Speaker with LED Connections

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A project I have worked on is a proof-of-concept light show with music. Using some knowledge from my circuits classes, I wanted to create a display which would light up in response to music being played through it. I went through several prototypes before I found a circuit which would work. For my audio input, I used the output of an electric guitar. This amplified signal would first be fed through an array of LEDs in parallel and then in series with a small speaker so that the music could be heard as well as the lights seen. 

The end result is that the lights flash on and off (and brighter/dimmer) as the music gets louder and softer, respectively. This is because the LEDs have a voltage threshold below which they will not light up, and an operational range in which they will get brighter until their brightness is maxed out. Another interesting result is that the audio signal through the speaker is distorted because the diodes act as half-wave rectifiers to the alternating-current signal from the amplifier. I have plans for a follow-up project in which differently colored LEDs will light up in response to different frequencies (and therefore musical notes) being played. Another improvement could be to put the speaker in a resonant housing to boost the sound output.

I came up with the idea for this project myself but once I did a little research I was inspired by some similar projects I saw online. In the course of doing this, I learned some things about testing a project. My prototypes had differing combinations of series and parallel LEDs as well as different places for the speaker. I also learned about signal power and how even once amplified, the signal’s energy can be depleted by fairly low-power devices. I saw first-hand how the voltage drop across the LEDs could reduce the power such that the speaker would not make sound.  This project was a good learning experience and I see it as a precursor to more advanced audio projects I might try in the future. There was a lot of satisfaction for me in making something that I could interact with so much.

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