Embedded Lab

Here’s another entry for the 555 contest. This project is about an automatic hand dryer that turns on when the hands are brought close to the dryer. It uses infrared diodes and a photo diode sensor to detect the presence of hands. The optical sensor mechanism then triggers the 555 timer which is configured in a monostable mode. The 555 output activates a relay switch that turns the fan on. The duration of the monostable output (fan on time) is defined by the resistance and capacitance connected to 555.