Low frequency noise (vibrations) have better production. The Bass drum and a woofer will sympathetically resonate with each other. If the coupling is tight enough ( we streached the bass-drum over the speaker, forming a resonant cavity.
Apart from some weird sound effects and goose-pimples, The dual led did dance nicely with both colors red and green (AC !)
Higher Audio freq nort good .
Try this: 1. clamp a Hack-saw bladeto a 2x2 block.
2. Pull out the solenoid in a relay and fix it below the free end of the blade.
3. Find a Hard disk and murder it for the magnets. Fix the magnet to the relaycoil iron core, at the bottom.
4. connect a dual Led , 2 leads to the coil terminals.
5. Twang the blade, making sure it doesnt touch the coil iron.
6. Watch and have fun :lol: :lol: