Methods, systems, and devices are provided that may include Stirling cycle configurations and/or linear-to-rotary mechanisms in accordance with various embodiments. Some embodiments include a Stirling cycle device that may include a first hot piston contained within a first hot cylinder and a first cold piston contained within a first cold cylinder. A first single actuator may be configured to couple the first hot piston with the first cold piston such that the first hot piston and the first cold piston are on different thermodynamic circuits. The different thermodynamic circuits may include adjacent thermodynamic circuits. The Stirling cycle configuration may be configured as a single-acting alpha Stirling cycle configuration. Some embodiments include a linear-to-rotary mechanism device. The device may include multiple linkages. The device may include a cam plate coupled with the multiple linkages utilizing a cam and multiple cam followers. The linkages may include Watt linkages.

A multi-stage system includes a block defining a cylinder, the cylinder comprising an inlet thereto and an outlet therefrom and a linear grove disposed axially within the cylinder, an infinity; a power transfer shaft configured for rotation within the cylinder, the power transfer shaft comprising a shaft portion and an infinity portion, the infinity portion defining an infinity profile; and a piston configured to reciprocate within the cylinder, the piston defining a first compression chamber and a second compression chamber within the cylinder, the piston slidably engaging the infinity profile of the power transfer shaft.