Indian Institute of Technology Hyderabad HOMEMADE METAL DETECTOR BY V.KARTHIK CH12B1025 P.JANAKIRAM ES12B1014 D.NANI CH12B1008

INTRODUCTION  A Metal Detector is a device which is used to detect a metal object that is not visible to our naked eye.  It consists of an oscillator which produces an alternating current that passes through coil producing alternating magnetic field  The first industrial metal detectors were developed in 1960s widely used for mining and other industrial purposes.

APPILICATIONS The most common applications for metal detector include the following :  Helpful for soldiers to detect land mines.  Security in the places like airports, metro railways e.t.c.  Archaeology department like treasure hunting.  To detect foreign bodies in food items.  Construction industry.

COMPONENTS CD DVD TAPE CALCULATOR 9V BATTERY THE SIMPLE COMPONENTS PRESENT IN OUR HOMES USED TO MAKE THE METAL DETECTOR

COMPONENTS OF TYPICAL METAL DETECTOR  Stabilizer (optional) - used to keep the unit steady as you sweep it back and forth  Control box - contains the circuitry, controls, speaker, batteries and the microprocessor speakerbatteriesmicroprocessor  Shaft - connects the control box and the coil; often adjustable so you can set it at a comfortable level for your height  Search coil - the part that actually senses the metal; also known as the "search head," "loop" or "antenna"

OPERATING PRINCIPLE  The basic principle of operation is based on ELECTROMAGNETIC INDUCTION which is a 3 coil design.  In this design there is an AM (amplitude modulated) transmitting coil and two receiving coils one on either side of the transmitter. amplitude modulatedtransmitter  When a metal contaminant is introduced into the product an unequal disturbance is created. Then it creates a very small electronic signal that is amplified through special electronics.  The design and physical configuration of the receiving coils are instrumental in the ability to detect very small metal contaminates of 1mm or smaller.  The amplification produced then signals a mechanical device mounted on the metal detector.

MODERN DEVELOPMENTS In the 1920s Gerhard Fisher had developed a system of radio direction finding, which was to be used for accurate navigation.Gerhard Fisher Fisher in 1925s put forward his model by a radio beam could be distorted by metal, then it should be possible to design a machine which would detect metal using a search coil resonating at a radio frequency. Charles Garrett in 1950s pioneered the BFO (Beat Frequency Oscillator) machine technology in todays world.Charles Garrett Modern top models are fully computerized, using integrated circuit technology which allows the user to set sensitivity, track speed, threshold volume, notch filters, etc., and hold these parameters in memory for future use.

REFERENCES detector1.htm detector1.htm html html