The paper describes the design of a microalternator in which negative-resistance devices are employed to obtain representative constants of the model's rotor circuits. Dimensional scaling in assessing the parameters of model alternators is reviewed. Methods of calculating the model's principal constants from design data are outlined for a machine of salient-pole-rotor construction. Core and short-circuit losses are examined, and the choice of design criteria is discussed. Test results for a machine of salient-pole construction are given which compare very favourably with the constants derived from design considerations. Attention is also given to the special facilities which are provided by the time-constant regulator and other associated auxiliary equipment.