basic chua's circuit

chua's diode
chua's diode alternative
gyrator simulating inductor
Gyrator simulating an inductor
fully realized chua's circuit
complete Chua
Building Chua's Circuit

There are many variations on how to build Chua's circuit, but this is the basic design. [Figure A]
As you can see, there is not much to it. This is the standard Chua's circuit used in research and a number of experiments, but there are many different ways to realize the full circuit.

Chua's circuit is literally the simplest chaotic circuit. However, when building this circuit at home be aware that, as a chaotic circuit, very slight variations can cause large effects or failure of the entire circuit. A loose connection or uneven voltages will dramatically affect the output.

Building Chua's circuit on a breadboard can be a frustrating endeavor if care is not taken. Even a slight bump can loosen connections enough to wildly change the output. But that can be fun too! Also, the quality of the output from a breadboard will be quite less than that of a soldered circuit board.

The Chua's diode must be constructed as no one manufactures them. There are a number of ways to create a Chua's diode, which is actually a type of nonlinear resistor. In Figure B you can see Chua's diode made from only resistors and op-amps. Figure C is a little different and employs standard diodes. Both designs equally satisfy the circuit, but Figure B is easier to make.

The inductor can also be replaced and accurately simulated with an additional circuit called a gyrator, as shown in Figure D, out of the same components. To understand how this simulation is accomplished, please read this PDF on the Antoniou Inductance-Simulation Circuit.

Thus, with this inductor simulator, a fully realized circuit can be built from only resistors, capacitors and op-amps! [Figure E] These circuit components can be found lying around in most labs and are readily available off the shelf in any RadioShack or similiar establishment.