We found this circuit in a publication by General Electric in the 1980s. The transistors and the PUT are from that time. The control is done by a tachometer based on an optical coupler.
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...