This 1965 circuit uses a Philips 4068 tube to measure extremely small charges. The circuit has as indicator a micro ammeter and the transistors are of the time.
This circuit is from the 1993 Motorola Linear Interface ICs. Equivalent operating may be used and...
This reflex receiver was obtained from a 1963 documentation. The transistors are germanium, and...
This linear modulator was found in old documentation. The integrated circuit used is uncommon...