DIY Super Simple Sensitive Metal Detector

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.
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
The concept borrows caharacteristics of BFO (beat frequency oscillator), and IB (induction balance) principle, so this can be called a BB (beat balance) metal detector. The main characteristics of beat balance (BB) are as follows:
- Depending on the way it is designed, a BB metal locator potentially offers the same sensitivity as IB
- It requires no receiver amplifier or level detector, thus significantly simplifying design and reducing cost.
- Both search oscillators are identical, therefore BB offers high immunity to voltage and temperature variations.
- Each search coil has the opposite response to metal, thus BB has a high degree of immunity to ground mineralisation.
The two coils should be identical and the method of making is as follows:
Each coil has a diameter of 12cm, and consist 70 turns of 30 SWG (0.32mm) enamelled copper wire. Then the coils are folded in the shape of the letter D, wrapped tape around them, screened them using aluminium foil bound with tinned copper wire (taking care to leave a small gap so that the screen doesn’t behave like a shorted turn), and tie-wrapped them on to a plastic plate. Next we need to attach the coils to the circuit by means of the specified microphone cables, being careful to identify the beginning and end wires correctly as shown.
Setting up the Metal Detector is very simple:
- First we need to place the two windings so that the gap between them is the smallest and the variable capacitor is in the middle position.
- A very high frequency tone is now heard on the handset.
- Next we need to gradually increase the overlap, reducing the frequency of the sound in the handset.
- So we continue until the moment when the sound is lost.
- Then we move the variable capacitor to the moment when a sound with the lowest frequency is heard.
- Now the detector is the most sensitive.
- The detector works surprisingly stable, but from time to time it needs to be precisely adjusted with the variable capacitor.
For a clearer presentation, I connected the headphone output to an audio amplifier, otherwise the headphone volume is quite sufficient for outdoor work. In the video, you can follow the sensitivity of this detector in the air. On the ground, the situation is completely different and depends on its composition and humidity.
Detailed instructions and schematic at:
www.hackster.io/mircemk/diy-s...
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If you are interested in this area, see the Playlist with all my Metal Detectors at:
• Homemade sensitive Met...
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[@risyant]

Thank you my friends, You are the best🙏

[@milekokotov1964]

Excellent! Simplicity is key to brilliance!

[@MirkoPavleskiMK]

Thanks :)

[@Anil_Gurung8874]

कमपुनेटकोदेखाइये

[@olenagamma9141]

Very amazing! I’ll have to learn how to do this

[@thomaso.scarborough6934]

Brilliant! And very nicely presented.

[@MirkoPavleskiMK]

Thanks

[@electronic7979]

Excellent project 👍

[@MirkoPavleskiMK]

Thanks

[@youtubadas6853]

It is the best metal detector!

[@shamy6346]

Thank you ☆☆☆☆☆👍

[@NN-uy6ik]

Hi Mirko, how do you make a frequency signal to the coil ? Thank you for your answer

[@alexrublinetsky]

Thank you Mirko. I had a double D coils from my previous experiments with slightly different parameters: 0.3mm, 50 turns with 16cm diameter. I tried to build your version with them. At first I tried using the coils without the foil shield and it kind of worked, but was very insensitive and reacted not just at metal, but, for example, at my hand. I added the foil shield to each coil leaving about 3cm gap and connected the shields to each other and to the ground. Now I cannot make it work at all. I have high frequency signal at the output (~13KHz) and the frequency does not change when I change the overlap, but the signal disappears when I move the coil sides too far or too close.
My board is connected to the coils with unshielded but very short wires (less than 10cm)
Any suggestions for diagnosing this problem?

[@MirkoPavleskiMK]

I really do not know, maybe you can try without Mosfet transistor, as in the original

[@fifisadeghi2471]

Very good 🙋‍♂️👍👍👍👍👍👍

[@MirkoPavleskiMK]

Thanks

[@jsonbourne9799]

Thank you Mirko! I have a couple of questions: 1) How do you bond the earth wire to the Faraday shield (aluminium foil), and 2) does the cable from the circuit board to the base plate need to be shielded?

[@MirkoPavleskiMK]

I wrap a bare wire around the aluminum foil and insulate it with tape. Cable from the circuit board to the base plate need to be shielded

[@JandersonSantosk8]

Só não entendi o esquema da bobina ela sai 3 fios o fio do meio vai no neutro confirmar?????

[@atetescaxo]

I have 0.2mm copper wire. Can I use it or do you advise to use 0.3? In the case I use 0.2 are the number of turns and diameter of coils the same?

[@MirkoPavleskiMK]

You can use 0.2mm with same name of turns and diameter of coil

[@sebastiandesy4859]

I found every other component but can't figure where to search for the crystal earpice. Aliexpress search doesn't yield any results. Is it possible to use normal headphones?

[@MirkoPavleskiMK]

I use a piezo buzzer, you can use a piezo element (speaker).

[@sebastiandesy4859]

@@MirkoPavleskiMK Great! Thank you for your answer.

[@MiraMate]

that's genuine talented skill
hi, do you want to teach others about our PEMF device? (from MiraMate)

[@Anil_Gurung8874]

येबनानेकाकमपुनेटकोदेखाइये

[@ckhs1719]

Can I replace this amp with tl061?

[@MirkoPavleskiMK]

4xTL061 or one TL064

[@JoeNathan42420]

So the coil is wound into the letter (D), wrapped in electrical tape, wrapped in aluminum foil and wrapped in electrical tape again?

[@MirkoPavleskiMK]

Exactly

[@JoeNathan42420]

@@MirkoPavleskiMK awesome thanks for replying so quickly friend.

[@buzzardvl8518]

Where is Arduino? )))
You are the best

[@onethingui]

Work with LM324N?

[@MirkoPavleskiMK]

No

[@petermainakanyora2817]

Can get the circuit and components use

[@MirkoPavleskiMK]

www.hackster.io/mircemk/diy-super-simple-sensitive-metal-detector-09483a

[@rukshanrukshan221]

how to make a long-range (10 meter) pulse Induction Metal Detector?

[@MirkoPavleskiMK]

That's impossible

[@user-iv7os1nk5w]

if you create a powerful impulse of the right shape, then it is possible

[@sharukhmatekuki5830]

Nice 👍🏻👍🏻 🇮🇳 Kuki 07|05|2022

[@tammamabouraied9138]

I implemented the circuit that you used, Ne555, FET 2n22222 transistors, 100qf chemical capacitors, lenticular, variable resistors 100 and 10, and many elements in detail and with all professionalism, but it failed and I repeated the experiment and did not get anything, so my friend I advise you if your main goal is to collect money from views, change the private content Don't make people pay for lies you're fine


[@MirkoPavleskiMK]

Dear friend, as I emphasize in the video and the text, the device was presented in the prestigious magazine Everyday Practical Electronics in June 2006, and my main goal is to test the features described in the above magazine with a video presentation. So this is not my personal project but I can assure you that if you make it according to these instructions, it works flawlessly. In fact, you can see it in the video itself

[@tammamabouraied9138]

would like to explain to you that I did not mean to annoy you or deny you. I watched the video and applied the circuit in detail and followed your steps in full, but it works. It is not sensitive to metals. The transistor opens. There is no pulse. Everything that I connected the know-how to the battery gives only a pulse that works by lighting Wayne ... Fanatic with any value with any equivalent And if it succeeds, I will talk to you in the comments and I want to increase the depth and set the circuit and the Arduino to select the frequency