Astable 555 (CB21101E)

This 50% duty cycle configuration was found in a Popular Electronics from the 1990s. The operating frequency is given by C1.

DC-AC converter (CB12410E)
Published in 1988 in Hands-On Electronics, this circuit converts the 12 V of a battery into 120 V...
Shield for Digital Transmission (CB20175E)
This circuit was found in an American technical manual from the 1980s. The LM111 is an uncommon...
Square to Sinusoidal Converter (CB6595E)
This circuit was obtained in an American publication of the time. Transistors are commonly used. The...