This is a pulse induction metal detector made by Future Electronics Egypt (Arduino Egypt). It uses a single search coil and pic micr-controller.
It can detect metal objects under ground, through wall and above ground as well. Typical minimum depth range from 25 to 30 cm underground. This range is obtained with very rough quick made coil (not optimized) using 10 cm diameter object.
With optimizaed coil range of detection increase to more than 40 cm.
The metal object detection is indicated by LED. Recommended voltage supply is 12 V with small current. However the Metal detector was extensively tested and found to be stable operation in range of voltage supply (9 : 12 V).
Watch this video showing test of the sensor (If Video is not working, please click here)