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 optp-coupler realized with cadmium-sulphide photocell (c.d.s) at the input. The output of the sensor is conditioned by quad-2-input schmit 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, strem 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.
1.2 OBJECTIVE OF THE PROJECT
The major objective of this project is to design and implement automatic hand-dryer with temperature display. The project is also aimed at familiarizing the graduates of Computer Engineering in 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 project within a specified time.
1.3 SIGNIFICANCE OF THE STUDY
This project design and implementation of automatic hand-dryer with temperature display signifies 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 automatic hand-dryer with temperature display. It covers the following; IC Liner Temperature Sensor (LM 35), Opto-coupler 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 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 basically 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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