Smartphone function generator review

[BinaryMike]

At Elektor magazine's website: https://www.elektormagazine.com/news/review-function-generator-in-the-pocket

The squarewave ringing complaint is likely down to audio filter performance of the phone used for testing. Other phones might do better, but perfect squarewaves are unlikely from this type of hardware.

 

[elnaldo]

Square waves from both of my phones, very different devices, running 2 different softwares, look +- like the 3rd graph in this image:

I use this app (NO AFFILIATION), I find easy to use the "presets" where you change the freq on the fly, and it allows custom freqs, also goes very low, 25Hz, useful to center Voice Coils when refoamung a woofer, but it lacks of 2 channels
https://play.google.com/store/apps/details?id=net.digitalantics.android.tonegen&hl=es

And this one (NO AFFILIATION), my preferred one, since you have 2 channels and allows phase shift ( I use it to generate balanced signals, same signal 180º reversed), but it goes down only to 250Hz, and no custom freqs.
https://play.google.com/store/apps/details?id=de.guentherkrauss.audio.audiotesttonegenerator

 

[pdm4606]

I especially like the RPM indicator for my iphone. Just lay the phone on the TT and wahha!!........ it tells you the RPM.