Pinpointer FM-2 v2

Pinpointer FM-2 v2

In present post we show the method for building the most simple metal detector Pinpointer FM-2 V2. This Pinpointer based metal detector can be used by professionals to  pinpoint accuracy and can be made for children,   despite its important characteristics.This is probably the simplest metal detector can be collected by beginners..

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May be heard or collected before, metal detectors such as “Pirate PI” and “VINTIK-2”. But with the advances of technologies, the use of the microprocessors and microcontrollers has greatly simplified the complex schemes of metal detectors. Here we have a scheme for a more advanced metal detector called FM-2 V2. In this new version of the device, two LEDs have been added to discriminate the metal, and  for alert the user that the device is on, and a variable resistance to increase or decrease the sensitivity level, the device has become more stable during the search operation.

Specifications and technical features:

  • Battery size – 9 volts
  • The depth of metal detection is about 15 cm.
  • Discrimination function (Ferrous metal)
  • LED indicator for discrimination
  • Power indicator

The printed circuit board PCB of this metal detector FM-2 V2 is designed in order to use the normal DIP components, which will be suitable for everyone, because many beginners have difficulties with the SMD components.

Schematic diagram for FM2 V2

In this new version of the firmware  for PIC microcontroller has been optimized. It is possible to use two types of controller, either PIC12F675 or PIC12F629 (separate firmwires).
In this version,  the problem of frequent reboot have been solved, meaning that you do not need to restart the device constantly, the device has become more stable at work, you can now work with device all the day without any problems.
The added  alert notify the user that the device is running is very useful, for example if you turn on the device and forget to turn it off, the device will remind you every two minutes with a tone.

A visual signal with a flashlight was also added to alert the low battery level. If the battery voltage drops below 5.5 volts, the detector emits a visible signal on the LED. But this alarm is only embedded with the PIC12F675 microcontroller.

The circuit is almost the same as the previous version of the device with a slight adjustment by adding two resistors.

Pinpointer FM-2 v2

The circuit uses an LM317 voltage regulator, connecting its legs as shown in the picture below.

Pinpointer FM-2 v2

For those who cannot find the LM317, they can search the old electronic parts of the receivers and they will definitely find the AMS1117 -3.3v SMD voltage regulator, but it can be adapted to the printed board well.

Pinpointer FM-2 v2

Generally the following part-list is needed  to build the Pinpointer :

  • USB PIC K150 ICSP
  • PIC12F629
  • PIC12F675
  • AMS1117 أو M317
  • 1N4007 – 100
  • BC547 – 100
  • BC557 – 50
  • Quartz
  • Resistors
  • Ceramic capacitors
  • Chemical capacitors
  • Film capacitor 22 nF
  • Film capacitor 100nF
  • Led (different colors)

The Printed circuit board for the device is very simple and can be design at home:

Pinpointer FM-2 v2Pinpointer FM-2 v2

Pinpointer FM-2 v2

Search coil design for FM2 V2
The inductance value of the search coil for this pinpointer  is 1500 mH,
In order to make a correct  number of turns needed you can visit the  site Coil32.
The coil contains 150 turns when choosing a wire diameter of 0.3 mm and a coil diameter of 150 mm.

Pinpointer FM-2 v2

After the coil is well prepared and combined with a tape, it is absolutely necessary to protect the coil from the magnetic field and other effects so that the metal detector does not react together and does not give a  fake alerts. We take the aluminium foil from the kitchen and wrap the coil tightly around the coil, leaving the ends separated   and should not touch each other.

Pinpointer FM-2 v2

Then take a wire and clean the ends from the insulator and wrap it around the coil from one end of the screen paper, and then tighten and wrapped tightly again with tape tape.

Pinpointer FM-2 v2

then attach the coil to the printed circuit board of the device.

Pinpointer FM-2 v2

If you do everything correctly, the device should work  without problems, the first time you turn it on. Carefully check the parts are well soldered.
When the device is turned on, it must make a distinct sound, which means that the device is turned on and working properly.

Download the necessary files

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