Batteries - Fisher Gold Bug DP Owner's Manual

ELECTRICAL INTERFERENCE (EMI)
EMI is usually easier to control in the All-Metals mode than in the Discrimination mode.
On the Gold Bug DP, setting the discrimination level between 60 and 70 will usually
reduce interference. In the Discrimination mode, the detector may chatter if the
searchcoil is not in motion, but once you start sweeping it over the ground, the signal
from the ground will usually suppress the EMI chatter, except for an occasional pop or
click which will not sound like a real target.
If you are conducting an indoor demonstration, you may find that changing the
orientation of the searchcoil will reduce the pickup of EMI.
If you carry a cell phone or other high-tech electronic equipment while metal detecting
and you encounter EMI, try turning the device off and see if that solves the problem.
Turn such devices completely off, not just into standby mode.
When working near overhead power lines, you may get the best results right under the
power line and the worst results when standing at a 30° to 45° angle to the power line.
Many sources of EMI are intermittent. You may find that an area which is difficult to
search at one time of day may be easier after 5 PM, or on weekends. Power lines are
usually quietest late at night, and on weekend mornings.
Small searchcoils usually pick up less EMI than larger searchcoils. On a site with severe
electrical interference, a small searchcoil is often a better choice than a large one.
Distinguishing Electromagnetic Interference from other problems
EMI will often vary as you walk around from place to place, and it will also vary with
changes in the orientation of the searchcoil. This is almost never the case if there is a
functional problem with the metal detector itself.
The most common cause of a noisy metal detector, where the problem is not EMI, is a
defective searchcoil. If striking the searchcoil with your hand causes the noise to start
or stop, the problem could be a defective searchcoil. Also, a defective searchcoil often
causes noise of a more intermittent nature than electrical interference.
The second most common cause is a loose searchcoil connector. The noise from a
loose connector will usually be very erratic or intermittent in nature. Try unplugging the
searchcoil and then reconnecting it to ensure the connector is firmly installed.
If you use a searchcoil cover, dirt or water can accumulate inside it, and movement of
those materials can cause false signals while sweeping the searchcoil. Searchcoil
covers must be periodically removed and cleaned.
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BATTERIES

A 3-segment battery indicator at the bottom of the display indicates the
battery condition.
The detector requires a single 9-volt ALKALINE battery.
Do not use ordinary zinc carbon batteries.
Do not use "Heavy Duty" batteries.
Rechargeable batteries can also be used.
If you wish to use rechargeable batteries, we recommend using a
Nickel Metal Hydride rechargeable battery.
The battery compartment is located on the back side of the housing.
Slide the battery door to the side and remove it to expose the battery
compartment.
BATTERY LIFE
Expect about 15 to 20 hours of life from a 9-volt alkaline battery.
Rechargeable batteries can provide up to 8 hours of usage per charge.
SPEAKER VOLUME AND BATTERY CHARGE
You may notice the speaker volume drop when only one battery segment is
illuminated.
With one segment flashing, low speaker volume will be very apparent.
BATTERY INDICATOR
The 3-segment battery indicator has 3 stages of indication.
These indications are accurate for a 9-volt alkaline battery.
Segments Illuminated
3 -segments
2 -segments
1 -segment flashing
After the 1st segment begins flashing, expect the detector to shut off within 10
minutes.
A rechargeable battery will usually illuminate two to three segments
throughout most of its useful charge. But as soon as it drains to the 1-segment
level, it will then lose its charge very rapidly.
Battery Voltage
more than 8.5 volts
more than 7.5 volts
more than 6.8 volts
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