This was the Swiss Army knife of audio. Using a single BC548 transistor (or sometimes a FET), this preamp could amplify microphone signals, guitar pickups, or line-level audio to drive a power amplifier. The PCB layout in the 305 book is so small you could fit it on a postage stamp. Modern guitar pedal builders still trace this schematic for boost pedals.
In an era of bulky linear transformers, these circuits were lifelines. Look for: elektor 305 circuits
: Automation ideas, timers, and lighting controls. This was the Swiss Army knife of audio
If you are trying to reproduce these boards, note that Elektor used a unique "pin grid" for ICs; their standard was to keep traces as short as possible to prevent oscillation—a lesson modern high-speed designers still follow. Modern guitar pedal builders still trace this schematic
: Circuits related to radio and TV, such as tuners, modulators, and demodulators.