Hi forum,
I'm trying to build a simple LED bracelet that would light up when (very loud) ambient music has
lots of bass in it (for example, when the beat 'drops').
However, I encountered the problem where the microphones in my junk bin are all 'telephone' grade ones -
that meaning with a small bandwidth, most likely outside the range of 20-200Hz.
I started wondering if I could use some reed switch to register the sound, but it seems reed switches
have a resonant frequency of about 8kHz.
Can you propose a sensor to be used, seeking maximum simplicity and low energy consumption?
(you may have guessed that I'm building a glowing party bracelet and the overall size is the main limiting factor)
Thanks!
Maybe a place to start would be designing a mechanical circuit that has a resonance peak near the range you're interested in? You'll want something with a large surface area that can be sensitive to bass vibrations, without being affected by body motion.
If you can create a mechanical surface that's sensitive enough to the bass, you may be able to pick up those vibrations with piezo.
Use an electrect microphone capsule which should be fairly sensitive to bass.
... and a low pass filter ... etc.
Here is the frequency response of an ordinary electret mic. It goes lower than 20Hz but the graph stops at 25Hz. A cheap one measures a little different at high frequencies.