Audio VU Meter with 9 LEDs, LB1409
This audio VU meter uses the LB1409 integrated circuit to drive 9 LEDs, providing a visual indication of audio signal levels.
Circuit Operation
The IC lights the LEDs in a thermometer-style display, where the number of illuminated LEDs corresponds to the audio input voltage. As the signal amplitude increases, more LEDs light up, forming a moving light bar to indicate the instantaneous audio level.
Adjustment
The input signal level can be fine-tuned using PR2, allowing calibration of the VU meter so that it accurately reflects the audio amplitude.
Key Features
- Displays audio signal amplitude on 9 LEDs
- Thermometer-style light bar for easy visualization
- IC: LB1409 — designed for LED audio level indicators
- Adjustable input level via PR2 potentiometer
- Compact and simple design for audio monitoring
Construction Notes
- Use LEDs with similar brightness for consistent display.
- Include current-limiting resistors as per the IC datasheet for each LED.
- Keep audio input wiring short and shielded to minimize noise interference.
- Follow the supply voltage recommended in the datasheet for proper IC operation.
Components Layout
