Smart Hunter EN

Donations

The purpose of this project is to make a cheap but effective VLF metal detector. If you want to support the project you can make your donation here! Thank you!

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Metal Detector "Smart Hunter"

Metal detector “Smart Hunter” is a project that will help you build a powerful VLF metal detector. This metal detector is based on an Arduino microcontroller and a smartphone. Here you will find all the necessary tutorials. Just follow the tutorials step by step and if you have any questions contact us. This metal detector is able to detect a gold ring or a coin at a distance of 30 cm, a lid of a pot with the diameter of 20 cm can detect at 90 cm! Start now and build your own “Smart Hunter” metal detector!

Premium Version

Premium version is a bit different from the free version because it has an internal generator, so in the Premium version it is not necessary to use arduino nor the MOSFET, which facilitates the assembly. The frequency of internal generator can already be chosen within the app in the PRO menu. The generator can generate from 20 Hz to 20 kHz but to detect what we are going to do we will need only from 4 kHz to 20kHz, because the working frequency of most of the “VLF” metal detectors is between 4 kHz and 20 kHz. The assembly is the same as in the free version, but in the Premium version it is easier for not using the arduino and also cheaper. Operation of the internal generator: internal generator generates the sine wave with the selected frequency and the generator signal goes to the transmitter coil (Tx), but since the signal is weak, we must amplify it, that’s why we use an amplifier.  In the online store Aliexpress there are many different amplifiers, in the video tutorial i use one of those cheap amplifiers. This amplifier is cheap and very easy to use, has only input/output and power “5v” . The receiver coil still unchanged as in the free version. That means that we mount the receiver coil (Rx) as we can see in the schematic, only if we use Premium version we no longer need the arduino part. On the internet there many schematics how to make an homemade amplifier , so if somebody want to build a homemade amplifier it also will work. The amplifier used in this video has output 3 watts , if we are going to use the coil with bigger size then we must use amplifier with output  15 watts more or less  ( depends on the  size of the coil). Below in the section “Free Version” we can find video tutorials how to make the coils and how to adjust them, this assembly is the same for the both coils. ,

The PCB of version 2.0.0

A new version of the PCB has been launched. In the new version 2.0.0 a preamplifier has been added to the receiver coil, which has considerably increased the sensitivity and stability of this MD. When using this version, you must select the  value of the “Rx splitter” 1000 or 500 in the application configuration. You can try an other values, but the tests showed that these are the two most optimal values. You can also try changing the volume of multimedia on your smartphone, since it is responsible for the strength of the signal that goes to the transmission coil. Increase the volume almost to the maximum for more sensitivity. Increasing the sensitivity without losing stability can change the resistance R4. Less than 1.5k, I do not recommend putting, you have keep in mind if we increase the value of this resistance the sensitivity decreases, but the stability improves.

Assemble the PCB and tests (Soon wil be translated):

Schematic of Premium version v 2.0.0

Free Version

Components:

  • Arduino nano or Arduino uno.
  • MOSFET IRF740 (It can be replaced by another).
  • Resistance of 10K.
  • Resistance of 2K.
  • 2 Diodes N4148 (can be replaced by others).
  • 3 Capacitors 1 mF .
  • Button
  • "MiniJack 3.5 mm" 4-pin connector
  • 0.6 mm enameled copper wire (for the transmitter coil).
  • 0.2 mm enameled copper wire (for the receiver coil).

Schematic:

Download Arduino sketch and schematic here :

3D coil model for 3D printing.

Here you can download 3D coil model for printing on 3D printer. It’s free! Just download it and it ready to print! Inside the file you can find full 3D model for printers with hotbed bigger than 300x300mm, and also 3D models for printers with hotbed less than 300x300mm. Enjoy! 

99 thoughts on “Smart Hunter EN”

  1. In your Smart Hunter version 2.0.0 you only have one Rx+ that connects to a pre-amp and one TxIn that connect to input of audio amplifier.
    How do you connect the Rx- and the other TXin? Do you tie both to ground? How do you then connect the shielding around the Rx coil?

  2. Hi,
    Just starting to make the Premium version circuit. In schematic there is both sound channel connected to XPT8871, but in PCB only one. Which one is correct?

  3. In “Smart_hunter_premium_v_2.0.0\PCB Print\PCB_Smart-Hunter-Premium-PCB-2.0.0\Component list.pdf” the diagram shows component U4 but the components do not show U4. I think it should be U2.

    Some of the components have a * after the units – e.g. 0.1uF*

    What does the * mean?

    Thanks for creating this project. I am waiting for my PCBs to arrive!

  4. I bought premium and i use external pwm signal generator 1 Hz to 150 kHz as Tx. Application is working well But i cant see any difference between discrimination or not although i set different sound.

  5. Hi

    Is version 3 compatible with the Android App currently available on the play store?

    Please can you update the english V2 page?
    I have just spent a lot of time, and a bit of money on buying everything for V2, only to discover in the comments that there is a V3 on the Russian page.

    I am now trying to work out which components I have already ordered can be used for the new V3.

    Your V3 board has no space for the charging board.
    I assume that we still need the tc4056a, and we keep it off the custom PCB?
    If not, how do we integrate the battery?

    V2 board used mt3608 (xy-016) and V3 board uses MT3608 (LEDy).
    I ordered a mt3608 but never saw the part in brackets (xy-016 / LEDy) .
    Does that matter?

    C11 is a 500uF capacitor. I only see 470uF capacitors commonly available.
    Those 500uF that I do find are for vintage items and they seem too large for the board.
    Can you give me a link to the exact 500uF that I need, or can I use 470uF?

    Some of the capacitors have values but no units.
    Can you confirm that I have them correct?

    13 47uF C1
    14 0.1uF C8
    15 0.033uF C9
    16 10uF C10

    C7 is a 0.1uF capacitor.
    C6,C5,C2 are 100nF capacitors
    However, 0.1uF is 100nF
    So, how is C7 different from C6, 5 and 2?

    Can I use 18650 batteries for this?
    What capacity would I need?

    Please also add the connector from the coil bracket to the rod to your 3d models page.

    Some of the components have a * after the units – e.g. 0.1uF*
    What does the * mean?

    Thanks for a great project – looking forward to building it!

  6. Hello
    Great design, smart hunter works very well, I made the coil according to your description, but I have a question about the coil. Will the garret ace 150/250 detector’s coil be suitable? And have you thought about using some kind of operational amplifier on the RX side?
    greetings

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