LM2901 LED bar-graph meter

Several LED above and other components used to determine the signal amplifier, when in a state of high and low . If the signal received from the amplifier circuit is high then the LED lamp are lit up everything and more bright LED lamps, but otherwise if the received signal is low then the lights on only one or two , even absent or faint.

To use the circuit you can connec with the output amplifier or speaker output , if there is reinforcing the other in the amplifier , can be connected to the output.
Led signal meter