A very simple metal detector can be assembled by everyone with their own hands without understanding the electronics at all. With it, you can search for metal objects both in the ground and in the wall. The design consists of only three items, which are probably lying almost in each box in the drawer.
- Unnecessary remote control from any device.
- AM / FM radio.
- Wire for the manufacture of coils with a diameter of 0.4-0.2 mm.
Making a metal detector from a remote control and a radio receiver
The first step is to make a coil. Here you need to understand that all sizes and number of turns are selected exclusively empirically, and the example below is not ideal.
Take a wire of 0.35 mm and wind a coil with a diameter of 10 cm. Number of turns 50. To prevent unwinding, fasten it with electrical tape or nylon ties.
We disassemble the bullets. We clean the enameled output and solder them parallel to the infrared LED.
Next, we assemble the remote control. Be sure to insert good batteries into it. We turn on the radio and set it to the “AM” range (medium waves).
Push any button on the remote control.
The receiver is located near the remote control, and the coil is a bit far.
Repeating sounds should be heard in the receiver, which should disappear when you release the button. By rotating the tuning wheel of the receiver, we achieve the minimum audibility of these vibrations.
We bring a metal object to the coil at some distance. The sound in this should be amplified.
That's all. Sensitivity with proper adjustment is quite acceptable: it is enough to detect steel dowels or fittings in the wall.
This metal detector works on the principle of spurious harmonics. As soon as the metal is brought to the coil, its inductance changes, which means the frequency of the signal and all harmonics. What actually captures the radio.
To increase the sensitivity it is necessary to experiment with the coil by changing its size and number of turns. And with a radio, changing ranges and making an accurate search by adjusting.
See an example of work in the video: