This automotive circuit was obtained from an 80's schematic from the integrated circuit factory itself. The voltage regulator is still common, but the operational amplifier is of the time.
This bipolar reference of temperature compensated voltage was found in an old documentation on...
This circuit is from a1970 documentation. R1 may have 10k and P1 47k. The transistors can be BC558...
This sensitive millivoltmeter for alternating voltages was found in a French publication in 1996...