Transducer

As a pianist, I produce a lot of noise when practicing everyday. I wanted to test if I could harness this sound to generate electricity. To do this, I decided to try to reverse a speaker's electromagnetic induction. Instead of an AC signal inducing an oscillating magnetic field, which then interacts with a permanent magnetic to move the voice coil, and consequently, the speaker cone, I wanted to induce, then amplify an AC signal from sound vibrations that move the cone, then use it to power a circuit.

1. 8 in loudspeaker
2. 110v to 12v AC transformer
3. 4 1N4148 diodes
4. 1 capacitor (0.001F)
5. 2 LEDs
6. Sound Generator (https://onlinetonegenerator.com)
7. Decibel Meter (App on iPhone)

Because the transformer is a step down transformer, I connected the output leads (12v) to the woofer and the input leads to the multimeter.

I attached four diodes, a resistor, and capacitor to the transformer to rectify the signal into a DC voltage.

I played sounds at different frequencies and different loudness to test the optimal frequency for generating the biggest voltage with the 8-in woofer. 40 Hz seems to be the most optimal.