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.
In the 70s, Ibrape launched an excellent audio pre-amplifier kit to be used in amplifiers of the...
This amplifier stage was found in a 1956 Sylvania manual and has an unusual configuration with a...
Found in a QST magazine from the 90s, this powerful unit is intended to supply a VHF transceiver for...