Fisher Impulse User Manual
Impulse
Pulse Induction Metal Detector
Operating Manual
FISHER RESEARCH LABORATORY
CONTENTS
About Your Impulse................................................................pg. 1
Condensed Operating Instructions ...................................... pg. 3
Assembly .................................................................................pg. 4
Setting Up ................................................................................. pg. 6
For Land or Shallow Water ................................................. pg. 6
For Diving ............................................................................. pg. 7
For Hipmounting..................................................................pg. 8
Control Panel .......................................................................... pg. 9
Tuning.......................................................................................pg. 10
Searching ................................................................................ pg. 10
On land or Shallow Water ................................................. pg. 10
Underwater.......................................................................... pg. 12
Pinpointing............................................................................... pg. 13
Target Recovery ..................................................................... pg. 15
Recovery Tools ................................................................... pg. 15
Operating Tips ......................................................................... pg. 16
Batteries ...................................................................................pg. 17
Home Recharger ................................................................pg. 18
Auto Recharger ..................................................................pg. 18
Tips about Nicad Batteries ................................................. pg. 19
Maintenance ..........................................................................pg. 20
Storage................................................................................. pg. 20
Cleaning..............................................................................pg. 20
Battery Compartment ........................................................pg. 20
Treasure Hunter’s Code Of Ethics .......................................... pg. 21
Where To Use Your Metal Detector In The U.S. .................... pg. 22
Specifications .........................................................................pg. 23
ABOUT YOUR DETECTOR
Fisher Research Laboratory has been producing rugged, high
quality, high performance metal detectors since 1931, longer than
any other company in the world. Your IMPULSE is a product of
that proud heritage. Designed for deep-sea treasure hunting,
the IMPULSE will also do the job in surf, on the beach, in fresh
water or on land.
Pulse induction (PI) metal detectors have been around for years.
Their ability to detect metal in black sand and salt water make
pulse induction metal detectors particularly suited to underwater
treasure hunting, wreck diving, shallow-water treasure hunting
and beach combing.
However, pulse induction metal detectors have had their
drawbacks. Most have been heavy, expensive and unstable,
requiring the operator to retune frequently. Pulse induction metal
detectors also have had high battery drain, creating frustrating
power loss and added expense.
But worst of all, pulse induction metal detectors have been
plagued by slow response. Because the search coil is slow to
respond to a target, sensitivity and depth can be maximized only
at slow sweep speeds, forcing the operator to slow down,
thereby covering less ground. “Autotune” pulse induction
detectors do have a rapid response, but the search coil must
be in motion to detect a target.
In 1985, engineers at Fisher Research Laboratory began work
on a new pulse induction metal detector, one that would
combine extreme depth in salt water with high battery
performance, stability, low cost and fast target response.
Their answer is the IMPULSE—a no-motion detector that responds
instantly to targets and frees the operator to hunt fast, slow or
with no motion at all. In addition, battery life of the IMPULSE has
been greatly extended over previous pulse induction detectors.
In fact, battery life of the IMPULSE is better than most inductionbalance metal detectors. And stability is greatly improved. There’s
no need to retune the IMPULSE every few feet.
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ABOUT YOUR DETECTOR
Here are some important features built into your IMPULSE:
1. LCD: A liquid crystal display gives a visual
indication of signal strength; with a bar graph that
climbs as the signal strength increases. The LCD also
constantly monitors battery strength.
2. LED: A light emitting diode flashes when a target
is located.
3. VCO Pinpointing: An audio signal tone increases
in pitch and volume as the center of the search
coil passes over the target.
4. Leak proof: The IMPULSE is leak proof to 250 feet.
5. Salt Water Operation: Salt water or wet sand is
no problem for the IMPULSE. Its pulse induction
technology virtually ignores salt water, making it
the ideal underwater and beach-hunting machine.
6. Black Sand Operation: The IMPULSE penetrates
black sand and some highly mineralized soils where
ordinary detectors won’t work at all.
7. No-motion Pinpointing: You can sweep the
IMPULSE search coil, or hold it motionless over your
target and still get a target response.
8. Target Response: Sweep your search coil fast,
slow or not at all. The IMPULSE responds to targets no
matter how fast or slow you sweep the search coil.
9. Spider Coil: The 8-inch, open-center Spider coil
makes pinpointing easier. It’s lightweight, tough,
Electro-Static Insulated (ESI shielded) and 100
percent waterproof. Unlike most single-coil pulse
detectors, the IMPULSE has a receiver coil in the
center for easier and more accurate pinpointing.
10. Lightweight, Balanced and Comfortable: Only
about 5 pounds total weight with a cushioned
armrest and foam grip.
11. Hip-mountable: For almost effortless searching, the
control housing slides off the handle and onto your belt.
12. Battery Life: About 40 hours on carbon-zinc
batteries. Even more with alkalines.
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ABOUT YOUR DETECTOR
13. All Metals: The IMPULSE detects all metals. It
has no “discrimination” circuitry, which drastically
reduces the ability of a pulse induction metal
detector to detect gold and silver.
14. Easy to Use: Just pick it up, turn it on and adjust
the TUNER control to the threshold level. You’re
ready to hunt.
CONDENSED OPERATING INSTRUCTIONS
Your IMPULSE is fairly simple to operate; however, its no-motion
design makes it operate differently from more-common, VLF,
induction-balance metal detectors. Therefore, even if you are
an experienced detector user, we strongly recommend that you
read this entire manual before starting. But if you just can’t wait,
here are some quick instructions to get you going on land.
1. Hold the coil up and away from any metal.
2. Set the tuner full counter clockwise, just before
it clicks into the “BATT TEST” position.
3. Set the VOLUME control knob to “10.”
4. Hold the search coil 1 to 2 inches above the
ground and adjust the TUNER control knob until the
audio tone can just barely be heard (usually one
or two bars on the LCD).
5. Readjust the volume control to a comfortable level,
when the search coil is passed over a large target.
6. You’re ready to go. Walk slowly and keep the coil
close to and parallel to the ground.
7. To pinpoint a target, locate the spot where the
volume and pitch of the audio signal peak. The LCD
signal-strength meter will also peak when the
center of the search coil is directly over the target.
8. To pinpoint the target more precisely, detune the
detector by readjusting the TUNER control counter
clockwise. This will reduce the sensitivity of the
search coil until only the center, or hot spot,
responds to the target.
3
CONDENSED OPERATING INSTRUCTIONS
9. Retune your IMPULSE before resuming your
search.
10. Good Hunting!
ASSEMBLY
Light emitting
diode (LED)
Liquid crystal
Display
Control panel
Foam hand grip
Adjustable
arm rest
Arm rest
screws
Fisher M-Scope IMPULSE pulse induction metal detector.
Battery access panel
(not shown)
Fiberglass upper stem
8-inch Spider coil
Nylon wing nut
Fiberglass
reinforced
lower stem
Coiled
cable
Headphone
plug
Submersible
headphones
Your Fisher IMPULSE requires very little assembly. Unpack it
carefully and save the carton, which may come in handy for
future storage or shipment.
1. Remove the headphone, handle and searchcoil assemblies from the carrying case. Be careful
not to damage the foam-rubber inserts or put any
strain on the cable connections.
2. Adjust the lower stem to the approximate length
you will be using; extended for stand-up use or as
short as possible for diving. To extend the lower
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ASSEMBLY
stem, push in the spring lock, pull out the lower stem
and let the spring lock snap into another hole.
3. If you will be using the IMPULSE on the handle and
not body mounted, wind the search coil cable
around the handle assembly as shown in the diagram
on page 4. Secure the cable with the two Velcro
straps included with your IMPULSE. Make sure there
is some slack at the control-housing end and enough
at the other end to attach the search coil.
4. Remove the Delrin bolt and nylon wing nut from
the search coil. Line up the hole in the lower stem
between the two holes in the search coil “ears”.
Attach the coil to the stem with the bolt and wing
nut and finger tighten.
5. The armrest may be repositioned for maximum
comfort by removing the armrest screws, sliding the
armrest to the next screw hole and reinstalling the
arm-rest screws.
Arm rest
Built-in detector stand
Upper stem
The arm rest can be
repositioned by
readjusting two
screws on the upper
stem.
5
SETTING UP
FOR LAND OR SHALLOW WATER
Put the headphones around your neck to keep them out of the
way while making the following adjustments:
1. Adjust the stem length and coil angle so the search
coil rests flat on the ground about 6 inches in front and
slightly to the right of your right foot (to the left of your
left foot if you’re left handed). Your arm should be
straight and relaxed with the handle grip held firmly
but comfortably.
Remember, as you increase the shaft length, you also
increase the strain on your wrist and arm. The IMPULSE
is balanced for comfortable searching in a tight
semicircle around the front of the operator.
2. Leave enough slack in the coil cable to allow the
coil to swivel as far as it can in either direction. The
coil wing nut should be tight enough to prevent the
coil from moving.
3.
You should now be able to move into your
“search” position by leaning slightly forward and
raising the search coil approximately 2 inches above
the ground. Your arm should still be straight and the
coil should be parallel to the ground, about 12 inches
in front of your foot. The coil angle may have to be
slightly readjusted at this point.
When searching on land or
in shallow water, keep your
arm straight and your
search coil no more than 2
inches above ground.
6
SETTING UP
FOR DIVING
Unlike induction-balance metal detectors, the IMPULSE ignores
the disruptive influences of salt water and black sand. This
capability, along with its deep-seeking sensitivity to iron, makes
it ideal for underwater treasure hunting and wreck diving. The
IMPULSE is also waterproof to a depth of 250 feet. Remember,
always practice safe diving methods.
Caution: Hipmounting the IMPULSE control housing is not
recommended for underwater use. The search coil cable may
become entangled with a submerged object, making it difficult
for the diver to resurface quickly in case of emergency.
1. Adjust the stem length as short as you can without
having the search coil detect your diving gear.
2. Adjust the search coil parallel to the seabed,
river or lake bottom.
3. Make sure extra cable is coiled tightly on the upper
stem as closely as possible to the control housing, with
just enough slack near the search coil to allow it to
swivel as far as it can in either direction. Extra cable
near the search coil may generate false signals.
4. Remove the tethered earphone plugs for rapid
pressure equalization as you dive and return to the
surface.
Shortened stem length
Extra cable
When diving with your
IMPULSE, use the shortest
possible stem length, with
the extra cable wrapped
tightly around the stem, as
close as possible to the
control housing.
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