Publication · 2025

Analog Audio Spectrum Analyzer with Sallen-Key Filters and LED Drivers

Original design and testing of a two-band analog audio signal analyzer using filters, peak detection, and LED indicators.

Joshua Parr · UVA ECE 2600 Electronics · Undergraduate electronics technical report

Engineering problem

Separate audio into bass and treble bands to illuminate LEDs proportionally to each band’s signal level.

Design and tests

The original report describes second-order Sallen-Key filtering at approximately 320 Hz and 640 Hz, peak detectors, analog and PWM LED-driver stages, and component selection using Python, circuit calculations and Multisim simulation. Experiments used Analog Discovery 2 with WaveForms.

Evidence

Download the original report. This is a student engineering project and its reported results should not be generalized beyond the documented test conditions.

Scope and limitations: Original course project, not a peer-reviewed study or a calibrated commercial audio instrument.