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Searching for buried treasure can be a
profitable-and sometimes expensive-
pastime. Before you purchase any equip-
ment, know its capabilities.
ROBERT F. GALLAGHER

MOST PEOPLE WHO USE METAL DETEC- range from $40.00 to $350.00-plus. criminator is a circuit with a built-in
tors don't seem to be too concerned It's much like any other hobby or ability to tell the differences among an
with what makes their detectors de- sport. Initially, you wouldn't buy the extremely wide variety of objects while
tect. After reading over the instruc- most expensive golf clubs after making rejecting trash.
tions, they blithely set out to make their the decision to become a weekend Metal detectors are much more
fortunes. golfer. sophisticated today than they were a
Many coin collectors are using their Today, there are a number of ama- few years ago. There were no discrim-
metal detectors for what is called "coin teur treasure hunters who not only inators, and no matter what the detec-
shooting." Other hobbyists are con- are concerned with what they find, tor cost, it could not tell the difference
cerned with digging up artifacts-things but who want to know something about between trash and treasure.
that were popular during Revolution- the circuitry that stirs up the buzzing Today, leading manufacturers offer a
ary times-like cannon balls as big as sounds that indicate when they should diversity of detectors with prices falling
shotputs, or tools and eating utensils start digging. in the range of $40.00 to $440.00.
from that era. Other treasure hunters
look for valuable objects on the bot- Kinds of metal detectors What's available
tom of streams and lakes. There are two basic types of metal - Metal detectors are available from
Some experts say it doesn't matter detector circuits-the transmitter/ many sources. We have listed the most
whether you're using an inexpensive receiver (T/R) and the very low fre- available ones at the end of this article.
or expensive detector. But as we see quency (VLF) type. For more information circle the appro-
it, the construction of a detector, and The T/R type is where a transmitter priate numbers on the Free Informa-
its circuitry, are important in the pro- circuit radiates a signal, that, when tion card in this issue.
duction of a quality product, and in bounced back, is detected by the re- Although considered low-priced, the
doing the job for which it has been ceiver circuit. When a conductive tar- $79.95 Deluxe TR Earth Challenger
purchased. get interrupts the field, an audio re- has a sensitivity found in higher-priced
We spoke with a man who decided sponse is generated. models. Features include a 10 -turn
about a year ago to make "coin shoot- Basically, the VLF unit is a T/R type metal/mineral tuner, 6 -inch water-
ing" a hobby. His advice is to gather circuit that operates below 30 kHz. It proof search coil, a 1/4 -inch stereo ear-
as much literature as possible on vari- is typically more sensitive and has phone jack for plugging into the user's
ous types of metal detectors before greater depth capabilities than the own headset, eight "AA" batteries
you make a decision to buy one. He higher -frequency T/R type circuit. with snap-lock battery door, and an
selected a detector that has helped The word "discrimination" is im- adjusting telescope shaft which ex-
him dig up about 1500 coins during portant to the treasure hunter. He tends to 44 inches. It's of all -metal
the past year. doesn't want to spend half of his free construction and weighs two pounds,
That's prudent-when you figure time digging up bottle caps, pull tabs, five ounces. Its circuit is shown in
that metal detectors cover a price- foil, or other useless objects. The dis - Fig. 1.
ALMOST _IKIE SELECTING golf clubs. 3rospective -letal detector buyer checks therm out.

COIN SHOOTING is the function of the Heath GD -1190. Search coil is optimized for this.

Bounty Hunter, a Tempe, Arizona The Red Baron's synchronous -

based detector manufacturer, has in- phase discrimination circuitry enables
troduced a unit called the Red Baron. discrimination at VLF depths. It's a
Considered high-priced, it sells for technique that uses a type of analog
about $400.00 and comes with an eight - computer that reads the sensing signal
inch coil. of the combined targets and matrix
A versatile detector, mode changing, (supporting soil around the target)
and retuning are combined in one then subtracts the effects of the ma-
control button. It handles mineralized trix-leaving only the sound of the
GROUNDTRACK metal locator from Heateklt Is and non -mineralized soil in all-metal target itself to analyze.
said to work in up to two feet of water. or discriminate modes. Recently, Bounty Hunter added a
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TR discriminator to the Red Baron, operation with good depth and sta- cludes a battery check and a sensitivity
and now offers a selection of three bility in non -mineralized ground). meter. It weighs only 33/4 pounds and
modes: VLF (normal mode) SPD Another popular Bounty Hunter reportedly is ideal for those who fancy
(ground -reject discrimination) and offering is the 840 VLF/TR. A discrim- "coin shooting."
TR discrimination (for standard TR inator with pushbutton tuning, it in - Edmund Scientific has a unit priced

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hoards of coins, gold and silver bullion, compliments on its Wildcat VLF Dis-
treasure chests, ore veins, and other criminator. Priced at about $280.00, it
deep treasure caches. This unit also boasts instant tuning and true discrim-
has industrial uses, as it is capable of ination when used in just about any
tracing water, gas, and sewer pipes- kind of terrain.
and electrical or phone cables-whose Batteries are included with this unit,
whereabouts have been forgotten. which features a 61/4-inch, water-
When assembled, it measures 51 proofed search coil, a sensitivity ad-
inches, weighs just 11 pounds, and has juster, 31/2 -inch intensity meter, bat-
an output frequency of 82 kHz + 5 tery tester, and push-button tuning for
kHz. Housed in a closable, two -sec- making quick adjustments.
tion, high -impact plastic case, it fea- The Heath Company, a well known
tures moisture -proof solid-state cir manufacturer of electronic kits, also
cuits and offers quite a good penetra- has a line of metal detectors. All of
tion sensitivity. their detectors are available only in
Fisher's top -of -the -line model is kit form. The top -of-the -line model
listed as a VLF 555-D. The VLF dis- GD -1290 features a VLF circuit, ad-
criminate mode rejects unwanted tar- justable discrimination, 6 -inch search
gets while still detecting deep coins coil, and collapsible shaft. It contains
that other detectors miss, claims the both a meter and speaker for the de-
manufacturer. tector output plus a headphone jack.
Edmund Scientific reports many Power is supplied by 6 "AA" cells or
an optionally available nickel -cadmium
HUNTING UP THE RIGHT SPOT to dig takes
METAL DETECTORS battery pack. The model GD -1290 sells
practice to fine-tune your skill in using the for $189.95.
device For more information, circle the There are two more metal detectors
corresponding number on the Free in the Heath Company line. The model
Information card inside the back GD-I 190 has many of the features of
at about $40.00. It is recommended cover.
for the beginner who wants a fully tran- the model GD-/290, but it sells for
sistorized detector offering quality Bounty Hunter, Inc. $119.95. Known as the "Cointrack,"
performance. 1309 West 21st Street its purpose is obvious from its name.
Another respected name in the Tempe, AZ 85282 The lowest -priced model in the
metal detector field is "Fisher." The CIRCLE NO. 96 Heath line is the GD-348 and it sells for
Fisher Research laboratory at Los $79.95.
Edmund Scientific It seems to us that there is a metal
Banos, California, has developed an 101 E. Gloucester Pike
effective research and development detector available in just about any-
Barrington, NJ 08007 body's price range. But all of the ex-
program. CIRCLE NO. 97
One of their most popular TIR detec- perts emphasize: Don't invest too
tors is called Gemini II, and sells for Fisher Research Laboratory much money until you really know
about $350.00. (See schematic. Trans- 1005 Street I
what you're doing, or what you're
mitter in Fig. 2, receiver in Fig. 3.) Los Banos, CA 93635 looking for. Everyone agrees that
It fills the needs of an enthusiastic CIRCLE NO. 99 treasure hunting is fun and profitable-
group of serious treasure hunters, who and the more knowledge you gain, the
Heath Company more profitable it becomes. And we
actively search for-and sometimes lo- Benton Harbor, MI 49022
cate-major treasures. mean that in more than one sense of the
CIRCLE NO. 98 word. R -E
Gemini II users have come up with