| T O P I C R E V I E W |
| emfMonk |
Posted - 12/08/2018 : 22:37:00
hello,
im new here. i used 390 model to detect radiation levels at home.
I got high EF reading with constant beeping, says "Static" (range 30 to 200 V/m, 2 inches from the wall) from the wall behind the headboard of my bed. Im not sure what is causing this. There is nothing on the other side of the wall. May be some electric wiring within the wall is causing the spike in the reading. There are 2 electric outlets and a desk phone outlet on the wall, but none in use.
I have disturbed sleep, was wondering if this may be the reason. Can anyone help throw some light on safe EF reading for home.
EMF and RF reading are normal.
Thanks in advance
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| 12 L A T E S T R E P L I E S (Newest First) |
| EmfDev |
Posted - 08/16/2019 : 16:11:43
That's right the static charges from the body is transferred. The unit has it's own ground. |
| Eric Potratz |
Posted - 08/16/2019 : 15:42:08
Hey EfmDev, is it a differential probe?
I'm trying to get a sense for exactly what EF the probe is measuring. Potential difference between the top and bottom of the device?
I understand that holding the device amplifies the detected EF. If there is no grounding through the hand, perhaps the higher V/m reading is a skin effect (ie., transfer of charge or radiative field) over the body? |
| EmfDev |
Posted - 08/16/2019 : 15:18:06
It's not single-ended probe and it it won't be grounded while holding it. |
| Eric Potratz |
Posted - 08/16/2019 : 14:12:19
Hey EmfDev,
Is the EMF-390 EF detector using a differential or single-ended probe? If single-ended probe, I assume the ground is the reference, and the ground is exposed to the hand while holding? |
| Bill D. |
Posted - 08/16/2019 : 10:37:31
Hi Eric. You are correct. By static charge I was thinking of charges that build up due to friction or causes other than oscillating current.
The 390 is able to pick up electrostatic fields and in some cases distinguish them from radiative fields. It becomes more sensitive when there is relative motion between the charge and the meter. So if I hold a charged comb by the meter I may get 30 V/m. But if I wave it (or the meter) rapidly the reading may rise to more than ten times that much. The same thing happens with magnetic fields. A moving magnet causes a much higher reading than a stationary magnet. |
| EmfDev |
Posted - 08/16/2019 : 09:59:02
Hi Eric, it might be able to distinguish static from oscillating EF. It will display possible sources on the screen.
I believe it should be able to detect EF up to 100-400kHz but low sensitivity in that range. |
| Eric Potratz |
Posted - 08/16/2019 : 09:51:19
Hey Bill,
Makes sense, but I don't look at the buildup of charge or self-capacitance as any different than static charge. The "near field" (NF) as just the transition from charges at rest to charges in motion (static field > radiant field) where the electric and magnetic fields are not yet balanced/synced.
I originally meant to ask, how do the GQ device(s) detect electric field (EF)? Is the EF sensor able to distinguish static fields and radiative fields? If picking up both static and radiative charges/fields then I imagine there is a frequency (>200Hz?) by which the EF sensor won't pick up the electric field?
My EMF-390 arrives next week so I haven't had a chance to compare it with my electrostatic field meter yet... |
| Bill D. |
Posted - 08/16/2019 : 09:01:53
Electric fields around AC wires, appliances, and antennas are caused mostly by the near field effect and self-capacitance. This is different than a static charge and is not necessarily accompanied by a magnetic field. Near fields do not behave like RF fields. They have their own rules.
See (search for "near field" or "near-field" in these docs):
https://en.wikipedia.org/wiki/Near_and_far_field
https://www.edn.com/design/sensors/4342455/Understanding-electromagnetic-fields-and-antenna-radiation-takes-almost-no-math
https://www.researchgate.net/profile/Bertil_Persson/publication/236163732_Radiation_at_Home_Outdoors_and_in_the_Workplace/links/0c960516a5d0bb9946000000/Radiation-at-Home-Outdoors-and-in-the-Workplace.pdf |
| Eric Potratz |
Posted - 08/15/2019 : 18:40:08
Is the electric field (EF) measuring the static charge that the sensor is pointing at? Are these devices using a rotary shield like an electrostatic field meter? Thanks. |
| mbrando |
Posted - 12/23/2018 : 17:56:11
I noticed that I see high V/m near radio antenna, however it drops off quickly inch by inch as you move away from it. A 6 to 12 inch distance can make a difference in your reading. |
| EmfDev |
Posted - 12/11/2018 : 21:24:10
Maybe try to move your bed away from those outlets to see if there's improvement in your sleep. |
| EmfDev |
Posted - 12/11/2018 : 21:23:01
Static could mean that there is EF but there is very little to no EMF detected by the device so there might not be current around the wall but there can be EFs from the outlets/wiring. The EF could be coming from there. It can still have EF even if its not in use because of the voltage. |
