CHAPTER-1

INTRODUCTION

1

This circuit automatically turns ON a night lamp when bedroom light is

switched OFF. The lamp remains ‘ON’ until the light sensor senses daylight in

the morning. A white LED is used as the night lamp. It gives bright and cool

light in the room. When the sensor detects the daylight in the morning, a

melodious morning alarm sounds. The circuit utilizes light depandent resistors

(LDRs) for sensing darkness and light in the room. IC NE555, which is

configure as a monostable. NE555 is activated by a low pulse applied to its

trigger pin2. Once triggered, output pin3 of NE555 goes high and remains in

that position until timer is triggered again at its pin2. The musical tone of the

alarm is generated by UM66 IC. The circuit can be easily assembled on a

general purpose PCB. Enclose it is a good quality plastic case with provisions

for LDR and LED. Use a reflective holder for reading. Placing LDRs away

from the LED, preferably on the backside of the case, to avoid unnecessary

illumination. The speaker should be small so as to make the gadget compact.

2

CHAPTER-2

FUNCTIONAL BLOCK DIAGRAM

2.1: FUNCTIONAL BLOCK DIAGRAM

3

ac line

Fig 2.1: Functional block diagram of automatic night lamp

with morning

alarm.

2.2: Explanation of block diagram:-

2.2.1. AC mains:-

230v Regulated AC mains Regulated

9v dc Fig 2.2.1: Block diagram of a regulated power supply.

Each of the blocks is described in detail below,

Transformer: - Steps down high voltage AC mains to low voltage AC.

Rectifier: - Converts AC to DC, but the DC output is not perfect it is

pulsating type.

Filter: - Filtering the DC from varying greatly to a small voltage.

Regulator: - Eliminates ripple by setting DC output to a fixed voltage.

Power supplies made from these blocks are described below with a circuit

diagram and a graph of their output.

2.2.2. Transformer only:-

4

Transformer Bridge rectifier

IC Voltage regulator

Night lamp

Morning alarm

9V Backup power supply

Transformer Rectifier Filter IC Regulator

Filter

Fig 2.2.2: Transformer and output waveform

The low voltage AC output is suitable for lamps, heaters and special AC

motors. It is not suitable for electronic circuits unless they include a rectifier

and rectifying capacitors.

2.2.3. Transformer + rectifier:-

Fig 2.2.3: Transformer + rectifier and output waveform

The varying DC output is suitable for lamps, heaters and standard motors. It

is not suitable for electronic circuits unless they include a filtering capacitor.

2.2.4. Transformer + rectifier + filter:-

5

Fig 2.2.4: Transformer + rectifier + filter and output waveform

The filter DC output has a small ripple. It is suitable for most electronic circuits.

2.2.5. Transformer + rectifier + filtering + regulator:-

Fig 2.2.5: Transformer + rectifier + filtering + regulator and output waveform

The regulated DC output is very filter with no ripple. It is suitable for all

electronic circuits.

2.3. Transformer:-

6

Fig 2.3: An ideal transformer

The transformer is based on two principles: firstly, that an electric current

can produce a magnetic field (electromagnetism) and secondly that a changing

magnetic field within a coil of wire induces a voltage across the ends of the coil

(electromagnetic induction). Changing the current in the primary coil changes

the magnetic flux that is developed. The changing magnetic flux induces a

voltage in the secondary coil.

An ideal transformer is shown in the adjacent Fig2.3. Current passing

through the primary coil creates a magnetic field. The primary and secondary

coils are wrapped around a core of very high magnetic permeability, such as

iron, so that most of the magnetic flux passes through both the primary and

secondary coils.

2.4. Bridge rectification:-

7

Fig 2.4: Full wave bridge rectifier circuit and rectified output voltage /

current waveforms.

The four-diode rectifier circuit shown to the right serves very nicely to

provide full-wave rectification of the ac output of a single transformer winding.

The diamond configuration of the four diodes is the same as the resistor

configuration in a Wheatstone bridge. In fact, any set of components in this

configuration is identified as some sort of bridge, and this rectifier circuit is

similarly known as a bridge rectifier.

8

To understand how the bridge rectifier can pass current to a load in only one

direction, consider the figure to the left. Here we have placed a simple resistor

as the load, and we have numbered the four diodes so we can identify them

individually.

During the positive half-cycle, shown in red, the top end of the transformer

winding is positive with respect to the bottom half. Therefore, the transformer

pushes electrons from its bottom end, through D3, which is forward biased, and

through the load resistor in the direction shown by the red arrows. Electrons

then continue through the forward-biased D2, and from there to the top of the

transformer winding. This forms a complete circuit, so current can indeed

flow. At the same time, D1 and D4 are reverse biased, so they do not conduct

any current.

During the negative half-cycle, the top end of the transformer winding is

negative. Now, D1 and D4 are forward biased, and D2 and D3 are reverse

biased. Therefore, electrons move through D1, the resistor, and D4 in the

direction shown by the blue arrows. As with the positive half-cycle, electrons

move through the resistor from left to right.

In this manner, the diodes keep switching the transformer connections to the

resistor so that current always flows in only one direction through the resistor.

We can replace the resistor with any other circuit, including more power

supply circuitry (such as the filter), and still see the same behavior from the

bridge rectifier.

2.5. IC Voltage regulator:-

9

The latest generation of IC voltage regulators has devices with only three

pins: one for the unregulated input voltage, one for the regulated output

voltage and one for ground. The new devices can supply load current from

100mA to more than 5A. Available in plastic or metal packages, these three

terminal voltage regulators have become extremely popular because they are

inexpensive and easy to use. Aside from a couple of bypass capacitors, the need

any external component.

Vout fixed value

Erroramplifier

Fig 2.5: Fundamental block diagram of a three-

terminal IC voltage regulator.

The integrated three-terminal voltage regulator typically incorporate many

of the function discussed so far in a single package as illustrated in Fig 2.5.

2.6. 9V BATTERY BACKUP:-

A 9V battery is connected across the circuit. When the AC is not available

then the required voltage is supplied by the battery to the circuit.

2.7. NIGHT LAMP:-

This circuit automatically turns on a night lamp when bedroom light is

switched OFF. The lamp remains ON until sensor senses daylight in the

10

Thermal shutdown current limiting

Series-pass element

Precision reference element

- +

morning. A super bright white LED is used as the night lamp. It gives bright

and cool light in the room.

2.8. MORNING ALARM:-

An alarm gives a warning signal to let people know that something has

happened. When the sensor detects the daylight in the morning, a melodious

morning alarm sounds.

11

CHAPTER-3

OVERVIEW OF COMPONENTS

3.1 IC7806:-

Fig 3.1: 78xx adjustable output regulator 7-30v thumb.

12

The 78xx series is designed to output one voltage level, as they come in 5v,

6v, 7v, 8v, 9v, 10v, 12v, 15v, 20v and 24v fixed output voltages and can output

up to 1A of current as a positive voltage regulator.

The 78xx series of voltage regulators are designed for positive input. The ‘xx’

indicates the output voltages of the device as generally the series named e.g.

7805, 7806,7807,7809,7810,7812,7815,7820 and 7824 and depend on every

manufacturer for differing naming schemes.

But there is space to tweak the 78xx series such they can deliver over 1A

output current or need to obtain adjustable voltages and currents even this

device mainly as a fixed voltage regulators, following each datasheet for this

purpose. The series 7800 regulators provide eight voltage options, ranging from

5 to 24v, as indicated in table.

Table 3.1: Positive voltage regulators in 7800 series.

These ICs are designed as fixed voltage regulators and with adequate heat

sinking can deliver output currents in excess of 1A. Although these devices do

not require any external component, such component can be employed for

providing adjustable voltages and currents. These ICs also have internal

thermal overload protection and internal short-circuit current limiting.

3.2 NE555 TIMER:-

13

Device type

Output voltage in volts

Maximum input voltage in volts

Minimum input voltage in volts

7805 7806 7808 7810 7812 7815 7818 7824

+5 +6 +8 +10 +12 +15 +18 +24

35 35 35 35 35 35 35 40

7.3 8.3 10.5 12.5 14.6 17.7 21.0 27.1

Introduction:

The 555 timer IC was first introduced around 1971 by the Signetics

Corporation as the SE555/NE555, was called “The IC Time Machine”, and was

the very first and only commercial timer IC available. It provided circuit

designers and hobby tinkerers with a relatively cheap, stable and user-friendly

integrated circuit for both monostable and astable applications. The 555 come

in two packages, either the round metal-can called the 'T' package or the more

familiar 8-pin DIP 'V' package. About 20-years ago, the metal-can type was

pretty much the standard (SE/NE types). The 556 timer is a dual 555 version

and comes in a 14-pin DIP package, the 558 is a quad version with four 555's

also in a 14-pin DIP case. Inside the 555 timer, are the equivalent of over 20

transistors, 15 resistors, and 2 diodes, depending of the manufacturer. The

equivalent circuit, in block diagram, providing the functions of control,

triggering, level sensing or comparison, discharge, and power output. Some of

the more attractive features of the 555 timer are Supply voltage between 4.5

and 18 volt, supply current 3 to 6 mA, and a Rise/Fall time of 100 nSec. It can

also withstand quite a bit of abuse. The Threshold current determine the

maximum value of Ra + Rb. For 15-volt operation, the maximum total

resistance for R (Ra +Rb) is 20 Mega-ohm. The supply current, when the

output is 'high', is typically 1 milli-amp (mA) or less.

General Description:-

The LM555 is a highly stable device for generating accurate time delays or

oscillation. Additional terminals are provided for triggering or resetting if

desired. In the time delay mode of operation, the time is precisely controlled by

one external resistor and capacitor. For astable operation as an oscillator, the

free running frequency and duty cycle are accurately controlled with two

external resistors and one capacitor. The circuit may be triggered and reset on

14

falling waveforms, and the output circuit can source or sink up to 200mA or

drive TTL circuits.

Features:-

Direct replacement for SE555/NE555

Timing from microseconds through hours

Operates in both astable and monostable modes

Adjustable duty cycle

Output can source or sink 200 mA

Output and supply TTL compatible

Temperature stability better than 0.005% per °C

Normally on and normally off output.

Pin Diagram:-

15

Fig 3.2.1: Pin diagram of NE 555 timer.

Pin1 (Ground): The ground (or common) pin is the most-negative supply

potential of the device, which is normally connected to circuit common

(ground) when operated from positive supply voltages.

Pin2 (Trigger): This pin is the input to the lower comparator and is used to

set the latch, which in turn causes the output to go high. This is the beginning of

the timing sequence in monostable operation. Triggering is accomplished by

taking the pin from above to below a voltage level of 1/3V+ (or, in general, one-

half the voltage appearing at pin 5).

Pin3 (Output): The output of the 555 comes from a high-current totem-pole

stage made up of transistors Q20 - Q24. Transistors Q21 and Q22 provide drive

for source-type loads, and their Darlington connection provides a high-state

output voltage about 1.7 volts less than the V+ supply level used. The state of

the output pin will always reflect the inverse of the logic state of the latch, and

this fact may be seen by examining. Since the latch itself is not directly

16

accessible, this relationship may be best explained in terms of latch-input

trigger conditions.

Pin4 (Reset): This pin is also used to reset the latch and return the output

to a low state. The reset voltage threshold level is 0.7 volt, and a sink current of

0.1mA from this pin is required to reset the device. These levels are relatively

independent of operating V+ level; thus, the reset input is TTL compatible for

any supply voltage. The reset input is an overriding function; that is, it will

force the output to a low state regardless of the state of either of the other

inputs. It may thus be used to terminate an output pulse prematurely, to gate

oscillations from "on" to "off", etc. Delay time from reset to output is typically

on the order of 0.5 μS, and the minimum reset pulse width is 0.5 μS.

Pin5 (Control Voltage): This pin allows direct access to the 2/3 V+

voltage-divider point, the reference level for the upper compared to indirect

access to the lower comparator, as there is a 2:1 divider (R8 - R9) from this

point to the lower-comparator reference input, Q13. Use of this terminal is the

option of the user, but it does allow extreme flexibility by permitting

modification of the timing period, resetting of the comparator, etc. When the

555 timer is used in a voltage-controlled mode, it’s voltage-controlled operation

ranges from about 1 volt less than V+ down to within 2 volts of ground

(although this is not guaranteed). Voltages can be safely applied outside these

limits, but they should be confined within the limits of V+ and ground for

reliability. By applying a voltage to this pin, it is possible to vary the timing of

the device independently of the RC network. The control voltage may be varied

from 45 to 90% of the Vcc in the monostable mode, making it possible to

control the width of the output pulse independently of RC.

Pin6 (Threshold): Pin 6 is one input to the upper comparator (the other

being pin 5) and is used to reset the latch, which causes the output to go low.

17

Resetting via this terminal is accomplished by taking the terminal from below

to above a voltage level of 2/3 V+ (the normal voltage on pin 5). The action of

the threshold pin is level sensitive, allowing slow rate-of-change waveforms.

The voltage range that can safely be applied to the threshold pin is between V+

and ground. A dc current, termed the threshold current, must also flow into

this terminal from the external circuit. This current is typically 0.1μA, and will

define the upper limit of total resistance allowable from pin 6 to V+. For either

timing configuration operating at V+ = 5 volts, this resistance is 16 Mega- ohm.

For 15-volt operation, the maximum value of resistance is 20 Mega Ohms.

Pin7 (Discharge): This pin is connected to the open collector of an NPN

transistor (Q14); the emitter of which goes to ground, so that when the

transistor is turned "on", pin7 is effectively shorted to ground. Usually the

timing capacitor is connected between pin7 and ground and is discharged when

the transistor turns "on". The conduction state of this transistor is identical in

timing to that of the output stage. It is "on" (low resistance to ground) when the

output is low and "off" (high resistance to ground) when the output is high. In

both the monostable and astable, time modes, this transistor switch is used to

clamp the appropriate nodes of the timing network to ground. Saturation

voltage is typically below 100mv (milli-Volt).

Pin8 (V+): The V+ pin (also referred to as VCC) is the positive supply voltage

terminal of the 555 timer IC. Supply-voltage operating range for the 555 is +4.5

volts (minimum) to +16 volts (maximum), and it is specified for operation

between +5 volts and +15 volts. The device will operate essentially the same

over this range of voltages without change in timing period. Actually, the most

significant operational difference is the output drive capability, which increases

for both current and voltage range as the supply voltage is increased.

Sensitivity of time interval to supply voltage change is low, typically 0.1% per

18

volt. There are special and military devices available that operate at voltages as

high as 18 volts.

Monostable Multivibrator Circuit details:-

Pin 1 is grounded. Trigger input is applied to pin 2. In quiescent condition of

output this input is kept at + VCC. To obtain transition of output from stable

state to quasi-stable state, a negative going pulse of narrow width (a width

smaller than expected pulse width of output waveform) and amplitude of

greater than + 2/3 VCC is applied to pin 2. Output is taken from pin 3. Pin 4 is

usually connected to + VCC to avoid accidental reset. Pin 5 is grounded through

a 0.01 u F capacitor to avoid noise problem. Pin 6 (threshold) is shorted to pin

7. A resistor Ra is connected between pins 6 and 8. At pins 7, a discharge

capacitor is connected while pin 8 is connected to supply VCC.

555 monostable-multivibrator-operations

The operation of the circuit is explained below-

Initially, when the output at pin 3 is low i.e. the circuit is in a stable state, the

transistor is on and capacitor- C is shorted to ground. When a negative pulse is

applied to pin 2, the trigger input falls below +1/3 VCC, the output of

comparator goes high which resets the flip-flop and consequently the transistor

turns off and the output at pin 3 goes high. This is the transition of the output

from stable to quasi-stable state, as shown in figure. As the discharge transistor

is cutoff, the capacitor C begins charging toward +VCC through resistance Ra

with a time constant equal to RaC. When the increasing capacitor voltage

becomes slightly greater than +2/3 VCC, the output of comparator 1 goes high,

which sets the flip-flop. The transistor goes to saturation, thereby discharging

the capacitor C and the output of the timer goes low, as illustrated in fig 3.2.1

Thus, the output returns back to stable state from quasi-stable state. The

19

output of the Monostable Multivibrator remains low until a trigger pulse is

again applied. Then the cycle repeats. Trigger input, output voltage and

capacitor voltage waveforms are shown in fig 3.2.1

Monostable Multivibrator Design Using 555 timer IC:-

The capacitor C has to charge through resistance Ra. The larger the time

constant RaC, the longer it takes for the capacitor voltage to reach +2/3VCC. In

other words, the RC time constant controls the width of the output pulse. The

time during which the timer output remains high is given as tp =1.0986RaC

Where Ra is in ohms and C is in farads. The above relation is derived as

below. Voltage across the capacitor at any instant during charging period is

given as, VC = VCC (1- e-t/RaC)

Substituting VC = 2/3 VCC in above equation we get the time taken by the

capacitor to charge from 0 to +2/3VCC. So

+2/3VCC = VCC (1 – e-t/RaC) or t – RaC loge 3 = 1.0986 RaC

So pulse width, tP = 1.0986 RaC s 1.1 RaC

The pulse width of the circuit may range from micro-seconds to many

seconds. This circuit is widely used in industry for many different timing

applications. In this mode of operation, the timer functions as a one-shot. The

external capacitor is initially held discharged by a transistor inside the timer.

Upon application of a negative trigger pulse of less than 1/3 VCC to pin 2, the

flip-flop is set which both releases the short circuit across the capacitor and

drives the output high. The voltage across the capacitor then increases

exponentially for a period of t = 1.1 RaC, at the end of which time the voltage

equals 2/3 VCC. The comparator then resets the flip-flop, which in turn

discharges the capacitor and drives the output to its low state. Since the charge

and the threshold level of the comparator are both directly proportional to

supply voltage, the timing interval is independent of supply.

20

(a)

(b)

Fig 3.2.2 :( a) Monostable Mode and (b) Waveforms generated in this mode of

operation.

3.3 MUSIC GENERATOR UM66:-

21

General Description:-

UM66 is a pleasing music generator IC that works on a supply voltage of 3V.

The required 3V supply is given through a zener regulator. Its output is taken

from the pin no1 and is given to a push pull amplifier to drive the low

impedance loud speaker. A class A amplifier before push pull amplifier can be

used to decrease the noise and improve output. UM66 is a 3-pin IC package just

looks like a BC547 transistors. Here is the simplest melody generator circuit

you can make using an IC. The UM66 series are CMOS IC’s designed for using

in calling bell, phone and toys. It has a built in ROM programmed for playing

music. The device has very low power consumption. The melody will be

available at pin3 of UM66 and here it is amplified by using Q1 to drive the

speaker. Resistor R1 limits the base current of Q1 within the safe values.

Capacitor C1 is meant for noise suppression.

Features:-

62 Note ROM Memory

Voltage rating: 1.3V to 3.3 V

Power on reset

Fig 3.3: Pin diagram of UM 66.

3.4 LIGHT DEPENDENT RESISTER (LDR):-

22

Fig 3.4: Light Dependent Resistor figure

Operation:-

A light dependent resistor or photo resistor is a resistor whose resistance

decreases with increasing incident light intensity. It can also be referenced as a

photoconductor. A photo resistor is made of a high resistance semiconductor. If

light falling on the device is of high enough frequency, photons absorbed by the

semiconductor give bound electrons enough energy to jump into the conduction

band. The resulting free electrons conduct electricity, thereby lowering

resistance.

Photo resistors come in many different types. Inexpensive cadmium sulfide cells

can be found in many consumer items such as camera light meters, streetlights,

clock radios, alarms, and outdoor clocks. LDRs or Light Dependent Resistors

are very useful especially in light/dark sensor circuits. Normally the resistance

of an LDR is very high, sometimes as high as 1000000 ohms, but when they are

illuminated with light resistance drops dramatically. The animation opposite

shows that when the torch is turned on, the resistance of the LDR falls, allowing

current to pass through it. When the light level is low, the resistance of the LDR

is high. This prevents current from flowing to the base of the transistors.

Consequently the LED does not light. However, when light shines onto the LDR

its resistance falls and current flows into the base of the first transistor and

23

then the second transistor. The LED lights. The preset resistor can be turned

up or down to increase or decrease resistance, in this way it can make the

circuit more or less sensitive.

A photoresistor or light dependent resistor or cadmium sulfide (CdS) cell is a

resistor whose resistance decreases with increasing incident light intensity. It

can also be referred to as a photoconductor. A photoresistor is made of a high

resistance semiconductor. If light falling on the device is of high enough

frequency, photons absorbed by the semiconductor give bound electrons

enough energy to jump into the conduction band. The resulting free electron

(and its hole partner) conduct electricity, thereby lowering resistance. A

photoelectric device can be either intrinsic or extrinsic. An intrinsic

semiconductor has its own charge carriers and is not an efficient

semiconductor, e.g. silicon. In intrinsic devices, the only available electrons are

in the valence band, and hence the photon must have enough energy to excite

the electron across the entire band gap. Extrinsic devices have impurities, also

called dopants, and added whose ground state energy is closer to the

conduction band; since the electrons do not have as far to jump, lower energy

photons (i.e., longer wavelengths and lower frequencies) are sufficient to trigger

the device. If a sample of silicon has some of its atoms replaced by phosphorus

atoms (impurities), there will be extra electrons available for conduction. This

is an example of an extrinsic semiconductor.

24

Applications:-

Photoresistors come in many different types. Inexpensive cadmium sulfide

cells can be found in many consumer items such as camera light meters,

streetlights, clock radios, alarms, and outdoor clocks. They are also used in

some dynamic compressors together with a small incandescent lamp or light

emitting diode to control gain reduction. Lead sulfide (PbS) and indium

antimonite (InSb) LDRs (light dependent resistor) are used for the mid

infrared spectral region. Ge: Cu photoconductors are among the best far-

infrared detectors available, and are used for infrared astronomy and infrared

spectroscopy.

25

CHAPTER-4

CIRCUIT WITH DESIGN GUIDE LINES

4.1 CIRCUIT DAIGRAM WITH EXPLANATION

26

Fig 4.1: Circuit diagram of automatic night lamp with morning alarm.

EXPLANATION:-

This circuit is powered from a standard 0-9v transformer. Diodes D1 through

D4 rectify the AC voltage and the resulting DC voltage is smoothed by C1.

Regulator IC 7806 gives regulated 6v DC to the circuit. A battery backup is

provided to power the circuit when mains fail. When main supply is available,

the 9v rechargeable battery charges via diode D5 and resistor R1 with a

reasonable constant current. In the event of mains failure, the battery

automatically takes up the load without any delay. Diode D5 prevents the

battery from discharging backwards following the mains failure and diode D6

provides current path from the battery.

The circuit utilizes light-dependant resistors (LDRs) for sensing darkness and

light in the room. The resistance of LDR is very high in darkness, which

reduces to minimum when LDR is fully illuminated. LDR1 detects darkness,

while LDR2 detects light in the morning.

The circuit is designed around the popular timer IC NE 555(IC2), which is

configured as a monostable. IC2 is activated by a low pulse applied to its

trigger pin2. Once triggered, output pin3 of IC2 goes high and remains in that

position until IC2 is triggered again at its pin2.

27

When LDR1 is illuminated with ambient light in the room, its resistance

remains low, which keeps trigger pin2 of IC2 at a positive potential. As a result,

output pin3 of IC2 goes low and the white LED remains OFF. As the

illumination of LDR1’s sensitive window reduces, the resistance of the device

increases.

In total darkness, the specified LDR has a resistance in excess of 280-kilo

ohms. When the resistance of LDR1 increases, a short pulse is applied to

trigger pin2 of IC2 via resistor R2 (150kilo-ohms). This activates the

monosatable and its output goes high, causing the white LED to glow.

Low-value capacitor C2 maintains the monostable for continuous operation,

eliminating the timer effect. By increasing the value of C2, the ON time of the

white LFD can be adjusted to a predetermined time.

LDR2 and associated components generate the morning alarm at dawn.

LDR2 detects the ambient light in the room at sunrise and its resistance

gradually falls and transistor T1 starts conducting (IC3) gets supply voltage

from the emitter of T1 and it starts producing the melody. The musical tone

generated by IC3 is amplified by single-transistor amplified T2. Resistor R7

limits the current to IC3 and zener diode ZD limits the voltage to a safer level

of 3.3 volts.

The circuit can be easily assembled on a general-purpose PCB. Enclose it in a

good-quality plastic case with provisions for LDR and LED. Use a reflective

holder for white LED to get a spotlight effect for reading. Place LDRs away

from the white LED, preferably on the backside of the case, to avoid

unnecessary illumination. The speaker should be small to make the gadget

compact.

4.2 DESIGN GUIDELINE

28

FORMULAS

TRANSFORMER:

Turns ratio = VP/VS = NP/NS and power out= power in

VS×IS = VP×IP

Where,

VP =Primary (input) voltage VS =Secondary (output) voltage

NP =Number of turns on primary coil NS =Number of turns on secondary coil

IP = Primary (input) current Is =Secondary (output) voltage

RECTIFICATION:

,

Where:

Vdc, Vav - the average or DC output voltage,Vp - the peak value of half wave,Vrms - the root-mean-square value of output voltage.π = ~ 3.14159

555 timer IC:

Monostable mode:

The pulse width of time t, which is the time it takes to charge C to 2/3 of the supply voltage, is given by

Where, t is in seconds, R is in ohms and C is in farads.

Astable Mode:The frequency of the pulse stream depends on the values of R1, R2 and C:

29

The high time from each pulse is given by

and the low time from each pulse is given by

Where, R1 and R2 are the values of the resistors in ohms and C is the value of the capacitor in farads.

4.3 COMPONENT SPECIFICATION

30

4.3.1. IC NE 555N 4.3.2. IC 7806

4.3.3. MUSIC GENERATOR UM66 4.3.4. LIGHT DEPENDENT RESISTOR

4.3.5. 8Ω, 4.5W SPEAKER 4.3.6. RESISTORS 220Ω, 560Ω, 580Ω, 1k, 120k, 150k

4.3.7. LIGHT EMITTING DIODE 4.3.8. ZENER DIODE

31

4.3.9. TRANSISTOR BC548 4.3.10. CAPACITOR 0.01Μf

4.3.11. Transformer 230v, AC 50Hz. 4.3.12. 9v Battery.

4.4 COST

32

Name of the components used Cost (Approx)

Serial nos.

TOTAL= 261(approx.)

33

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12. 13.

Resistors1k (2Pcs), 150k (2Pcs), 120k, 220k, 580k, 560k

Capacitors1000μ, 0.01μ (2Pcs)

Diode1N4007 (4Pcs), 1N4001 (2Pcs)

Zener diode 3.3v, 0.5w

TransistorsBC548 (2Pcs)

LED White

LDR (2Pcs)

IC(7806, NE555, UM66)

Transformer(230v AC 50Hz)

Battery (9v)

Speaker (8Ω, 4.5w)

PCB

Wire (1Pkt)

10

12

30

10

10

4

10

60

30

10

20

25

30

CHAPTER-5RESULT AND ANALYSIS

5.1: RESULT:

MEASURED VALUE:

Light Condition:

34

Night Lamp:

LDR value: 638kΩ

IC NE555 (Pin8) VCC: 5.86v

IC NE555 (Pin3) VCC: 5.85v

Morning Alarm:

LDR Value: 788kΩ

LDR VCC: 5.86v

T1 (Base): 5.02v

R7: 4.44v

R7(IC UM66, Pin 2) VCC: 3.28v

IC UM66 (Pin1): 0.95v

Night Condition:

Morning alarm:

LDR Value: 220kΩ

T1 (Base): 2.92v

R7: 1.25v

IC UM66 (Pin2) VCC: 1.05v [Varying w.r.t. light]

IC UM66 (Pin1): 0.66v

5.2: ANALYSIS:

The advantage of the project is low cost, reliable circuit and applicability like bedrooms, hostels and hotels.

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CHAPTER-6

CONCLUSION

In our day-to-day life, we always want to satisfy our needs to makes our life

comfortable and easy. As we know, every alarm needs to be set first, to work on

and the alarm will automatically OFF according to how long the time that we

set. This concept is very good because it is very useful in our life especially for

working person. However, the common alarm also has their own

disadvantages. First, it was wasting our time because we need to set alarm

every day. Besides, we also got trouble. As we know, the function of alarm is a

machine that we can set to make a noise at a particular time to wakeup. Hence,

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the best alternative is to design an alarm that is automatically set. This is what

we have tried to achieve here. Our project is to make a night lamp with

morning alarm.

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CHAPTER-7

PHOTO

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40

CHAPTER-8

BIBLIOGRAPHY

BIBLIOGRAPHY

TEXT BOOK:-

1. Electronic devices and circuits…..................J.B.Gupta.

2. Op-Amps and linear integrated circuits…….Gayakwad.

WEBSITES:-

1. www.electronics.Com.

2. www.scridb.Com.

3. www.efy.Com.

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APPENDIX-A

DATASHEET

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