The color music device is fully implemented using transistors. Transistors T1 and T2 operate as a microphone preamplifier, with microphone sensitivity adjustable via a trimmer.
The audio signal is divided into three frequency bands - low, mid, and high frequencies - using RC filters (resistors and capacitors). Each frequency band controls a separate group of LEDs.
The device is suitable for sound and music visualization.

Technical Specifications:
Type: color music device.
Number of LEDs: 9 (3 channels x 3 LEDs).
Frequency channels:
- low frequencies,
- mid frequencies,
- high frequencies.
Input: built-in electret microphone.
Adjustment: microphone sensitivity (trimmer).
Implementation: transistor-based.
Supply voltage: 9 - 18 V DC.
PCB dimensions: 78 x 47 mm.

This product is a DIY assembly kit.
It is also available as a fully assembled module - Product code 1525 (separate product).