We found this circuit in a Mullard manual from 1960. The transistor is a phototransistor of the time. The gain is 3 dB.
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...