This circuit uses three inverters to generate a rectangular signal whose frequency depends on R1 and C1. The circuit is from a March 1996 Electronics Now.
This simple metronome, from 1985 documentation uses only transistors and has two settings. For...
This circuit is suitable for modulating AM transmitters. The circuit is from a 1977 radio amateur...
This flasher was found in an old Hands On, but uses common components. The optocoupler can be...