General metal detector and detecting questions that come to mind

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

General Detecting Questions about metal detectors and your metal detector

Why are there so many types of searchcoils?

There are two main types of searchcoils currently on the market—the concentric and the widescan. The concentric coil uses two round antennas, one inside the other. This coil is used on most detectors that are designed for coin, jewelry, and relic hunting. Concentric coils discriminate very well and pinpoint very easily due to the fact that the strongest signal is always in the center of the coil. Widescan coils use two D-shaped antennas that are placed back to back. Because of this configuration, they are also called “double-d” coils. The widescan coil is less affected by mineralization than the concentric, so it is generally used for gold prospecting or relic hunting in bad ground. Pinpointing is done with the heel or toe of the coil. After determining the type of coil that is best for your type of hunting, the next thing to consider is the size.

There are many different sizes of coils available and each one may fine tune your hunting but only if you get the correct size. Larger coils go deeper than smaller coils but only on larger targets. When using a large coil, you may lose sensitivity to small targets. A large coil is also more susceptible to masking. Masking happens in the Discriminate mode when a good target and junk target are both under the coil at the same time. If the targets are close enough together, the bad target will be discriminated out, and at the same time, the detector will not be able to pick up the good target. Masking is very common in junky playgrounds and in-and-around old house sites.

Smaller coils will concentrate the signal and make the detector more sensitive to the little targets. Unfortunately, smaller coils tend to lose depth when compared to their larger cousins. Being that these coils don’t have as wide a search pattern, they are also less likely to mask targets in trashy hunting situations.

Knowing where you are going to hunt and what you are hunting for will go a long way in helping you choose the right coil for your needs. A larger coil is needed when hunting in a clean area or when hunting for relics that may tend to be deeper. A small coil will help find the smaller targets such as gold nuggets or fine jewelry or can be used when coin & jewelry hunting extremely trashy sites.

Can one detector really do it all? Most metal detectors are designed to excel at one type of hunting or another but can be used for other types of hunting as well. For example, most gold prospecting metal detector machines use some form of higher gain in the circuitry to get better sensitivity to small gold nuggets in the ground. While this is a good thing for prospectors, coin hunters may find it annoying that their detectors are picking up every bit of a pulltab that has been run over with a lawnmower.

The art of metal detector design is the art of compromise. By accenting certain characteristics of any detector, you take away from other features. Any detector that does it all may not work as well for certain very specific treasure hunting. Talk to as many people as is possible and be realistic about your hunting needs. Finding a detector with the features that will best suit your hunting style is the most important choice you can make when deciding on a new detector.

What is the best metal detector?

This is probably the #1 question that I get asked. Unfortunately, there is no one single answer. Each metal detectorist has specific needs that cannot be answered by one single detector. The easiest way to find the “best” detector is to evaluate your detecting style, your experience level, and the time that you will spend hunting. After taking all of these things into consideration, then you will be able to find a detector that fits your needs and your budget.

Are detectors with a lot of knobs better than those with just a few?

How much better is a $1000 detector than a $200 detector and in what ways?

The answers to these questions are connected, so I will try to answer them together. Generally speaking, the higher the price of a detector, the more features that it will have. More features translate into more knobs. The more features and/or knobs that a detector has, the more you are able to tune the detector to the type of hunting conditions that you are likely to encounter.

With that being said, the downside to a large number of features is that even though you are able to fine tune the detector to match the local conditions, there are also more ways of setting up the detector incorrectly. Setting up a machine “wrong” may result in a decrease in depth and sensitivity and your $1000 machine may be outdone by a $200 one.

Will metered detectors find coins deeper than non-metered?

The use of a meter on a detector is no longer any indication of its depth capabilities. When metered machines were the top-of-the-line machines, engineers matched the detectors with the best possible circuitry. With the advent of more cost effective digital signal processing and LCD displays, there are a number of units available that are inexpensive and have meters. While these detectors have acceptable depth, there are plenty of other machines that have better.

The main thing to remember is that a metered machine will give an accurate audio signal on a target much deeper than an accurate meter reading. Air tests are a good indication of the ability of any display-type detector, but once the target is in the ground, there are several variables that may come into play affecting the reading. The most common is the fact that pulltabs and gold rings fall into the same area based on the mixing of alloys. The orientation in the ground can also cause some confusion for the detector. If you choose to get a metered machine, dig any target that gives a good audio signal regardless of the meter reading. You may dig up more trash, but in the long run, you will find more desirable targets.

Is a crystal-controlled detector better than one that is not crystal-controlled?

Most manufacturers use crystal resonators in their machines because of the tight tolerances of the resonator. If the part is listed as 15.7 kHz, all parts will be exactly that frequency. The downside of these super tight tolerances is that the detectors are more likely to crosstalk with each other. In other words, the transmit and receive signals from two or more different machines will start interfering with each other.

Tesoro detectors use an LC or tank circuit to generate operating frequency. A capacitor and an inductor are paired together and create a naturally occurring efficient frequency. Variation in the capacitor and inductor cause slight variations in the operating frequency, which reduces the likelihood of crosstalk with other Tesoro machines. The variation is small enough that it does not affect the performance of the detector.

Are multi-frequency detectors better than single frequency types?

The tank circuit described above generates a sinusoidal or SINE wave form. The SINE wave is efficient to generate and has no harmonics.

Two frequency machines may combine a pair of SINE waves but are more likely to use a square wave. Multi-frequency machines almost always use a square wave or modified square wave. Square waves are rich in harmonics and take more battery power to generate. Harmonics generated by a square wave can be counted as individual frequencies and can be used to give more information as to target type and depth.

 

COILS

What is the difference between a wading coil and a regular coil?

When hunting in water, most coils tend to float. As customers want lighter and lighter coils, most manufacturers will fill coils with some type of foam or other lightweight hollow material. This naturally creates air pockets inside the coils and tends to make them float.

A wading coil is filled with one or more materials that have neutral buoyancy when placed in water. This keeps the coils from either floating or sinking and makes water hunting easier for the detectorist.

Are aftermarket “Hot” coils that are advertised any good and why don’t the manufacturers make them?

If you look closely at the advertisements of most so-called hot coils, you will find that they are slightly larger than the stock coils that they are replacing. As noted above, a larger coil may go deeper, but it has other drawbacks that may make it unsuitable for your particular style of hunting. Most manufacturers already make coils that are larger than the stock coils. These coils are specifically designed by the company engineer to match the circuitry of the particular unit that you are using. Why would you want to buy a coil that is not designed or built by the manufacturer?

 

OPERATION

How deep do detectors go?

The answer to this question comes in two parts. The first part has to do with the detector circuitry and coil design. Environmental factors make up the second part of the answer.

Coil and circuitry design determine the overall ability of a detector to find targets. During the design phase of any detector, the engineers decide which features to include. The things that they consider are the type of hunting and who will be using it. A beginner’s model may not have the bells and whistles of the more professional models, but it will be easier to use. The more specific a detector’s design, the narrower set of features it will have. Some detectors designed for the ultimate depth will be hard for a beginner to use or may be too sensitive to use in trashy areas. Coil size will affect the depth of the detector but may not be suited for a particular type of hunting.

Environmental factors include just about everything except the detector and coil. Just a few of the things to take into consideration are the following: size and shape of the target, soil conditions, orientation of the target in the ground, content of the target, and any outside interference, such as electrical wires and radio or cell phone traffic. Weather conditions, such as rain-soaked ground or even an incoming thunderstorm, may also play a part in the depth and sensitivity of any detector.

With all that being said, an average detector using a stock coil in moderate ground should see the following targets with these ranges:

Target size Depth
Dime to nickel: 4 to 8 inches
Quarter to half dollar: 6 to 12 inches
Dollar to fruit jar lid: 8 to 16 inches

Knowing your detector and using it properly are the two most important things that you can do to get the best depth and sensitivity out of any machine.

How do you set up and use a metal detector?

Whenever you are using a detector, comfort should be your primary goal. A detector that is easy and comfortable to use allows you to be in the field longer and to find more targets.

The shaft of the detector should be adjusted so that the searchcoil is just off the ground when your arm is in a natural and relaxed position. Your hand should be lightly on the grip and your elbow straight but not locked. This initial setup allows you to swing the detector with an easy shoulder movement. The coil should move in an approximate three foot arc in front of you. This is called the sweep. While sweeping your coil, try to avoid swinging from the elbow.

How do I know where to dig?

Once your detector beeps, you have to pinpoint your target. Pinpointing your target is a skill that is very important to practice and learn. The faster that you can locate your target, the more time you can spend searching for treasure. The technique for pinpointing varies depending on the type of coil that you are using. But the basics are the same.

“Xing” the target with your coil is the most common type of pinpointing. To “X” a target, run your coil over the target and make a mental note of where the audio signal is the loudest. Start with your normal right to left sweep to find the loudest audio signal. You should shorten your normal sweep down to about two to four inches. Once you have a good idea of where the target is, run the coil 90 degrees over the target to tighten up the pinpointing. You can do this one of two ways. First, you can physically step to the left or right of the target so that the coil goes over the object using a normal sweep but turned 90 degrees. Second, instead of stepping to the side and sweeping the coil left to right, you can push and pull the coil forward and backward over the target. Try using both methods to find the one that works best for you.

Pinpointing with a concentric coil: Most coin and relic machines use a concentric coil. These types of coils pinpoint in the physical center of the coil housing. Most concentric coils will have a hole in the center of the coil so it is easier to make the mental note of the location of the target.

Pinpointing with a widescan or double-D coil: The widescan coil is slightly different from the concentric coil. By design, there is no center spot on the coil but a center strip of pinpointing area. The best pinpointing method is to use the very front of the coil or toe or the very rear portion or heel of the coil. Once you have gotten the signal, back the coil away from the target and use the toe of the coil to find the best signal. Pinpoint in the usual manner after that. To use the heel of the coil, push the coil past the target and use the end of the coil closest to you for the pinpointing.

Regardless of the type of coil or the pinpointing method that you feel most comfortable with, practice will make you a better pinpointer and save you time and effort in the field. How much discrimination should I use?

In the late sixties and early seventies, as metal detectors became more popular, most of them on the market were all metal machines and could not discriminate any junk targets. As detectors became more sophisticated, the ability for discrimination got better and better. Now coin hunters can knock out the junk targets and keep the good ones in, or so they thought.

Metal detectors judge targets based on their conductivity. Iron and silver targets are easy to separate because they are on opposite ends of the conductivity scales. However, the real struggle comes in the area of nickels, pulltabs, and gold rings. All of these targets are in the same area on the conductivity scale and can change due to the size, shape, and alloy of the target.

For most coin and relic hunting situations, I recommend a setting just high enough to knock out the iron and foil. This allows you to get all of the other valuable targets without fear of having them discriminated out.

What is Notch Filter Discriminate and how does it work?

Notch discriminate differs quite a bit from regular discrimination. When using standard discrimination, the higher the knob is turned up, the more items that are discriminated out. As discussed before, when pulltabs are totally discriminated out, so are gold jewelry, rings, and nickels. Notch filter discriminate is designed to knock out some pulltabs and to keep the good targets in. It is virtually impossible to knock out all pulltabs and keep all gold jewelry. The reason is due to the conductivity of the targets in this range.

A notch discriminate works by filtering or discriminating a band of target signals out without affecting targets higher or lower than the band. This can be done either with an analog or digital circuit.

When using a notch filter, check the setup by doing numerous air tests before taking it out to the field. It is to your advantage to make sure you are aware of how your detector reacts to both good and junk targets. If your Notch can be adjusted, tune it to knock out the most common types of pulltabs in your area while keeping in the targets you wish to find. The initial setup can be a bit time consuming, but once it is done, you will be able to find less junk targets and keep the good finds.

Can iron be rejected and gold nuggets still be found?

Generally speaking, the best way to hunt for gold nuggets is to hunt in the All Metal mode. Nuggets, depending on their size, shape, purity, and orientation in the ground, will all create different signals. If you hunt in the Discriminate mode, some nuggets may be lost. The best way to get rid of iron is to search in the All Metal mode and then check the targets in the Discriminate mode. This allows you to search and find all of the possible gold nuggets. Checking the targets with the Discriminate mode turned up just high enough to knock out the small iron will give you much more information before you decide to dig. Practice this by doing air tests to see the best setting for your particular detector.

My detector still finds large iron targets, even with the Discriminate set high. Is this normal?

Most detectors can be fooled by some iron targets. There are two different ways that the machine can be fooled.

Circular iron can fool a detector because of its shape. Any iron, such as a ring or washer or even bent nails, are hard for the machine to identify accurately. As the iron starts under the coil, it gives the same type of signal as a coin. When the target is directly under the coil, it reads as iron, then reads as a coin as the coil sweeps over it. In most cases, the detector may give a signal, but it will be a broken or chirpy signal. With a little practice, the broken signals will start to stand out from good repeatable signals.

Large rusty iron can also give off signals no matter where the discrimination is set. When iron or any ferrous target is in the ground long enough, it starts to rust and break down. This causes a large halo of super mineralized dirt around the target. The halo is different enough from the surrounding ground matrix that the detector picks up a signal. The strength of the signal is so large that it momentarily overdrives the detector and it beeps. Signals of this nature usually seem bigger than the size of the coil.

The best thing to do when getting either a broken signal or a very large signal is to dig the target. Most of the time, it will probably be junk, but every now and then, you will be happily surprised by a very unique target.

Why do some pennies read differently than others?

The big difference is in the makeup of the actual penny itself. Older pennies, ones made before 1982, including the wheatback-style, are almost pure copper and will read up in the range of dimes and some other silver coins. The newer pennies are made mostly of zinc and tend to read in the screwcap range.

What is the best frequency for my type of hunting?

Contrary to popular belief, there is no one best frequency for any specific metal or metals. Any VLF-style detector that is operating between 3 and 30 kHz will do a fine job for any type of hunting that is done. This frequency range gives good depth, target separation, and is not overly affected by ground mineralization.

The ability to pick up good targets and separate trash from goodies is more due to the design of the detector, type of coils used, and several other engineering points that are brought up during the R&D phase. Comparing feature points of the detector model to the type of hunting you are planning to use it for will help you more than just comparing frequencies.

What is “crosstalk” and how can I avoid it?

Crosstalk is the interference that is caused by two detectors operating on the same frequency being in close proximity to each other. Depending on the gain and signal strength of the detectors, crosstalk can happen anywhere from 3 to 15 feet of the two detectors.

Crosstalk is most annoying when at a seeded treasure hunt. When you have a field with 50 to 100 or more hunters in it, you are bound to get at least one detector that is close enough to your frequency to cause crosstalk. Most manufacturers offer some sort of frequency shifter for coin hunt situations.

Frequency shifters change the transmit and receive signals just slightly enough to keep another detector from interfering with yours.

How much does the moisture in the ground have to do with detection depth?

Moisture in the ground by itself has very little affect on the operation of a metal detector. Fresh water, such as rain or irrigation, is not much more conductive than the dirt it soaks into. Most metallic items in moist soil will start to corrode. As these items start to break down, they create a halo of super mineralized soil around the target. The halo effect makes the target appear bigger to the metal detector. Iron and other ferrous targets will corrode faster than other targets. Gold does not corrode, and silver, copper, and brass corrode more slowly than iron. So, while the halo effect will work on some targets, it will not work on all.

Saltwater is a little different than freshwater. Due to its nature, saltwater is more conductive than fresh. This may give a little extra punch down into the ground but will also cause most machines to chirp and chatter quite a bit more. It is especially bad at the surfline on a wet saltwater beach. You can effectively tune out most saltwater effects when the saltwater is consistent (when the coil is covered by a foot or so of water, for example). Along the surfline, the waves are still washing up on the shore and the sand is drying out. This causes pockets of sand that may be higher or lower in conductivity than the surrounding area and can play havoc on your detector. It is best to hunt in the Discrimination mode with the Discrim-ination knob turned up high enough to knock out iron and foil. This will cancel out a good portion of the saltwater effects. You may also have to turn down your sensitivity to stabilize the detector.

 

HEADPHONES

What are the best headphones to use?

Every detectorist has a slightly different style and likes a different type of headphone. For each style of hunter and hunting, there are several headphones.

The most obvious difference is the earpiece. A lot of detectorists like the full-cup style. These phones fit completely over your ear and block out most of the background noise. They work well for when you are trying to hear the faintest of signals. The downside is that if it blocks out the surroundings, you may not hear snakes or other predators around you.

On the other end of the scale are walkman or earbud-style headphones. They will concentrate the signal in your ear but will allow you to hear the surroundings around you as well. Earbuds are also much cooler to wear during the hot summer months.

Along with the types of cups are the ohm ratings and frequency ratings to consider. Headphones that are designed for listening to digital music have very high ohm and frequency ratings. They will allow you to hear greater nuances in the detector signals but are very expensive. Lower-priced headphones may not have the range of their higher-priced brothers, but considering that you are only listening for a beep, they work very well. If you are out in the field and accidentally break your phones, the inexpensive ones are much easier on the pocketbook.

There are a number of headphones that have active electronics inside them as well. Most of these types of phones have some form of compression/limiter circuit in them. They work by amplifying weak signals and limiting the strong ones. They will work well for chasing some of those elusive small, deep targets but may make shallow and deep target signals sound the same.

With all of the headphone choices out there, try as many as you can, think about the type of hunting that you do, and where you will be doing it. When you consider all of these factors, you will find the headphones that work best for you and your detecting style.

How much will using headphones increase the battery life?

Headphones take much less current to drive than the speaker in the detector. This fact by itself would tend to show that you will increase your battery life by using headphones. But you have to remember that even though the detector is not making any noises, the electronic circuits are still running. A detector that generates a square wave or has a display will be using more power than a detector that is using a sinusoidal wave and has no display. The increase in battery life will depend on your detector and hunting style.

 

BATTERIES

Are rechargeable batteries better than alkalines?

There are two aspects of rechargeable batteries to consider. The first is cost. Rechargeables are quite a bit more expensive than regular batteries, but the cost is offset so that you will not have to buy them as often.

The second consideration for rechargeable batteries is the voltage. Most rechargeables have slightly lower voltage than their counterparts. Alkaline batteries have a voltage of 1.5 volts per AA cell. Most rechargeable batteries have a voltage of around 1.2 volts per AA cell. If your detector uses 8 AAs, you will have 12 volts with the alkalines and roughly 9.6 volts with the rechargeables. This should not affect your depth and sensitivity, it but will affect the time that you are able to hunt.

 

LAST BUT NOT LEAST

Are there any good places left to hunt?

Most places that come easily to mind have probably been hunted to death. If you thought of that site, chances are someone else has thought about it as well.

Doing research is the best way to find new places to hunt. Every city has some form of museum or historical society. This is a great place to start.

Joining a local treasure-hunting club can help as well. Check with your local dealer to see if there is a club near you. You may also want to contact a national club such as the “Federation of Metal Detector and Archaeological Clubs,” “American Metal Detecting Association,” or the “Gold Prospectors Association of America.” A national organization will have several local groups that will allow you to contact hunters that share the same interests as you do.

 

How do I set my Sensitivity control to get maximum depth?

The Sensitivity control on most detectors is used to set the trigger point of any signal. The higher the Sensitivity setting, the smaller amount of signal a target needs to produce to have the detector give an audio signal. A very small or very deep target will not produce the amount of signal that a large or shallow target will. By increasing the sensitivity, the machine will give an audio signal to the smaller and deeper targets, but the detector may become too sensitive and start picking up ground effect or outside interference such as electrical lines or radio frequency noise.

The easiest way to set your Sensitivity is to turn it up until the machine starts to chatter. When the machine chatters, turn the Sensitivity control back until the chatter just goes away. This will give you the maximum sensitivity without any excess noise. If you can turn your Sensitivity control wide open without chatter, leave it there. Your machine will be operating at its maximum power capabilities.

What is ground balancing?

Ground balance is a form of discrimination that cancels out the effect of mineralization. Ground balancing is the physical act of finding the balance point where the effects of the ground are neither too positive nor too negative. When a detector is set with a positive ground balance, it will react to the mineralization matrix just like a target. When this happens, you will get an audio signal and targets in the ground will be masked by the mineralization. If a detector has been set up with a negative ground balance, the detector is discriminating out the ground and will go silent. A severe loss of depth and sensitivity are the results.

Finding the balance point between these two extremes is very important for the best operation of any machine. Most factory preset detectors are set just slightly positive. This will allow the user to work different types of soil conditions. A slight positive setting will also keep the detector from reading small ripples in the dirt and the hole you are digging to retrieve a target.

What is the difference between Preset, Manual, and Automatic Ground Balance?

All VLF-style metal detectors have some form of ground balance or mineral rejection. This keeps the detector working as close to its peak as possible and not be affected by mineral masking. When reading literature on all of the detectors, it can be confusing as to what the detector is actually doing.

Factory preset is the most common type of ground balance. It is used on most machines that are called “turn-on-and-go.” The ground balance is set internally by a technician at the factory. It will work fine for most coin, jewelry, and relic hunting needs almost anywhere in the world. Factory preset does not require the user to do anything to set the ground balance.

Manual ground balance is used on detectors designed to work in highly mineralized conditions. The ground balance is set by the user and is tuned to the local ground conditions. In bad ground, a manual ground balance can give you better depth and sensitivity than a factory preset. Unfortunately, if the ground balance is set incorrectly, a loss of depth and sensitivity will result. When working with a manual ground balance, constant attention is a must. If the ground conditions change, the detector must be retuned to the ground matrix to ensure the best operation of the machine. Manual ground balancing is a learned skill and must be practiced for best results.

While manual and preset ground balance are pretty clear, automatic ground balance causes some confusion. In the earlier days of metal detecting, any machine that was not a manual ground balance was referred to as an automatic ground balance. The term was used because the detectorist did not have to tune the machine; it was “automatic.” In the late 80s, several detectors were introduced that had microprocessor controlled ground balance. That is to say that the detector sensed the ground condition and reacted to change by adjusting an internal electronic potentiometer. True automatic ground balancing had arrived. Some manufacturers and dealers still use the automatic title for factory preset machines. If you have a question about whether or not any detector is truly an automatic ground balance or not, check the machine with a mineral sample. If the machine actively tunes to the sample, it is an automatic.

What is the best type of ground balance?

This is another question that involves an honest evaluation of your detecting needs. Most detectorists who hunt a few hours here and there for fun or those who are novices would probably benefit from a preset type of machine. There are fewer knobs to worry about and the setup time is very short. This means more time swinging the coil and more chances of finding targets.The more advanced detectorist or one who is hunting in very mineralized soil (gold prospecting or relic hunting) should get some form of adjustable ground balance. Manual ground balance is good for the avid hunter who wants to be able to tune the detector to his exact specifications. Depending on ground conditions and personal hunting habits, a slightly positive or negative ground balance can help the detectorist find targets. An automatic ground balance will always tune to its programmed parameters and can’t be fine tuned to the user’s specifications.Matching your detecting style and hunting habits to the type of ground balance of the detector will result in better finds.

How do I set up a manually adjusted ground balance detector?

Most manually adjusted machines are easy to set up, once you have practiced the skill necessary. Start with the machine in the All Metal mode with the Threshold hum set low and steady. Lift the coil straight off the ground and allow the threshold to retune. Do not swing the coil in an arc off the ground. Moving the coil in an arc causes the machine to read the ground in an uneven manner and will complicate the ground balance procedure. Once the threshold has retuned, push the coil down to about one inch above the ground. One of three things will happen. The threshold noise will get louder; it will get quieter; it will stay the same. When the threshold sound stays the same, the detector is telling you that it is no longer being affected by the mineralization in the ground and you are ready to hunt. If the sound gets louder, you will need to turn the ground balance knob counterclockwise. If the sound gets quieter, turn the ground balance knob clockwise. Repeat the above steps until you find the spot where the detector no longer reacts to the ground and the threshold hum stays the same on the way down.

If you have a manually adjusted machine, it is very important to make sure that you are very comfortable setting the ground balance. You can practice this in your backyard or anywhere you can find a small area with no metal targets in the ground. Spinning the knob one way and setting the balance, then spinning it the other and resetting the balance is a good way to practice this skill. If you practice this just five minutes a day, you will get very good at ground balancing.

What is Super Tune?

Super Tuning is a technique to get better depth and sensitivity out of any machine that has an adjustable Threshold control.

The Threshold control is normally used to set the level of hum in the All Metal mode. A light steady hum is usually desired so that any small or deep target will cause a change in the audio sound. To Super Tune a detector, put it in the Discriminate mode and turn the Threshold knob all the way to the clockwise position. At this point, the All Metal mode will no longer operate correctly, but you will see an increase in depth and sensitivity while hunting in the Discriminate mode.

What is High Output Technology?

Most metal detectors work by sending out a signal, receiving it back, amplifying the return signal, and deciding whether or not to beep. One way of making the detector more sensitive is to increase the amplification of the return signal. This works well up to a point but can cause a machine to overload the circuits and become chirpy. Another way is to increase the initial signal going out, but once again, too much power and the signal will become unstable.

High Output Technology combines the increased transmitted signal and the high gain amplification of the return signal to get the best depth and sensitivity out of our lightweight, compact detectors. When a detector becomes chirpy, the most common reason is the noise to signal ratio. Signal refers to the information being passed through the circuitry and noise is any type of other interference. As the signal is amplified, the noise gets amplified as well. At Tesoro, we use high tolerance components and design them into the circuit to create a lower noise to signal ratio.

What is Target ID and how does it work?

Target ID is a feature that will give the metal detectorist more information about the target while it is still in the ground. It cannot tell you exactly what the target is due to the many variables present in an unknown target. A short list of these variables are as follows: the metal content of the target, the size and shape of the target, the target’s orientation in the ground, the mineralization matrix of the ground itself, depth of the target, detector settings, and outside interference such as weather conditions, cell phone traffic, and electrical lines. All of these things can cause changes in the meter readings.

A basic detector works by transmitting a signal and receiving it back. This creates a field of electromagnetic flux lines around the coil. As metal passes through the field, it breaks or distorts the flux lines. A simple discrimination circuit measures the amount of distortion or shift and beeps or doesn’t beep based on the settings of the machine. During the design phase of any metered-style machine, the engineer measures the amount of shift that the most common targets cause and programs a microprocessor to respond with a meter reading for those types of shifts. The testing can include simple air tests, field tests in a controlled environment, such as a test garden, or even complex reports from several different field testers. But at some point, someone decides that a type of target shift represents a specific meter reading. While this information can give a detectorist a basis to dig or reject a target, it is in no way perfect.

Is there a way that I can get more target information from a non-metered machine?

There is an easy way to find out more information about any target while it is still in the ground. When you get a target, shorten your sweep to about two to four inches over the target. As you move the coil over the target, slowly turn up the Discriminate knob. Check to see where the target goes away. Most detectors now have icons on the discriminate control representing the targets knocked out. This gives you the ability to make better decisions about digging any given target.

The best way to start practicing this method is to do several air tests and see how your detector responds. When you have a good feel for what your detector is telling you, try it in the field. For the first couple of months, check the target with your Discriminate and see if you can identify the target. Dig every target and verify how correct you are. After a while, you will become very good at identifying targets while they are still in the ground. You will dig less junk and be a more successful treasure hunter.

If you choose to use this method, always remember to turn your Discrim-inate knob back to the low setting before continuing to hunt.

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

Key Features of Garrett Ace 250 Metal Detector and Specifications

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

Garrett Ace 250 metal detector specifications and  Features

you can study the features and specifications to decide whatever ace 250 will fit your needs or not. However, there are more Garrett Ace 250 Metal Detectors Sold nationwide than all other brands and models combined. This popularity of this detector shows how people who bought it liked it and told about it to others to buy.

    • Electronic Pinpointing: to precisely locate target and speed  recovery

Specifications:

Target ID Cursor Segments 12
Iron Discrimination Segments 2
Accept/Reject Discrimination YES
Search Modes 5 (plus Pinpoint)
Sensitivity/Depth Adjustments 8
Electronic Pinpointing YES
Frequency 6.5 kHz
Audio Tone ID Levels 3
Standard Searchcoil 6.5″ x 9″ PROformance™
Length (Adjustable) 42″ to 51″ (1.06m – 1.29m)
Total Weight 2.7 lbs. (1.2 kgs.)
Batteries 4 AA (included)
Warranty 2 Year, Limited Parts/Labor
  • Accept/Reject Discrimination: to modify  discrimination patterns
  • 5 Search Modes: select pre-set discrimination pattern or create your own
  • Pushbutton Controls: with One-Touch operation
  • Other features: 3-piece travel/storage, disassembles to 24″; adjustablearm cuff; quarter-inch (1/4″) size headphone jack.

Search Modes (Discrimination Patterns): 5 plus electronic pinpointing

  • All Metal (Zero)
  • Jewelry
  • Custom
  • Relics
  • Coins
  • Pinpoint
    • Continuous Coin Depth Indicator: to determine target depth
    • Battery Condition Indicator: shows battery life continually
    • Interchangeable ACE series: searchcoils: are available
    • Expanded Target ID Legend: easy-to-read above large LCD screen

Garrett ACE 250 Metal Detector

 

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

metal detector terms

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

metal detector terms

DetectionNet : A website for Metal Detectors

Audio ID: See Tone ID. Audio Response: See Target Response.Air Test:  A test performed by moving various sized metal samples beneath the metal detector search coil to check the metal detector’s features and target response.  This test is not an accurate indicator of ground depth penetration capability.Alkaline: A type of battery able to sustain longer periods of current drain with greater storage life when compared to the standard carbon-zinc type.

All Metal: Any operating mode or control setting which allows total acceptance of any type of metal targets. Usually associated with the Ground Balance mode.Auto Tune: Circuitry which continuously retunes the detector’s threshold to the initial manually tuned audio level. The retuning rate following target rejection or drift can be preset or variable.Back Reading: A false signal, when operating in the discriminate mode, caused by a rejected target coming within one inch of or contacting the searchcoil bottom.Bench Test An air test to determine at what approximate discriminate settings various metal samples are rejected or accepted. The test is conducted in a non- metallic area.Black Sand One of the most extreme components of nonconductive, negative ground minerals. Also called magnetite (Fe304) or magnetic iron oxide.

Body Mount: A configuration whereby the control housing is separated from the control shaft and fastened to the operator’s body lessening arm fatigue and expanding usability for shallow water hunting. Also known as hip mount.

Cache: Any intentionally buried or secret hoard of valuables.

Carbon-Zinc: The most common standard dry cell battery type.Coil: See Searchcoil.Coin Depth Indicator: A visual indicator used in conjunction with calibrated circuitry to indicate depth of buried coins in inches or millimeters.Concentric: A searchcoil configuration using one or more transmit and one receive windings having unequal diameters aligned on a common center; most recently arranged on the same plane and called coplanar concentric.Conductive Salts: One of the major mineral types which make up the positive ground matrix. Wet, ocean-salt sand produces a positive rise or metallic type response on an air tuned threshold.Conductivity: The measure of a metal target’s ability to allow eddy current generation on its surface.Control Housing: A metal or plastic box which holds circuit boards, indicators, meter, controls and power supply.

Convertible/Combination: A metal detector configuration allowing versatility in operator handling, i.e., hand held to body mount.

Coplanar: Any searchcoil configuration in which transmit and receive windings occupy the same level or plane.

Crystal Controlled Oscillator: A transmit oscillator employing a crystal to maintain stable output frequency.Depth Penetration: The greatest measure of metal detector’s ability to transmit an electromagnetic field into the soil matrix and produce a target signal.

Detection Pattern: The densest or strongest region of the searchcoil’s electromagnetic field where detection occurs. Its shape is balloon and changes in size directly proportional to target surface area.Detuning: Adjusting the audio threshold into the null or less sensitivity tuning zone. Also a method of narrowing a target signal width manually for precise pinpointing. This is accomplished by retuning to audio threshold over the target response area.

DISC: See Discrimination.

Discrimination: Adjustable circuitry which ignores or nulls audio responses from a specific conductivity range allowing positive responses to be heard from metals higher in conductivity above the discriminate control setting. Designed primarily to eliminate audio response from trash metals. See also Motion Discriminator.

Drift: A loss of threshold tuning stability caused by temperature change, battery condition, ground mineral content or detector design.Double Blip: A signal characteristic common to elongated ferrous targets such as nails or coins lying close to the surface detected in the All Metal no-motion mode.Double D or 2 D: See Wide Scan.

Eddy Currents: Small circulating currents produced on the surface of metal by the transmitted electromagnetic field. These currents then produce a secondary electromagnetic field which is then detected by the search coil receiver windings resulting in inductive imbalance between the windings.

Electromagnetic Field: An invisible force extending from top and bottom of the searchcoil created by the flow of alternating oscillator frequency current around the transmit winding. See also Detection Pattern.

Electronic Pinpointing: An automated detuning feature which narrows signal response for the purpose of target pinpointing. Elliptical Coil: A searchcoil with an ellipse shape. This coil can be either concentric or widescan type.Faint Signal: A sound characteristic of targets that are sometimes deeply buried or very small in size.False Signal: An erroneous signal created by over shoot, ground voids or highly mineralized hot rocks. See also Back-Reading.Faraday-Shield: A metal foil wrapping of the searchcoil windings or metallically painted searchcoil housing interior for the purpose of eliminating electrostatic interference caused by wet vegetation.Ferrous: Descriptive of any iron or iron bearing material.

Ferrous Oxide: An oxidized particle of iron which generally becomes nonconductive and makes up the natural negative ground mineral matrix. Hematite, which is also iron oxide (Fe203) will respond as positive or metallic. See also Black Sand.

Frequency: The number of complete alternating current cycles produced by the transmit oscillator per second. Measured in cycles per second. VLF Very Low Frequency = 3 to 30 kHz; LF Low Frequency = 30 to 300 kHz;MF Medium Frequency = 300 to 3000 kHz; HF High Frequency = 3 to 30 MHz.

Frequency Shift: A feature which suppresses the audio interference (cross-talk) between two detectors using identical transmit frequencies in close proximity.

Ground Balance: A state of operation using specialized circuitry to ignore the masking effect that iron ground minerals have over metal targets.

Ground Balance – Factory Preset: A feature which eliminates the manual ground balance control and its adjustment from the operator’s setup procedure. This adjustment is performed internally by the factory to optimize operation over an average range of nonconductive soils.

Ground Balance – Manual Adjusted: A feature requiring a manual control adjustment procedure to neutralize the effects of negative minerals in the search matrix.

Ground Balance – Self Adjusting: A feature which senses change in ground mineral content and continuously readjusts the ground balance while in operation. Sometimes called Ground Tracking or Automatic Ground Balance.

Ground Filter: Complex circuitry found in motion-type detectors which separates mineral signal from the metal signal allowing it to be further processed by the discrimination circuitry.

Hand Held: A metal detector configuration whereby the operator holds a shaft or handle which supports the searchcoil and control housing. Also called pole mount.

Head: See Searchcoil.

Hz or Hertz: Cycles per second. See also Frequency.

Hip Mount: See Body Mount.

Hot Rock: A rock which contains a higher concentration of nonconductive ground minerals than the surrounding matrix to which the detector is balanced. A metallic (positive) response will be heard in the motion and non-motion modes and a null or negative drop in threshold is heard in the all-metal, ground balance mode over these rocks.

Isolator: A nonmetal stem which attaches the searchcoil to the control shaft eliminating metallic interference in the detection pattern. On some detectors, the entire lower shaft is made of a nonmetal substance.

kHz or Kilohertz: 1000 cycles per second. See also Frequency.

LCD or Liquid Crystal Display: Used on a metal detector as a graphic visual indicator same as a meter/needle indicator.

LED or Light Emitting Diode: A semiconductor which produces an illuminated visual response.

Loop: See Searchcoil.

Matrix: Refers to the total volume of ground penetrated by the transmitted electromagnetic field, which may contain varying amounts and combinations of minerals, metals, salts and moisture.

Metal: Metallic substances such as iron, foil, nickel, aluminum, gold, brass, lead, copper, silver, etc.

Metal Detectorist: A person operating a metal detector in the field. This name is preferred by many over Treasure Hunter.

Meter: A detector component that provides visual information to aid in target identification. Meters feature either an LCD or needle indicator which may display intensity of signal, target depth, target identification, type of metal, or battery condition.

Mineral-Free Discriminator: Any metal detector that can reject or ignore trash metals while simultaneously balancing ground mineralization.

Mineralized Ground: Any soil that contains conductive or nonconductive components.

Mode: A condition of operation, selected by the operator, for specific desired function(s).

Motion Discriminator: A detector type that requires searchcoil motion to activate its simultaneous ground balance and discriminate functions. See also Mineral-Free Discriminator and VLF/TR.

Narrow Response: A target that produces an audio response so short that pinpointing is almost not needed.

Negative Ground: Soil that contains non-conductive minerals which have a negative or nulling effect on an air-tuned threshold.

Neutral Ground: Soil that has no nonconductive or conductive mineral properties. Lacks mineralization.

Ni-Cad or Nickel-Cadmium: A rechargeable type of battery cell.

Non-Ferrous: Not of iron. Metals of the precious class (i.e., gold, silver, copper, etc.)

No-Motion: Refers to any mode of operation that does not require searchcoil motion to trigger target response. Also called non-motion.

Notch Accept: Operation whereby all target responses are “tuned-out” except those the instrument is adjusted to accept in the notch “window.”

Notch Discrimination: Filtering circuitry which allows a “window” of desirable targets to be accepted within the entire rejection range of unaccepted targets, i.e., rejecting nails, foil and pulltabs while accepting nickels and gold rings of the same conductivity. This circuitry can also be adjusted to reject all metal targets while accepting only a specific conductivity range.

Notch Level: A control used to select the target level or target conductivity which the notch filter will act upon.

Notch Reject: Operation whereby all targets within the notch width at chosen notch level will be “tuned-out.”

Notch Width: A finite discrimination range of target conductivities (“window”) at the chosen notch level.

Null: The zone just below audible threshold in metal detector tuning. This also refers to the momentary drop or quiet response of threshold sound as the searchcoil passes over a discriminated or rejected target.

Overlap: The amount of searchcoil swing advance not greater than the searchcoil’s physical diameter.

Overshoot: A common false signal heard as the searchcoil passes over a rejected target when using a no-motion All Metal mode in conjunction with automatic retuning. Excessive tuning restoration pushes the audio above threshold level creating a positive response at the edges of target detection periphery.

Phase Response: The length of time between eddy current generation sustained on a metal’s surface and the resultant secondary electromagnetic field effect on the searchcoil’s receive winding. Related to target conductivity.

Pinpointing: Finding the exact target location with respect to a searchcoil’s designated center. Accomplished by interpreting the centers of audio response width in perpendicular directions or scans. See also Detuning.

Positive Ground: Soil which contains conductive minerals or moist salts which have a positive or upward effect on an air-tuned threshold.

PI or Pulse Induction: A mode of operation where the transmitter circuit pulses an electrical current into the ground be fore it quickly shuts down. The eddy cur rents dissipate immediately from poor conductors such as wet salt sand and ground minerals. Metals hold eddy cur rents because they are better conductors. When the receiver circuit comes on, it picks up the returning signal from metal; the eddy currents in the ground minerals have already disappeared.

Quick Response: A short time period between metal sensing and peak audio/ visual indicator indication usually associated with all frequency ranges of TR detectors.

Rejection: An indication of target nonacceptance by a null in threshold or broken sound while operating in a discriminate mode.

RF-Two Box: A radio frequency detector having its own transmit and receive windings separate and in an orthogonal configuration. This detector is capable of deep large object detection while naturally ignoring small targets such as nails and individual coins.

Scan: Refers to 1) the effective searchcoil detection width or 2) searchcoil movement over the ground.

Scrubbing: The searchcoil is pressed and held in contact with the ground while searching to maintain even audio threshold. With newer detectors, this technique is used to gain depth.

Searchcoil: A circular (or other shaped) plastic housing containing single or multiple transmit and receive windings (wire coils) in a specific configuration. A searchcoil emits and receives signals from the ground and metal targets. Also called loop, coil or head.

Searchcoil Cable: An electrostatically shielded cable of conductors (wires) which convey signals to and from the searchcoil and control housing.

Sensitivity: The capacity of a metal detector to perceive changes in conductivity within the detection pattern. Generally, the more sensitivity a detector can smoothly provide, the more depth it will achieve in sensing targets.

Signal: An audio response or visual indication alerting the operator that a target has been detected.

Signal Width: The total distance of ground an audio signal is sustained during search- coil travel or scan.

Silent Search: Refers to detectors capable of producing a target signal while operating below the threshold audio. Also called silent operation.

Scuff Cover: A protective cover for the searchcoil bottom. Also called coil cover or skid plate.

Slow Motion: A description of searchcoil speed required to operate the motion discriminate mode.

Stability: The ability of a metal detector to maintain manually adjusted tuning thresh- old under the effects of outside interference. See also Drift.

Surface Area: Refers to the area of a target closest to the searchcoil where eddy current generation can take place.

Surface Mount: The art of mounting electronic components on the surface of a printed circuit board rather than using the “through board” method. This allows more technology in a much smaller space and with much higher tolerances.

Sweep: The motion employed in moving the searchcoil across the ground.

Target: Refers to any object that causes an audio or visual response in a detector.

Target Masking: When large sizes or high concentrations of trash metals drive the threshold into the null zone suppressing weaker, positive responses from deeper or smaller targets.

Target Response: See Signal.

Ten-Turn: A control which can be manually rotated ten times to cover the full electrical range of the function. Usually associated with tuning or ground balance function.

Test Garden: A mapped plot of buried targets at various depths to aid in learning characteristic target responses and in comparing metal detector performances under a given ground mineral content. Also called test plot or test bed.

TH’er,TH’ing: Universal word contractions for treasure hunter and treasure hunting. Also known as Metal Detectorist.

Threshold: Continuous tone that establishes a reference point for tuning the detector to ground balance it. The threshold tone also establishes the minimum sound level for deep targets in the discriminate mode.

Tone ID: Circuitry producing different audio tones for each target’s conductivity range, i.e., low tone for nickel, high tone for coins.

TR or Transmitter-Receiver: Term describing method of operation of early detectors. Some manufacturers still produce this type of detector. Electromagnetic field distortion caused by mineralized ground interferes with depth penetration as this type of detector does not ground compensate. It does balance conductive salt water effects so, it is primarily used in salt water and on low mineral salt water beaches or low mineral inland locations.

Visual ID: A feature in which a visual indication is produced to help identify the target.

Visual Indicator: A meter, LCD or LED that signals a target’s presence.

VLF or Very Low Frequency: See Frequency.

VLF/DISC: Term associated with detectors capable of mineral-free operation in both the Discriminate and All Metal modes.

VLF/TR: A class of detector that can operate in both the All Metal, Ground Balance mode and the No-Motion Discriminate, Non-Ground Balance mode.

Wide Response: A target that produces an audio signal over an area wider than the searchcoil diameter.

Wide Scan: A coplanar searchcoil with two “D” shaped transmit and receive windings positioned back to back and overlapping. This searchcoil type is capable of detecting a target across at least its full diameter. Also called Double-D or 2-D.

Zero Discrimination: Used to describe detectors whose discrimination control allows the acceptance of all metals at zero setting.

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

Garrett Metal Detectors and Tesoro Metal Detectors for treasure hunting

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

Tesoro and Garrett Metal Detectors are fun to use. You can Join in on the fun sport of treasure hunting with the purchase of a quality metal detectors. Both Garrett Metal Detectors and Tesoro metal detectors metal detectors are available and the best quality products. It is guaranteed  that all of these products are durable, effective and within the price range of the average consumer. Using one of these products is sure to help you find any hidden metals, regardless of whether the product is used recreationally,professionally or in search of profit.The metal detectors available for sale are of a variety of grades and are built for a variety of purposes,meaning that regardless of your goals, you are sure to find a product that is appropriate for your project.Many of the products available for purchase are models that have been used by professionals, which really shows the quality of both Garrett metal detectors and Fisher metal detectors. From military grade products, which are used to detect explosives on battlefields, to metal detectors used to uncover historical relics, these products are tried and true. Additionally, even if you are looking for a very specific type of metal detector, you are sure to find what you are seeking. Not only is there a vast wealth of products to choose from, but there is also a variety of accessories that are available for purchase. Whether you require a specialized grip, a certain output device or another form of customization, you are sure to find the appropriate product in this selection.Professionals and hobbyists alike find the best metal detectors available within this selection. Regardless of whether you need a hardcore product for heavy duty work or a light and effective product for a family camping trip, Garrett metal detectors and Fisher metal detectors are great choices. View the gallery today and get started on with these exciting products
Back to Detection.com

 

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

metal detecting terms help. All about metal detectors

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

metal detectors terms: AC (Alternating Current) – Metal detector modes that require loop motion to respond to metal.Air Test – Testing a metal detector’s response to various metallic samples with the loop held away from ground. All-Metal – Describes any mode or control setting allowing total acceptance of all types of metal targets, iron and non-iron. Audio Identification – Circuitry or mode producing different audio tones (pitches) for different target types. AutoTrac (Automatic Ground Tracking) – A feature that continually and automatically readjusts the ground balance (ground rejection) of a metal detector
during searching.

TERM EXPLANATION

All-Metal Mode A metal detector setting that detects all metal objects, no discrimination
Audio Threshold The background audio level produced when no target is being detected – it is best to adjust the audio threshold to the lowest audible level, and recommended the operator use headphones when treasure hunting
Audio Tone The pitch or frequency of the sound made by a detector. The tone on the GTI 2500, 1500 and GTP 1350 detectors can be adjusted on a treble to bass scale.
 Back Reading – A false target response caused by
either overloading due to a very strong target near the
loop, or a rejected trash target very close to the loop.
Cache Larger deposits of treasure that generally consist of money and valuable objects
Classifier A filtering device, typically found at the head of a sluice, which helps prevent rocks and other large debris from falling into a gold pan.
Coin Shooting Hunting for coins regardless of location or era of coins targeted
 Conductive Salts – One of the major mineral types
which makes up the positive ground matrix. Wet
ocean salt/sand will produce a positive indication
much like a metal target.
Composite Digger Trowel made of durable plastic that helps prevent coin damage during recovery. Ideal for soft terrain
Control Box Contains the detector’s main circuitry, controls, speaker, batteries and microprocessor chip
 DC (Direct Current) – Used to refer to metal detector
modes that do not require loop motion to respond to
metal targets.
DD Searchcoil A special configuration of the transmit and receive coils to minimize the effects of ground minerals
 De-tuning – A method of narrowing a target signal’s
width and length for precise pinpointing.
DSP (Digital Signal A highly advanced computer chip used in Garrett detectors and other sophisticated Processor) electronic equipment
Discrimination The ability of a metal detector to reject a target, such as a pull tab and foil or accept a target such as a coin or jewelry based on its metallic composition
FastTrack (See Garrett’s exclusive technology that analyzes ground mineralization and adjusts to “cancel” Ground Balance) its effects in a matter of seconds
Frequency The number of times per second the energy transmitted from a detector’s coil changes direction (e.g. 7.0 kHz = 7000 times per second) – higher frequencies are typically used to find targets such as gold nuggets, while lower frequencies are best for general purpose hunting.
Gold Pan A bowl-shaped, shallow container that traps gold flakes
Gravity Trap™ A patented gold pan made by Garrett which has 90 degree riffles to trap small gold
Ground Balance An adjustment made to “cancel” or ignore ground mineralization; may be done manually (See GroundTracking) or automatically
Ground Tracking The ability of a metal detector to continuously measure the ground’s mineralization and automatically adjust the detector’s ground balance setting for optimum performance
GTA (Graphic Target Analyzer) Exclusive Garrett technology that visually identifies a target’s conductivity or ID and also shows the discrimination pattern
GTI (Graphic Target Imaging) Exclusive Garrett technology that measures and displays a target’s true size and depth
LCD (Liquid Crystal Display) A graphical display that indicates target information, detector settings, etc…
Multiple Frequency See Pulse Induction and Multiple Frequency article
Microprocessor Computer chip that performs digital functions that make many features such as Target ID and Discrimination possible on today’s Garrett detectors
Mono Searchcoil Refers to searchcoils with one ring where both transmitter and receiver antennae are located
Motion Mode Refers to the setting where coil motion is needed to detect targets
 Negative Ground – Soil containing mostly magnetic
minerals.
Notch Discrimination Targets above and below these discrimination settings
 Null – A decrease in sound caused by rejection of targets
or ground mineralization.Oscillator – An electronic component or circuitry
designed to generate a specific rate of current frequency
to power the loop’s transmit winding.Overlap – Advancing each sweep of the loop in small
increments to insure good area coverage. Each sweep
should overlap the last by at least 50%.Overload – Occurs when the receiver of a metal detector
becomes overwhelmed due to too much signal
(ground and/or target).Overshoot – A false signal heard as the loop passes
over a rejected target when using a non-motion discriminate
mode in combination with automatic tuning.
Excessive tuning restoration pushes the audio above
the threshold level creating a positive response at the
edges of target detection.
Pinpoint A mode of operation that allows the operator to detemine the precise location of a target still in the ground
Pulse Induction Used primarily for heavily mineralized environments such as the beach or the gold fields of Australia and is found in many of today’s specialty detectors (See also Multiple Frequency)
PowerMaster Exclusive Garrett feature that increases the detector’s ability to detect deeper and wider – up to 20 percent
Probe A long screwdriver-like device usually made of brass used to penetrate the ground and physically locate a detected target before digging it up
Prospecting Hunting for valuable metals such as gold
Relic Hunting Hunting for targets with historical value, such as old battlefield items or family heirlooms
Salt Elimination A detector’s ability to eliminate the interference of salt mineralization, which adversely affects detection depth and target ID capabilities
ScanTrack A unique Garrett feature that automatically adjusts to the operator’s scan speed to achieve optimum performance
Searchcoil Also referred to as the “coil”, the searchcoil is the flat, typically circular disk swept over the ground to sense the presence of metal
Sensitivity Generally synonymous with Depth, the adjustment that determines how deep or small a target can be detected – the higher the sensitivity, the greater the detection depth
Shaft The adjustable stem that connects the control box and the searchcoil
Single Frequency Offers greater potential depth capabilities, better discrimination and enhanced target ID under most common soil conditions where most treasure hunting occurs (See Multiple Frequency article for more information).
Super Sluice™ Large 15″ gold pan with 1/2″deep riffles. Traps small gold nuggets up to one ounce and larger in size
Surface Elimination A detectors ability to ignore all targets located on or near the ground’s surface, which is useful in heavy trash areas
Surface Mount PC Board Technology The latest trend in constructing electronic circuit boards
Target Any metallic item sensed by a detector
 Target Masking – When large size or high concentrations
of trash metals, or extreme ground mineralization,
drive the threshold into the null zone suppressing
weaker positive responses.
Target ID Cursor A graphical indication of the target’s probable identity (e.g. coin, gold, pull tab) based on its electrical properties
Volume Control The ability to adjust the loudness of the audible response produced by the detection of a target

Zero Discrimination – Used to describe detectors
whose discrimination control allows the acceptance
of all types of metals when set to the zero position.

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

how search coils work -Metal Detector SearchCoils

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

SEARCH COILS: The search coil is a vital part of your metal detector. It is the flat, typically circular disk, which generates a magnetic field & senses metallic targets in surrounding environment. It is located at the end of the stem and is connected to the control housing via a cable normally wound around the stem. The size and depth of the magnetic field is determined by the shape and size of the search coil. Understanding the purposes behind the various sizes and shapes of searchcoils will empower you with the ability to choose the best searchcoil for each application.HOW SEARCHCOILS WORK:Searchcoils generally consist of two internal sets of coiled wires, a Transmit Coil (TX) and a Receive Coil (RX). Mono coils can be different in that one coil acts as both the TX and the RX. When the detector is turned on, the TX coil generates a magnetic field in the surrounding space.When a metallic object is within this generated magnetic field, it will create a distortion in the magnetic field. The RX coil will sense this distortion and send a signal to the control housing.A searchcoil’s detection pattern is determined by the combination of the TX’s generated field pattern and the RX’s sensing field pattern.

SEARCH COIL DEPTH:The detection depth of a searchcoil, as a rule-of-thumb, will be approximately equal to its diameter, for a coin-sized object. However, as a searchcoil’s size increases and its field pattern becomes larger, the field pattern becomes less concentrated and begins to miss small objects. For a coin-sized object, this effect becomes noticeable when using searchcoils larger than about 15” in diameter. Since the field generated by a large searchcoil is larger, deeper and less concentrated than a small searchcoil, it is the best choice when hunting for targets that are usually large and deeply buried, such as caches or relics.

SIZES & SHAPESThere are a variety of searchcoil sizes and shapes. The correct one to use depends on the environment it will be used in as well as the targets being sought. A change in any one of these variables may require a different searchcoil.

Generally, searchcoils are circular or elliptical in shape. An elliptical searchcoil is more maneuverable than a circular searchcoil and its narrow width actually provides greater coverage than a circular coil due to its elongated length. However, a circular searchcoil has slightly more detection depth and sensitivity in non-mineralized soil, so it is still the most commonly used shape. Searchcoils also come in a 2-box configuration, which are used for detecting deeply buried targets.

Searchcoils range in diameter from a few inches to several feet. Those less than 6” in diameter are generally considered small, 6-11” in diameter are considered medium and over 11” are considered large. As noted earlier, there is a direct relationship between the size of a magnetic field and the size of a coil. The bigger the coil, the larger the magnetic field. Therefore, larger searchcoils generally detect deeper than smaller searchcoils.

SEARCH COIL DEPTH:The detection depth of a searchcoil, as a rule-of-thumb, will be approximately equal to its diameter, for a coin-sized object. However, as a searchcoil’s size increases and its field pattern becomes larger, the field pattern becomes less concentrated and begins to miss small objects. For a coin-sized object, this effect becomes noticeable when using searchcoils larger than about 15” in diameter. Since the field generated by a large searchcoil is larger, deeper and less concentrated than a small searchcoil, it is the best choice when hunting for targets that are usually large and deeply buried, such as caches or relics.

Small Searchcoils

Because the magnetic field of a small searchcoil is concentrated within a small volume, it is the best choice for hunting in areas with a lot of metal debris. This allows you to maneuver through and around trash to locate good targets, especially when searching in tight places where large searchcoils cannot go. In addition, because of their concentrated detection field, small searchcoils are the best for detecting very small objects. However, a small searchcoil provides less coverage per sweep; more scans will be required to cover a search area.

Medium Searchcoils

For general-purpose hunting, which typically includes coins and coin-sized targets, a medium sized searchcoil (8 – 9”) is the best choice. Because a medium sized searchcoil provides the best combination of magnetic field concentration, detection depth and capability to detect the greatest range of target sizes within the detection area, it is standard with most detectors. In addition, it’s lightweight and easy to maneuver.

Large Searchcoils

Large searchcoils generate wider and deeper magnetic fields than small coils and consequently provide greater depth and coverage. This means that scanning a search area requires fewer sweeps with a large searchcoil than with a smaller coil. This larger scan area, however, can become a problem in trashy areas where the searchcoil is metal detecting several targets at once.

CONFIGURATIONS

In addition to searchcoil sizes and shapes, there are also a variety of searchcoil configurations available, with each proving to be the best choice depending on hunting applications and ground conditions. The configuration of a searchcoil refers to the arrangement of the TX and RX coils within the searchcoil shell. There are basically five configurations: Concentric, Mono, Imaging, Double-D and 2-box.
Concentric Searchcoil

Concentric COILS

The concentric configuration consists of a TX coil and RX coil which are usually circular and arranged as shown at left. The advantage of this configuration is that both the TX and RX coils are wound as large as possible within a given searchcoil diameter. This provides the largest possible detection field and greatest detection depth, making the concentric coil potentially the most sensitive configuration available.In addition, concentric coils also provide the most symmetrical detection field, allowing ease in pinpointing and consistency in target identification. For these reasons, they are the most commonly used searchcoil and will provide the best overall performance in most environments.Unfortunately, this configuration is the most susceptible to interference from ground minerals, which results in substantial loss of performance when used over heavily mineralized ground.

Mono Search coils
Mono

A mono-coil is available only on Pulse Induction detectors and is a variation of the concentric configuration. The mono-coil can be manufactured with the TX and RX coils located together or as a single coil acting as both TX and RX.Detection and performance characteristics of the mono are essentially the same as the concentric in that it provides the maximum possible sensitivity, but suffers some performance in mineralized ground.

ImagingAn Imaging searchcoil is an enhanced version of the concentric configuration that features an additional RX coil. This extra coil provides the detector with additional target information necessary for true target-depth perception and true target-sizing capabilities.With this additional sizing information, the detector can more fully characterize a target and for the first time distinguish between trash and good targets of the same conductivity (e.g. a quarter vs. a soda can). Only Garrett’s GTI series offers this technology; no other detector in the world has this capability.

Double-D The Double-D configuration is designed to significantly reduce ground interference and, thereby, recover the performance lost by a concentric coil over mineralized soil. With the Double-D, it is the arrangement of the TX and RX coils that produce a canceling effect of ground signals.This configuration is called DD because both TX and RX coils are in the shape of a “D”. The positive detection field of the DD runs beneath the overlapping center section from front-to-back. The remaining portion of the coil actually produces negative (i.e. canceling) detection fields. It is this canceling field that allows the DD coil to maintain performance over mineralized ground.Because of its small positive detection field, the DD is inherently less sensitive than a concentric searchcoil of the same size, over non-mineralized ground. The Double-D will, however, significantly outperform the concentric coil over mineralized ground. For this reason, it is highly recommended when hunting over mineralized ground commonly found when prospecting and relic hunting. 2-Box: In a 2-box configuration, the TX and RX coils are physically several feet apart. This configuration provides a lightweight, manageable means of achieving the performance of a 3′ to 4′ diameter searchcoil. Because of its large size, and consequently large detection field, the 2-box is the best choice for detecting large, deeply buried objects such as relics and caches. Also, because of its large detection field, it ignores objects smaller than about 3″ in diameter. This characteristic is advantageous when hunting in areas heavily littered with small trash objects.There’s also an enhanced version of the 2-box, only available from Garrett. It is the Treasure Hound with Eagle-Eye pinpointing. This version incorporates an additional pinpointing coil for precise target location

 

 

 

 

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

metal detector searchcoils and how they work

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

HOW metal detector SEARCHCOILS WORK

metal detector  Searchcoils generally consist of two internal sets of coiled wires, a Transmit Coil called TX and a Receive Coil called RX. Mono coils can be different in that one coil acts as both the TX and the RX. When the detector is turned on, the TX coil generates a magnetic field in the surrounding space.SEARCH COIL BASICS The searchcoil is a vital part of your metal detector. this part does emit the signal toward the target and the signal induced get reflected back to it. It is the flat, typically circular disk, which generates a magnetic field and senses metallic targets in the surrounding environment. It is located at the end of the stem and is connected to the control housing via a cable normally wound around the stem. The size and depth of the magnetic field is determined by the shape and size of the searchcoil. Understanding the purposes behind the various sizes and shapes of searchcoils will empower you with the ability to choose the best searchcoil for each application.

SEARCHCOIL DEPTH

The detection depth of a searchcoil, as a rule-of-thumb, will be approximately equal to its diameter, for a coin-sized object. However, as a searchcoil’s size increases and its field pattern becomes larger, the field pattern becomes less concentrated and begins to miss small objects. For a coin-sized object, this effect becomes noticeable when using searchcoils larger than about 15” in diameter. Since the field generated by a large searchcoil is larger, deeper and less concentrated than a small searchcoil, it is the best choice when hunting for targets that are usually large and deeply buried, such as caches or relics.

SIZES & SHAPES

There are a variety of searchcoil sizes and shapes. The correct one to use depends on the environment it will be used in as well as the targets being sought. A change in any one of these variables may require a different searchcoil.

Generally, searchcoils are circular or elliptical in shape. An elliptical searchcoil is more maneuverable than a circular searchcoil and its narrow width actually provides greater coverage than a circular coil due to its elongated length. However, a circular searchcoil has slightly more detection depth and sensitivity in non-mineralized soil, so it is still the most commonly used shape. Searchcoils also come in a 2-box configuration, which are used for detecting deeply buried targets.

Searchcoils range in diameter from a few inches to several feet. Those less than 6” in diameter are generally considered small, 6-11” in diameter are considered medium and over 11” are considered large. As noted earlier, there is a direct relationship between the size of a magnetic field and the size of a coil. The bigger the coil, the larger the magnetic field. Therefore, larger searchcoils generally detect deeper than smaller searchcoils.

Small Searchcoils

Because the magnetic field of a small searchcoil is concentrated within a small volume, it is the best choice for hunting in areas with a lot of metal debris. This allows you to maneuver through and around trash to locate good targets, especially when searching in tight places where large searchcoils cannot go. In addition, because of their concentrated detection field, small searchcoils are the best for detecting very small objects. However, a small searchcoil provides less coverage per sweep; more scans will be required to cover a search area.

Medium Searchcoils

For general-purpose hunting, which typically includes coins and coin-sized targets, a medium sized searchcoil (8 – 9”) is the best choice. Because a medium sized searchcoil provides the best combination of magnetic field concentration, detection depth and capability to detect the greatest range of target sizes within the detection area, it is standard with most detectors. In addition, it’s lightweight and easy to maneuver.

Large Searchcoils

Large searchcoils generate wider and deeper magnetic fields than small coils and consequently provide greater depth and coverage. This means that scanning a search area requires fewer sweeps with a large searchcoil than with a smaller coil. This larger scan area, however, can become a problem in trashy areas where the searchcoil is metal detecting several targets at once.

CONFIGURATIONS

In addition to searchcoil sizes and shapes, there are also a variety of searchcoil configurations available, with each proving to be the best choice depending on hunting applications and ground conditions. The configuration of a searchcoil refers to the arrangement of the TX and RX coils within the searchcoil shell. There are basically five configurations: Concentric, Mono, Imaging, Double-D and 2-box.
Concentric Searchcoil

Concentric

The concentric configuration consists of a TX coil and RX coil which are usually circular and arranged as shown at left. The advantage of this configuration is that both the TX and RX coils are wound as large as possible within a given searchcoil diameter. This provides the largest possible detection field and greatest detection depth, making the concentric coil potentially the most sensitive configuration available.

In addition, concentric coils also provide the most symmetrical detection field, allowing ease in pinpointing and consistency in target identification. For these reasons, they are the most commonly used searchcoil and will provide the best overall performance in most environments.

Unfortunately, this configuration is the most susceptible to interference from ground minerals, which results in substantial loss of performance when used over heavily mineralized ground.

Double-D

The Double-D configuration is designed to significantly reduce ground interference and, thereby, recover the performance lost by a concentric coil over mineralized soil. With the Double-D, it is the arrangement of the TX and RX coils that produce a canceling effect of ground signals.

Mono

A mono-coil is available only on Pulse Induction detectors and is a variation of the concentric configuration. The mono-coil can be manufactured with the TX and RX coils located together or as a single coil acting as both TX and RX.

The detection and performance characteristics of the mono are essentially the same as the concentric in that it provides the maximum possible sensitivity, but suffers some performance in mineralized ground.

ImagingAn Imaging searchcoil is an enhanced version of the concentric configuration that features an additional RX coil. This extra coil provides the detector with additional target information necessary for true target-depth perception and true target-sizing capabilities.With this additional sizing information, the detector can more fully characterize a target and for the first time distinguish between trash and good targets of the same conductivity (e.g. a quarter vs. a soda can). Only Garrett’s GTI series offers this technology; no other detector in the world has this capability.

This configuration is called DD because both TX and RX coils are in the shape of a “D”. The positive detection field of the DD runs beneath the overlapping center section from front-to-back. The remaining portion of the coil actually produces negative (i.e. canceling) detection fields. It is this canceling field that allows the DD coil to maintain performance over mineralized ground.

Because of its small positive detection field, the DD is inherently less sensitive than a concentric searchcoil of the same size, over non-mineralized ground. The Double-D will, however, significantly outperform the concentric coil over mineralized ground. For this reason, it is highly recommended when hunting over mineralized ground commonly found when prospecting and relic hunting.

2-Box

In a 2-box configuration, the TX and RX coils are physically several feet apart. This configuration provides a lightweight, manageable means of achieving the performance of a 3′ to 4′ diameter searchcoil. Because of its large size, and consequently large detection field, the 2-box is the best choice for detecting large, deeply buried objects such as relics and caches. Also, because of its large detection field, it ignores objects smaller than about 3″ in diameter. This characteristic is advantageous when hunting in areas heavily littered with small trash objects.There’s also an enhanced version of the 2-box, only available from Garrett. It is the Treasure Hound with Eagle-Eye pinpointing. This version incorporates an additional pinpointing coil for precise target location.
When a metallic object is within this generated magnetic field, it will create a distortion in the magnetic field. The RX coil will sense this distortion and send a signal to the control housing.A searchcoil’s detection pattern is determined by the combination of the TX’s generated field pattern and the RX’s sensing field pattern.
Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

Metal Detector Terms Part 2

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page

Electromagnetic Field: An invisible force extending from top & bottom of the metal detector searchcoil created by the flow of alternating oscillator frequency current around the transmit winding. See also Detection Pattern.

Eddy Currents: Small circulating currents produced on  surface of metal by the transmitted electromagnetic field. These currents then produce a secondary electromagnetic field which is then detected by the search coil receiver windings resulting in inductive imbalance between the windings.

Electronic  Pinpointing An automated detuning feature which narrows signal response for the purpose of target pinpointing.

Elliptical Coil: A search coil with an ellipse shape. This coil can be either concentric or widescan type.

Faint Signal: A sound characteristic of targets that are sometimes deeply buried or very small in size.

False Signal: An erroneous signal created by over shoot, ground voids or highly mineralized hot rocks. See also Back-Reading.

Faraday-Shield: A metal foil wrapping of the searchcoil windings or metallically painted searchcoil housing interior for the purpose of eliminating electrostatic interference caused by wet vegetation.

Ferrous: Descriptive of any iron or iron bearing material.

Ferrous Oxide: An oxidized particle of iron which generally becomes nonconductive and makes up the natural negative ground mineral matrix. Hematite, which is also iron oxide (Fe203) will respond as positive or metallic. See also Black Sand.

Frequency: The number of complete alternating current cycles produced by the transmit oscillator per second. Measured in cycles per second. VLF Very Low Frequency = 3 to 30 kHz; LF Low Frequency = 30 to 300 kHz;MF Medium Frequency = 300 to 3000 kHz; HF High Frequency = 3 to 30 MHz.

Frequency Shift: A feature which suppresses the audio interference (cross-talk) between two detectors using identical transmit frequencies in close proximity.

Ground Balance: A state of operation using specialized circuitry to ignore the masking effect that iron ground minerals have over metal targets.

Ground Balance – Factory Preset: A feature which eliminates the manual ground balance control and its adjustment from the operator’s setup procedure. This adjustment is performed internally by the factory to optimize operation over an average range of nonconductive soils.

Ground Balance – Manual Adjusted: A feature requiring a manual control adjustment procedure to neutralize the effects of negative minerals in the search matrix.

Ground Balance – Self Adjusting: A feature which senses change in ground mineral content and continuously readjusts the ground balance while in operation. Sometimes called Ground Tracking or Automatic Ground Balance.

Ground Filter: Complex circuitry found in motion-type detectors which separates mineral signal from the metal signal allowing it to be further processed by the discrimination circuitry.

Hand Held: A metal detector configuration whereby the operator holds a shaft or handle which supports the searchcoil and control housing. Also called pole mount.

Hz. or Hertz : Cycles per second. See also Frequency.

Hip Mount: See Body Mount.

Hot Rock: A rock which contains a higher concentration of nonconductive ground minerals than the surrounding matrix to which the detector is balanced. A metallic (positive) response will be heard in the motion and non-motion modes and a null or negative drop in threshold is heard in the all-metal, ground balance mode over these rocks.

Isolator: A nonmetal stem which attaches the searchcoil to the control shaft eliminating metallic interference in the detection pattern. On some detectors, the entire lower shaft is made of a nonmetal substance.

kHz or Kilohertz: 1000 cycles per second. See also Frequency.

LCD or Liquid Crystal Display: Used on a metal detector as a graphic visual indicator same as a meter/needle indicator.

LED or Light Emitting Diode: A semiconductor which produces an illuminated visual response.

Loop: See Searchcoil.

Matrix: Refers to the total volume of ground penetrated by the transmitted electromagnetic field, which may contain varying amounts and combinations of minerals, metals, salts and moisture.

Metal: Metallic substances such as iron, foil, nickel, aluminum, gold, brass, lead, copper, silver, etc.

Metal Detectorist: A person operating a metal detector in the field. This name is preferred by many over Treasure Hunter.

Meter: A detector component that provides visual information to aid in target identification. Meters feature either an LCD or needle indicator which may display intensity of signal, target depth, target identification, type of metal, or battery condition.

Mineral-Free Discriminator: Any metal detector that can reject or ignore trash metals while simultaneously balancing ground mineralization.

Mineralized Ground: Any soil that contains conductive or nonconductive components.

Mode: A condition of operation, selected by the operator, for specific desired function(s).

Motion Discriminator: A detector type that requires searchcoil motion to activate its simultaneous ground balance and discriminate functions. See also Mineral-Free Discriminator and VLF/TR.

Don't be shellfish...Share on FacebookTweet about this on TwitterShare on Google+Share on LinkedInDigg thisShare on StumbleUponBuffer this pageFlattr the authorShare on RedditShare on TumblrPin on PinterestEmail this to someonePrint this page