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.
This simple bridge circuit can be used for impedance or resistance measurement using a high...
This circuit can source up to 1,000 V from a 9 V battery. Output current is very low, some...
The figure shows how to change the frequency of a 5 V LED blinking. The capacitor can have other...