8. Control, adjustment and indi ation applian es
The control, adjustment and indication appliances lie on the front (Fig.3) and the back panel of
the electronic control module.
Description of the particular appliances:
1. VOLUME/POWER knob:
- It serves for both switching on/switching off the metal detector and adjusting the audio
volume control. The chosen position from the knob scale (usually between the 3rd and
the 5th level) should correspond to pleasant sounds made by the metal detector, i.e.
that are neither loud, nor uiet.
2. THRESHOLD knob:
- It serves for assigning the necessary audio threshold. It is adjusted with no metal
objects around the metal detector’s search coil and depends on the terrain. The best
depth for finding metal objects is achieved, when the THRESHOLD knob is turned in a
position, corresponding to a uiet “buzzing” sound made by the metal detector in
working mode (makes recurring sound). This mode is suitable for experienced seekers.
The beginners should work at lower levels.
3. NOTCH LEVEL knob:
- It serves for adjusting the detection/rejection level of the contemporary non-ferrous
pollutants (aluminum, bottle/jar covers, foil, silver-paper) and determines the metal
detector’s responses when detecting an iron.
For levels between “0” and “2”, the metal detector detects both non-ferrous and ferrous
metals, and when detecting ferrous metal (iron) it makes double recurring sound, while
when detecting non-ferrous metal – single non-pausing sound. The device detects the
contemporary non-ferrous pollutants (aluminum, bottle/jar covers, foil, silver-paper) at a
varied degree when turned to levels from “6” to “10” and rejects them fully when turned
to level “10” (either detects them when they are shallowly buried or does not detect
them at all).
4. DISCR LEVEL knob:
- It serves for adjusting the detection/rejection level of iron, usually when NOTCH LEVEL
knob is turned to levels from “6” to “10” and for adjusting the depth of discrimination
(the maximum depth to which the metal detector distinguish the metals).
In “0” position, the metal detector makes unaltered sound for all metals, i.e. it does not
distinguish them.
When the level is turned to a higher position, the metal detector starts to distinguish the
metals, and each successive level betters the discrimination, i.e. at level “10”, the metal
detector rejects the iron at an utmost degree and has the maximum depth of
discrimination.
When detecting non-ferrous metals (copper, bronze, silver, gold) it makes deep-toned,
non-pausing sound, while for the ferrous metals (iron) the sound is pausing (recurring).
For levels from “5” to “10”, the metal detector rejects the iron objects at a different
level, i.e. when detecting iron or tin-foil object it is making either no sound or a uiet
pop sound.
The most practical working mode, when searching for non-ferrous metals, are the levels
from “6” to “8”. When detecting unstable (whether its corresponding to a real object)
signal - usually for heavily corroded iron or iron with alloys, the level could be turned to
“10” in order to get more accurate signal discrimination. The surface sweeping of the
particular terrain could contribute to the further improvement of the detecting, because it
results in shortening the distance to the buried detected object.
5. Loudspeaker:
- It serves for producing a sound when an object is detected. The sound is deep-toned
and non-pausing for non-ferrous metals and recurring (repeating) for ferrous metals
(iron). The loudspeaker lies on the back panel of the electronic control module.
