I stumbled upon this simple metal detector circuit. I was very skeptical about whether it really had this function. Later, after analysis, I found the relevant video to confirm that it really did, and then I did it myself.
Be sure to check the relevant information before you start making it, and figure out the principle of the metal detector.
1. Tools and materials
- 47kΩ resistor
- Two 2μ2F capacitors
- Circuit board
- 9 volt battery, switch, some wires
- 100 m copper wire with a diameter of 0.2 mm
- Tape and glue
Buzzer You can use a 10μF capacitor and speaker (8 ohm impedance).
- Breadboards and wires
- pliers, scorpion
- Soldering iron and solder wire
- Sharp knife, ruler, pencil, compass
- Hot glue gun
This picture is found online. I just added a switch between the switch and the circuit and replaced the speaker with a buzzer.
The coil is the most difficult part. By calculation, a 90mm diameter coil requires approximately 250 windings, a diameter of 70 mm requires 290 windings, and an inductance of up to 10 mH. You can also buy off-the-shelf coils online.
The coil core is made of cardboard. The coil used was an enamelled copper wire with a diameter of 0.2 mm. I circled 260 laps. Please hang the paint on the thread before welding.
After testing, it works! (Video can't get it)
After the test was successful, I made this PCB circuit.
6. Cardboard structure
I made this cardboard structure for the aesthetics and ease of use of the final work.
So the parts are all ready. Here's how to assemble them all. First fix the switch with a glue gun, then put it into the battery, and finally fix the board with a glue gun.
This metal detector is very simple. But its detection capabilities are also limited. When working outdoors, it does not work properly. However, for beginners, this is really a good work, I like it very much!