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This time I will show you how to make a sensitive metal detector also capable of discriminating between ferrous and nonferrous materials. The sensitivity is satisfactory, given that it is a relatively simple device.

This is a continuation of David Crocker’s project presented at the Arduino CC Forum in 2013. I decided to test its code because I did not find any evidence (Picture or video) that this metal detector was made by anyone and works well.

First I made a basic version with the code presented on GitHub, to make sure of the functionality of the device and then I upgraded the code so that it has an audible signal, and on a 16 on 2 LCD display visual information about the type of object detected (Ferrous or nonferrous material) and LCD bar graph for the proximity of detected objects.

The device is very simple to build and consist of only a few components:

- Arduino Nano microcontroller
- Operational amplifier (in my case LT1677, but you can use TL081 or 741 )
- Few resistors and capacitors
- Small transistor and speaker
- LCD display
- 3 switches
- Potentiometer
- Battery
- And search coils”

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