This circuit is from an American 80's documentation. The integrated circuit is from the time and the sensor consists of a smoke chamber measuring its transparency change.
This circuit is from the 80's component manual itself, but can be applied to more modern...
New Low-Power PIC24 “GA7” Microcontroller Family Now Available CHANDLER, Ariz., Dec. 12, 2016 — The...
The JFETs of this old circuit admit modern equivalents and their characteristics determine the maximum...