1. The Transmitter Coil: The metal detector has a coil of wire, called the transmitter coil, that generates an alternating magnetic field. This field expands and collapses rapidly.
2. The Target: When a metallic object enters the field, it disrupts the field lines and induces eddy currents in the object.
3. The Receiver Coil: Another coil of wire, called the receiver coil, is located near the transmitter coil. The changes in the magnetic field caused by the eddy currents in the target object are picked up by the receiver coil.
4. Signal Processing: The receiver coil's output is amplified and processed. The strength of the signal indicates the size and conductivity of the target object.
Types of Metal Detectors:
* Pulse Induction (PI) Metal Detectors: These detectors use a single coil that acts as both transmitter and receiver. They send a pulse of energy and then listen for the reflected signal. They are better at detecting large, deep objects.
* Very Low Frequency (VLF) Metal Detectors: These detectors use separate transmitter and receiver coils. They operate at a specific frequency, allowing for better discrimination between different types of metals.
In summary, metal detectors utilize inductive sensors to detect changes in the magnetic field caused by the presence of metallic objects.
