Audio amplifier 741 (CB20478E)

This low power audio amplifier was found at 1992s Popular Electronics. Transistors are general purpose common types.

Transformer Audio Output Stage (CB18304E)
This circuit with only one transistor was found in Japanese documentation from the 1960s. The...
ADC buffer (CB9313E)
This circuit was found in documentation from Analog Devices from the 90s. The circuit uses...
Optical isolator (CB8272E)
This sensor circuit from a 1967 Ferranti documentation uses components from the era. The circuit...