1. A control system for a refrigeration system including a compressor, a condenser, and an evaporator, all connected in a closed refrigeration circuit, which compressor includes an adjustable capacity control means, means for regulating the adjustable capacity control means, and an electrical prime mover connected to drive the compressor, which control system comprises: means for providing a timing signal; means for providing a position signal which varies as a function of the setting of the adjustable capacity control means; and a drive control circuit, having a first input coupled to the means for providing a timing signal, a second input coupled to the means for providing the position signal, and an output coupled to the means for regulating the adustable capacity control means, which drive control circuit produces an output drive signal having at least one characteristic which varies as a function of the position signal, thus driving the means for regulating the adjustable capacity control means as a function of the position of the adjustable capacity control means.