Chapter 11. Metal Checker: The Electronic Switch

An Electronic Tester

Have you noticed household objects that appear to be made of metal when they’re not? You and a friend can build an instrument that checks the metal properties of household objects in your home using an Arduino and a few electronic parts. The Arduino Metal Checker emits a tone when a metal object is placed across its test probes. With this awesome electronic instrument, you and a friend can uncover the metal mysteries hidden inside of your home. The Metal Checker uses an Arduino, two fixed resistors, one transistor, and a piezo buzzer. The Metal Checker is shown in Figure 11-1.

Parts List

  • Arduino microcontroller
  • MakerShield kit
  • Q1: 2N3904 NPN transistor
  • R1: 330Ω resistor (orange, ...

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