Found in a 1960 General Electric documentation, this crowbar circuit blows the fuse in case of excess current. The circuit is for 12 V sources triggering between 14 and 17 V.
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...