“Extremely simple Metal Detector whose making requires only one cheap integrated circuit TL084. It can detect metal coin at 15cm distance, and big plate at more than 50 cm.
As I mentioned before, the device is very simple to make and contains only a few components:
- TL084 general purpose quad operational amplifier (You can also use TL074 or TL064)
- Small variable capacitor with capacitance of 100pF taken from old portable AM Radio
- Crystal earpiece who need to connect to this jack
- and search coils
This time I will introduce you to another extremely simple Metal Detector whose making requires only one cheap integrated circuit. The project was presented in Everyday Practical Electronics Magazine by Thomas Scarborough in June 2006. At the expense of simplicity, the results are incredibly good. The device is characterized by excellent stability and sensitivity, so for example a small metal coin can be detected at a distance of 15 cm, and a larger metal object at more than 50 cm.”