Bluetooth Speaker Tech: DIY LED, Touch

Enhancing the user experience of our Bluetooth speaker, we've implemented a set of innovative features. To adjust volume and change tracks, a tactile button interface is incorporated. The utilization of LED backlighting not only ensures visibility in low-light conditions but also introduces a sophisticated sensor circuit. This circuit intelligently adapts the backlight brightness to an ultra-low level during nighttime use, mitigating any discomfort caused by excessive glare. The decision to prioritize the production of the button board is based on its simplicity and efficiency.

Examining the front side of the prototype PCB reveals strategically positioned button patterns without a solder mask layer. This design choice facilitates light transmission, contributing to an aesthetically pleasing and functional device:

Turning the attention to the back side, a distinct section in the bottom left corner accommodates additional circuitry essential for the assembly:

Post-soldering, the back side exhibits a professionally assembled and integrated circuitry:

The functionality of the device is augmented by the BS816 6-button touch control chip, specifically designed to detect and respond to five touch-sensitive buttons.

A subtle yet crucial element is the front-facing light sensor, seamlessly integrated into the PCB without protrusion:

This light sensor, coupled with a delay circuit, ensures a gradual adjustment of the backlight. After a brief period of ambient light reduction, the backlight dims to prevent abrupt changes that may occur when interacting with the touch-sensitive buttons:

Fine-tuning the user experience, two potentiometers are employed for brightness and dim light threshold adjustments:

Upon powering the device, eight backlights illuminate. However, meticulous attention to detail reveals uneven light distribution:

To address this, we repurpose a backlight board salvaged from a damaged smartphone screen. This component, once cut to size, is seamlessly integrated above the button board. A final touch involves applying copper foil to the back, ensuring a uniform and controlled light emission:

Achieving a harmonious light distribution, this modification enhances both aesthetics and functionality:

Completing the design, the touch buttons are precisely sized for optimal user interaction:

In environments with limited ambient light, the intelligent dimming feature ensures that the backlight does not disturb sleep:

For a comprehensive understanding of the device, refer to the circuit diagram below. The impedance transformation achieved on the left, coupled with a first-order RC low-pass filter, ensures precise control over the backlight's brightness. This innovative approach delivers an optimal user experience: