This circuit uses a heated filament as a sensor. With the air current it changes resistance, and the circuit detects it. The circuit is from a 1969 EEE.
We found this circuit in the July 1994 issue of Electronics Now magazine. The circuit can use...
The transistors in this 80's documentation project may be BC548, the most modern equivalents of...
This circuit was found in an Electronic World of 1968. The circuit uses power transistors of the...