Automatic exhaust fan control apparatus and method

摘要

A control apparatus for operating an exhaust fan in order to control humidity and odor in an enclosed confine includes a switch mounted within a path of electric power between an electric power source and the exhaust fan. A humidity sensor outputs a humidity signal defining level of relative humidity within the enclosed confine and a resistive voltage divider provides a reference voltage signal. A comparator compares the humidity signal with the reference signal and provides a control signal when a value of the humidity signal is equal to or greater than a value of the reference signal, the control signal causing the switch to supply the electric power to the exhaust fan. A timing circuit is activated by the control signal and is operable to maintain presence thereof for a predetermined period of time when the value of the humidity signal decreases below the value of the reference signal.