This circuit found in a 1964 US publication reverses the signal level by providing 9 to 0 V outputs from 0 to 9 V signals. Transistors may be equivalent.
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...