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The other day when I was searching instructables I come across on interesting and simple circuit for metal detector. It is build with 555, coil and few other components. Instructable that inspire me to do this project was this one. Main debate was: does it really work?
After quick research I found this video that proof it works. That was the time when I decided to make my own metal detector. I do believe, that before you start working on metal detector you should read more about metal detectors and how they work.
I am not hold responsible for any damage that occurred during reproduction. The idea is not mine. I only added switch beetwen battery and circuit and instead of speaker I am using a buzzer.
The most difficult part is making coil. In great help was web calculators for air coils. With them, I calculated that with coil 90 mm width I need about 250 windings and with diameter 70 mm 290 windings that inductance can be 10 mH. You can also buy already made coils online.
I made coils core from cardboard. Coil is made from lacquered copper wire which is 0,2 mm in diameter. Before soldering, you must clean up both ends of coil.
You can do that with help of sandpaper. I made circuit on breadboard because I didn’t want when PCB would be finished it wouldn’t work.