From the Blog
Metal Detector Operation
What a hobby! Metal detecting is one of the fastest growing hobbies in the world. Why? It is the only hobby you get paid to do, if you learn the proper operation of your metal detector, where to hunt for "treasure" and avoid common mistakes. You can make money, build some great coin collections, get healthy exercise, relax and experience some wonderful excitement too.
For metal detecting to be rewarding it is essential that you have a basic understanding of how a metal detector operates. All metal detectors have an invisible field around the coil or loop as it is sometimes called. When this field comes in contact with metal either underneath it in the ground (or in the water) or sometimes above it in the air, the detector gives a signal. This is a simple description of how hand held metal detector works.
There are three general types of metal detectors in use in the hobby. The oldest type is the BFO (Beat Frequency Oscilator). Ther are simple to use but limited in their depth capabilities. The most common type is the VLF (Very Low Frequency) and they have many great features with the cost increasing in a direct relation to the bells and whistles that are added. These capabilities or features include: discrimination, Notch Discrimination, Target Identification, Target Tone ID, Target Signature, Multiple Signature, Multiple Frequency, Silent Search, Ground Balance, Depth Reading and several others including some computer visualization features.
The third type is the PI (Pulse Induction). This type is generally not good at discriminating targets but work best in highly mineralized soil like gold fields and are excellent in salt water beach detecting. The PI and VLF (operating in all metal frequency) have far superior depth to the older BFO units. Depth is important but not the most important element to metal detecting success. I have dug more than 150,000 coins (and thousands of other treasures) and 80 percent of them have been less than 5-7 inches deep and even the older BFO units can go these depths in lightly mineralized soil. The single most important element to metal detection success is knowledge. Let us examine the basic features of metal detectors that will increase the success potential.
All metal detectors have a loop or coil. Each coil type has its own special characteristics. The two most common types are the concentric and the double "D". Both of these are wide scan coils. This means that nearly the whole loop area will receive signals from metal objects that are not buried deep. This is easily seen by putting a penny or dime on top of the ground that is clear of other metal and move the coil back and forth over it at just and inch or two above the ground. Neraly every area of the coil will elicit a signal from the coin. Now raise the coil to about four or five inches above the coin and do the same movements again. This time not all areas of the coil will obtain a signal. The higher you raise the coil above the coin the smaller the area of the coil receives a signal. The field that is emitted from these standards coils is in essence cone shaped. The deeper a coin or other metal object is buried the greater the need to overlap the coil sweep.
Most metal detectors come with a standard coil size of 8-10 inches. For most coin and jewelry hunting this is best. If an area has a lot of trash or junk metals a smaller 4-6 inch loop could increase the number of good finds. The larger the loop the greater the depth capabilities but 12-16 coils will also be less sensitive to smaller size targets and are harder to pinpoint. The smaller coils will not go as deep but can find the smaller nugget size items and are much easier to pinpoint targets. Two other shaped coils are also becoming popular. The elliptical coils have similar depth levels of the round ones but give greater search area. The "Big Foot" coil is becoming very popular with competition hunters is also called the "figure eight" loop. This coil is very efficient for fast searching at deeper levels. The search area of this narrow 18 inch rectangular coil is nearly the entire coil with very little cone effect. White's Metal Detector Company has popularized this coil and made it very easy to pinpoint targets.
It is very important that you understand your detector's coil features. The easiest way to do this is to do an air test with a coin. Keeping the coil in a horizontal position, turn the detector on and adjust it for coin hunting. Take a penny or dime and move it back and forth in all directions and various depth levels determining the cone effect, the coil effects at shallow distances, sensitivity around the coil edges and how to adjust your detector for its best depth. Turning the coin on its edge and doing the same movements will also help with understanding the signals from coins turned on edge in the ground.
As I mentioned earlier, the single most important key to success with a metal detector is knowledge. The first source of information is your owner's manual. Read your operator's manual through several times. After reading it go practice using your detector. Repeat this process until you understand all of the characteristics of your machine.
Another great help with your metal detector is field tests found in treasure magazines or online. Experienced users making a field test on the same model detector that you own can add to your knowledge. Metal detector forums online also provide informative comments on detector use. There are also some great metal detector dealerships that offer assistance with training on detectors that they sell.
Utilize the operational techniques discussed above and practice, practice, practice! Knowledge plus skill deliver results. There is treasure everywhere to be found and it can be yours.