We find this oscillator in a 1980s documentation. The frequency depends on the crystal and the transistor used must be able to oscillate at the desired frequency.
This circuit visually indicates that a high voltage is present in an outlet or other point. The...
This circuit found in a 1988 documentation consists of a timer or sequential timer controller. The...
Using a 4017 as a base, this circuit from a 1990s Popular Electronics generates low-frequency...