This power source was found in a Motorola manual from 1968. Transistors are from the era, and current equivalents can be used.
This circuit came out in an American magazine that no longer exists. It's the Electronic...
This circuit can be added to any audio amplifier design, consisting of a good tone control with an...
Using a 741 op amp with symmetrical source, this circuit was found in a 1982 documentation. The...