Heat engine

An apparatus comprising:

• (a) a heat engine comprising:
• (i) a container defining a sealed region within which a working fluid is circulated when the heat engine is in use, the sealed region having a heating chamber and a cooling chamber, the heating and cooling chambers being in fluid flow communication via a working fluid passageway;
• (ii) a variable heat source thermally connected to the heating chamber whereby the variable heat source provides variable heat levels to the working fluid;
• (iii) a displacer movably mounted in the sealed region between a first position and a second position to define a displacer cycle profile;
• (iv) a piston movably mounted in the sealed region between a first position and a second position to define a piston cycle profile;
• (b) an power output member drivenly connected to the heat engine and having an output for supplying work;
• and,
• (c) a feedback member responsive to power demand from the power output member to modulate the amount of heat provided by the heat source to the working fluid.