This circuit was found in an American documentation from 1969. The circuit is a multi-indicator with resistors typically 47 k for R1 and 100 k for the others.
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...