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Air Flow Detector #1:
This simple circuit uses
an incandescent lamp to
detect airflow. With the
filament exposed to air,
a constant current
source is used to
slightly heat the
filament. As it is
heated, the resistance
increases. As air flows
over the filament it
cools down, thus
lowering its resistance.
A comparator is used to
detect this difference
and light an LED. With a
few changes, the circuit
can be connected to a
meter or ADC to provide
an estimation on the
amount of airflow.
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