Maryland Free-State Treasure Club


Zeroing In

(Back to Tips)

Zeroing In On Good Targets

     The search coil and circuit board of metal detectors are sensitive and accurate. So much so, the audio and VDI (Visual Display Indicator), if equipped, are kept busy with various ferrous and conductive debris in the ground.

     Metal detectors would also read the ground were it not for the ground-balance function on most brands and models which tunes out the ground. But the contents of soil and sand aren’t perfectly uniform, sometimes making deeper targets read unreliably.

     Aluminum cans, foil, nails, iron chunks, pull tabs and other metal debris can resemble good targets, but, with practice, can be mostly avoided. When entering a new location, note how various targets respond audibly and visually. Factor in the depth at which they were recovered.

     When a questionable target is detected, sweep the search coil at alternate 90-degree angles to check the reliability of the signal. Using all-metal, or pinpoint mode will determine the proximity of adjacent objects and help determine the sweep angle while in motion (discrimination) mode. In some cases, audio tones and VDI numbers will jump wildly around or a signal might sound alternately promising and disappointing when swept in opposite directions.

     Observant detectorists learn the nature of targets in varying soil and at various depths - but only with practice.

     Most trash targets give loud and clear signals and are hard to resist digging. And so we dig the same signals find the same trash. Over and over.

     Good deep metal targets such as coins, rings, relics, etc., can have weak signals unless they are very close to the surface or very large, like a buckle. Smaller coin-sized targets can give off a very faint signal. Ground balancing the detector helps but soil is never consistent.

     Often, the junk will be only one or two VDI numbers away from good targets which is complicated by the numbers or tones jumping around. This is where practice comes in.

     Practice by making a test garden: Clear a large area of your or a friend's lawn of anything that gives a signa in pinpoint (all metal) mode. Then bury some clad, silver coins and common trash targets about two or three feet apart and two-inches deep. If you bury the objects any deeper, you might not be able to detect them, as recently buried objects haven't had time to react to the compounds in the dirt (especially in dry conditions). Mark each object with a large plastic disk, such a jar lid, glued sturdily to the top of a plastic tent peg driven into the ground flush enough for your lawn mover to go over it. Paint the disk with white weather-proof Rust-Oleum. Mark each cap with a number, using black Rust-Oleum, that represents what's buried, and keep a list handy

     You'll find most junk will give you a better signal than the coins. If you cannot detect all of your buried objects, get busy with your ground-balancing adjustments until you can (many detectors allow offsetting the GB).

     Learning how to set your detector to the conditions at hand is one of the secrets of successful treasure hunters.

     Now take your knowledge to a local park and dig all of the signals you hear, good and bad, noting the sound or VDI range of the trash as well as the good targets. The test garden will have taught you enough to be well on your way to finding more treasure and less trash. When in doubt, dig it.