Designs often require that components come from a list of available sizes. In this example, we show how the Genetic Algorithm can be used to find values for the Resistors and Thermistors in a circuit that meet our design criteria. The example uses optimization techniques to minimize the difference between a desired response curve and the curve generated from a simulation of the circuit. Because Resistors and Thermistors are only available in standard sizes, this becomes an interger-constrained problem as our design variables are limited to these standard sizes.