Mini Megaphone (CB8952E)

Found in Popular Electronics' 90s, this small megaphone is based on LM386. The circuit uses a high impedance microphone.

Phonographic amplifier (CB22486E)
This headphone amplifier was found in a 1966 documentation. The transistor is made of germanium and the...
CMOS Injector (CB15763E)
The signal injector illustrated in the figure uses a single integrated circuit and generates...
Digital Music Box (CB16961E)
The note sequence for this circuit is achieved through integrated circuits controlled by the 555....