This circuit is from an old American documentation from the 70s. Transistor 2N3904 can be replaced by BC548. The relay must have 100 mA of maximum current.
This symmetrical 1.2 to 35 V source was found in a 1994 documentation. The integrated circuits are...
Found in a 90s Elektor, this mixer makes use of integrated circuits of the time. The supply must be...
This amplifier is specifically designed for portable radio and recorders with a 4 ohms load....