2
In theory, this number will not change when the probe is reoriented in a different direction. In practice, the reading
will often change somewhat whenever the probe direction is reoriented. This problem occurs if the meter is either not
properly “zeroed” or if the probe is near a small magnetized object which has a field that is not uniform across the
thickness of the probe. (As shipped, the meter is properly zeroed to /- 0.10 gauss for each of X,Y,Z. Methods
for altering and checking the meter zero are described later.) The field is not uniform if its source is a small part or if
the field is strong only in a region that if a few millimeters wide. If you find a location on a magnetized surface where
the field very strong and then move the probe away a few mm, the reading will not change much if the field is
uniform. If the field magnitude instead changes by more than a factor of two over a distance of a few mm, then it is
not uniform and it is more difficult to read consistently with a probe that is about 6 mm wide.
Polarity of the probe:
The X,Y,Z sensors read positive when the north pole of a magnet is pointed toward them.
That is, if a magnet is placed on the right side with its north pole pointing to the left in the image above, then if the
“View” button is pressed so that Z is displayed, the number shown will be positive (no negative sign will be present).
If the magnet is then turned 180°, the number will become negative. Note that a south pole that is pointed toward the
Z face will produce a negative value for Z. Also, if the Z face is pointed toward the Earth north pole, Y will read
negative
-- the Earth
north
pole is actually the
south
pole of a magnet.
Alarm:
The alarm will sound (and a red light will appear from under the label) when the magnitude of the field
exceeds a level that you set. The alarm will never sound or light unless you set a level, and it will not sound or light
when muted (by setting it to 0.00). It will also become muted whenever the meter is turned off and back on. To set a
level, Press
and continue to press
“Alarm Set”. The level will be displayed (initially 0.00) and can be changed by
turning the OFFSET knob. Clockwise increases the number; counter-clockwise decreases it (one click CCW from
0.00 is the highest alarm level: 790.00 gauss; more clicks CCW will decrease that level). At any time, the level can
be directly reset to 0.00 (muted) by pushing
down
on the OFFSET knob while pressing “Alarm Set”. Once “Alarm
Set” is released, the level will be remembered and can be modified later by pressing and holding “Alarm Set” again.
There are about 100 different alarm levels that can be selected, from 1.00 to 790.00 (these values will be obvious).
The alarm will produce sound and light only
during
the times that the magnitude exceeds the level you had set, and a
delay of about 5 milliseconds is required for the alarm sound to begin. There is about a 5 millisecond lag (after the
