Device is extremly simple and consist only few components:
- Arduino nano microcontroller
- small Oled display
- Led and resistor
- and Hall effect sensor, in my case UGN 3503U.
It is important to use a ratiometric linear sensor that gives a voltage at its output that is proportional to the strength of the magnetic field. This sensor picks up field strength in the units of ‘GAUSS’, and its range is from 0 to +/- 900 Gauss. By using ADC feature we will convert output voltage to a number.
As the magnet approaches the sensor, the magnetic field becomes stronger and the reading increases. If we turn the magnet on the other side, the polarity changes and the value of the screen has a negative sign. The LED is activated when the magnetic field exceeds +/- 15 Gauss and is a visual indication that the sensor is in a magnetic field. This diode also serves for easier detection of pulsed magnetic field.
Finally, the device is mounted in a suitable box made of PVC board and coated with colored self-adhesive wallpaper.