Heath Consultants Magna-Lock - Manual (Page 3)

3
Theory of Operation
The Magna-Lock locator finds ferromagnetic objects by
sensing the magnetic field radiated by the object. The loca-
tor contains two sensor coil assemblies that are precisely
spaced and electronically balanced to achieve a near mag-
netic balanced operating condition. In a uniform magnetic
field, such as the earth’s field, the two sensor coils maintain
a magnetic balanced status, because both of the coils expe-
rience the same magnetic lines of force. However, when a
ferromagnetic object is approached the field strength and
angle of the magnetic lines upon each sensor is different.
This difference, although minute, is enough to offset the criti-
cal balance and produce an audible indicating signal.
When no ferromagnetic objects are present, the speaker
emits a steady low frequency tone. As the object is ap-
proached, the audio frequency increases until the center of
the object is directly beneath the locator’s lower tip. The fre-
quency peaks and then decreases as the object is passed.
The peak indicates the exact location of the object.
Nonferrous objects do not effect the locator. Objects
made of brass, aluminum, copper, etc. are ignored.
Sensor coils unbalanced by iron stake’s magnetic field.