Solar flashlight (CB20488E)

This circuit charges a battery to power a flashlight at night. The circuit is from an English publication from 1991.

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...