Types of Detectors:
VLF (Very Low Frequency), also known as induction balance, Metal Detectors are the most popular detectors in use today. They work by transmitting and receiving signals through a search coil by measuring the reactive conductivity of metal. Ferrous metals such as iron and steel are all magnetic. Non-magnetic metals include aluminum, gold, silver, bronze, platinum, and brass.
A pulse induction (PI) detector is primarily for use under water and works in a way that is similar to RADAR. This type of detector should be weighted for ease of use under water. They have an audible tone and usually cannot discriminate, but can penetrate deeper. Penetration ability is enhanced by the presence of salt. When used on land, a PI detector can search deeper, but won’t pick up small items.
Discrimination allows a detector to overlook certain metals in order to eliminate trash targets. For example, in coin and relic hunting, you might want to set the discrimination level just high enough to cancel out iron and foil. A Notch Filter allows discrimination of a specified metal or metals, rather than a range of metals.
Ground Balance is a feature on all VLF detectors. It’s a type of discrimination that cancels out the effects of ground mineralization. Preset Ground Balance is most commonly slightly positive, making it easier to find targets being masked by mineralization, and will work well in most situations. Novices and those who hunt infrequently, for fun, will appreciate the short set-up and ease of detectors with a factory preset. Manual Ground Balance is set by the user according to local conditions and can provide better depth and sensitivity than presets, but needs constant attention and lots of practice. Gold prospectors, relic hunters, and those who hunt frequently in highly mineralized areas will benefit from this type of Ground Balance. An Automatic Ground Balance detector senses the ground condition and reacts to change by adjusting an internal electronic potentiometer. It cannot be fine-tuned to user specifications.
A pinpoint switch enables the user to shift from discriminate to all-metal mode. This reduces the size of the signal in order to pinpoint the item under the center of the coil.
A meter or VDI (Visual Display Indicator) provide a visual signal to use in tandem with the audio signals.
A Depth Indicator can help the user determine how deep to dig for a target.
A multiple frequency detector can be used on land or under water and is good for all-purpose use, as well as for coin and relic hunting. Frequency can be set by the user or it can be chosen automatically by the detector. These detectors provide a more stable signal in highly mineralized ground, however they require more time and effort to learn to use. Higher frequencies allow for greater depth.
For more information on how metal detectors work, check out the article at www.electronics.howstuffworks.com/gadgets/other-gadgets/metal-detector2.htm.
Coil Type, Size, and Shape:
Concentric coils have two round antennas, one inside the other. They are used in most detectors designed for coin, jewelry, and relic hunting. They discriminate well, and because the strongest signal is in the center of the coil, they pinpoint easily.
Wide Scan coils have two D-shaped antennas placed back-to-back (double D coils). They are less affected by mineralization, and better for gold prospecting and relic hunting in bad ground. Pinpointing is done using the head or toe of the coil.
Size matters. Ground penetration is generally a little deeper than the diameter of the coil. A 10” coil works better for smaller items than a 15” coil. For small items, deep down, it’s best to dig first, then detect. 3-5” coils are best for high trash areas because they offer better differentiation. They’re a great choice for finding gold nuggets and fine jewelry in trashy areas, searching crevices and for pinpointing. Use larger coils in clean areas or where targets are deeper, keeping in mind it won’t be as sensitive to small items and will be susceptible to masking. Masking happens when a detector is unable to pick up a good target because it’s lying next to, or under, a junk target that has been discriminated out.
Hot (aftermarket) coils are slightly larger versions of name-brand coils. “Ultimate Depth” models may be difficult for a beginner to learn to use and will be too sensitive for trashy areas.
Elliptical coils generate a longer, narrower signal that allows for better frequency interactions and may gain greater depth.
Rectangular coils can offer a wider search pattern and greater depth.
Round coils are the most common and are used for the majority of circumstances.
Wading coils are filled with materials that allow the detector to maintain neutral buoyancy when placed in water, to keep it from floating. Regular coils are filled with foam, or a similar material, to make it float.
Choosing a Detector:
1. A no-name detector is more of a toy than a tool and will most likely be a waste of money and a source of frustration. You’ll get greater depth, better warranty service, more how-to information, and a lot more use with any name brand.
2. Beginners will do well with the least expensive model that offers full-range discrimination and has a comfortable weight and design. Unless you plan to dedicate a good deal of time and effort to learn what settings work best for you and your circumstance, choose a simple, less expensive model for your first detector. Once you are experienced, you can always graduate to one that’s more complex.
3. A detector that operates on 12 volt batteries will operate better than one with a single 9 volt. Rechargeable batteries have a lower voltage, meaning less time between charges. Lithium batteries are not allowed on airplanes.
4. Decide whether your primary use will be on dry land or under water and choose a model best suited for that use.
5. Higher priced models should have more than one tone, include visual target identification, have a depth indicator, and the ability to pinpoint. Mid-range detectors should include pinpointing.
6. Waterproof models are always a good idea for detecting in rainy conditions.
7. For reliable advice on specific models, we recommend posting a query on multiple metal detecting forums. Here, you can find experienced users that are willing to share their knowledge and aren’t selling a particular brand. Here are a few to get you started.
Beginning Metal Detecting
Out of the Box
Read through the booklets and watch the DVDs that may have come with your detector. For most brands, you can also find YouTube videos with quality how-to information. After you get it put together, comfort will be your primary concern. Adjust the length of the down rod and angle the coil so that the coil is parallel to, and just off the ground while your arm is neutral and relaxed. Hold the hand grip with a light touch. Your arm should be extended, but not locked. You should now be able to make slow, overlapping, side-to-side sweeps with an approximate 3-foot arc, keeping the coil an inch or less from the ground, using easy shoulder movement. Avoid elbow swinging.
Set Discriminate to All Metal Mode until you are familiar with the sound differences. After you’re comfortable with the various settings, you can set it according to how much trash you expect to find (higher for high-trash areas), knowing that you’ll be giving up some depth, and you won’t be able to detect smaller pieces the higher you discriminate.
Most detectors are factory preset to a slightly positive Ground Balance. This will work well in most situations, and enable you to find targets that would otherwise be masked by ground mineralization.
For Manual Ground Balance, refer to the instructions that came with your machine. You’ll need to pay constant attention and make adjustments as conditions change. Interference may come from electrical lines, clouds, wind, cell phones, radio, etc., and being in close proximity to other metal detectors can cause cross-talk. Practice is the key to really get to know this machine setting.
Some detectors have Automatic Ground Balance which self-adjusts to ground conditions and cannot be fine-tuned to user specifications. When checked with a mineral sample, if the machine actively tunes to the sample, it’s automatic.
The use of a Meter or Visual Display Indicator (VDI) will give you a best guess of a target’s composition, but it won’t be exact. Pull tabs and gold rings fall into the same area, based on the mixing of alloys. Dig any target that gives a good audio signal, regardless of meter reading. Yes, you’ll dig lots of trash, but you’ll also find more desirable targets. Any number of environmental factors can affect meter readings and audio signals. Size, orientation, content, and shape of the target, and soil conditions are a few.
Set up a Test Garden. Using pieces of different metals to learn sounds, bury known targets at known depths and practice finding them with your detector adjusted to different sensitivities and discrimination. Gold has a unique sound. To test your ability to pinpoint, bury a trash item and a non-trash item at the same depth so that they are almost touching.
Where to Start
Start near your home, in areas people have tended to gather over the years. Learn your machine’s functions by learning to determine trash from treasure.
On old homesteads, you can locate initial hotspots by looking around larger old trees, where a porch or cellar may have been located, the path leading from house to outhouse, bunk houses, barns, or around a well. For each hot spot, set your detector to pick up copper pennies and silver dimes, but ignore aluminum and ferrous targets. After finding copper and silver, lower the discrimination to pick up nickels, pull-tabs, and small gold.
Sand Scoops are desirable for detecting on sandy beaches as are Serrated Trowels for digging in lawns and grassy areas. Knee pads will allow for greater comfort when kneeling, and a pouch or apron will help to keep trash separate from treasure. A coil cover will protect your coil in rocky areas (clean them frequently).
Headphones are nice for when there are two or more detectors in the same area or you don’t want to disturb others. Cup-style can cancel background noise, and are not recommended where predators may be present. Earbuds are cooler in warm weather, and do not block outside noise. Stereo headphones allow the user to set volume levels for each ear.
You’ll want to have extra batteries every time you venture far from home. A snake bite kit is a must-have in certain areas. Other accessories to consider are a smaller coil, a separate pin pointer, and a GPS.
Code of Ethics (Adapted from Western and Eastern Treasures Magazine)
1. Respect private property. No hunting without permission of the owner.
2. Fill all excavations.
3. Appreciate and protect natural resources and wildlife.
4. Be thoughtful, considerate, and courteous.
5. Build fires only in designated or safe places and only if needed for safety and security.
6. Leave gates as found.
7. Remove and dispose of any found trash.
8. Do not litter.
9. Do not destroy property.
10. Do not tamper with signs, structures, or equipment.
To Find a Local Organization
The Federation of Metal Detector and Archaeological Clubs Inc. (FMDAC) is a non-profit that is dedicated to the promotion and protection of the hobby of recreational metal detecting and prospecting. They maintain a list of local clubs and offer lots of great information. Visit their website at www.fmdac.org. You can also contact them by phone at 717-355-0691, or email firstname.lastname@example.org.