Pink and violet cranks of the same radius are coaxial.
Input: pink crank regularly rotating.
Output: violet crank performing rotary oscillation.
Green double coulisse has revolution joint with blue slider.
The output oscillating angle can be changed by adjusting center distance A between the green coulisse rotary axis and the crank axis (moving rotary axis of the green double coulisse).
The video shows the adjusting process to get large angle and reversely.
The adjustment can be carried out without stopping the input crank.
Spring slider (in brown) prevents the output crank from rotating full revolution at unstable positions of the output crank (when the output crank is perpendicular to the green coulisse).
The center distance A must be larger than the crank radius. If not, the output motion is unstable.