This circuit was found in American documentation from the 1980s. The integrated circuit used is a voltage comparator of the time. Modern equivalents can be tested.
This circuit was found in an old American documentation. The integrated circuit used is uncommon...
SST OXY Flex Oxygen Sensor The purpose of this SST sensor is to measure oxygen level in enclosed...
Circuits similar to this can be found in this section. This is from 1967 General Electric...