Here's a fantastic project using an arduino, a motor, and a piezosensor which allows you to both record and detect knocking patterns to unlock a door.
这里有一个神奇的项目使用阿尔·杜伊诺，马达和一个压电传感器既可以记录和检测模式，以敲车门的锁打开。
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We use ordinary microphone as our snoring recorder and compare its sensitivity with snoring microphone and piezosensor, which are often utilized in clinical Settings.