Other versions exist on this site from various publications. This one is from the Radio Electronics Experimenter from 1990. The bargraph circuit uses the UAA170.
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....
This treble and bass control drains some milliamperes from a 12 V supply and can be used with any...
This is a very simple configuration with a power transistor to control a DC motor from 3 to 12 V...