Knock Sensor by switchback42

Use a gemma, piezo, and a 1 megaohm resister to detect sound. Code found at the following URL: https://www.arduino.cc/en/Tutorial/Knock

Embed This Sketch

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<iframe style="height: 510px; width: 100%; margin: 10px 0 10px;" allowTransparency="true" src="https://codebender.cc/embed/sketch:917940" frameborder="0"></iframe>

Embed The Serial Monitor

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<iframe style="height: 510px; width: 100%; margin: 10px 0 10px;" allowTransparency="true" src="https://codebender.cc/embed/serialmonitor" frameborder="0"></iframe>