This circuit uses a parallel resonant crystal to control the frequency. The circuit is from Radio Electronics magazine, February 1993. Equivalent transistors can be used.
This circuit detects a light window using two operating systems. The circuit is from a July 1992...
This circuit was obtained in a 70s American documentation. The integrated circuits of the time are...
-- This old oscillator takes advantage of a transistor radio output transformer of the time. The 2...