Analog circuitry for the van der Pol and FitzHugh-Nagumo equations

An analog circuit for the FitzHugh-Nagumo equations is given that uses readily available integrated circuitry. The mathematical model for this circuit is derived, and simple analysis is given, to show how the circuit works. Specifications for a reliable and easily built analog neuron are given with components that cost only a few dollars. The circuit is useful as a research and educational device.