3 V buffer (CB7142E)

This 3 V rail to rail buffer was found in a National Semiconductor documentation. The gain is unit.

Microphone balanced amplifier (CB9388E)
This circuit was found in an old American documentation. The integrated circuit used is uncommon...
SST OXY Flex Oxygen Sensor
SST OXY Flex Oxygen Sensor The purpose of this SST sensor is to measure oxygen level in enclosed...
SCR Charger CIR13730S (CB6397E)
Circuits similar to this can be found in this section. This is from 1967 General Electric...