Very simple Pi that works good

[bernte_one]

simple and works

so if you have a arduino environment and some spare parts why not?

i love projects from russia

[kt315]

speedy translated
All hello!
So, we submit to your attention the new project - the Metal detector on Arduino!
Long I bore idea to create the metal detector on Arduino and here at last came true
For creation of the metal detector on Arduino it was necessary to begin with studying of the principles of operation of metal detectors and left at me on it, it isn't a lot of, many, 2 months: shock:
Well naturally from time to time and with days off
Before solving by what principle the metal detector will work at Arduino the different principles, such as were studied:
1. The elementary metal detector on beats working by the principle of a frequency meter.
Its work consists in comparison of frequencies between two generators, one setting reference generator and other generator with LC a contour.
At control of frequency of generators are equalized and at a present of a metal subject to the coil of other generator there is a change of frequency and respectively indication of this change.
Pluses of this metal detector in that that it can define type of metal, color and not color.
Minuses - the small depth of detection, bad stability of frequency, not steady against hindrances.
2. Pulse metal detector. the scheme is a little on more difficult, incorporates a powerful transistor key the operational amplifier.
The principle of its work consists in the following, the transistor key switches current in the coil, she creates round herself an electromagnetic field, in the presence of a metal subject in the field of a coil field in it the fading vortex currents are directed. At the time of recession of an impulse there is a detecting of these vortex currents through the operational amplifier connected to the same coil.
Further, the signal from the amplifier is processed and displayed on the LED and sound indicator.
Pluses - good sensitivity on metal subjects, stable work, the coil very simple in production also doesn't demand shielding.
Minuses - aren't present opportunity to define metal type.
3. Metal detector balance. This type of metal detectors more difficult and its production to beginners will be beyond the power.
The principle of its work consists in data of balance of electromagnetic fields in two coils, a reception and transferring. Without measuring devices it is very difficult to make it and it isn't always possible.
In the transferring coil electromagnetic impulses are created and the reception coil fixes their change at violation of frequency balance from emergence of an action field of coils of a metal subject.
Almost all industrial and professional metal detectors work by this principle.
Pluses of the balance metal detector - good sensitivity, definition like metal.
Minuses - difficult in production, existence of measuring devices is required.

[kt315]

After studying of various principles of operation of metal detectors I decided to stop on production of the pulse metal detector.
As the basic scheme the scheme of the metal detector the Pirate was chosen. From it I took part with a transistor key, changed a little, changed the scheme of turning on of the field transistor on the compound bipolar transistor.
Also I took the scheme of inclusion of reception part on the operational amplifier, I changed it for work with widespread OU TL072CP.
And its indication I realized formation, generation of impulses, processing of a signal from OU on Arduino's controler of UNO.
The scheme turned out very simple and small, and it is easy to bring together its in house conditions without printed-circuit board.
I collected everything on a model payment, stability of the scheme despite hinged wires, very much even the good.
I upload pictures of the metal detector on Arduino.

[kt315]

With the coil it was necessary to experiment
Having reeled up some different coils, different diameter and with the different section of a wire at me it turned out to come to the optimum size and sensitivity, and both on small, and to large metal subjects.
Sensitivity on a coin of 5 kopeks of the USSR about 15 - 16 cm.
On a copper plate of 5х5 cm - 20 cm.
Iron jar from under coffee - 40 cm.
Also I realized on Arduino automatic balancing of the metal detector and a linear scale on light-emitting diodes by which it is possible to determine distance to a metal subject.
The sketch of the metal detector on Arduino

[kt315]

[kt315]

who there did ask the true static mode?? =)))