AVT1853 - RGB LED

The key to a successful party is not only good music, but also good lighting. The presented RGB LED driver system will satisfy the expectations of even the most demanding party goers.

Schematic diagram of RGB illuminophony is shown in Figure 1. It consists of a microcontroller, operational amplifier and power transistors. The input signal through the capacitor C1 is fed to the input of the operational amplifier. The input bias voltage is determined by a divider built from resistors R9, R10, R13, R14. The microcontroller (ATmega8) is clocked by an internal RC oscillator running at 8 MHz. The analog signal from the audio amplifier is measured by the A/D converter and applied to the PC0 input. The program “selects” from the audio signal the components that lie in the following frequency ranges:

• High: 13…14 kHz.
• Average 6…7 kHz.
• Low 500 Hz…2 kHz.

The program then calculates the luminous intensity for each channel and controls the output transistor proportionally to the result. Actuating devices are transistors T1 ... T3 (BUZ11) with a high current load capacity. The board has a CINCH input for direct input of an AUDIO signal with a level of 0,7 V (typical headphone output). The audio source can be selected using the SEL jumper: CINCH (RCA) or microphone (MIC).

The effect is selected with the MODE button (S1):

• Red color.
• Blue color.
• Green color.
• White color.
• Lighting.
• Random color change to the beat of the bass.
• An exception.

We start the assembly with soldering resistors and other small elements to the board, and finish with the assembly of electrolytic capacitors, transistors, screw connections and the CINCH connector.

The microphone can be soldered directly to the curved strip with gold pins. A device assembled without errors, using a programmed microcontroller and working elements, will work immediately after switching on the supply voltage.

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