FoxyPI - motion/non-motion pulse induction metal detector, built on the Arduino Nano 3.0, with audiovisual indication, setting parameters via the menu, automatic or manual ground balancing.
Hex-file for Arduino Nano 3.0 (version 3.3 from 04/16/2019) - https://acdc.foxylab.com/sites/default/files/FoxyPIv3_3.ino.eightanaloginputs.hex
Elf-file for Arduino Nano 3.0 (version 3.3 from 04/16/2019) - https://acdc.foxylab.com/sites/default/files/FoxyPIv3_3.ino.elf
With a sharp decrease in the current in the search coil, its magnetic flux also decreases sharply. This phenomenon causes the occurrence of eddy currents in the target, penetrated by this magnetic flux. The resulting eddy currents counteract the reduction of the magnetic flux, which is manifested in a change in the voltage curve on the coil and is noticed by the device.
The detection range of targets in the "air" test in non-motion (in a motion a little less) mode:
(the test was carried out with the batteries discharged to 1.3 V , therefore, the data are understated)
golden ring (3) - 9 cm;
coin 5 roubles (U.S. quarter analog) (2) - 15 cm;
HDD plate (1) - 33 cm.
The first result of the first garden search with version 3.3:
The result of the second garden search with FoxyPI v3.3:
One of the finds after electrolytic cleaning:
A strange stone I found using FoxyPI v3:
During operation, the device should be located at a distance from working televisions, computers, power transformers, CFLs.
Firmware for testing of FoxyPI v3 (hex-file):
In test mode, the metal detector generates a current pulse with a duration of 150 μs in the search coil after switching on, and then it displays the received signal on the screen. Pressing a button generates a new impulse, etc.
Examples of signals: