Suggested by General Electric in a 1970 documentation, this circuit makes use of some components of the time, in the case of transistors. The circuit detects smoke by the transparency changing of the air.
For reference only, this is the first IF amplifier stage of a common transistor radio from the...
This circuit from July 1975 Radio Electronics uses any operating system with a symmetrical source....
This setting is valid for other transconductance operational amplifiers. The circuit is from...