Remanent magnetism in homemade Fluxgate sensor

[John]

Hi all...
A little mentioned item in literature and published experiments seems to be magnetization of the fg sensor. I am experimenting with a fg sensor, but found that approaching (near enough) with anything magnetized seems to leave the core magnetized.
Is there a solution for this? I'm not entirely sure why this happens - I am saturating the core in both directions, shouldn't the magnetization disappear?
Thanks in advance for pointers.
John

[Glen Atwelll]

Re: Remanent magnetism in homemade Fluxgate sensor

I spotted the solution to your problem while researching sensors for my own problems... REVERSE the direction of the Current from time to time.... I found this was being done is smaller sensors.....
""The flipping coil periodically applies brief (3 to 5 µs) magnetic pulses to the sensor, first in one direction, then the other, which 'flips' over the output characteristic of the sensor (which is bi-stable). After rectification and smoothing, the time-averaged output signal is then free from sensor offset. The compensation coil uses an electromagnetic feedback loop to ensure the sensor always operates at its 'null-point', where both sensor offset and signal characteristic are unaffected by temperature fluctuations. ""
Hope this helped...



sources