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I want to measure magnetic fields with my oscilloscope, so I need a magnetic field sensor / probe.

My oscilloscope does a FFT for 50Hz to 2MHz.

The sensor should be 3D, because I don't care for direction. The sensor should be sensitive enough for measuring human exposure at computer workstations.

I have read that a Hall effect sensor should do this and is fairly easy to drive, which would explain why I haven't found any good ready to use sensors in the internet.

My search coil tends to be very sensitive at 590KHz, maybe an article about search coil calibration would be helpful.

When choosing a Hall effect sensor,

  1. Do I have to consider my frequency range (50Hz to 2MHz?)
  2. Are all Hall effect sensors sensitive enough for measurements of human exposure at computer workstations (60cm to CCFL screens?
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What you're after is a "B Field Probe". Usually you need to include a low noise amplifier between it and the scope as the signal strength is usually very small.

At their simplest they are just a PCB with a connector and an optional protective coating.

Hall effect sensors may work, but the signal strength would be so tiny I suspect it would put you down in the noise.

I actually suspect for a CCFL screen you may have an easier time with an E-Field probe, as the voltage swings tends to be fairly high.

These sensors are directional, however if you want the 3D value, just rotate the sensor,

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  • \$\begingroup\$ I always hoped B field probes are only for going near to circuitry and there are other sensors designed for distant measuring. \$\endgroup\$
    – Hansebenger
    Commented May 4, 2020 at 9:03
  • \$\begingroup\$ Its usually an antenna by that point, past a certain distance its just EM radiation, you cant separate one from the other. rfcafe.com/references/electrical/near-far-field.htm \$\endgroup\$
    – Reroute
    Commented May 4, 2020 at 9:06
  • \$\begingroup\$ For 50Hz to 2MHz it's quite a distance to far field. I have also read that B field probes don't receive this frequency well, so a explanation why B field probes are better than Hall effect sensors for this would be great. \$\endgroup\$
    – Hansebenger
    Commented May 4, 2020 at 20:32
  • \$\begingroup\$ Where can I get a B field probe? A quick google search, amazon search, digikey search didn't yield anything. \$\endgroup\$
    – Joseph Summerhays
    Commented Apr 1 at 0:34
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  1. Even good Hall Effect sensors are only up to 200kHz and yes you have to consider, often the rise time is specified.
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