers. Or you can feel the inductor after a while and notice that its temperature increases because of the current flow.
- Make sure not to touch the bare wires of the capacitor to anything other than the bare ends of the battery or inductor; otherwise, you can discharge it.
- "Fundamentals of Physics;" Halliday & Resnick; 1989
- Homemade Capacitors