This circuit was found in a 90's EDN. The circuit provides two 15 V outputs and one 5 V output from the 12V voltage of a car battery. The components are from that time.
This experimental amplifier was found in the 1960 Mullard transistor reference manual. The...
This circuit from Motorola is from 1968, appearing elsewhere on this site. The transistors admit...
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...