An opposed piston, internal-combustion engine including a cylinder with a bore and opposed pistons disposed within the bore is provided with one or more hypocycloidal drives that convert the linear motion of a piston to rotary output motion. An electrical generator includes an opposed piston, internal-combustion engine with a coil mounted to the skirt of a piston and a hypocycloidal drive connected by a rod to the piston. The construction of the hypocycloidal drive imposes a sinusoidal period on the linear motion of the piston. As the piston transports the coil though a magnetic field, a sinusoidal voltage is induced in the windings of the coil.