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Mugless
Australia
11 Posts |
 Posted - 06/28/2020 : 06:34:11
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Hi GQers,
A typical EMF reading in my room with nothing but my laptop running = 1.5 mG = 0.15 microT.
The Earth's field ranges between approximately 25 microT and 65 microT, or, 250 mG to 650 mG.
It appears as though the GQ 390 is not measuring the 'background' earth's magnetic field.
Please can someone explain what is happening with the readings?
Thank you.
Douglas
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| Reply #1
EmfDev
2142 Posts |
Posted - 06/29/2020 : 09:09:55
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| The Earth's field is not electric, and thus wont produce current for the EMF sensor to detect. EMF meters cannot measure the Earth's magnetic field. |
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| Reply #2
Bill D.
USA
46 Posts |
Posted - 06/29/2020 : 11:02:12
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You can induce an electric current in the EMF sensor by moving it rapidly through any stationary magnetic field. But this will not give you an accurate measurement (you would need a Gauss meter). The instructions for the Trifield Natural EM Meter explain:
"the meter reads any change in the magnetic field caused by rotating the meter in the Earth's magnetic field, by a moving magnetic object, or by DC currents carried by wires or the atmosphere. The Earth's field strength is about 50 microteslas (500 milligauss), so rotating the meter from north to south rapidly (within a 0.5 second interval) causes a momentary reading of about 100 (a change from -50 to +50). If subsequently held still, the needle will settle back to zero. For the best readings of transient fields, the meter should be placed on a stationary platform because of sensitivity to slight rotations while hand-held."
The highest reading I can get on the 390 using this technique is about 4 mG in Ohio (the change, I presume, would be 8 mG [-4 to +4]). |
Edited by - Bill D. on 06/29/2020 12:08:33 |
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| Reply #3
Bill D.
USA
46 Posts |
Posted - 06/29/2020 : 14:45:18
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| To show how delicate this measurement is, I attempted it again without wearing my watch and the reading never reached 3 mG. When you move the detector near or across a quartz watch, the response is significant. |
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| Reply #4
Mugless
Australia
11 Posts |
Posted - 06/30/2020 : 22:15:50
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quote:
Originally posted by EmfDev
The Earth's field is not electric, and thus wont produce current for the EMF sensor to detect. EMF meters cannot measure the Earth's magnetic field.
Thx EmfDev.
Well, that was silly of me!
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| Reply #5
Mugless
Australia
11 Posts |
Posted - 06/30/2020 : 22:17:54
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Thx Bill,
That all makes perfect sense.
Doug |
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Topic |
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EMF readings and earth magnetic field
