Need help circuit homebrew metal detector

[Sara-7]

Hello friends

so recently i searched on the internet and found a video of an Indian guy making a metal detector circuit but unfortunately there is no diagram and it was a messy build.

i tried to imitate the video but i just can't make it work because I'm not an expert in electronics components.

please, kindly, watch the video in the link below and if any smart guy/girl of you who can draw a diagram of what he build and share it please, it would be so kind.

PS: i have the same components except of HB06 diode (which i searched online but never found anything about it)

thank you very much my friends i appreciate your effort and time

 

[BradtheRad]

This forum has many existing threads about metal detectors. Your title is revised so that a list of related threads appears further down this page.

The video appears to be a successful working project. Since he doesn't present a schematic, it's hard to guess how to duplicate it. Sometimes a maker hopes to charge money for his design if anyone wishes to build it.

I suppose his circuit beeps when one of two coils shifts its resonant frequency of oscillation, due to nearby metallic substance affecting inductor coil parameters.

You can find various metal detector schematics on the internet.

 

[Sara-7]

This forum has many existing threads about metal detectors. Your title is revised so that a list of related threads appears further down this page.

The video appears to be a successful working project. Since he doesn't present a schematic, it's hard to guess how to duplicate it. Sometimes a maker hopes to charge money for his design if anyone wishes to build it.

I suppose his circuit beeps when one of two coils shifts its resonant frequency of oscillation, due to nearby metallic substance affecting inductor coil parameters.

You can find various metal detector schematics on the internet.

thank you for your kind reply.

you are right, there are many other diagrams for many metal detectors, but this one became sort of a challenge for me since i tried many time to make it with no success and i want to beat the challenge.

also it seems to have a good range and a relatively simple design.

it also may be fake, but the channel has good reviews and many other clear videos of other projects.

i hope someone who can help decipher the schematic of his project.

 

[Audioguru]

Like many You Tube videos from "over there", the video might be faked since in the beginning it says a TIP41 bipolar transistor but a picture is shown of a STK5006 Mosfet.

 

[D.A.(Tony)Stewart]

This is a Mickey Mouse iron screw detector with very low sensitivity. If you buy any metal detector to find gold, either the metal is flash gold-plated over steel or you got screwed buying a fake Mickey Mouse gold finder.

However, very sensitive dual facing-D head metal detectors can detect trace magnetic elements in the clasp. These tend to cost about $1.4k on Amazon.. Get a rare earth magnet and test your jewellery to see if its magnetic.

The TIP41 acts like a 0.2 ohm switch but the STK5006 acts as a 20 mOhm switch and is better to prevent from burning too hot. The diode protects the gate against large negative Vgs swings and the caps filter the 9V battery and form a resonant oscillator that draws more current near a magnetic screw.

This is a primitive design. Keep looking for a better one. maybe this one ?

--- Updated Sep 25, 2021 ---

Some work by detecting a beat frequency between two coils intersecting or facing each other in the middle. Others like this use a large loop area to only measure the change in resonant frequency using a common 4046 PLL IC and tracking the change in control voltage. Everything must be rugged to be very stable.

But to make a significant improvement, you ought to learn how to detect a few parts per million change in magnetic flux distortion from different depths https://www.minelab.com/knowledge-base/key-technologies

There are thousands of scholar research topics on wireless power transfer. But the technology is relevant to metal detector antenna design. Search Google scholar for WPT antenna from low f to RF

 

[Sara-7]

Like many You Tube videos from "over there", the video might be faked since in the beginning it says a TIP41 bipolar transistor but a picture is shown of a STK5006 Mosfet.

you have eagle eyes.. i congratulate you for your details attention.

but in principle is his circuit correct? would it serve its purpose?

 

[D.A.(Tony)Stewart]

you have eagle eyes.. i congratulate you for your details attention.

but in principle is his circuit correct? would it serve its purpose?

No. It is not very sensitive compared to $1k commercial metal detectors.. Did you understand my description of the different characteristics of these two transistors in a Colpitts flyback oscillator