In the figure we have the configuration of series regulator protector suggested by Motorola in 1968 documentation. The transistors are of the time, being able to be used modern equivalents.
We find this circuit in a 2005 Linear Technology manual. The circuit applies to small DC motors...
This 12V battery charging circuit automatically shuts off at the end of the charge. The disconnect...
This is one of many Morse code audio oscillators that can be found in this section. The circuit...