Found in a 1980s American documentation, this circuit has a current consumption of only 1 mA. The crystal can be from 100 kHz up to a few megahertz.
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...