Metal Detecting - Understanding the Technology Is Important
Metal Detectors use one of three types of technology:
BFO (Beat Frequency Oscillation) - Metal Detectors using BFO
technology have two coils of wire, one large coil is located in
the search coil of the detector, the other small coil of wire is
located within the System Control Pack. Each coil of wire is
connected to an oscillator that produces pulses of current.
These pulses of current pass through the coils generating radio
waves. A receiver housed within the System Control Pack receives
the radio waves and makes a series of tones based upon the
frequencies of the radio waves. When the detector search coil
passes over a coin or other metal item a magnetic field is
created around the coin or metal item, this magnetic field
causes interference with the frequency of the radio waves
generated by the search coil. And changes the tone produced by
the reciever. Metal Detectors using BFO technology are the ones
your likely to get when paying under $100 for, that's right, the
cheapies. The BFO technology is the easiest and cheapest to
make, thus the prices of the detectors are cheap. The only
problem is, BFO technology is very limited when compared to PI
and BFO detectors, and the ability to distinguish between junk
metals and silver or other coins is very poor.
PI (Pulse Induction) - Metal Detectors using PI technology
sometimes use a single coil or a series of coils working
together as a transmitter and receiver. Short bursts of
electrical current are send through a coil of wire, causing a
magnetic field. When the burst of electrical current ends the
magnetic field reverses polarity. A sharp electrical spike is
created, then more pulses are created, the whole process repeats
and works like a series of echoes, giving a different report or
echo depending upon the metal it encounters. This type of metal
detector is not very good for discrimination between different
types of metals or coins, but it is good to use where some other
types of metal detectors have trouble working, such as in
salt-water, and metals can be detected much deeper with this
technology than the others.
VLF (Very Low Frequency) - Metal Detectors using this technology
have two search coils. One coil called the 'transmitter coil'
transmits electricity rapidly many times per second, first in
one direction around the coil, then in the other direction. The
other coil called the 'Receiver Coil' acts just like the name
implies it receives frequencies or data that come or 'bounce'
back from the objects the transmitter coil detects in the search
area. This type of Metal Detector is great for it's ability for
being able to distinguish between different types of metals.
The first metal detector my wife and I bought together cost
about $69.00 it was one of them cheap ones that used the 'BFO'
technology. This was one of them metal detectors you see in the
magazines that sell other household items, etc. You can buy
cheap metal detectors like these at most Radio Shack stores, and
some K Marts and Wal Marts. The first day we took the metal
detector outside we started finding some neet things and my wife
and I were hooked. We did find our share of junk items in the
yard, like aluminum foil, nails and the usual pull tabs and junk
metal. But we also found 7 old diecast cars in great condition.
They were all different and were 'TOOTSIE' diecast vehicles. I
looked on eBay and the bunch was worth around $15 or more. We
also found a 1961 silver Roosevelt dime in fine condition, in
our yard, plus the usual pennies.
After reading about how the 3 different types of Metal Detector
technologies work and differ from each other, you must decide
how or what you will be mostly using your metal detector for.
Will you be hunting for small objects like coins, jewelry and
gold nuggets, or searching for a large cache or object. The
things you may want to use your detector for, play one of the
most important factors besides pricing in deciding what type of
detector to buy. Most folks want a detector that is great at
finding coins, gold nuggets, and jewelry on the land and in
small creeks and streams, this would be a detector using 'VLF'
technology. Almost all of the modern detectors have a waterproof
search coil which make searching in shallow creeks and streams
possible.
There is Computer Software that is made just for the hobby of
Metal Detecting. The software is called: Metal Detector -
Treasure Hunter Professional, and may be seen at this website
address: http://www.rb59.com/md/meal.html
By Robert W. Benjamin
Copyright 2005
You may publish this article in your ezine, newsletter on your
web site as long as it is reprinted in its entirety and without
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About the author:
Robert W. Benjamin has been in the software business on the
internet for over 5 years, and has been producing low-cost
software for the past 25+ years. He first released products on
the AMIGA and C64 computer systems in the late 1970's-80's.
RB59.COM Software http://www.rb59.com/software