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EEE 432 Measurement & Instrumentation
Term roject resentationLDR and NTC Based Fire Detection System
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Contents
Circuit schematic
Sensors to be used
Other components used in the circuit
Brief descriptions of the materials
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Circuit Schematic
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Circuit Schematic
NTC will serve as a heat sensor meanwhile LDR will serve as a light sensor.
When there is neither heat nor light in the surrounding area, Logic 1 willbe obtained at the inputs of the NOR gate and the output will be Logic 0.
Thus, BJT transistor will be OFF.
When there is a sudden light and heat in the surrounding area, Logic 0 willbe obtained at the inputs of the NOR gate. Regarding this, BJT transistorwill be ON and will energize the relay. As a consequence, the buzzer which
is connected to the relay contact will be activated.
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NTC
As a special resistor, NTC (Negative Temperature Coefficient) thermistorcan vary its resistance more significantly with the temperature thanstandard resistors.
It exhibits decreasing resistance characteristics with increasingtemperature.
NTC thermistors are composed of metal oxides. A mixture of two or moremetal oxide powders are combined with suitable binders, are formed to a
desired geometry, dried, and sintered at an elevated temperature.
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NTC
General Characteristics
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NTC
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LDR
Photo resistors, also known as light dependent resistors (LDR), are lightsensitive devices most often used to indicate the presence or absence oflight.
Their resistance is very high (sometimes up to 1M) in the dark but whenexposed to light, the resistance drops dramatically, even down to a fewohms depending on the light intensity
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LDR
Modern light dependent resistors are made of lead sulfide, lead selenide,indium antimonide, and most commonly cadmium sulfide (CdS) andcadmium selenide.
To manufacture a cadmium sulfide LDR, highly purified cadmium sulfidepowder and inert binding materials are mixed. Electrodes are vacuumevaporated onto the surface of one side.
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LDR
General Characteristics
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LDR
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NOR Gate using CMOS
TC4007UBP contains three elements of P-channel enhancement type MOSFET and three elements of N-channel enhancement type MOS FET.Depending on how connections are made, NOR Gate application is easilyobtained.
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Relay
A relay is a simple electromechanical switch made up of anelectromagnet and a set of contacts. In other words it is an electricallyoperated switch.
Relays are used where it is necessary to control a circuit by a low-powersignal (with complete electrical isolation between control and controlledcircuits) or where several circuits must be controlled by one signal.
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Buzzer
A buzzer or beeper is an audio signalling device. Similarly, the relay will beconnected to interrupt its own actuating current, causing the contacts tobuzz. The word "buzzer" comes from the rasping noise thatelectromechanical buzzers made.
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Buzzer
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DEMONSTRATION
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Thank you for your attention.
zgn Arslan
Buse etinkaya
