Metal Detecting - Understanding The Technology Is Important
By Robert W. Benjamin, Fri Dec 9th

Metal Detecting for fun or profit can be one of the mostexciting and rewarding of hobbies. A metal detector can costvery little, as low as $50 or higher that $400 for a top of theline model. This is one hobby where you really do get what youpay for, because the more expensive top of the line detectorsuse the most advanced technology and they have the best featuresavailable.

Metal Detectors use one of three types of technology:

BFO (Beat Frequency Oscillation) - Metal Detectors using BFOtechnology have two coils of wire, one large coil is located inthe search coil of the detector, the other small coil of wire islocated within the System Control Pack. Each coil of wire isconnected to an oscillator that produces pulses of current.These pulses of current pass through the coils generating radiowaves. A receiver housed within the System Control Pack receivesthe radio waves and makes a series of tones based upon thefrequencies of the radio waves. When the detector search coilpasses over a coin or other metal item a magnetic field iscreated around the coin or metal item, this magnetic fieldcauses interference with the frequency of the radio wavesgenerated by the search coil. And changes the tone produced bythe reciever. Metal Detectors using BFO technology are the onesyour likely to get when paying under $100 for, that's right, thecheapies. The BFO technology is the easiest and cheapest tomake, thus the prices of the detectors are cheap. The onlyproblem is, BFO technology is very limited when compared to PIand BFO detectors, and the ability to distinguish between junkmetals and silver or other coins is very poor.

PI (Pulse Induction) - Metal Detectors using PI technologysometimes use a single coil or a series of coils workingtogether as a transmitter and receiver. Short bursts ofelectrical current are send through a coil of wire, causing amagnetic field. When the burst of electrical current ends themagnetic field reverses polarity. A sharp electrical spike iscreated, then more pulses are created, the whole process repeatsand works like a series of echoes, giving a different report orecho depending upon the metal it encounters. This type of metaldetector is not very good for discrimination between differenttypes of metals or coins, but it is good to use where some othertypes of metal detectors have trouble working, such as insalt-water, and metals can be detected much deeper with thistechnology than the others.

VLF (Very Low Frequency) - Metal Detectors using this technologyhave two search coils. One coil called the 'transmitter coil'transmits electricity rapidly many times per second, first inone direction around the coil, then in the other direction. Theother coil called the 'Receiver Coil' acts just like the nameimplies it receives frequencies or data that come or 'bounce'back from the objects the transmitter coil detects in the searcharea. This type of Metal Detector is great for it's ability forbeing able to distinguish between different types of metals.

The first metal detector my wife and I bought together costabout $69.00 it was one of them cheap ones that used the 'BFO'technology. This was one of them metal detectors you see in themagazines that sell other household

items, etc. You can buycheap metal detectors like these at most Radio Shack stores, andsome K Marts and Wal Marts. The first day we took the metaldetector outside we started finding some neet things and my wifeand I were hooked. We did find our share of junk items in theyard, like aluminum foil, nails and the usual pull tabs and junkmetal. But we also found 7 old diecast cars in great condition.They were all different and were 'TOOTSIE' diecast vehicles. Ilooked on eBay and the bunch was worth around $15 or more. Wealso found a 1961 silver Roosevelt dime in fine condition, inour yard, plus the usual pennies.

After reading about how the 3 different types of Metal Detectortechnologies work and differ from each other, you must decidehow or what you will be mostly using your metal detector for.Will you be hunting for small objects like coins, jewelry andgold nuggets, or searching for a large cache or object. Thethings you may want to use your detector for, play one of themost important factors besides pricing in deciding what type ofdetector to buy. Most folks want a detector that is great atfinding coins, gold nuggets, and jewelry on the land and insmall creeks and streams, this would be a detector using 'VLF'technology. Almost all of the modern detectors have a waterproofsearch coil which make searching in shallow creeks and streamspossible.

There is Computer Software that is made just for the hobby ofMetal Detecting. The software is called: Metal Detector -Treasure Hunter Professional, and may be seen at this websiteaddress: http://www.rb59.com/md/meal.html

By Robert W. Benjamin

Copyright © 2005

You may publish this article in your ezine, newsletter on yourweb site as long as it is reprinted in its entirety and withoutmodification except for formatting needs or grammar corrections.

About the author:Robert W. Benjamin has been in the software business on theinternet for over 5 years, and has been producing low-costsoftware for the past 25+ years. He first released products onthe AMIGA and C64 computer systems in the late 1970's-80's.

RB59.COM Software http://www.rb59.com/software