just occurred to me you might maybe be able to use the magnetometer to get some measurement of strong EM - I'm doubtful though xD
I don't know the specs of cell-phone magnetometers by heart, but it seems to me they would be most sensitive around DC, since the Earth's magnetic poles only flip once every two hundred thousand years or so (~ .1 picohertz). Most man made magnetic fields are of much higher frequency than that.
See this funny thread for more laughs.
::Reads linked thread::
Okay I think I vomited in my mouth a bit xD Oh deary-deary-dear! That was magical xD
I tried out five or six "EMF" (which is "Electro-Magnetic Field" rather than electromotive force) apps on my smartphone and was pleased with the results - by which I mean I figured out how each of them worked and it doesn't involve electromagnetic fields...
The test setup was simple: set the phone up, watch the screen, and then deliberately introduce EMF on different frequencies.
A DC bulb, an AC bulb, a VHF radio at 4W (distance of 1 meter), UHF radio at 4W (distance of 1 meter) done nothing except make the speakers on my computer make a "BOOP" noise.
It was the only proof of any EMF I had anywhere...
It would seem that the apps use a mixture of the various sensors in your phone to make a pseudo-random number.
-Barometer: higher pressure = higher readout (confirmed by putting my phone in a jar and increasing the pressure)
-Accelerator: moving the phone forward then back causes a "spike" in the readings
-Magnetometer: rotating it causes a decrease in the readings
-Microphone: some of the apps used sound to change the figure (constant sound = decrease EMF, silence = decrease reading: sudden sound = increment substantially, sudden quiet = decrements substantially)
-Random Number God: the number drifts over time
The funny thing is if you combine these, you could probably get a very accurate indication of where the user
thinks EMF is in their house (it's whatever they waved their phone near
![Wink ;)](https://www.eevblog.com/forum/Smileys/default/xwink.gif.pagespeed.ic.cldandycH0.png)
)
The best part about these apps is the sheer number of reviews raving about how accurate the readings are... it's a classic reporting bias with a nice little bit of detection bias and some sampling bias layered on top! Which is a fancy way of saying "only people who believe in EMF poisoning bother downloading the app - normal people haven't heard of EMF - and people who actually
know a little about EMF ignore it!"
The sad thing is that I'm not convinced that downloading and testing these apps wasn't a total waste of my time
![Popcorn :popcorn:](https://www.eevblog.com/forum/Smileys/default/EatingPopcorn.jpg.pagespeed.ce.yJ6TmC5fSa.jpg)
If I were nefarious
![Evil >:D](https://www.eevblog.com/forum/Smileys/default/xevil.gif.pagespeed.ic.tdrs7Uj5gu.png)
I'd totally make a little wideband scanner so that EMF-junkies can spot sources of EMI... This idea popped into my head because I picked up a new Uniden UBC3500-XLT Scanner today, and I just discovered that it:
a) can be tuned to my computer monitors (which apparently emit EMI at some multiple of 134.450 MHz)
b) the demodulated audio ("buzz-uzz-uzz-uzz") changes depending what is being displayed on the monitor
The EMF "Ghost" Detectors are actually a pretty ingenious scam - and a good example of using the Divine Fallacy (I can't explain why there is EMF here, therefore it must be something supernatural) to garner money from people with poor critical thinking skills.
I wish I'd thought of it
You know... I could probably make a black-box with a bunch of sensors (humidity, light, motion, pressure, temperature, maybe a rudimentary direction-finding antenna (mounted backwards for the lolz)) and market it as a ghost-finding unit... only I'd probably give it a touchscreen so you can log your trip, and more importantly, so it can double as a weather-clock/media center for non-ghosthunters......)
Hmm, maybe I should turn my moral compass off for a week or two, make a ton of cash, and then turn it back on... and admit that it's not a ghost detector, but actually an overly-enthusiastic low-end weather station
And finally, I leave you with......... the
Harmony ChipIt combines crystal healing with EMF protection. Clears electro-smog, most chronic health problems, pacemakers? (how can you "heal" a pacemaker?), body hair (excess OR not enough - it knows what you want) and my favourite - and the reason I'm going to buy a hundred of them - it even cures "Anger"
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/xfacepalm.gif.pagespeed.ic.EBDwh1hCfo.png)
Only $180.