The selected circuit was found in GE's 1977 semiconductor manual. 3N84 is a controlled silicon switch and SCRs support equivalents. The transistor can be a BC558, depending on the supply voltage.
The presented circuit has compensation for cold junction. In addition to a voltage reference, it...
This “people detector” with pyroelectric sensor was found in the April 1991 issue of Radio...
This circuit from a 1988 documentation uses an NTC sensor to keep a greenhouse temperature...