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In normal operation, when the searchcoil passes over a metal object, the electrical signature
(2-digit I.D.) of the metal object is displayed on the numeric display for 4 seconds, unless
superceded by another object sooner. On a given buried object, the number will bounce
around if the signal is weak or if the amount of ground mineralization is high.
At the top of the display, an arrow indicates the classification of the object.
NUMERIC TARGET I.D. (2-digits)
The following table shows the numbers typically associated with certain commonly
encountered nonferrous metal objects. Older silver U.S. coins usually read about the same
as their modern clad equivalents. Modern quarter-sized dollar coins like the Susan B.
Anthony and the Sacagawea read about the same as a quarter. Many Canadian coins are
minted from a magnetic nickel alloy which gives very inconsistent readings and may
register as iron. Most one-ounce silver bullion coins will fall into the same range as the
modern U.S. $1 Eagle.
OBJECT
foil from gum wrapper
U.S. nickel (5¢ coin)
aluminum pull-tab
aluminum screwcap
zinc penny (dated after 1982)
aluminum soda pop can
copper penny, clad dime
U.S. quarter (25¢ coin), clad
50¢ coin, modern clad
old silver dollar coin
US silver Eagle $1 coin
PROBABLE TARGET I.D.
The probable target ID zones at the top of the LCD display represent the signal ranges
produced by various coins and types of metal objects. When a metal target is detected, the
microcomputer analyzes the signal and categorizes it based on what kinds of metal objects
usually produce that kind of signal. The microprocessor then displays an arrow along the
top of the LCD screen above the icon which represents that category.
For instance, if the detected signal fits within the parameters usually exhibited by zinc
pennies and the electrically similar aluminum screwcaps, the microcomputer will
categorize the signal as "zinc penny/aluminum screwcap". The LCD screen will then
illuminate the arrow above the zinc/screwcap icon.
Copper pennies (pre-1982) will usually register in the 10¢ zone.
Most gold jewelry is small, and will tend to read in the 40-60 range. Silver jewelry usually
has more metal in it and therefore tends to produce higher readings.
LCD VISUAL DISPLAY
TARGET I.D.
40 - 55
typically 58
60 - 75
70 - 80
typically 78
75 - 85
typically 83
typically 89
typically 92
typically 94
typically 95
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