Metal Detector Circuit Diagram and Working

In our daily life, we have got used to witness many detectors that detect metallic devices like guns, bombs, etc. To prevent any unlawful entry of guns and bombs in public places, a security system is developed by designing various electronics projects by using a proximity sensor. So, a metal detector is used to sense any existing metal which is nearby. A Metal detector is an electronic device which is used in many places like theatres, shopping malls, hotels, etc., to detect any metallic objects like knives, guns or any other explosives kept hidden within the baggage of person carrying them with bad intentions; such metal detectors are especially useful to detect the presence of hidden items within objects.

Metal Detector

The first industrial metal detector was developed in the year 1960 and was used for mineral prospecting and other industrial applications. A metal detector is an electronic device that includes an oscillator which produces AC that passes through a coil producing an alternating magnetic field. If a part of the metal is near to the coil, eddy current will be induced in the metal and this produces a magnetic field of its own. If another coil is used to measure the magnetic field, the change in the magnetic field, the change in the magnetic field due to the metallic object can be detected.

The metal detectors are used to detect the weapons like guns, knives in the airports, and also used in the construction industry to detect steel reinforcing bars in wires, concrete, pipes buried in floors and walls.

Simple Metal Detector Circuit

The main components of a simple metal detector circuit are LC circuit, proximity sensor, and the buzzer. The LC circuit is nothing but an inductor and capacitor, which are connected in parallel. This circuit activates the proximity sensor when it senses any metal close to it. This sensor glows the LED and makes a buzzer.

When the LC circuit has any resonating frequency from any metal which is close to it, the electric field will be created, which will lead to induce a current in the coil and change the signal in the flow of the signal through the coil.

A Variable resistor is used to change the value of the sensor, which is equal to the LC circuit. When the metal is detected, the circuit will have a changed signal. This changed signal will be given to the proximity detector, which will detect the change in the signal and react accordingly. When the metal is detected by the coil, the o/p of the sensor will be of 1mA. When the coil is near to the metal, then the o/p of the sensor will be around 10mA.

When the o/p pin is high, the R3 resistor will provide a positive voltage to transistor the Q1 to turn ON the LED, which will glow and generate a buzzing sound. Here, the R2 resistor is used to limit the current flow.

A Metal Detector Circuit using IC 555

A simple metal detector circuit diagram project is designed using IC 555, as you can see in the 555 timer circuits, these circuits detect the metals and magnets. When a magnet is near to the 10mH choke, the o/p frequency changes. This circuit can be powered from a power supply, which can provide an o/p DC voltage between 6V to 12V. If metal is near to the coil L1, it produces a change of o/p oscillation frequency, and then generate a buzzing sound.

Metal Detector Robotic Vehicle Operated by Android Application

The main intention of this project is to design a robotic vehicle that can detect metals ahead of it on its path. This robotic vehicle is controlled by an android application

This project includes a metal detector circuit that is interfaced with the control unit, which generates an alarm to the user when a metal is near to it. An 8051 microcontroller is used for the desired operation. At the transmitter side, an Android application is used to send commands to the receiver. The robot moves forward, backward, right, or left. At the receiving end, two motors are interfaced to the 8051 microcontrollers for the movement of the vehicle.

The android application acts as a remote while the receiver end Bluetooth device is fed to the microcontroller to drive DC motors through a motor driver IC for the desired operation. A metal detector circuit is placed in the robot, and the operations of the robot are carried out automatically if it detects any metal underneath. As soon as the robot detects a metal, it generates an alarm sound. Furthermore, this project can be developed by fixing a wireless camera to the robot So that the operator can control the robotic movement remotely by watching it on a screen

Metal Detector Robotic Vehicle using RF Technology

The main aim of this project is to design a robotic vehicle that can sense metals ahead of it on its path and this robot is controlled by a remote using RF technology.

A metal detector circuit is placed in the robot’s body. The operations of the robot are carried out if it senses any metal underneath. As soon as the robot senses this metal, it generates an alarm sound. This is to alert the operator of a possible metal ahead on its path.

Further, this project can be developed by mounting a wireless camera on the robot so that the operator can control the movement of the robot remotely by watching it on a screen.

Hope this article gives you provided you with brief information about the metal detector circuits and its principle of operation. Are you aware of any other practical applications of metal detectors or heat detectors? you can share your technical knowledge by posting your comments in the comments section below..

 Photo Credits:

• Metal Detector Circuit by blogspot
• Metal Detector Circuit using IC 555 by talkingelectronics