The coolest thing I ever did with that was finding wires in a friends wall - we needed to drill a hole and it was unclear whether the wires went up (problem) or right from the outlet. I didn't have a cable finder on hand but did have the epiphany to put a large load on the outlet (we used a kettle, a hairdryer would also work, just needs a lot of watts) and use the Fourier transform magnet spectrum to find the 50 Hz grid frequency in the wall. Worked beautifully.
Sadly, since most smartphone magnetometers seem to have a sample rate of 100/s, this will not be applicable to Americans and everyone else with a 60 Hz grid frequency, the 50 Hz were already at the Nyquist–Shannon limit.
gus_massa 12 minutes ago [-]
> this will not be applicable to Americans and everyone else with a 60 Hz grid frequency, the 50 Hz were already at the Nyquist–Shannon limit.
The trick should work fine, but you may confuse the 60Hz signal with a 40Hz signal [1] [2].
This should work for higher frequencies too, but if the frequency is toooo high the problem is that the magnetometers averages a short period of time (or use a window) instead of being an actual an instant measurement.
[1] Calculated using my fingers moving in the air. 60=50+10 -> 50-10=40. I think it's 40Hz, but I would need a pencil and paper to be sure.
> However on android the sampling rate of the acceleration sensor is limited to 50/s. At least if you install through the official app store.
My understanding is that it’s the same even on iOS (or at least on my iPhone SE 2020). More specifically, the output only measures till 50hz (but the sensor sampling rate is actually 100hz - Nquist, you need double the measured frequency as sampling frequency, yada yada.)
user_7832 50 minutes ago [-]
By the way, it’s important to note that measuring vibrating things can permanently damage the OIS VCs in the camera. (See: Apple’s warning against motorcycle mounts.) my iPhone already had a broken OIS so I didn’t mind as much.
OuterVale 13 minutes ago [-]
I've had great fun using Phyphox to visualise my hand getting closer/farther from my phone based on the presence of my magnet implant. So many cool little things the app can visualise and measure, especially when used it creative ways.
samch 2 hours ago [-]
One of my kids has science project due each quarter in school, and this is our go-to app. We’ve measured acceleration in an elevator, sound attenuation of an audio source in a small vacuum chamber, and the Doppler effect. The app makes it easy to capture and export the data points to make graphs. I highly recommend this even just to play around with.
perlgeek 1 hours ago [-]
I used it just the other day.
My parents have a sound bowl, and I wanted to know the resonance frequency. Took an audio spectrum, zoomed in on the first peak, read the frequency (iirc it was around 208 Hz).
Good toolkit to have around. Recently used it to verify the true RPM of a system (using the accelerometer spectrum tool) against its control loop implementation.
TeMPOraL 2 hours ago [-]
Indeed. I always keep it installed on my devices, as it turns the phone into a poor man's tricorder, and that's handy sometimes.
Most recently I used it to check light levels at home in different rooms, to determine where we need to boost or replace LED strips. Sure, there's million Lux meter apps, but Phyphox is better than all of them and demonstrates why these things shouldn't be dedicated apps in the first place. In the past I also made use of EM and vibration frequency displays to troubleshoot hardware.
A complement to that is https://play.google.com/store/apps/details?id=org.intoorbit.... which, once upon a time, helped me track down a source of rage-inducing, late-night high-frequency beeping that was driving us insane - down to specific apartment in a block on the other side of the street. I ended up friends with those neighbors, after teaching them how to disable the alarm clock on their Bluetooth radio when they go away for a weekend.
_Microft 5 hours ago [-]
The title was slightly editorialized for clarity.
takahitoyoneda 19 minutes ago [-]
[dead]
henryAlbigale 4 hours ago [-]
Cool app dude
Rendered at 13:33:36 GMT+0000 (Coordinated Universal Time) with Vercel.
Sadly, since most smartphone magnetometers seem to have a sample rate of 100/s, this will not be applicable to Americans and everyone else with a 60 Hz grid frequency, the 50 Hz were already at the Nyquist–Shannon limit.
The trick should work fine, but you may confuse the 60Hz signal with a 40Hz signal [1] [2].
This should work for higher frequencies too, but if the frequency is toooo high the problem is that the magnetometers averages a short period of time (or use a window) instead of being an actual an instant measurement.
[1] Calculated using my fingers moving in the air. 60=50+10 -> 50-10=40. I think it's 40Hz, but I would need a pencil and paper to be sure.
[2] https://en.wikipedia.org/wiki/Aliasing
In Germany phyphox is quite popular in physics education.
However on android the sampling rate of the acceleration sensor is limited to 50/s. At least if you install through the official app store.
[1] https://iopscience.iop.org/article/10.1088/1361-6552/aac05e
My understanding is that it’s the same even on iOS (or at least on my iPhone SE 2020). More specifically, the output only measures till 50hz (but the sensor sampling rate is actually 100hz - Nquist, you need double the measured frequency as sampling frequency, yada yada.)
My parents have a sound bowl, and I wanted to know the resonance frequency. Took an audio spectrum, zoomed in on the first peak, read the frequency (iirc it was around 208 Hz).
The interface is more polished, but the information is less technical than Phyphox (as the app is geared towards being a survival toolkit).
[0] https://github.com/kylecorry31/Trail-Sense
Most recently I used it to check light levels at home in different rooms, to determine where we need to boost or replace LED strips. Sure, there's million Lux meter apps, but Phyphox is better than all of them and demonstrates why these things shouldn't be dedicated apps in the first place. In the past I also made use of EM and vibration frequency displays to troubleshoot hardware.
A complement to that is https://play.google.com/store/apps/details?id=org.intoorbit.... which, once upon a time, helped me track down a source of rage-inducing, late-night high-frequency beeping that was driving us insane - down to specific apartment in a block on the other side of the street. I ended up friends with those neighbors, after teaching them how to disable the alarm clock on their Bluetooth radio when they go away for a weekend.