AUTOMATIC HAND DRYER WITH TEMPERATURE DISPLAY
This project work deals on the design and implementation of an automatic hand-dryer with display capable of drying up a wet hand inserted under its vent and goes off automatically as soon as the ands are removed. The system also incorporates a decimal counting unit that displays the temperature of the blown out air in 0C. This system is configured using an optocoupler realized with cadmium-sulphide photocell (c.d.s) at the input. The output of the sensor is conditioned by quad-2-input schmitt trigger NAND gate (74132) which serves as the control logic used to trigger a one-shot delay that biases a transistor switch. The transistor commutes a TRIAC (solid state relay) that switches on/off the blower connected to it. When a wet hand is inserted under the vent and blocks the line-of-sight of the sensor, the blower starts to blow automatically as long as the hands are still blocking the c.d.s, else it will stop. The seven-segment display displays the temperature of the blown out air in 0C and resets simultaneously with the switching off of the dryer.
Engineering is concerned with goal-oriented projects. Projects that can eliminate problems like time lapse, stream and energy spent, cost and environmental dangers/hazards. This project work on the design and implementation of an automatic hand-dryer with temperature display is built to eliminate the dangers and problems associated with the manual process of hand-dryer and to display the temperature of the air used in drying the object. This project is realized with passive and active components. And it is pure hardwired in that it does not use micro-program control.
1.1 GENERAL DESCRIPTION OF THE PROJECT
This project design and implementation of automatic hand-dryer with temperature display is achieved in several blocks all combined to form one functional unit. The first block in the opto-coupler realized with laser diode and LDR whose output is conditioned by 74LS132 that generates control logic. This control logic is used to bias a transistor switch that energizes the electromagnetic relay which switches the dryer. The control logic is also used to trigger/power the temperature display circuit. This section is realized with IC linear temperature sensor (LM35) whose output is fed to a quad-comparator with Hysteresis. This comparator output reset a frequency generator which is counted by a 2-digit decimal counting unit that displays the temperature of the blowers air in degree calcius. The system dries the hand and displays the temperature using seven segment display.