SunRobotics Metal Detector Sensor with Speaker TTL Output for Arduino Electronic Components Electronic Hobby Kit

Working: The 555 IC timer here acts as a square wave generator to generate pulses. In the circuit, there is an RLC circuit formed by a resistor, capacitor, and inductor. This RLC circuit is the metal detection part. A potentiometer is used to change the range of detection and it can detect up to 3cm. When electricity flows through the coil, a magnetic field is created all around it. When we move the detector over a metal object, the moving magnetic field creates electricity in the metal which in turn creates a magnetic field around the metal. It's this second magnetic field, around the metal, that the detector picks up. The metal detector has a second coil of wire in its head (known as the receiver coil) that are connected to a circuit containing a speaker. As we move the detector about over the piece of metal, the magnetic field produced by the metal cuts through the coil. Now if we move a piece of metal through a magnetic field, you make electricity flow through it. So, as we move the detector over the metal, electricity flows through the receiver coil, making the speaker beep. When we power it up, the LED turns green in color and when it detects any metal the second LED gets turned on which is red in color and if it doesn’t detect any metal then it is off.