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 power supply was originally created for the CB16760E (Loudness System) but can be used in any...
Found in 1980s Electronic Engineering, this circuit uses common phototransistors as sensors. The...
This simple, unregulated power supply with an approximate 6 V output voltage can supply currents up to...