This circuit uses a capacitor that depends on the frequency of the crystal. We found it in a 1967 documentation. The maximum frequency is around 100 kHz.
Found in 90's Electronic Engineering, this circuit produces a pulse with a delay that depends on R3...
This circuit was found in the December 1984 issue of Radio Electronics magazine. The circuit has a...
Found in 90s Radio Electronics, this circuit is intended for amplifying analog video signals....