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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.

Step 1: Parts and materials

Parts:
- 555
- 47 kΩ resistor
- two 2μ2 F capacitor
- PCB
- 9 V battery, switch, battery cable and some wires
- buzzer
- 100 m of copper wire, 0,2 mm in diameter
- gaffer tape and wood glue

Instead of buzzer you can use 10 μF capacitor and speaker (8 Ω impendence).

Tools:
- breadboard and wires
- pliers, tweezers, pliers for making holes
- soldering iron and soldering wire
- sharp knife, ruler, pencil and pair of compasses
- hot glue
<p>What's the frequency range for the working?</p>
<p>what's the frequency range for the working?</p>
Can u please provide circuit diagram? For PCB?
<p>i want to make a metal detector using tda0161, when the detector detects the metal from a specific distance the buzzer sounds but as the metal comes near and near the buzzer sound increases!!</p><p>so anyone guide me for this</p><p>i want to use this with arduino</p>
<p>i tried this project following the exact schematic.</p><p>It doesn't seem to work. I have checked the wiring thrice.</p><p>Can you please suggest me the possibilities where all it could have gone wrong?</p>
maybe you could have added a non necessary capacitor for the speaker.
<p>Very nice.</p>
<p>any body send me proposal of simple metal detector plz....... my email is </p><p>hjanbaz4082@gmail.com</p>
<p>hiiii sir use this ckt bt its cannot work...</p>
I want pcb layout <br>Any one can send the layout <br>On phaleshjain42@gmail.com
<p>hey can i use a three leg capacitor</p>
<p>what is the diameter for the the cardboard used for coil?</p>
<p>hi, if i use normal inductor like the one in pic what is the range of detection ?<br>or it should be direct contact between the metal and the inductor ??</p>
<p>What could be the problem if the buzzer is producing sound even without placing any metal near to it? Can anyone help me out with this?</p>
<p>Hey!...Its me again. Can you suggest a way to make the metal detector louder?....Can I also add a small light bulb in the circuit so that it lights up when its passed over metal?</p>
<p>Usually it helps if you put higher voltage on piezo element. Just try not to destroy the buzzer.</p><p>You could ad a small bulb but it will requaire some microcontroller processing. Lower in the comment section user arzedur did just that.</p>
<p><em><strong>hi every one &lt; can u help me </strong></em></p><p><em><strong>any project for gold detector i need this devices</strong></em></p>
<p>Ohk.....thanks!.....But I gotta make a VLF metal detector........do you have any website recommendations???</p><p>Or.............is a BFO metal detector better than a VLF one??</p>
<p>Its a cool project, I want to make it too but what kind of metal detector is this? Is it a VLF, PI, or BFO metal detector?.....Please Reply ASAP! Thanks! </p>
<p>It is close to BFO metal detector (but it is not one). It uses a oscillator and oscillators frequency changes with change of inductance. And that is all what is similar to BFO. </p><p>My simple metal detector is more proof of concept than a real deal....</p>
<p>cool diy project... I prepared everything except the inductor part.. Since I am new to winding the inductor, I have some doubts..</p><p>what is the thickness of the cardboard core of the inductor?</p><p>do I need to cover the winding using tape?</p><p>can overlapping of turns reduce the effect of inductance?</p><p>thanks in advance....</p>
<p>Cardboard do not efect inductance so it doesn't matter what thickness you are using. In fact any non magnetic or non conductive material will do the job. Also in my case cardboard is a way to mount coil on some kind of handle. You can make coil without any &quot;core&quot;. Cardboard that I am using is about 5 mm thick.</p><p>You do not need to cover windings but make sure wire will not unwind on its own. So tape is dual purpose in my case: coil can not unwind itself and it looks kind of cool to me.</p><p>Overlapping can reduce inductance but effect is minimal. Just make sure you are using insolated wire and you can do few more loops.</p>
<p>thnk u</p>
<p>this was easy :D </p><p>I converted the output signal into a TTL level. i programmed the arduino so that a few LEDs light up when a metal in the near of the coil.</p>
<p>hi.. do you have the arduino sketch for this??</p><p>thanks</p>
<p>Hi,</p><p>any chance to get info about coil. could you share code for arduino, please.</p><p>Thanks </p>
Nice! :D
<p>cool diy project... I prepared everything except the inductor part.. Since I am new to winding the inductor, I have some doubts..</p><p>what is the thickness of the cardboard core of the inductor?</p><p>do I need to cover the winding using tape?</p><p>can overlapping of turns reduce the effect of inductance?</p><p>thanks in advance....</p>
<p>cool diy project... I prepared everything except the inductor part.. Since I am new to winding the inductor, I have some doubts..</p><p>what is the thickness of the cardboard core of the inductor?</p><p>do I need to cover the winding using tape?</p><p>can overlapping of turns reduce the effect of inductance?</p><p>thanks in advance....</p>
Hi.i have a quasion<br>the coil has 250 turns with 90mm width<br>so i need about 71 meters of transformer wire 0,2mm,right?<br>did you make the coil with about 71 meters of transformera wire?or im in wrong?
<p>it is which type of metal detector vlf.PI or bfo</p>
<p>kindly upload a photo where soldering is shown.... also tell me is it 2.2microF capacitor 16V??</p>
<p>Can u please share a video of proper demonstration of the whole building process ?</p>
<p>Can u tell me the detection range of this circuit?</p>
<p>magnific, please contac me to jonath55@hotmail.com</p>
What's the rating of the buzzer?<br>
<p>what will be the frequency while calculating inductance???? </p>
One does not need frequency for calculating short cylindrical air coil inductance.<br> <br> You can find formulas <a href="http://en.wikipedia.org/wiki/Inductor" rel="nofollow">here</a>.
<p>hi, if i want to use 0.3mm coil in the same diameter , hoe many turns i need to do ?</p><p>thanks...</p>
<p>Hi Mr <a href="http://www.instructables.com/member/vonPongrac/" rel="nofollow">vonPongrac</a> . I like your project. Can u tell me how to do the coil in details pls? sorry I can't understand. and if we buy the 10mH inductor, is it need to put underneath the two cardboard? thank u so much.</p>
<p>In my case cardboard is only a bracket to mount coil on it. And it looks good. You can use 10 mH inductor as it is.</p>
<p>hi again.. how much is the DC current rating for the inductor and tolerance? Because I did bought the one that 10mA dc current rating and 10% tolerance but the sound of the speaker does not change. </p>
<p>I can't tell what are the ratings. It depends on wire gauge (resistance), frequency and coil inductance (I=U/Z, Z=R+jwL). I can measure resistance and inductance and I know what maximum voltage rating is. But I realy can not determine frequency (I should measure it but I don't own oscilloscope or frequency counter). I can guess that it is around 10 mA max like yours.<br></p><p>I do imagine that you bought yourself a inductor with core. It also depends on inductors core and how inductor is designed. With this aplication you should use inductor, that allows great dissipated magnetic field. Dissipated magnetic field is reason why this should work with cored inductors. In my case I only have main magnetic field (dissipatted magnetic field is almost infinitesimal) and greater area that magnetic field is covering. Because of that I should have greater frequency change.<br><br>All of stated above are only my predictions about this circuit. So reality can vary.</p>
<p>alright. Thank u so much for your help. :)</p>
<p>Also, in video provided in Intro, inductor is very small. I guess that it is similar to what you have bought. So it does work with small ready made inductors.<br><br>Check your connections and orientation of components one more time.</p>
<p>thnk u it was vry useful for us as v r doing this project.i have 2 questions.will the buzzer be<strong> continuously giving sound</strong> or only wen it is brought near the metal???can u<strong> list the things which this metal detector works</strong>???reply me fast!!!!</p>
<p>It will buzz all the time. Sound frequency should change when coil will be near metal object.<br>I tested it with nails, some tools that where on my bench, bike frame, on some metal shelfs. In terms of materials, it works best with steel.</p>
<p>Sir can I ask why is the buzzer continuously giving sound even if the metal is away from it? I just want to confirm it thank you</p>

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Bio: I am an engineer and a maker who loves technology challenges.
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