Metal detectors put an electromagnetic field into the earth. If that field passes over a metal object, eddy currents are set up in it, which disturbs the field, loads the coil, changes the V-I phase, etc. The circuitry detects these changes and processes them. Different metals, different shapes, etc., produce different responses. The circuitry and firmware produce different audio and/or graphic displays depending on the response. Iron is typically pretty easy to separate from other metals, but my detector (a Minelab Explorer SE) can also tell the difference between a zinc penny, a nickel, a bronze penny (dimes sound the same, unfortunately), a nickel, a quarter, and a half dollar. Deeper coins have much "noisier" responses, and this is where experience comes in. I can detect a dime or a penny to about 8" deep. Most good detectors have similar capabilities.I have heard that type of site is better than the beach. Knowing history of
places where people could have lost thing to fire and kinds of reasons. How do the
new detectors tell coins are underground from metal,I am surprised to hear ,
I was going to say 7 foot but I corrected my self,how far under ground are
the detectors dependable.