Based LM324 LED VU-Meter

This circuit uses two quad op-amps to form an eight LED audio level meter.

 

Vu meter

The 1K resistors in the circuit are essential so that the LED's turn on at different audio levels. This circuit is easily expandable with more op-amps, and is not limited to use with the LM324.

The 33K resistor on the schematic is to keep the signal input to the circuit at a low level. The circuit in it's current form will accept line level inputs from sources such as the aux out on a Hi-Fi, all though could be easily modified to accept speaker inputs.

The audio + is connected to the main positive rail, while the audio - is used for signal input.

50k pot can be used to change the sensitivity of the circuit.

List components

resistors = resistors Number 7 Value 1k

resistors = resistors Number 8 Value 330R

resistors = resistors Number 2 Value 20k

resistors = resistors Number 1 Value 33k

led = led number 8

ic = lm324

Variable resistor = 50k 

tags:  led, circuit, meter, LEDs, op-amp, amplifiers, LED Flasher