The Story

CosBox began as an ambitious attempt to recreate the iconic Stormtrooper voice using real-time digital audio processing. The original design combined an ESP32, an I2S MEMS microphone, a high-quality Class-D amplifier and a wireless glove controller to transform the wearer's voice while also playing character sound effects.

After months of development, the system performed exceptionally well on the workbench. However, real-world troop events revealed a challenge that many costume builders will recognise: once sealed inside a plastic helmet, the close proximity of the loudspeaker and microphone created severe acoustic feedback that proved impossible to eliminate consistently.

Rather than compromise reliability, the project took a different direction. The live voice changer was replaced with a powerful wireless sound playback system capable of instantly triggering a virtually unlimited library of MP3 sound effects from a handheld remote. Running from a single rechargeable 18650 battery, CosBox became a completely self-contained, wearable audio platform that could be installed in almost any costume.

Prototype

Like many successful hardware projects, CosBox didn't begin with a custom PCB. The earliest prototypes were assembled from off-the-shelf development modules to prove the concept and explore the audio processing, wireless control and power management before committing to a permanent design.

As the project evolved, the circuitry was migrated onto Veroboard, allowing the individual modules to be replaced with the actual components intended for the final design. One of the more challenging devices was the Class-D audio amplifier, supplied only in a tiny TSSOP surface-mount package. To evaluate it without manufacturing a PCB, the amplifier was first soldered onto a TSSOP-to-DIP adapter, making it possible to integrate into the Veroboard prototype while thoroughly testing the audio performance and supporting circuitry.

This intermediate stage proved invaluable. It allowed the analogue and digital sections to be refined, the power supply to be validated, and the audio path to be optimised before investing time and money in PCB manufacture.

From Prototype to KiCad

Once the hardware had been proven, the entire circuit was recreated in KiCad. The schematic was captured, components selected, footprints assigned and electrical rules checked before progressing to PCB layout. Careful consideration was given to component placement, routing, power distribution and audio signal integrity to produce a compact board suitable for installation inside wearable costumes.

By following a structured development process—modules, Veroboard, schematic capture and finally a professionally manufactured PCB—each stage built confidence in the design while minimising risk, ultimately resulting in a reliable and compact all-in-one costume sound system.

Originally built for a Stormtrooper, CosBox has since been successfully adapted for Chewbacca, a TIE Fighter Pilot, Ghostface and other character costumes simply by changing the sound library. What started as a voice changer evolved into a versatile, reliable and reusable costume sound system that brings characters to life with professional-quality audio.

One feature the users particularly like, is the profile selector when it starts. This means the user can change their costume and easily select a different character, multiple times in the same day!

Looking back, the greatest success of CosBox isn't the hardware itself—it's seeing it used in the real world. From its beginnings as a collection of prototype modules to a professionally designed PCB powering multiple costumes, the project has continually evolved through practical experience and feedback. I hope sharing that journey, along with the design files and lessons learned, helps others create even more immersive and reliable costume electronics in the future.

Please see other maker projects completed on YouTube here:

 www.youtube.com/@workbenchbycc