This circuit is designed to measure very weak currents, in the order of picoamperes. We found it in an American documentation from the 80s. The integrated circuit is from that time.
This circuit allows you to read temperatures with a common digital voltmeter. We found it in the...
This circuit for the 1.5 to 15 V scaled ranges was found in a 1982 documentation, but uses current...
The integrated circuit of this 1976 configuration is the 7400 and the type crystal in televisions of the...