Design and Construction of Automatic Hand Dryer With Temperature Display

Design and Construction of Automatic Hand Dryer With Temperature Display

ABSTRACT

This project work deals with the design and implementation of an automatic hand-dryer with a display capable of drying up a wet hand-inserted under its vent and goes off automatically as soon as the hands are removed.  The system also incorporates a decimal counting unit that displays the temperature of the blown-out air at 0C.  This system is configured using an optocoupler realized with cadmium-sulfide photocell (c.d.s) at the input.  The output of the sensor is conditioned by quad-2-input Schmit to trigger the 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 at 0C and resets simultaneously with the switching off of the dryer.

CHAPTER ONE

INTRODUCTION

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 a 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 purely hardwired in that it does not use micro-program control.

1.1 GENERAL DESCRIPTION OF THE PROJECT

This project design and implementation of an automatic hand-dryer with temperature display are achieved in several blocks all combined to form one functional unit.  The first block in the optocoupler is realized with a laser diode and LDR whose output is conditioned by 74LS132 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 degrees celsius.  The system dries the hand and displays the temperature using the seven-segment display.

1.2 OBJECTIVE OF THE PROJECT

The major objective of this project is to design and implement an automatic hand-dryer with a temperature display.  The project is also aimed at familiarising the graduates of Computer Engineering with electronic system designs involving digital systems and random logic.  The project is aimed at acquainting the young graduate on the ethics of engineering, technical and scientific writing which forms the nucleus of Engineering professional practice.  It is also aimed at testing/accessing the young Engineers’ ability to realize engineering projects within a specified time.

1.3 SIGNIFICANCE OF THE STUDY

This project design and implementation of an automatic hand-dryer with temperature display signify a lot in automation and control.  It means a lot in CEE, EEE, and Physics and Electronic. This project is a marketable product for homes and restaurants.  A project of this type if properly modified can function as a temperature control system for server room, kiln, and ovens.

1.4 SCOPE OF THE PROJECT

This project work focuses on the design and implementation of an automatic hand-dryer with a temperature display.  It covers the following; IC Liner Temperature Sensor (LM 35), Optocoupler using LDR and laser diodes, decimal counting unit, and Quad-comparator (LM 339).  It covers other passive and active components used in the design.  The project also x-rays the mode of calculation of the basic circuit parameters used in the design.  This report does not cover the design of the motor used in the hand dryer.

1.5 PROJECT REPORT ORGANIZATION

This project report is presented in five chapters to appropriately illustrate the steps involved in its implementation. Chapter one covers the introduction and objectives of the system while chapter two is the literature review and theories relevant to the project.  Chapter three focuses on the system design and analysis while chapter four x-rays the system implementation, testing, and result.  The fifth and last chapter covers the summary and conclusion.

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