The Counterfeit Coin Detector Patent Archive

Every device ever patented to catch a bad coin

Sizing slot

Six circular diagrams of a metal coin-testing disk showing concentric slots labeled a, c, and diameter markings 10, 25, and 50, with a pivoting knife-edge rod extending from the side, illustrating coins tilting up or down depending on weight.IMPROVEMENT IN COUNTERFEIT-COIN DETECTERSJohn W. Sutton · March 27, 1877Patent drawing of a folding pocket coin balance, showing a slotted metal plate pivoting on knife-edge bearings between two hinged standards mounted in a shallow box, with a small counterweight at one end and a removable supplemental plate with smaller slots for testing gold coins.COIN-TESTER.Merritt Clarke · March 6, 1883Patent drawing of a mechanical coin detector showing front and interior views with a row of coins in a horizontal channel, a vertical entry chute, a spring-loaded slide with finger hole, and small cross-section detail figures at the bottom of the page.COIN-DETECTOR FOR COIN-CONTROLLED APPARATUS.Arthur L. Pratt · May 26, 1896Patent drawing of a countertop coin-detector showing a boxed housing with three coin slots and internal balance beams mounted on a turned pedestal base, plus detail views of individual pivoting coin-rest balances and their adjustable weighted arms.COIN-DETECTORThomas I. Porter · March 13, 1900Patent drawing of a rectangular vending-machine coin box housing two parallel slotted shafts with gear wheels, springs, set screws, and diverging chutes, shown in six views labeled Fig. 1 through Fig. 6.SPURIOUS-COIN DETECTOR FOR VENDING-MACHINES.Leslie A. Vandiver · May 4, 1909