This oscillator for the fifth overtone of a crystal was found in a Radio Electronics magazine from May 1970. Transistors are RF types, and the transistor determines the maximum frequency achieved.
This low frequency circuit was found in documentation from the 1980s. The values of R and C...
This source for devices for automotive use was found in a 1985 documentation. The power...
Found on Popular Electronics in the 1980s, this circuit detects a change in air pressure using a...