My first research in terms of IB technology. The head couldn’t keep up with the hands, but there is a result! Meet the world's simplest digital IB metal detector.

Selective microcontrollermetal detector "KROT-M".

Main technical characteristics:

• Coin with a diameter of 25mm (air) up to 30 cm
• Helmet 0.8m
• Maximum up to 2.0m
• Sound indication multi-voice selectable
• Visual indication LCD 16x2
• How IB works
• Selective search mode
• Sensor ring or DD diameter 10-30 cm
• Range of possible operating frequencies 6-12 kHz
• Supply voltage 7.0-9V
• Current consumption no more than 90 mA
• The weight of the structure, which is 850 grams in the photo on the left, can be disassembled into two parts.

Basic functionality

* Operating modes: dynamic, static (pinpointer)
* Selectable types of signal parameters indication
Indication of the numerical value of the VDI and graphical indication of the amplitude.
Indication in the form of histograms - VDI and amplitude
* Main sound indication 3-tone - color, black and overload
* Selectable sound indication for color
Changing the beep tone from VDI , sound discrimination
Changing the volume of a sound signal, a function of amplitude
Multi-tone PWM
* Supply voltage indication
* Visual and audio indication of overload.
* Availability of a discriminator: color -10 segments with a step of 10 gr.
Iron - 6 segments with increments of 20 gr.
* Sensitivity setting separately for “color” and “black” targets - from 0 to 9
* Availability of manual ground balance in static and automatic (dynamic).
* Cash switchable backlight
* Availability of debugging mode
Digital frequency setting in the range of 6-12 kHz in steps of ~10 Hz
Indication of X and Y values ​​and dX dY for setting MD
Software selectable phase shift in 45 degree increments. hardware - smoothly + -20 gr
* Convenient and intuitive interface.
* Automatic recording of all settings into non-volatile memory
* Easy setup for different IB sensors
* Ability to create a profile for a specific sensor. In total you can create 4 profiles.

Scheme

Capacitors (except for those for power supply) use film or ceramic type NPO, X7R!
Button 5 - “static”, is not necessary - it is intended for the amateur.

Coil connection

Tx is possible without a screen.
This is how the electronic unit may look in the housing Z5, batteries inside.

Manufacturing: Manufacturing managerboards (new board below) is not complicated and only requires the skill of installing SMD components, standard size resistors and capacitors 0805. Capacitors C and C1 are film. All microcircuits are in DIP package.
But the productionThe device sensor and subsequent adjustment of the device will require certain knowledge and skills. And it is only available to trained radio amateurs! Personally, this site helped me in this regard. http://www.md4u.ru/forum/ .

Data for DD coil frequency 8-10 kHz, diameter 25-27 cm
Number of turns of transmitting TX ~45 turns of wire 0.4-0.5mm c1=0.3 uF
Number of turns of receiving RX ~200 turns of wire 0.15-0.22 mm C0=0.022 uF Not resonance C0=0.

If the sensor ring , O You can read the description of the sensor manufacturing technology .
Number of turns of transmitting coil TX ~50 turns of wire 0.3-0.5mm
Number of turns of compensating coil CX (selectable) ~20 turns of wire 0.3-0.5mm
Number of turns of the receiving coil RX ~200 turns of wire 0.15-0.22mm

Changes to the sensor parameters are allowed (wire, number of turns, winding diameter). In general, there is a huge field for experimentation. It is also possible to use a “proprietary” sensor(s).

Settings

First, let's get acquainted with the "Description of operating modes - menu"
We start by setting up the “virtual zero” of the receiving path. We turn off the coils, place a jumper from C0 to ground and, with the button “released”, achieve zero (in fact, the voltage on the 23rd leg of the controller is about +2.5V) readings at the output of the receiving path; we do this procedure in the “NL,Up” settings mode (in firmware versions 7 and higher) using the “+” button, remembering the value using the “0” button. Voltage readings should not change by more than +-1! We can immediately adjust the “correctness” of the supply voltage readings, similar to what was described above with the “-” button. In earlier versions, adjustments are made using resistors R1/R2 and R8/R7.

Next, we configure the transmitting TX to resonance or a state close to resonance. To do this, connect the transmitting coil TX, go into the settings mode (long press the "mode" button), submode X,Y and use the "+" and "-" buttons to find the resonant frequency based on the maximum voltage on the TX coil. The amplitude voltage value should be about 10-30 V (depending on the parameters of the TX circuit). Let's remember this frequency - F . Find resonance receiving coil RX can be calculated using the method of e.g. (for non-resonant - without capacitor C0, we skip this setting) It is recommended to set the receive RX ~20% lower. That is, if you have TX -10 kHz, set RX to ~8.0 kHz.) Let me remind you the frequency F can range from 4 to 16 kHz. Recommended frequency 6-12 kHz.
Next we set up the phase: When a copper coin approaches, Y and X should increase; when a ferrous metal (iron) approaches, Y increases and X decreases. If this doesn’t happen, use the “0” button (discretely in increments of 45 degrees) and trimming resistor R16 (smoothly) to change the phase until we achieve the correct reaction to metals . If this procedure does not work, you need to select capacitance C0, C1 or change the transmitter frequency . Next, you need to set the exact phase for correct VDI measurement construction resistor R16. N It is better to adjust the phase according to the ferrite - X to minus, Y in place or slightly to +. You can also adjust the phase according to the “standard” - for example, 5 kopecks USSR VDI value about +55.VDI Foil ~ 0-10, pure copper +80-+90, all pieces of iron are in the minus. If possible, correct the convergence using a tuning turn(s). There is one more subtlety: after tuning, change the frequency + -30 Hz. find the place where the values ​​of X and Y change (jump) the least!
Sensitivity Setting: Resistor R0 and R17 selects the current of the TX coil. The higher the current, the greater the sensitivity, both to targets and, unfortunately, to the ground. Recommended current for a resonant system is 40-80 mA, non-resonant 80-100 mA. The current in TX can be approximately estimated by the difference in the consumption of the device with and without a coil, then for a resonant system 20-40 mA, non-resonant 40-60 - depends on the quality factor of the circuit. Resistor R5 selects the sensitivity of the device in the RX channel; the lower its value, the higher the sensitivity. Recommended resistor values ​​for a resonant system are ~1k, non-resonant is ~200ohm. The sensitivity of the device must be adjusted so that there are no false alarms at the threshold (sensitivity) of 1.2 (of course, provided there is no interference). There is no need to chase high sensitivity through the air, 20-25 cm is just right! for a sensor with a diameter of ~20 cm. For a sensor with a diameter of 25 cm, respectively, 25-30 cm.
Resistor R13 adjusts the contrast of the indicator and its value depends on the type of indicator.
Note: INIn setting mode, the “+” and “-” buttons change the frequency on TX in steps of ~10 Hz. The "0" button changes the phase with a period of 45º.

New pay under the dip microcircuit. The board is functional and tested! For more reliable operation, it is advisable to leave the top layer of foil on the board and connect it at several (marked in blue) points. When installing the indicator, see the description; power pins vary!
Chips: MCP601 can be replaced by NE5534, K140UD1408, LF357, LM308.Microcontrollerit's better to put ATMEGA8А it consumes less and works better.

How to easily flash a microcontroller, you can read about it

We program fuses like this

Who wants to listen to the sounds of "Mole" or other MD on FM radio, you can put together a simple circuit.

Adjust to the desired frequency - spreading and squeezing the turns of coil L1
We select R4 based on the absence of distortion.

New firmware 0.2 with two dynamic modes and vector cutting of the soil.. Don’t forget to periodically adjust the ground with the “0” button. First, a meter from the ground for a short time “0”, then at the search distance for a long time “0”, the value of the soil coefficient should be minus (-10 - 70)

15.09.2011
1. The circuit has been changed, one resistor has been removed (formerly R4) and some values ​​have been changed (red color)
2. The board has been changed taking into account the new scheme.
3.New firmware 0.3 for testing.
The measurement speed has been increased by 20%, the soil accounting algorithm in modes “D” and especially “G” has been changed, and the ability to measure supply voltages above 10V has been added.
New firmware and changes in the circuit diagram allow the use of non-resonant RX, but you will have to sacrifice ~20% range...

15.10.2011
1.New firmware 0.4 for testing and firmware 0.4a + firmware 0.4v (for transistor TX)
A fifth button has been added for the pinpointer mode, the ability to reduce the TX frequency to 4 kHz has been added, and the sensitivity of the channels has been increased (only in 0.4).

15.11.2011
1.New firmware 0.5 for testing.
2. In (X,Y) mode:
a) added, the function of measuring the voltage in mV of the coil unbalance.
b) added the ability to automatically adjust the minimum voltage value imbalance coil - long press "0" (use with understanding!).
c) the form for displaying the initial phase setting values ​​has been changed, now: 0-0g, 1-45g, 2-90g, 3-135g
3. The initial state of the 15th leg of the microcontroller at the moment of initialization +5V has been changed - for a circuit with parallel TX drive on a transistor, this does not affect operation with serial drive.

How do MDs work? - Very simple! -article

Video "Mole brick and penny" firmware 0.6, DD20 coil (non-resonance), frequency 12 kHz, demonstrates automatic “cutting” of soil in dynamic mode, or how to check your device in winter..)

16.01.2012 I have corrected the article in light of recent observations...

15.02.2012 I corrected the circuit - inaccuracies were eliminated, resistors R17, R18 were added, some values ​​​​were changed, a connector for in-circuit programming was added (as an option), measuring and digital grounds were separated (they can be connected at one point through a resistor or inductor). All changes are not fundamental and do not bring significant improvements! The payment has been corrected.

23.02.2012
For "Men's Day" new firmware 0.7
1. Now thresholds for different profiles are also remembered.
2. Changed the type of discriminator - first black, then color.
3. Added a new mode in the settings - “NL,Up” Use the “+” button to select the coefficient for setting “0” (with the coil turned off, equivalent to selecting R1/R2) use the “-” button to select coefficient for setting "Supply voltage" ( equivalent to selecting R8/R7).
The settings are saved using the "0" button.
4. The voltmeter now also measures “negative” voltages.
5. Mode “G” is now again a “static” accounting of the soil; after correct adjustment to the ground, the depth is comparable to air...
6 Removed the auto-adjustment mode for the minimum coil balance voltage.
7. Other minor improvements.
I'm looking forward to interesting reports about the firmware!

CHRIST IS RISEN!
15.04.2012 - New firmware 0.8
1. Improved "histogram" mode. Allows you to identify objects with complex geometric shapes, etc.
2. In the “LED” backlight mode, the third parameter “SG” has been introduced, an economical mode for illuminated indicators and for those who like to search at night.
3. Improved "Static" mode. Now you can search in this mode.
4. The “Interference” mode has been introduced. It serves to localize the source of interference and evaluate his level . It is turned on by pressing the "Reg" button when turning on. Exit - turn off.
5. Other minor improvements.

05/15/2012 Firmware 0.8G -analogue 0.8, but you may have to tighten the phase -R16.

If you are interested in depth on real soil, learn to work in "G"
We work only after careful adjustment to the ground. You may have to do this often and several times.
The correctness of the setting can be assessed as follows: Soil coefficient from -10 to -80.

10/11/2012 Firmware 10. (more precisely, the two firmwares differ only in the initial phase. “10” as in “8G”, “10” as in “8” and below.)
Changed (simplified) menu. Now all four buttons in the main mode have two functions: “short” and “long” press. The "DEV" and "0" keys are the same as before. Key "-" short press - increase the threshold for "color" (like before) , long-term increase in filter number. "+" key: short increase in "black" threshold (like before) , long “on-off” of the indicator backlight.
In the main mode, the “fN” parameter appeared, where N is the filter number:
0 - filter as in firmware 8G and below for the “lightest soil” - air, sand..
1- Filter for light soil.
2- Filter for medium soil.
3- Filter for heavy soil.
Other improvements to improve the operation of the device.

12/15/2012 Firmware 12
Continuation of version 10.
The main menu has been slightly changed.
The settings are now hidden and are called up when you turn on the device and simultaneously press the “+” or “-” buttons. Exit the settings modes through “MODE” or “Off-On.” device.
Improved selection of "colored" targets at Fe0.
The VDI range has been increased to +-100.
The "color" range is now 2-tone 0-79 and 80-100.
Other software improvements that improve the operation of the device.

01/20/2013 Firmware 12A
Continuation of version 12
Improved "visualization algorithm" in main mode. Now the target can be scanned multiple times with accumulation (averaging) of the result of the displayed VDI.
Added "parameter display" function - button S5.

01/20/2013 Firmware 12B
Same as 12A, instead "parameter display", "pinpointer" - button S5
There is no interference level measurement mode.

____________________________________________________________________________________________________

C selective, microcontroller, 3-frequency
metal detector "KROT3-HM"

The hardware and software parts of the Krot2 metal detector are taken as the basis. Therefore, converting your “Mole-2” into “Mole-3” will not be difficult; you will need to add a couple of parts and “change” the program and, of course, configure the device again. The setup is very similar to the Krot-2 setup.

Frequencies are switched using toggle switch S.1. Frequencies are selected and adjusted by the user in the ranges: 6-17 kHz

Data for DD coil frequency 6.0 - 17 kHz, diameter ~30 cm
The number of turns of the transmitting wire TX 40-55 is 0.4-0.5 mm C1 = 0.047-0.47 µF. Selected according to the required frequency.

(No-resonance TX ~25 wires 0.5-0.8mm are allowed Connection 1-3)

Number of turns of receiving RX ~150 wires 0.15-0.22 mm No resonance.

Note: The demands on the coil are increasing, we now need to have balance at different frequencies!

I think it’s clear that the device can have a smaller number of frequencies, 2 or 1. This simplifies the switching and in the case of one frequency, “Mole3” turns into a single-part “Mole2”)

Scheme(correction from 09.23.15)


Changes are highlighted in red. Capacities “in green” are thermally stable, for example NP0 or x7R R10 = ~820 ohm

Firmware from 01/01/2016 Good firmware for 3 frequencies, upload everything else and you will understand it intuitively... Read what you don’t understand here

Firmware from 02/01/2016 Added gain for frequencies less than or equal to 8000 Hz.

HAPPY NEW 2017 A YEAR!

It is useful to periodically press “0” briefly, especially after switching frequencies.

********************************************************************************************************************

Firmware from January 1, 2014 Mole3. V11
The "menu" program is completely identical to the software for the MD "Mole2" but has 4 modes
"Freg_TX", "Coil Bl", "Ferrite" and "Ground bl" are additional FN parameters, where N is (1 to 3) the number of the frequency range.
Firmware from 02/10/2014. K3.V12 Inaccuracies corrected, sensitivity increased!

Firmware from 06/07/2014 K3.V10 The speed of filters has been increased. A “pseudostatics” mode appeared, as in “K2”. Entering the "factory" settings menu "+" when turned on.

MD "MOLE"

Specifications

Coin with a diameter of 25 mm (ground) up to 40 cm (depending on the sensor)) Helmet (-----) up to 1.2 m Maximum (-----) up to 3.0 m Sound indication selectable, from 2 to 90 tones,
Visual indication symbol. LCD 16x2 Operating principle IB Range of possible operating frequencies (8-17 kHz) Supply voltage 4.8-6 V Rated current consumption no more than 80 mA (without backlight) Operating temperature range 0 - 40°C (depending on the sensor)

Functionality

* Operating modes: dynamic, static – (pinpointer), static + dynamic.

* Numerical and graphic (sinograph) indication of VDI and amplitude.

* Selecting the VDI display mode.

* Sensitivity setting separately for “color” and “black” targets - from 0 to 9

* Select a filter for a comfortable search on different soils from 1 to 3.

* Selection of operating modes "Norma", "Fast" and "Fast+h"

* Multi-tone selectable sound indication - 2, 4, 10,90 tones.

* Adjustment of the volume change pattern and dependence on the depth of the target.

* Indication of supply voltage and automatic signaling of low battery power.

* Availability of discriminator: Color -9 segments with a step of 10 gr. Iron-5 segments in increments of 20g.

* Availability of a simple ground balance procedure.

* Availability of switchable backlight.

* Automatic recording of all settings into non-volatile memory.

Engineering or "factory settings"

* Select a "profile" for a specific sensor.

*Adjusting supply voltage readings

*Adjust display contrast.

* Automatic or manual adjustment to the operating frequency of the sensor.

* Automatic or manual phase adjustment according to ferrite.

* Adjustment of pumping power of the transmitting part.

* Automatic setting of the gain of the receiving part.

* Automatic or manual sensor balance.

The purpose of the buttons is the main operating mode:

Each of the buttons in the main mode has two functions. Functions are called by long or short presses. Above the buttons are the names of the functions called by a short press, and below by a long press. Let's look at the buttons and the functions they call in order:

Mode Button Short press of P/P turns the metal detector's pinpointer on and off. A long press on “Menu” takes the device to the user settings menu – read more below. The “0” button is used for ground balancing - read more below. Button "-". A short press of “Sens_FE” reduces the sensitivity of the device, a long press of “Filter” cyclically changes the filter number 1-3. "+" button. A short press increases the sensitivity of the device, a long press turns the LED backlight on and off.

Description of operating modes of MD "KROT2-XM"

(Firmware “Rating”)

A splash screen appears, the top line is the name of the firmware.

The last digit is “chip version”.

********* – profile name (can be edited)

If the coil is not connected, the message “Connect the coil! »

Switch to main mode

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This Krot-M and its continuations M2/M3 are a very interesting device. Making it yourself is quite easy. In this article you can find all the necessary information to assemble it.

Let's start with characteristics and descriptions.

Krot-M is a fairly serious device, it is selective and based on a microcontroller.

Relatively inexpensive and easy to assemble. As for reliability, some people claim that it may trigger falsely or react to swings. In most cases, all this is the result of incorrect configuration and assembly, the use of bad or incorrect parts. Among the advantages, I would like to note: an easy setup menu, good detection depth, relative cheapness.

Characteristics:

• Coin d = 25 mm – up to 30 cm.
• A medium-sized metal object (helmet) - up to 1 meter.
• Maximum sensitivity is up to 1.5 meters.
• The operating principle is inductive balance (IB).
• Sensor diameter – from 10 to 30 cm.
• Sound indication – multi-tone, from 2 to 14 tones.
• Visual indication (VDI) – present.
• Operating frequencies (depending on the firmware) – from 6 to 12 kHz.
• Search mode – selective mode.
• Current consumption – up to 90 mA.
• Operating voltage - from 4.8 to 9 V.

Scheme MD Krot-m

Below we provide a diagram and printed circuit board of Krot-M

All this can be downloaded in one archive, the board in .lay format

Here is the coil connection diagram.

Scheme of MD Krot-2M

Now keep the Krot-2m circuit and its printed circuit board. The archive will contain 2 types of printed circuit boards, for the Z78 case and the Z80 case. Also inside there will be recommendations for assembly and installation in the case, a list of parts and additional diagrams.

That's basically all there is to this metal detector. Here are some more firmwares and some recommendations:

Only the latest firmware is provided, if you need an earlier one, go to the author’s website and download it for yourself. Change in this firmware.