Coin Ping Tester

How it works: When struck, a coin vibrates at resonance frequencies determined by its material, diameter, and thickness. Gold vibrates differently to tungsten (elastic modulus 79 GPa vs 411 GPa). FFT analysis decomposes the sound into component frequencies and compares them with frequencies predicted from plate theory.

A single-frequency match against a theory value is weak evidence on its own: real coins of one type differ by several per cent, and a genuine coin can fall outside ±3%. The planned approach measures several vibration modes and combines them with the eddy-current pendulum, the weight and the size. What the ping test can and cannot do.

Always combine the ping with dimension & weight checks and the guided multi-factor scan.