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  • 8/8/2019 sun-up NEW1



  • 8/8/2019 sun-up NEW1


  • 8/8/2019 sun-up NEW1



    The name of the project itself suggest that itis something related to the sun or light.

    We all know that the radiations from the sunor the solar energy is used in various day today life applications .

    Our project is designed in such a way that itcan detect even a very small amount of lightwhich is indicated by the output buzzer.

    The sun up alarm can be used to provide anaudible alarm.

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  • 8/8/2019 sun-up NEW1


    S l.noS Components Quantity Description

    1 .1 . TransistorNPN Q 1 2N2222


    2.2. Photo resistor



    3 .3 . Resistorsa) 100 k(R1, R2)b)10 k(R3 )c)4.7k(R4)


    4.4. Piezo Buzzer 1

    5 .5 . 74 1 OperationalAmplifier


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    2 . Photo Resistor:It is a light dependent or a cadmium sulphide cell (cds)

    It is a resistor whose resistance decreases with the increase in intensity of


    The inexpensive cds are found in many consumer items such as camera

    ,light meters, street lights, clock radios, alarms and outdoor clocks.

    1. Transistor:The 2N2222, often referred to as the Quad Two transistor, is a small NPN

    transistor used for general purpose low-power amplifying or switching


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    4 . Piezo Buzzer:

    A piezo buzzer converts electrical signals into sound by using a piezo electric

    crystal element in it, which deforms slightly when voltage is applied to it.

    This crystal element is connected to a speaker cone or panel, which vibratesquickly when a rapidly changing voltage is applied.

    This vibration in turn sets up sound waves in the air , thus generating a tone

    at a frequency based on the frequency of the voltage wave.

    A resistor is a two terminal electronic component that produces a

    voltage across its terminals that is proportional to the electronic

    current through its in accordance with ohms law V=IR.

    3. Resistors:


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    continued 5 . 74 1 Op-Amp :

    An Op-Amp is a DC coupled high gain electronic voltage with differentialInputs and usually a single output.

    The Op-Amp is basically one type of differential amplifier.

    High input impedance at input terminals (ideally infinite) and low outputimpedance (ideally zero) are important.The output of the op-amp is controlled either by ve feedback which largelydetermines the magnitude of its output voltage gain or by +ve feedbackwhich facilitates regenerative gain and oscillation .

    The amplifiers differential inputs consists of v+ input and v- input where v+

    input is the voltage at the non inverting terminal and v- is the voltage atinverting terminal.

    Op-amp has two inputs inverting pin 2 non inverting pin3 the op-amp has oneoutput pin 6

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    If the voltage goes into pin 2 then it is known as inverting amplifier . If thevoltage goes into pin 3 it is non inverting amplifier.

    The circuit above it can be seen that we have used non inverting amplifier.However in the logic diagram of sun up alarm the 74 1 amplifier act ascomparator and not an amplifier.

    Though the 74 1 act as comparator it still detects the weak signals so that theycan be recognized more easily.

    Positive voltage is referred as high and negative voltage is referred as low .

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    WORK I :This circuit is for a simple buzzer that is activated by light, i.e., the buzzer ison when there's ample light and off when it is dark.

    A general-purpose operational amplifier, the 74 1, is used as a comparatorthat determines whether there's enough light to turn on a self-oscillatingpiezoelectric buzzer.

    The comparator compare two voltages and produce a signal that indicateswhich voltage Is greater .

    With respect to the diagram, if v1 isgreater than v 2 then the difference willbe positive and the result will beamplified to +vcc.

    If v2 is greater then the difference is veand the result will be amplified to vcc.If both the voltages are equal then the

    output =difference=zero

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    Its non-inverting input is connected to a photo resistor, a component whoseresistance decreases as more light shines on it. Its inverting input, on theother hand, is connected to an almost fixed voltage, i.e., a proportion of thesupply voltage as set by trimmer resistor R 2 .If there isn't enough light shining on the photo resistor, the buzzer is quiet.As more light shines on the photo resistor, its resistance decreases andcauses the voltage across R1 to increaseAt a certain level of lighting, the voltage across R1, which is also the voltageat the non-inverting input of the 74 1, becomes larger than the voltage at theinverting input.At this point, the 74 1 is triggered to output a 'high' level, turning on Q1. Q1then activates the self-oscillating piezoelectric buzzer.

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    S un-up alarm is used to provide an audible alarm when the sun comes up.

    It can be used in dark areas to detect light beams.

    S un-up alarm is expected to construct a safe place for any precious items.

    S un-up alarm is often used to detect head lights of the automobiles.

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