White’s Electronics Spectra VX3 - Manual (Page 13)

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Spectra VX 3 User’s Guide
To replace the batteries, slide open the battery holder lid by gen-
tly lifting the tab.
A fresh set of alkalines will operate VX 3 for about 7-8 hours
with no backlight. Use of the backlight will reduce battery life.
When you first power-up VX
3 a start-up screen will display
briefly with the battery voltage at the bottom. During operation,
if the battery voltage drops below 8 volts a low-battery icon will
display in the status bar:
You can also check the voltage at any time by selecting Back-
light,VIEW from the Live Control Bar, or pressing
MENU+ENTER to bring up the Info screen.
VX 3 automatically powers off if no activity occurs in a 20
minute time span. Activity is defined as the use of the keypad or
the trigger switch.
The Basics of VLF Operation
VX 3 is a multi-frequency (MF) induction-balance (IB) very
low frequency (VLF) transmit-receive (TR) metal detector. In
order to understand what all the user adjustments do, it is
important to have at least a rudimentary understanding of how a
modern metal detector works.
Metal detectors work on the principle of induction, discov-
ered by Michael Faraday in 1831. The typical induction-balance
metal detector
1
uses a transmit coil to produce a magnetic field,
and this magnetic field in turn produces a small reaction in
nearby metal targets. A receive coil is used to detect this small
1. The first practical metal detector was an induction-balance
design, built by Alexander Graham Bell in an effort to locate an
assassin’s bullet lodged in US President James Garfield. He
failed — not enough sensitivity. Ever since then, “more sensitiv-
ity” has been the goal of every detector.