Modem ? strange circuit sound
The coil, magnet and foam act like a speaker, producing quite the loud tone, ideal for the experiments I was doing.
What wasn’t expected, was how the different output tones from the Arduino and variable pot would make it sound a bit like a modem !
This sort of thing could be useful for amplifying tones, rather than building an audio amplifier.
To replicate, all you have to do is run loop code that will output to a pin at say 100-1000Hz. The coil is 450 turns of approx 42AWG wire wrapped around a drinking straw, magnet is a small neodymium and the hinges are bits of floppy disk material (tape would work just as well). The ability to vibrate within the coil is what creates the noise.
Maybe the tone adjustment pot is dirty in that one spot, I don’t know 🙂