Metal detectors are those equipments that are designed specifically to detect hidden metals. It can be used to detect metals that lie deep in the ground or water or otherwise in security matters to detect metals hidden by someone. At first metal detectors were used only for security purposes and to locate mines. Now there are several industry businesses that use metal detectors for their use, such as food processing, chemicals, packaging, textiles, pharmaceuticals and plastic industries. To avoid food poisoning it becomes important to check the foods for metal debris via metal detectors. In food processing industry the metal debris is broken down to pieces on the machinery. Besides these uses, many people use metal detectors for searching treasures and old coins hidden deep underground or water.