Electromagnetic Interference; Headphone Jack; Using Headphones - Teknetics Eurotek Owner's Manual

THE BASICS OF METAL DETECTING
The searchcoil produces a magnetic field and then detects changes in that
5. EMI (Electromagnetic Interference)
magnetic field caused by the presence of metal objects. This magnetic field
that the detector creates is also susceptible to the electromagnetic energy
produced by other electronic devices. Cell phones, cell phone towers,
power lines, microwave ovens, lighting fixtures, TVs, computers, motors,
etc... all produce EMI which can interfere with the detector and cause it to
beep when no metal is present, and sometimes to beep erratically.
The SENSITIVITY control lets you reduce the strength of this magnetic field,
and therefore lessen its susceptibility to EMI. You may want to operate at
maximum strength, but the presence of EMI may make this impossible, so if
you experience erratic behavior or "false" signals, reduce the sensitivity.

HEADPHONE JACK

This detector has a 1/4" headphone
jack.
It works with any stereo headphone
that has a 1/4" plug.
When the headphone jack is
connected, speaker volume is
disabled.
USING
HEADPHONES
Using a detector with headphones
facilitates detection of the weakest
signals and also extends the battery
life.
It also allows you to hear subtle changes in the sound more clearly, particularly
if searching in a noisy location. For safety reasons, do not use headphones
near traffic or where other dangers are present. This device is to be used with
interconnecting cables/headphone cables shorter than three meters.
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