Abstract: In a cryogenics refrigerator having a piston or piston-like displacer reciprocating in a cylinder, the position of the piston or displacer, the temperature at the cold end of the cylinder and/or a refrigeration gas pressure wave are monitored to provide one or more feedback signals. Valves or a linear motor drive are controlled through electronic control circuitry which responds to the feedback signals. A displacer may be driven by pressure differentials on a drive piston or by an electric motor. The preferred elements provide feedback throughout the refrigeration cycle and include a linear variable displacement transformer and an encoder disc. Preferably, the control circuitry is in the form of a programmable digital processor.