Authenticate your

Model coin: its reference frequencies are predicted by our resonance model from its weight, size and metal, and not yet confirmed with recordings.

Press Start test, hold the coin lightly at its center and tap its edge near the microphone. Your browser will ask to use the microphone: we send only the fifth of a second after each tap to our server, which analyzes it and discards it.

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1 Dollar "Trade Dollar" specifications and ping frequencies

The 1 Dollar "Trade Dollar" is a silver coin from the United States (1873–1885), weighing 27.22 g with a diameter of 38.1 mm. Tapped gently on its edge, a genuine one is expected to ring at about 4.5 kHz, 10.3 kHz and 17.6 kHz: its first resonance frequencies, set by its metal, size and thickness. A counterfeit made of a different metal, or with a different weight or thickness, rings at different frequencies, which is what the ping test above checks.

Ping test reference frequencies4494 Hz · 10258 Hz · 17631 Hz
MetalSilver
Composition90% silver, 10% copper
Weight27.22 g
Fine metal content24.498 g
Diameter38.1 mm
Thickness2.35 mm
Face value1 Dollar
CountryUnited States
Years1873 - 1885

These reference frequencies are predicted by our resonance model from the coin’s weight, size and metal, and not yet confirmed with recordings. Compare with the ping frequencies of every supported coin.

Authenticate Your 1 Dollar "Trade Dollar" on the Go

Download Pingcoin for iPhone or Android to instantly verify your 1 Dollar "Trade Dollar" and other precious metal coins using acoustic authentication.