Abstract:
The relative humidity sensor changes its
capacitance with the humidity. The humidity sensing
circuit is constructed around a 555 timer with
astable operation. It produces a rectangular wave.
In order to achieve the perfectively symmetrical
square wave as well as to reduce the frequency
value, CD4017BC that is divided by 10 Johnson
counter with 10 decoded outputs and a carry out bit
is added to the timer’s output. The resultant
frequency is applied into the computer system
integrating with the fuzzy logic. Fuzzy Logic
determines the frequency value and its rate of
change which are input to the fuzzy logic control
system that determines the real world constraint of
the dryer's heating rate to the dryer driver circuit
which is constructed with the pulse width
modulation (PWM) technique. Input and output
operations to and from the computer system are
carried out via parallel interfacing and Turbo C++
programming.
