This high sensitivity sensor was found in a 1967 General Electric SCR manual. The circuit admits equivalents by triggering a load according to the used SCR.
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...