Metal Detector
Nail Finder

Kits for Metal Detector kit - Nail Finder  $17.00 plus postage

See the following site for lots of projects on metal detectors:

See also our: Metal Detector Article

This project is an extension of Metal Detector MkII, with a small detecting head to find tiny components such as nails and lost components.
This is an essential tool for servicemen and anyone trying to find a metal object hidden or buried in timber,  soil or mud.  

It uses the Metal Detector MkII PCB and components but a new "head" is used that is wound on a 10mm ferrite rod. This head comes completely wound and ready for soldering to the PC board. 


The Metal Detector overlay clearly shows the position of each component

Under the board, in the location shown above, you will find a
390R SURFACE MOUNT resistor, soldered to the tracks.
When soldering the pot and transistor, only solder
one leg at a time so the surface mount resistor
does not move. This resistor adjusts for the type
of wire and coil-size.

When fitting the components on the Printed Circuit Board, use the overlay above to help locate the correct holes.
When fitting the positive lead of the 9v battery snap, make sure you put it through the large hole and solder it to the end of the switch as well as the adjacent land. 

All the components fit on the PC board with the coils and speaker on short leads


The Nail Finder head

Solder the wires from coil A and B to the board and turn the project ON.
If the squeal does not stop when the pot is rotated, swap the two wires on coil A.
Adjust the pot until you get a very low-frequency clicking noise. This is the most sensitivity setting.


Metal Detector Nail Finder
Metal Detector kit - Nail Finder Kit

1 - 18R    resistor            all 0.25 watt
2 - 330R    
2 - 1k
1 - 1k8
2 - 10k
1 - 56k
1 - 220k
1 - 270k
1 - 500R mini pot
2 - 10n ceramics
1 - 47n ceramic or poly
1 - 100n ceramic
1 - 100u electrolytic
1 - Nail-Finder head complete

1 - 1N 4148 signal diode
1 - 5v6 zener diode
1 - 3mm red LED
3 - BC 547 transistors
1 - BC 557 transistor
1 - BC 338 transistor
1 - 8R mini speaker
1 - 9v battery snap
1 - 9v battery (not in kit)
1 - 40cm very fine solder

1 - Metal Detector MkII PCB