Metal Detector for Identifying Metal Pipes, Nails, Cables

This metal detector circuit can be used for tracing out or locating concealed wires, nails, tubes or other similar metallic materials under a layer such as under walls, grounds, basements, wood furniture etc.


This gadget functions to identify metals of a specific dimensions from a distance of about 18-20 cm if correctly optimized.

Metal Detector for Identifying Metal Pipes, Nails, Cables

One amongst its primary uses is to sense the existence of metallic tubes (water tube, gas tube, electric cable, etc.). Identifying these is very beneficial when drilling or fitting nails on walls.

At any time a identification is conducted, the machine has to be calibrated as depicted below:
1) Keep the sample metal part of near the coil at some reasonable distance

2) Adjust potentiometer P entirely to the right, such that the RED LED just lights up
3) Turn the potentiometer to the left until the RED LED just turns off and the GREEN LED illuminates.

The detector is then ready for use. Keep in mind that calibration has to be repeated every once in awhile.
At any time the detector picks up the existence of metals, the RED LED illuminates and the GREEN switches off.

The coils L1 and L2, wrapped on the ferrite bar, must be completed meticulously, following cautiously the instructions of the diagram.

metal detector coil construction

Two simple 9-volt batteries are as much as necessary to power the equipment. To cover the gadget, it is suggested Never to utilize metallic housings.

PCB Design for the metal detector

pcb layout for the metal detector circuit track side


Parts List for the above metal detector circuit for locating underwall metals

All resistors are
Of 1/4 watt except if mentioned otherwise mentioned
R1 = 1 M
R2 = 47K
R3 = 1 K
R4 = 330
R5 = 330
PI = 10K
CI = 1 nF disc
C2 = 0.1 uF disc
C3 = 0.1 uF disc
C4 = 0.1 uF disc
C5 – 47 nF disc
C6 = 0.22uF.
D1 = M117
D2 = AA117
DL1 = Red Led
DL2 = Green LED
IC1 = UA741
T1 = BC237
Wire diameter 0.3 mm
l Ferritede = 8X10
1 IC socket 8 pins
Holder for 9 volt battery