This circuit is from an American manual from 1975. The transistors are types of the time, but equivalents can be used, as well as the relay that can be according to the supply voltage.
The circuit presented with low drift is from the Motrorola LinearDatabook of 1990. The circuit...
This strobe light circuit for car spot adjustment dates to 1987, when there were no electronic resources...
An interesting solution that can be provided in some cases is the one shown in the figure in which...