Does anyone know if multi engine electronic synchronizers are still available? If so from whom?

I recall a magazine article a decade or two back in which a digital box was used to put a pair of engines exactly in sync. You placed magnets on the drive shafts, and the box used a second servo to match the RPM of the stronger engine to that of the weaker engine. Your radio controlled only the weaker “master” engine. There may have been a little lag in the acceleration but at stable RPMs the two engines turned at the same speed. And if either engine died the radio controlled the remaining engine directly.

Thank you, but NO I do not want to know how to do this mechanically, I have a different application that needs the precision of the above box.

TIA Tom