Build a Larson Scanner with Sound Using an ESP32 -- Episode 670

Join Mark as he builds a customisable Larson scanner using an ESP32, complete with synchronised Cylon-inspired sound effects. The project supports 12 to 50 WS2812 LEDs and uses four potentiometers to adjust brightness, speed, tail length, and LED count. Sound is driven by an I2S audio board and a surface-mounted speaker. It’s all powered via USB and programmed easily through a browser—no Arduino IDE needed. Perfect for cosplay, props, or unique lighting effects

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Build a Larson Scanner with Sound Using an ESP32 -- Episode 670

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A Classic Effect with a Modern Upgrade

In this project, Mark builds a Larson scanner—an animated LED effect made famous by Knight Rider and Battlestar Galactica. Unlike many similar builds, this version includes synchronised sound effects, bringing an extra layer of authenticity to the visual sweep of the red “eye.” The project is customizable, allowing users to modify the number of LEDs used, brightness, animation speed, and tail length, making it suitable for a wide range of applications from cosplay to home decor.

ESP32 and Audio Integration

At the core of the build is an ESP32 development board—specifically one that supports dual-core processing. One core handles the LED animation, while the other plays the Cylon sound effect. The sound is generated through an I2S audio board connected to a speaker or speaker exciter, which vibrates a surface to act as a large resonating speaker. This unique approach allows for louder, more immersive sound without requiring a high-power amplifier.

LED Control and Hardware Configuration

The LED output is controlled via a WS2812-compatible LED strip, which can range from 12 to 50 LEDs depending on availability and desired size. Four 10kΩ potentiometers are used to adjust the setup: one for brightness (marked with an 'X' for easier access), one to set the number of LEDs, one to control the sweep speed, and one to set the length of the light "tail" left behind during animation. A single 330Ω resistor is included in the circuit, and the assembly is built on a breadboard with standard wiring.

Browser-Based Programming and Setup

Programming the ESP32 is straightforward. The firmware can be installed directly via a web browser interface, avoiding the need for a traditional Arduino IDE setup. Once connected via USB, the board can be flashed using Chrome or Edge. The Arduino sketch provided below supports real-time configuration through the potentiometers, making fine-tuning immediate and easy without needing to recompile or reflash the firmware.

All Done!

With the added sound feature, this Larson scanner project offers a richer and more complete experience than LED-only versions. You could say, that it's fully KITT'ed out! If you build your own version or make modifications, share them in the comments below!

Supporting Files and Links

• ESP32 Board Library
• Web Based Flash Programming
•  Episode 670 Resources 

Bill of Materials