here is my new concept for a free piston Stirling engine drive method.
Magnetic propulsion is a pretty nice effect what I found when i play with my magnets. :)
I used a ring and a disk magnet first, but the effect is working with normal magnets too.
The driver mechanism is so simple.
In this construction we have a gate line what we use to controll the displacer's moving.
The magnets are in attraction, but propulsion at a time if you look at this picture:
When we start to push the disk magnet across that middle line, then will pushed away, because the attraction is not enough strong to hold it.
Some people used this effect as like a basic overunity method for electromagnetic generator or something else.
Video from the magnetic propulsion effect:
Anyway, I used it for a simple free piston Stirling LTD.
Here is a schematic animated GIF from my engine: