Product Manual

Magna-Trak 200 Series Magnetic Locator • 3
2. THEORY OF OPERATION
The locator finds ferromagnetic objects by sensing the magnetic field radiated by the
object. The locator contains two sensor coil assemblies that are precisely spaced and
electronically balanced to achieve a near magnetically-balanced ≠operating condition.
In a uniform magnetic field, such as the earth’s field, the two sensor coils maintain a
magnetically-balanced status, because both of the coils experience 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 critical balance and produce an
audible ≠indicating signal (Fig. 1).
When no ferromagnetic objects are present, the speaker emits a steady low
frequency tone. As the object is approached, the audio frequency increases until the
center of the object is ≠directly beneath the locator’s lower tip sensor. The frequency
peaks and then decreases as the object is passed. The peak indicates the exact
location of the object.
Nonferrous objects do not affect the locator. Objects made of brass, aluminum,
copper, etc. are ignored.
Fig. 1
Sensor coils unbalanced by magnetic field of iron stake.