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.
In the figure we have the way to activate a red LED that needs 1.7 V or even others with higher...
This circuit was obtained in a 1979 publication, but it can be assembled with the BD135 instead of the...
Found in Radio Electronics from the 90's, this circuit employs a 3140 operational amplifier, still...