Generation of Squares with the Use of Nonlinear Resistors

Whenever great accuracy is not required, a convenient way to obtain squares, and hence, to multiply, in analog computers is by the use of nonlinear resistors, especially thyrite rods, in certain circuits. These circuits are usually determined, more or less empirically, by starting from schemes that have given good results in the past and modifying them, or by varying the numerical values of the resistors used, until "best" results are obtained. In the present paper the concept of "best" results is clarified. Furthermore, it is shown that, regardless of the complexity of the circuit, the input-output characteristic depends only on two parameters. An explicit method is given by which the numerical values of the resistors used in the thyrite circuit can be computed for the given characteristics of the thyrite rod used in order to achieve desired "best" results.