This commercial receiver from the year 1958 uses two AA cells as Power supply. The circuit is intend to receive MW station and the transistors are germanium types not easy to find today.
This 5 V power supply for TTL, Shields and microcontrollers is old, and the components can be...
This circuit generates a constant current limited by the characteristics of the operational...
The configuration below, which can be implemented with other operators, is from the National...