Long Dwell cams in Williams games extend pulse width to provide tolerance for aged and worn switches

Starjet is a Gottlieb value game from 1963 that uses pancake-style horizontal cam motor

Mark Gibson's Fun with Pinball website provides detailed circuit breakdowns and repair resources beyond bonus circuits

EM devices use motion to perform computation, while solid-state games use motion primarily for ball control and toy activation

Score reels advance exactly one step per electrical pulse; scoring 50 points requires five sequential pulses from the score motor

Score reel advancement occurs only when solenoid coil power is cut and the spring relaxes, not while the switch is held closed

Lockin circuits use a second switch path to indefinitely maintain relay activation until a release switch opens the circuit

The distinctive five-pulse reset sound ('da da da do dot dot') heard in EM games is the audible signature of the score motor's cams firing pulses during reset

Every score reel has at least one, usually two, zero-position switches that control when the reset motor stops advancing that digit

Williams used a score motor design very similar to Valley's design

Gibson has published detailed animations and device explanations on his website covering EM mechanisms

Electromechanical devices require motion to perform computation, unlike solid-state games where motion is primarily for toy activation

Score reels advance only when coil power is cut and the spring pulls the plunger back, not when the switch is closed

Lock-in circuits use two parallel paths: activation and maintenance, keeping a relay active until a release switch opens

The score motor runs through 180-degree cycles and fires pulses from cams; some cams fire once per half rotation, others fire five times

The characteristic reset sound in EM games is the five pulses from the score motor's cam firing five times per 180-degree rotation

Score reels have at least one, usually two zero-position switches that open when the reel reaches zero to stop the reset motor

Harry Williams used a very similar score motor design to Bally's design

Carry logic in scoring allows a 10-point reel to advance when a 1-point reel reaches position nine and advances to zero

Mark Gibson has been creating and traveling with the Fun with Pinball exhibit for five years

Mark Gibson is from Colorado

The baseball game custom build took months to complete, with rule design being the most time-consuming aspect

Mark Gibson has been building and operating the Fun with Pinball exhibit for approximately five years

Mark Gibson is retired and from Colorado

The Fun with Pinball exhibit was originally created for Maker Faire as an educational project

Flipper coils in mechanical pinballs use dual windings: a heavy winding for power and a light winding for holding the flipper up

The Fun with Pinball exhibit is a traveling exhibit that sets up at schools and events to teach people about mechanical pinball game mechanics