This circuit was found in an Electronic Design from the 90s. The circuit uses a type J thermocouple that can measure from -50 to + 100º C. Power is provided by a 3 V lithium battery.
This circuit controls loads powered by the power grid, remembering that it is a half wave...
This simple latching alarm circuit using CMOS gates was found in the May 1990 Radio Electronics magazine....
September 2016 - It can be obtained from Mouser Electronics modules with 2.4 inch from 4D Systems...