26 June, 2018

Smart Hunter EN

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! 

Download Arduino sketch and schematic here :

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 Amplifier

This is the amplifier i am using in the video. It’s a cheap amplifier, comes in pack of 10. Don’t even try the quality but at the moment it works well and the price is realy very cheap for that. Here below i leave the link to the Aliexpress store where i bought it. It is a stereo amplifier there are many models  in Aliexpress i can have a look.

Premium Version Schematic

Components Premium Version:

  • Resistance of 2K.
  • 2 Diodes N4148 (can be replaced by others).
  • 3 Capacitors 1 mF .
  • "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).

Video tutorial Premium Version

Free Version


  • 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).


Video tutorials:

How to assemble the circuit:

How to make coils part 1:

How to make coils part 2:

How to make coils part 3:

3D printed Coil / Part 1

3D printed Coil / Part 2

13 thoughts on “Smart Hunter EN

  • hola,
    me gustó mucho su proyecto y me gustaría felicitarlo …
    ¿podría responderme una pregunta?
    es posible hacer el tx coil 1 sin el “arduino nano” ejemplo hacer una placa sin o auxilio del mismo? utilizando otros tipos de componentes “ci, condensadores, resistores entre otros ….”
    desde ya gracias

    • Si, por supuesto es posible!Arduino utilizamos como un simple generador de onda cuadrada!
      Si buscas en internet puedes encontrar muchas circuitos para hacer generador de onda cuadrada, solo elige uno que te gusta!
      Uno de los mas populares esta echo con un integrado barato que se llama NE555.
      Tambien hay generadores de onda cuadrada echos con solo dos transistores!

    • The complect sketch and shematik you can download on this page.Just click “Download arduino sketch and shematik”
      You can get the components from an old electronik divices or you can buy in internet, i buy on Aliexpress it is cheap shop

  • Please bro .. in the the amplefire shematic there is no small coil .. there is just tx and rx coils i need to know if there is a small col .. and if it been .. how i can connect it ?

    • Hi!
      The small coil calls “Cx” coil!
      THis coil we need only when you put epoxy resin and the balance is incorrect!
      for exemple you adjust the balance to “100 amp” after fill with epoxy resin your balance go out to “400 amp” so in this way you need to put the “Cx” coil but if your balance is OK you don’t need this small coil.
      THe small coil if you need to put it we connect en series to Rx coil it is like a part of Rx coil. You can see in schematic of Free version there is schematic how to connect Cx coil

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