This circuit was found in a 80s American documentation. The zener diodes determine the points of action of each stage and the transistors can be general purpose types.
This simple circuit was found in a 1981 publication. As readers can see, we have an H switch and...
This circuit is from 2001 documentation with the purpose of controlling a pump that fills a water...
This simple CMOS metronome circuit can be mounted in a small box, providing both sound and light...