Chaos in electronic circuits

This paper describes three extremely simple electronic circuits in which chaotic phenomena have been observed. The simplicity of the circuits allows one to i) build them easily, ii) confirm the observed phenomena by digital computer simulation, and in some cases iii) rigorously prove the circuit is indeed chaotic. A consequence of i) is that the interested reader can build, and then see and even listen to chaos. It is to be emphasized that these circuits are not analog computers. They are real physical systems.