LED Music Visualizer (Project 0030)

by Lucas Demetriades

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Project Overview

This project adapts work by @saminecca and @LEDartist documented on Instructables.com to construct a simple music visualizer via high-pass filter, band-pass filters, and LEDs. Digital audio is converted into an analog signal to represent frequency (pitch) by color and amplitude (volume) by brightness.

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Tools and Materials

• Circuit Board
• 9 volt power supply
• Jumper Cables
• Three 100Ω resistors
• One 10μF capacitor
• Two N4148 diodes
• Four 10kΩ resistors
• One 2N3904 transistor
• Five 1μF capacitors
• Two 500Ω resistors
• Three 2N3906 transistors
• Six LEDs
• Two 1.5kΩ resistors
• One 180Ω resistor
• One 10kΩ resistor
• One 270Ω resistor

Project Files

Step-by-Step Instructions

Construct the audio input. These components account for input impedance and possible DC offset.

Construct the audio amplifier. This will amplify the signal such that it is useful to the proceeding functional blocks.

Construct the high-pass filter. This will filter for only high frequencies, which will light according to the volume of high-pitch notes from the input. The cutoff frequency should be 300kHz.

Construct the medium band-pass filter. This combines a low- and high-pass filter to filter for only medium frequencies, which will light according to the volume of medium-pitch notes from the input. The low cutoff frequency should be 100Hz and the high cutoff frequency should be 300Hz.

Construct the low band-pass filter. This combines a low- and high-pass filter to filter for only low frequencies, which will light according to the volume of low-pitch notes from the input. The low cutoff frequency should be 15Hz and the high cutoff frequency should be 100Hz. Congratulations!