Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It can be replaced with LED with appropriate series resistor. Transistors may be modern equivalents.
Based on an Analog Devices LTC1540, this circuit consumes only 50 uA, serving to monitor the...
This circuit was found in a 1980s documentation. The diodes may be general purpose diodes such as 1N34...
We found this digital timer circuit in a 1994 publication. The power is supplied by 12 V, which is the...