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.
Great sensitivity for the circuit can be obtained with a Darlington amplification step for the...
Found in a 90s Silicon Chip documentation this circuit is intended to protect a speaker system in...
This circuit was found in a Japanese publication from the 1960s. It uses germanium transistors and is powered...