LED VU Meter - PCB Designer

Volume Level Meter With 8 LEDs

The LED VU Meter circuit uses two LM339 quad voltage comparators to illuminate a series of 8 LEDs (light emitting diodes) indicating volume level.

Each of the eight comparators is biased at increasing voltages set by the voltage divider so that the lower right LED comes on first when the input is around 400 millivolts or 22 milliwatts peak in an 8 ohm system.

The divider voltages are set so that each LED represents about twice the power level as the other LED before so the scale extends from 22 milliwatts to around 2.5 watts when all LEDs are on, or lit.

The LED VU Meter circuit sensitivity can be reduced with the input control to read higher levels. This LED VU Meter project is easy to build and can be tested quite rapidly.

The power levels for each LED should be:

1 LED = 22mW 2 LEDs = 42mW 3 LEDs = 90mW 4 LEDs = 175mW

5 LEDs = 320mW 6 LEDs = 650mW 7 LEDs = 1.2 Watts 8 LEDs = 2.5 Watts

As usual, the best way to accomodate this circuitry is by using PCB print circuit boards. This PCB design is simple, easy and affordable even for students or hobbists alike!

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