This circuit is the factory version of the LM386 low-power amplifier. The sound quality is excellent, and the power can be supplied with voltages from 6 to 16 V.
This is the basic configuration for using a moving bar indicator or bargraph using the LM3914...
We found this circuit in a Popular Electronics from the 90s. Transistors can be modern...
We found this circuit in a Popular Electronics from the 80s. This circuit eventually doesn't work with...