CS102
19/04/2010
© 2008
Velleman Components nv
7
10.
Useful tips
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No detector is 100 percent accurate. Various conditions influence metal detection. The detector's
reaction depends on a number of things:
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the angle at which the object rests in the ground.
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the depth of the object.
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the amount of iron in the object.
•
the size of the object
Search coil sweeping hints
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Never sweep the search coil as if it were a pendulum. Raising the search coil while sweeping or
at the end of a sweep will cause false readings.
•
Sweep slowly. Hurrying will cause you to miss targets.
•
It is better to sweep the search coil from side to side in a straight line and keep the search coil
parallel with the ground.
•
The detector responds with a signal when it detects most valuable metal objects. If a signal does
not repeat after you’ve swept the search coil over the target a few times, the target is probably
junk metal.
•
False signals can be caused by trashy ground, electrical interference, or large irregular pieces of
junk metal.
•
False signals are usually broken or non-repeatable.
Pinpointing a target
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Accurately pinpointing a target makes digging it up easier. Accurate pinpointing takes practice,
and we suggest you practice finding and digging up small metal objects on your own property
before you search other locations.
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Sometimes, targets are difficult to accurately locate due to the sweep direction. Try changing
your sweep direction to pinpoint a target.
•
Follow these steps to pinpoint a target.
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When the detector detects a buried target, continue sweeping
the search coil over the target in a narrowing side-to-side
motion.
•
Make a visual note of the exact spot on the ground where the
detector beeps.
•
Stop the search coil directly over this spot on the ground.
Then move the search coil straight forward away from you
and straight back toward you a couple of times.
•
Make a visual note of the exact spot on the ground where the
detector beeps.
•
Repeat Steps 1-3 at a right-angle to the original search line,
making an "X" pattern. The target will be directly below the
"X" at the point of the loudest response.
Notes:
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If trash in an area is so heavy that you get false signals, slow your sweep and use shorter
sweeps.
•
Recently buried coins might not respond the same as coins buried for a long period of time
because of oxidation.
•
Some nails, nuts, bolts, and other iron objects (such as old bottle caps) oxidise and create a
"halo" effect. A halo effect is caused by a mixture of natural elements in the ground and the
oxidation created by different metals. Because of the metal mixtures, target signals might not be
in a "fixed" position. This effect makes these objects very hard to detect accurately.
Detection range
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The detection range will vary depending on the size of the object, the length of time an object
has been buried and the type of ground the object is buried in. The best soil is compact soil,
where you can locate coins at great depth, especially if they have interacted with the salts in the
ground, which makes them appear larger to the detector. The worst conditions for detecting are
in loose soil or freshly dug ground or when the object has only recently been buried. Ninety
percent of all objects are found within 6" of the surface. Adverse soil conditions can reduce the
detection range by as much as 50%.
Determining the target size and depth
•
An operator who is familiar with his instrument will be able to do an excellent job of determining
object size, shape and depth before he digs. He does this through careful analysis of the audio
