Exhaust fan with timer and humidity sensor
Summary
Exhaust ventilation fans eliminate humidity, odours and airborne particulates from bathrooms, closets, mudrooms, laundry, workout space, and other places in residential and business buildings. The analysed fan contains two ICs (a programmable timer and a quad operational amplifier) and more than 50 discreet components. Because the output voltage level of the CNT0 remainsHIGH until the next pulse on its clock input, the Rising Edge Detector makes the signal levelLOWon the DFF’s CLK input after the counter has counted till the end and the DFF output then goes LOW. All external components are availablein the GreenPAK Designer, except for the humidity sensor, which can be easily replaced with a capacitor. In this article, we analysed a typical cheap exhaust fan with an off-delay timer and a humidity sensor.