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Metal detector on a "permanent magnetic field" - is it possible?

Here is my idea metal detectorwill work?

The bottom line is, take a coil, for example, as in a metal detector, apply a direct current to it. A magnetic field will form around the coil.
So, while there is no steel object near the coil, it consumes minimal current. And as soon as a steel object enters the magnetic field, the coil immediately begins to "eat" more current, since it attracts a piece of iron to itself.

So, if we had a very sensitive ammeter, we could look for metal, including it in the gap with the coil. Only there measurements should be in milliamps, probably ... When the object is clearly in the center of the coil, the device will show the maximum current consumption.

And now about non-ferrous metals. When any metal enters an electromagnetic field, induction currents arise in it and, as a consequence, a magnetic field. For example, if you hang a coin on a thread and swing it near the magnet, it will always turn around on a certain side to minimize the "resistance currents", Foucault currents. Similarly, when we drive a coil over a non-ferrous metal, currents and an electromagnetic field will appear in the metal, which will “repel” the coil, as a result, it will also have to consume more current.

So the main question is, how can one make such a very sensitive ammeter, maybe based on a multimeter?
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24 commentary
If this is done stationary, it can and will work out. But imagine, you are walking in a field, the field is not even naturally or the forest. You swing and your metal detector sways. And at what speed do you have to move in order to catch a deviation? + Not all metals react to a magnet. I even find chips from metal with my metal detector, and with this you will only find a buried tank.
Of course, I’m not sure, but, I think, the force of attraction strongly depends on the mass of the object, its magnetic properties and distance.
I was thinking, what if putting a permanent magnet instead of a coil into metal detectors, on an elastic suspension, when you bring the suspension closer to an iron object, the magnet will be attracted and stretch the spring (fixing the attractive force). A small neodymium magnet, checked, attracts 25 cm. So even batteries are not necessary))
I completely agree with you !!! I will say more, the search for truth in wine often spills over into debate. It is only a pity that it is possible to find the truth in a dispute remotely, but unfortunately not in fault!
"Truth is born in debate !!!"
"The truth is in the wine!"
It follows: "The result of disputes is always one: wine!"
)))))))
What does this have to do with it?
You lagged behind the life of Ivan-)))
Magnetic force calculator
Quote: pogranec
what magnet can you measure force

So I say, first read the books before measuring the force with a magnet.))
Quote: Korolev
And where is the truth born there?

Truth is in guilt. ;)
A chat? And where is the truth born there?
As far as I understand it is necessary to measure the meager reaction (deviation) of a sufficiently large current (to excite a response of the object)? Or I'm wrong?
A bunch of "smart" words instead of opening a smart book and reading. And then try to count, instead of hovering in empire.
And with what magnet can you measure the repulsive or attractive force, for example, coins at a depth of 20 cm + 5 cm of air?
Author
There is a wheel with magnets placed on the motor shaft and the speed is measured with a multimeter.
Dmitry, you often throw interesting topics ... at the expense of a permanent magnet metal detector ... there you can measure not only the current in the gap but also the voltage jumps of the coil side ... I would measure a different value - the force of attraction or repulsion of the coil itself to a metal object (iron, cobalt, nickel - attracted) all other metals are repelled ... the truth is that you also need a sensitive dynamometer ... and you won’t hold the whole structure in your hands ... you need to put it on a platform with wheels .. hmm .. or on a hanging quadrocopter .. . quadrocopter metal detector (mine detector) by the way this is also a new idea ... just came up))
Right! The ark was built by an amateur, and the Titanic - specialists!
Not optimal. You start from the wrong end. First work out physics, then think about implementation.
Author
yes to hell with you, I’ll be fun myself
Author
the coil is turned on through a resistor
It is not necessary to take a standard coil, you can reel it right for his idea. But who is stopping the author of the idea from first working out the physical principle (magnetic field parameters, the disturbing effect of metals on them) and then already wondering whether it is possible to implement it in hardware?
<<на "постоянном магнитом поле" - возможно ли?>>
Almost impossible. There it already arises from the very beginning, and how to power a simple Coil from an MD (impulse)? Take, then, the battery "Krona" = 9v and connect to the coil ...And the coil is not wound with a thin copper wire and has R ~ 2 ohm. And what is the current buit ?? 9v / 2om = ~ 4,5A What buit with Krona? Pralna - she will dry up. And that’s it. Here they measure wrong ...
What does the electronics have to do with it? This is physics. Estimate what current you need to measure, and how to do it (if possible) is a secondary question.
Author
I wouldn’t ask if I knew electronics so deeply.
how to make such a very sensitive ammeter,
Do you want the necessary parameters of the device to be evaluated for you? PMSM, if your idea is - please be so kind as to figure out what current you need to measure.

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