How to Measure Planck’s Constant Using Lego
technologyreview.com
technologyreview.com
The interesting thing about h/e^2 as Hall resistance is that it's an off-diagonal term in the Onsager matrix, while here it is used to balance a diagonal term i.e; work.
Equally nice is to consume Newton's gravitational constant in g, the acceleration due to gravity, because somewhere the mass needs to come out, and there is no mass in the Maxwell equations. The Planck voltage sqrt(Ge^2/(hc^5)) is very small (compared with electrochemical potentials): 3.3e-29 Volts.