Technical History of the Pinball Flipper, Part 1: The Mechanically Switched Flipper
From the first electromechanical flippers of 1947 to the survival of full power, mechanically switched flipper control well into the early solid-state era.
A six-part series tracing the engineering evolution of the pinball flipper from 1947 to the present day: from the first electromechanically switched coils, through Data East's single-wound redesign, Williams FlipTronics, and Stern's node-controlled PWM era, to the removal of the end-of-stroke switch in favour of sensing the plunger directly from coil current, and the closed-loop current regulation that follows from it.
From the first electromechanical flippers of 1947 to the survival of full power, mechanically switched flipper control well into the early solid-state era.
How Kurt Deger's single-wound coil changed the flipper circuit, and what Data East's own Service Bulletin 49 reveals about the flipper board's design.
How Williams kept the dual-wound flipper coil but moved control onto the board, turning the end-of-stroke switch into pure position feedback electronics.
How Stern carried the single-wound flipper coil through WhiteStar, S.A.M., and SPIKE, and why the EOS switch survived after software took over the hold state.
The end-of-stroke switch can be removed from a flipper entirely, because the plunger's position is already encoded in the coil's own inductance value.
A controller already reading a flipper coil's current to sense the plunger can drive that same coil too, holding a target current like cruise control.