Length of two blue links is L.
Side lengths of right triangular links are L and L/2.
Input: the blue bar pivoted to the base.
The orange output link rotates around axis O although there isn’t its revolution joint with the base.
This avoids placing hinges at distant or inaccessible spots.
The transparent triangular link doesn’t belong to the mechanism. Its presence aims to show that the orange link dimensions are similar to green triangular links.