This circuit was obtained in a 1968 manual of General Electric. The components used are of the time, but they admit equivalent. Observe the optical feedback system for control.
This circuit, from a publication from the 1970s, can be implemented with more modern transistors and 6 or...
This circuit switches off a load in case of excess current acting as a fuse. The circuit is from a...
This circuit was obtained from a manual of the integrated circuit itself, but can be applied to...