how does this humidity sensor circuit work?
This is a 2 state circuit - the output is either low or high, on or off. The IC is a comparator.
The sensor varies in resistance with &quot;humidity&quot;.
When the comparator inverting input (from sensor) is at a lower voltage than the non-inverting input from resistor divider the comparator output is high and the output LED is off. When the sensor resistance increases until oa- rises above oa+ the comparator output goes low and the output LED turns on.