Found in a 1990 Hobbyst Handbook this circuit has an output power of a few tens of watts and serves as reinforced for the car's sound. The speaker can be 2 or 4 ohm.
This circuit is used to test PNP or NPN transistors giving the status indication through LEDs. The...
This circuit with three transistors was suggested in a Radio Electronics magazine from February 1963....
We find this circuit in an American 1980s documentation. The circuit can still be assembled...