Embedded Design for Power Saving Pir,Illum,Tem,Solar

EMBEDDED DESIGN FOR POWER MONITORING AND OPTIMIZATION

CONTENTS

CHAPTER 1: INTRODUCTION

Introduction ……………. 3

Aim of the Project ……………. 4

Silent features of Project ……………. 4

CHAPTER 2: MAIN BLOCK DIAGRAM

Block Diagram ……….……. 5

Description ……….……. 6

2.2 PIR Sensor ……………. 10

2.3 Illumination Control ……………. 13

2.4 Room Temperature Conditioner ………….... 18

2.5 IR Operated device control …………..... 25

2.6 Solar Tracking System ……………. 29

CHAPTER 3: PIN DISCRIPTION AND ITS ARCHITECTURE ………......... 32

3.1 PIN DISCRIPTION AND ARCHITECTURE OF 89C51 ……………. 32

3.2 ARCHITECTURE OF PIC MICROCONTROLLER ……………. 38

CHAPTER 4: POWER SUPPLY UNIT ……………. 42

CHAPTER 5: SENSOR’S ……………. 44

1


CHAPTER 6: PROGRAM FOR MICROCONTROLLER ATMEL 89C51 ……………. 50

CHAPTER 7: FLOW CHART FOR MC 89C51 ……………. 65

CHAPTER 8:ADVANTAGES, DISADVANTAGES, FUTURE DEVELOPMENT ………. 68

CHAPTER 9: BIBLOGRAPHY ….………… 70

CHAPTER 10: IC DETAILS & DATASHEETS ...…….….… 71

2


CHAPTER: 1

INTRODUCTION

In this sophisticated world every activity is getting atomized with the help of embedded concepts.

All the way so far we have seen that any controlling of parameters, utilizing natural resources for

circuit operation, preventing the devices from electric disorders, optimizing etc…, is carried out with

analogue instruments. So we decided to develop an electronic aid which is helpful for the above

purpose which is called as EMBEDDED DESIGN FOR POWER MONITORING AND

OPTIMIZATION.

In automation and instrument building we often are confronted by the necessity to precisely control

illumination of light, rotational speed of a fan, controlling the devices depending on the detection of

human being presence in the room or not, device switching using remote. Their illumination can be

controlled by switching ON the number of LED’S as per requirement; depending on the room

temperature speed of the FAN or conditioning unit of AC can be controlled as a function of applied

voltage. Here is a project for EMBEDDED DESIGN FOR POWER MONITORING AND

OPTIMIZATION.

It monitors the surrounding environment and electrical condition depending on those parameters the

embedded system will control the operation of the devices. like, if the room temperature is increased

more than the desired temperature the system will automatically controls the speed of the fan, in

other condition it will check for the natural light intensity depending on that microcontroller will

control how many set of LED’s should be switched ON, similarly one of the main feature of this

project is PIR sensor, this sensor is used to detect presence of anybody in the room or not with

3


respect to that the system will control the action of devices such that switching ON/OFF and this

project works on the dc power supply, in presence of sunlight the circuit will work with power

generated by the solar cells else with the main power supply.

This particular machine is a Embedded one, so that it is highly efficient and it is also packed with a

highly interactive and user friendly components with a wide application. This Cost effective unit is

surely a good example of technology being used for a very productive purpose. The unit being

flexible to use also renders the best of features found in some of the commercially available units.

AIM OF THE PROJECT:

“TO SAVE ENERGY, MAKE EFFICIENT UTILIZATION OF POWER”.

SILENT FEATURES OF PROJECT:

1. All the components required are easily available.

2. It is accurate [Errors are nullified] & precise as it is Digital.

3. It is much Economical compare to other analogue systems.

4. Manual errors can be avoided to some extent.

5. Automatically controlled & Easy to use.

4


CHAPER: 2 MAIN BLOCK DIAGRAM

LDR LED

TEMP

SENSOR

Fig .1

5

Comparator

MC

RELAY

RELAY

&

TRIAC

FAN

PIR


DESCRIPTION

The above block diagram shows the complete overview of project.

This project consists of following blocks ….

1) Human detection using PIR sensor

2) Illumination control.

3) Room temperature conditioner.

4) Solar tracking system.

As listed above, these are the main features of our project EMBEDDED DESIGN FOR

POWER MONITORING AND OPTIMIZATION.

In the above block diagram we can observe that it consists of different stages for all the

above stages explanation goes like this

6


2 PIR SENSOR

LED’S

Fig. 5

A PIR (passive infrared) detector coupled with an electric light is now widely

used for intruder protection. PIR are also available as stand-alone units which

usually have a switched output for controlling external loads. To enable the PIR

detector to work in daylight also, you have to cover the internal light/darkness

sensor (usually an LDR).

The PIR detector used in this circuit reacts to fast temperature variations caused by

the movement of people or animals in an enclosed space. All mammals radiate a

certain amount of heat, and it is this that causes local variations in temperature.

The radiant heat energy occupies the electromagnetic spectrum between light and

7

MC

89C51

RELAY &

TRIAC

PIR

FAN

RELAY


radio waves, i .e. 0.74….300m, which is usually called the infra-red region. The

radiant energy is picked up by a Fresnel lens, at the focus of which is a double

differential pyroelectric sensor. The detector is largely unaffected by other

electrical radiation. Also, it does not react to movement outside the guarded space.

METHODOLOGY:

The space to be monitored is divided by the lens into a number of zones.

The number of zones depends on the number of segments of which the lens is

composed. When somebody moves from one zone to other, there is a change in

temperature which is collected by the lens as a variation in radiant energy. As the

focus of the lens is a pyroelectric sensor which reacts to such a change by

generating a small electric signal. That signal is processed and used to

actuate/deactivate the appliances.

CIRCUIT DIAGRAM OF REGULATED DC POWER SUPPLY

FOR PIR SENS

8


Fig. 6

2.3 ILLUMINATION CONTROL:

LED’S

LDR

Fig. 6

Fig. 7

9

RELAY

POWER SUPPLY WHEN SUPPLY IS THERE

COMPARATOR

MC


METHODOLOGY :

As we observe in our daily life knowingly or unknowingly we leave lights, fan and other

appliances running which leads to a lot of power wastage.

In order to overcome the above disadvantage we have developed this project where by in this

illumination control is one part of it. Here in this stage depending on the natural light entering into

the room or office with the help of LDR the intensity is measured and given to the COMPARATOR

which will convert its equivalent digital signals at its output pin and those signals are fed to

microcontroller 89C51, here the decision is made how many number of LED’s to be switched ON to

maintain the room/office lights in required manner.

Depending on the natural light intensity number of LED should be switched ON and OFF. This

operation should be performed using COMPARATOR and MC. When ever the light intensity in a

room varies depending on that a digital signal has to be generated using COMPARATOR which

should be given to the microcontroller. In microcontroller a decision has to be made that how many

LED should turn ON or OFF. In above fig 2 a LED array is shown in 4 numbers, because a single

LED array consists of 9 LED’s therefore totally 3 1.

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LED ARRAY 1 LED ARRAY 2 LED ARRAY 3 LED ARRAY 4

Depending on the natural light intensity these array should be controlled. If intensity of natural light

is minimum then only LED array 1 should glow (9 LED’s), if there is no natural light then complete

4 LED array should glow. And if there is a continuous variation in natural light intensity then

depending up on variation in light intensity either LED arrays are selected. It means at a time it may

be single or double or treble or all LED arrays may be switched ON and OFF.

BUFFER AND DRIVER

INTRODUCTION:

HEX BUFFER / CONVERTER [NON-INVERTER] IC 4050: Buffers does not affect

the logical state of a digital signal (i .e. logic 1 input results into logic 1 output

where as logic 0 input results into logic 0 output). Buffers are normally used to

provide extra current drive at the output, but can also be used to regularize the

logic present at an interface. And Inverters are used to complement the logical state

(i .e. logic 1 input results into logic 0 output and vice versa). Also Inverters are

used to provide extra current drive and, like buffers, are used in interfacing

applications. This 16-pin DIL packaged IC 4050 acts as Buffer as-well-as a Converter. The input

signals may be of 2.5 to 5V digital TTL compatible or DC analogue the IC gives 5V constant signal

output. The IC acts as buffer and provides isolation to the main circuit from varying input signals.

The working Voltage of IC is 4 to 16 Volts and propagation delay is 30 nanoseconds. It consumes

0.01 mill Watt power with noise immunity of 3.7 V and toggle speed of 3 Megahertz.

11


ULN 2003: Since the digital outputs of the some circuits cannot sink much current, they are not

capable of driving relays directly. So, high-voltage high-current Darlington arrays are designed for

interfacing low-level logic circuitry and multiple peripheral power loads. The series ULN2000A/L

ICs. Drive seven relays with continuous load current ratings to 600mA for each input. At an

appropriate duty cycle depending on ambient temperature and number of drivers turned ON

simultaneously, typical power loads totaling over 260W [400mA x 7, 95V] can be controlled.

Typical loads include relays, solenoids, stepping motors, magnetic print hammers, multiplexed LED

and incandescent displays, and heaters. These Darlington arrays are furnished in 16-pin dual in-line

plastic packages (suffix A) and 16-lead surface-mountable SOICs (suffix L). All devices are pinned

with outputs opposite inputs to facilitate ease of circuit board layout.

The input of ULN 2003 is TTL-compatible open-collector outputs. As each of these outputs can sink

a maximum collector current of 500 mA, miniature PCB relays can be easily driven. No additional

free-wheeling clamp diode is required to be connected across the relay since each of the outputs has

inbuilt free-wheeling diodes. The Series ULN20x3A/L features series input resistors for operation

directly from 6 to 15V CMOS or PMOS logic outputs.

1N4148 signal diode: Signal diodes are used to process information (electrical signals) in circuits, so

they are only required to pass small currents of up to 100mA. General purpose signal diodes such as

the 1N4148 are made from silicon and have a forward voltage drop of 0.7V.

12


2.4 ROOM TEMPERATURE CONDITIONER

TEMP

SENSOR

Fig. 9

13

COMPARATOR

MCRELAY

&

TRIAC

FAN


Fig. 10

14


FAN DRIVER STAGE

The Counter & Switching section sends the signals to this Fan Motor Driver section to run the AC

Motor with required speed. This section has a Triac and Diac combination, which supplies regulated

Alternating Current to the Regulator circuitry of a fan.

INTRODUCTION:

POWER CONTROL: Many applications of electronics involve the control of appreciable levels of

voltage and/or current. Typical examples in the domestic world are the motor speed controllers

found in washing machines and the lamp dimmers which allow us to control the levels of

illumination in our homes.

THYRISTORS: Thyristors provide an alternative means of switching a high-voltage/high current load

from a much smaller triggering current source. Thyristors (or ‘silicon controlled rectifiers’ as they

are sometimes called) are three terminal devices, which can switch very rapidly from a conducting to

a non-conducting state. In the ‘OFF’ state, the Thyristors exhibits negligible leakage current, whilst in

the 'ON’ state the device exhibits very low resistance. This results in very little power loss within the

Thyristors even when appreciable power levels are being controlled.

Once switched into the conducting state, the Thyristors will remain conducting (i.e. it is latched in

the ‘ON’ state) until the forward current is removed from the device. It is important to note that, in

d.c applications, the necessities the interruption (or disconnection) of the supply before the device

15


can be reset into its non-conducting state. However, where a Thyristors is used with an alternating

supply, the device will automatically become reset whenever the mains supply reverses. The device

can then be triggered on the next half-cycle having correct polarity to permit conduction. Like

their conventional silicon diode counterparts, Thyristors have anode and cathode connections.

Control is applied by means of a third gate terminal and the device is triggered into the conducting

(‘ON’ state) by applying a current pulse of sufficient magnitude (and rise time) to this terminal.

TRIGGERING: While designing circuit using Thyristors as power control elements, trigger pulses

should have the fastest possible rise times. Thyristors will turn ON faster (and power dissipation

within the device will be minimized) as gate current is increased. Signals with slow rise times or

poorly defined edges are generally unsatisfactory for triggering purposes. In a.c. applications, the

Thyristor triggering circuit should be designed so that it will provide effective triggering over a

sufficiently wide angle of the applied a.c. supply voltage. Failure to observe this rule will generally

result in an inadequate range of control.

TRIACS: Triacs are a refinement of the Thyristor which, when triggered, conduct on both positive

and negative half cycles of the applied voltage. Triacs have three terminals: main terminal one

(MT1), main terminal two (MT2) and gate (G). Triacs can be triggered by both positive and negative

voltages applied between G and MT1with positive and negative voltages present at MT2 respectively.

16


By virtue of the symmetry in triggering, Triacs thus provide a means of controlling a.c. voltages over

both positive and negative half-cycles. Thyristors, on the other hand, can only provide control on

one, or other, of the half-cycles.

DIACS: In order to simplify the design of triggering circuits, a Triac is often used in conjunction

with a Diac. This device is somewhat similar to a Zener diode having bi-directional properties. A

typical Diac conducts heavily when the applied voltage exceeds approximately + 32V. Once in the

conducting state, the resistance of the Diac falls to a very low value and thus a large value of current

will flow (sufficient to trigger the Triac to which it is connected).

Circuit Description:

Triac’s make excellent variable a.c. power control devices. The present circuit is capable of handling

a resistive load of up to 1kW. At higher power levels (i.e. 150W plus) the Triac will require a heat

sink.

The present circuit shows a simple phase-triggered AC motor controller. Input from Counter &

Relay section and C1 are wired together as a combined variable potential divider and variable phase

shift network. The Diac is used as a simple trigger device that fires when the C1 voltage rises to

roughly 35 V [in either polarity] and then partially discharges C1 into the Triac gate, thus triggering

the Triac on. The Diac turns off automatically when the C1 voltage falls below 30 V or so.

17


CIRCUIT DIAGRAM OF FAN DRIVER SECTION

Fig. 12

Parts List:

SEMICONDUCTORS

D1 ER900 DIAC 1

T1 BT 136 TRIAC 1

R1 68 K Ohm ¼ Watt 1

R2 270 Ohm ½ Watt 1

R3 10 K Ohm ½ Watt 1

18

T1

P1

R

R1 Input from Counter & Switching sectionR3

R2

Fan Regulator

C1 C2 C3

D1

230 V AC


P1 100 K Ohm Preset 1

CAPACITORS

C1 & C2 300 nF / 400V 2

C3 33nF/ 400 V 1

When Input from Counter & Switching section is very low negligible potential divider action or

phase shifting takes place, and the C1 voltage closely follows that of the a.c. power line until the

trigger voltage of the Diac is reached, at which point the Triac fires and turns ON the motor with

predefined speed and removes all drive from the Input from Counter & Relay section-C1 network.

The Triac thus fires shortly after the start of each half-cycle under this condition, and almost full

power is applied to the load.

When Input from Counter & Switching section is very high, on the other hand, the potential divider

action is such that the peak voltage on C1 only just reaches the 35 V needed to trigger the Diac, and

the phase shift of C1 is close to 90°. Since the peak of a half-wave occurs 90° after the start of the

half-cycle, the net effect of the low voltage and near-90° phase shift on C1 is to delay the firing of

the Triac by about 170°. Under this condition, therefore, the Triac does not fire until 10° before the

end of each half-cycle, and negligible power is applied to the load. Thus, the Input from Counter &

Relay section-C1 and Diac network enables the firing of the Triac to be delayed between roughly

10° and 170° in each half-cycle, and efficient variable power control is available.

Since the Triac switches from OFF to ON very sharply, and switches fairly high currents, the

switching waveform is very rich in harmonics. So to keep the higher harmonics out of the supply

line the circuit must be incorporated with a filter. And also ensure that when Input from Counter &

Switching section is set near its minimum value, the charge currents flowing to C1 via Input from

19


Counter & Relay section are not so large that they damage R4. The preset P1 is the charge-current

limiting resistor and R2-C3 form the harmonic filter.

The resistor Input from Counter & Relay section has a considerable hysteresis or backlash, i.e., load

will not start to go ON again until heated [whose internal resistance is decreased] resistor [any of

VR1 to VR4 variable resistors of Counter & Switching Stage] restores its original [designed] value.

So, to over this backlash effect, the charge of C1 is fed to slave capacitor C2 via the relatively high

resistance of P1. C1 is slightly higher voltage than C2, and C2 fires the Diac once its voltage reaches

35V. Once the Diac has fired it reduces the C3 potential briefly to 30 V, but C3 then partially

recharges via C1 and P1. Little net change takes place in the C3 voltage as a result of the Diac firing,

and the circuit thus gives very little backlash. This little backlash can be further reduced to almost

zero by wiring Resistor R3 in series with the Diac to limit the C3 discharge voltage.

20


2.6 SOLAR TRACKING SYSTEM

SOLAR CELL

SOLAR TRACKING

LDR LED’S

21

MC

RELAY

COMPARATOR


CURRENT FLOWING FROM BATTERY WHEN POWER FAILURE Fig. 18

Since human evolution, mankind has exploited naturally available resources such

as Wind, Water & Solar energy. The availability of resources restricts the use of

Wind and Water energies as alternative power sources. But Sun is available

There are some hopes that the sun will become a main source of energy in the

21 s t century. By then, sources of oil will be almost exhausted and will only play a

minor part in the supplying of energy. The present interest in solar energy is

therefore not surprising. Some work has already been done with solar cells and

solar panels. However, these only operate with optimum performance when

positioned exactly at right angles to the sun. Unfortunately, this situation is not

usual in our latitudes unless the solar panels are rotated with respect to the sun.

The efficiency of a solar panel system can be improved if the panels track the sun,

and remain as long as possible at the most favorable angle of incidence.

The project consists of “SOLAR TRACKING SYSTEM” is an attempt to achieve

maximum utilization of the solar energy. This is achieved by tracking the

movement of the Sun, and keeps charging solar cells below the Sun’s availability

zone for maximum time. By this one can get the maximum utilization of the Sun

presence.

Most of the energy that we get from the greatest reservoir of energy, the Sun,

remains unused. The only way to store the energy from the sun is to convert it into

22


electrical form and then using this electrical signal to charge batteries and thus

store the energy in chemical form. For this we make use of solar panels consisting

of solar cells. The solar cell gives an electrical output which is proportional to the

intensity of light falling over it .

In case of power cut a illumination stage will get the supply from the battery

which is charged with the help of solar cells. As a future development we can use

heavy batteries with invertors to drive the other appliances.

23

+VccCOMMON

STEPPER

MOTOR

D1

D2

D3

D4

LE

D 1

LED 2

LED 3

LED

4

R9

R10R11

R12R

13

R14R15R16

T5

T6

T7

T8

R5

R6

R7

R8

T1

T2

T3

T4

R1

R2

R3

R4

I/P FROM

89C51

COUNTER


Fig. 18

CHAPTER: 3

PIN DISCRIPTION AND ITS ARCHITECTURE

3.1 PIN DISCRIPTION AND ARCHITECTURE OF 8051

Introducing the Intel’s Microcontroller 89C51

FEATURES

• 8K Bytes of In-System Reprogrammable Flash Memory

• Endurance: 1,000 Write/Erase Cycles

• Fully Static Operation: 0 Hz to 24 MHz

• 256 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Three 16-bit Timer/Counters

• Eight Interrupt Sources

• Programmable Serial Channel

DESCRIPTION

The AT89C52 is a low-power, high-performance

CMOS 8-bit microcomputer with 8K bytes of Flash

programmable and erasable read only memory

(PEROM). The device is manufactured using Atmel’s

high-density nonvolatile memory technology and is

24


Fig.19

compatible with the industry-standard 80C51 and 80C52 instruction set and pin out.

The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional

nonvolatile memory programmer. By combining a

25


Fig. 20

versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful

microcomputer which provides a highly-flexible and cost-effective solution to many embedded

control applications.

The AT89C51 provides the following standard features: 4K bytes of Flash, 256 bytes of RAM, 32

I/O lines, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full-duplex

serial port, on-chip oscillator, and clock circuitry. In addition, the AT89C51 is designed with static

logic for operation down to zero frequency and supports two software selectable power saving

modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and

interrupt system to continue functioning.

The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip

functions until the next hardware reset.

Pin Description

VCC

Supply voltage.

GND

Ground.

DC Characteristics

Operating Temperature.................................. -55°C to +125°C

Storage Temperature ..................................... -65°C to +150°C

Voltage on Any Pin with Respect to Ground .....................................-1.0V to +7.0V

Maximum Operating Voltage............................................ 6.6V

26


DC Output Current...................................................... 15.0 mA

27


28

COMPLETE CIRCUIT DIAGRAM [MOTHER BOARD] 89C51 +Vcc

P0.7

32

P0.6

33

P0.5

34

P0.4

35

P0.3

36

P0.2

37

P0.1

38

P0.0

39

P2.7

28

P2.6

27

P2.5

26

P2.4

25

P2.3 24

P2.2 23

P2.1 22

P2.0

21 1

P1.7

8

P1.6

7

P1.5

6

P1.4

5

P1.3

4

P1.2

3

P1.1

2

P1.0

1 1

19 XTAL1

18 XTAL2

30 pF

12 MHz

30 pF89C51

VSS

20

29 PSEN

30 ALE

31 EA

9 RST

+VCC

10 MFD/63V

20KΩ RESET

SWITCH

40

VCC

8 x 2.2 KΩ

AD7

AD6

AD5

AD4

AD3

AD2

AD1

AD0

RD

WR

T1

T0

INT1

INT0

TXD

RXD

17

P3.7

16

P3.6

15

P3.5

14

P3.4

13

P3.3

12

P3.2

11

P3.1

10

P3.0

A15

A14

A13

A12

A11

A10

A9

A8

230 AC

X1 D1 & D2 IC1

+VCC

R1

D3C1 C2 C3

PORT 0

PORT 1

PORT 2PORT 3


Fig. 21

29


CIRCUIT DESCRIPTION:

The mother board of 89C51 has following sections: Power Supply, 89C51 IC, Oscillator, Reset

Switch & I/O ports. Let us see these sections in detail.

POWER SUPPLY:

This section provides the clean and harmonic free power to IC to function properly. The output

of the full wave rectifier section, which is built using two rectifier diodes, is given to filter

capacitor. The electrolytic capacitor C1 filters the pulsating dc into pure dc and given to Vin pin-

1 of regulator IC 7805.This three terminal IC regulates the rectified pulsating dc to constant +5

volts. C2 & C3 provides ground path to harmonic signals present in the inputted voltage. The

Vout pin-3 gives constant, regulated and spikes free +5 volts to the mother board. The allocation

of the pins of the 89C51 follows a U-shape distribution. The top left hand corner is Pin 1 and

down to bottom left hand corner is Pin 20. And the bottom right hand corner is Pin 21 and up to

the top right hand corner is Pin 40. The Supply Voltage pin Vcc is 40 and ground pin Vss is 20.

OSCILLATOR:

If the CPU is the brain of the system then the oscillator, or clock, is the heartbeat. It provides the

critical timing functions for the rest of the chip. The greatest timing accuracy is achieved with a

crystal or ceramic resonator. For crystals of 2.0 to 12.0 MHz, the recommended capacitor values

should be in the range of 15 to 33pf2. Across the oscillator input pins 18 & 19 a crystal x1 of

4.7 MHz to 20 MHz value can be connected. The two ceramic disc type capacitors of value 30pF

are connected across crystal and ground stabilizes the oscillation frequency generated by crystal.

I/O PORTS:


There are a total of 32 i/o pins available on this chip. The amazing part about these ports is that

they can be programmed to be either input or output ports, even "on the fly" during operation!

Each pin can source 20 mA (max) so it can directly drive an LED. They can also sink a

maximum of 25 Ma current.

Some pins for these I/O ports are multiplexed with an alternate function for the peripheral

features on the device. In general, when a peripheral is enabled, that pin may not be used as a

general purpose I/O pin. The alternate function of each pin is not discussed here, as port

accessing circuit takes care of that.This 89C51 IC has four I/O ports and is discussed in detail:

P0.0 TO P0.7

PORT0 is an 8-bit [pins 32 to 39] open drain bi-directional I/O port. As an output port, each pin

can sink eight TTL inputs and configured to be multiplexed low order address/data bus then has

internal pull ups. External pull ups are required during program verification.

P1.0 TO P1.7

PORT1 is an 8-bit wide [pins 1 to 8], bi-directional port with internal pull ups. P1.0 and P1.1 can

be configured to be the timer/counter 2 external count input and the timer/counter 2 trigger input

respectively.

P2.0 TO P2.7

PORT2 is an 8-bit wide [pins 21 to 28], bi-directional port with internal pull ups. The PORT2

output buffers can sink/source four TTL inputs. It receives the high-order address bits and some

control signals during Flash programming and verification.

P3.0 TO P3.7


PORT3 is an 8-bit wide [pins 10 to 17], bi-directional port with internal pull ups. The Port3

output buffers can sink/source four TTL inputs. It also receives some control signals for Flash

programming and verification.

PSEN

Program Store Enable [Pin 29] is the read strobe to external program memory.

ALE

Address Latch Enable [Pin 30] is an output pulse for latching the low byte of the address during

accesses to external memory.

EA External Access Enable [Pin 31] must be strapped to GND in order to enable the device to

fetch code from external program memory locations starting at 0000H upto FFFFH.

RST Reset input [Pin 9] must be made high for two machine cycles to resets the device’s

oscillator. The potential difference is created using 10MFD/63V electrolytic capacitor and

20KOhm resistor with a reset switch

3.2 ARCHITECTURE OF PIC MICROCONTROLLER


Fig. 22

Micro-Controller IC PIC 16F505: This IC is pre-programmed to identify the signals it

receives at pin-4. The working voltage +Vcc is connected to pin-1 and pin-14 is made ground.

The program detects 256 diff signals and activates respective line of 8-channel amplifier stage.

Whenever it receives any signal at pin-4 [i.e. at input pin] it first checks whether it is a valid

command signal or not. If it found the received signal is a valid one, then decodes that RC5

coded signal back to original command signal. Then depends upon the command it activates the

corresponding line by making the respective pin HIGH. There are eight outputs coming out of

this PIC IC, viz., and pins 6, 7, 8, 9, 10, 11, 12, 13 & 14.


The PIC16C505 from Microchip Technology is a low-cost, high-performance, 8-bit,

fully static, EPROM/ ROM-based CMOS microcontroller. It employs a RISC architecture with

only 33 single word/single cycle instructions. All instructions are single cycle (200 s) except for

program branches, which take two cycles. The PIC 16F505 delivers performance an order of mag-

nitude higher than its competitors in the same price category. The 12-bit wide instructions are

highly symmetrical resulting in a typical 2:1 code compression over other 8-bit microcontrollers in

its class. The easy to use and easy to remember instruction set reduces development time

significantly.

The PIC16F505 product is equipped with special features that reduce system cost and power

requirements. The Power-On Reset (POR) and Device Reset Timer (DRT) eliminate the need for

external reset circuitry. There are five oscillator configurations to choose from, including INTRC

internal oscillator mode and the power-saving LP (Low Power) oscillator mode. Power saving

SLEEP mode, Watchdog Timer and code protection features improves system cost, power and

reliability.

The PIC16F505 is available in the cost-effective One-Time-Programmable (OTP) version, which

is suitable for production in any volume. The customer can take full advantage of Microchip’s

price leadership in OTP microcontrollers, while benefiting from the OTP’s flexibility.

The PIC16C505 product is supported by a full-featured macro assembler, a software simulator, an

in-circuit emulator, a ‘C’ compiler, a low-cost development programmer and a full featured

programmer. All the tools are supported on I B M P C and compatible machines.


3.2.1 Applications

The PIC16F505 fits in applications ranging from personal care appliances and security systems

to low-power remote transmitters/receivers. The EPROM technology makes customizing

application programs (transmitter codes, appliance settings, receiver frequencies, etc.) extremely

fast and convenient. The small footprint packages, for through hole or surface mounting, make

this microcontroller perfect for applications with space limitations. Low-cost, low-power, high-

performance, ease of use and I/O flexibility make the PIC16F505 very versatile even in areas

where no microcontroller use has been considered before (e.g., timer functions, replacement of

“glue” logic and PLD’s in larger systems, and coprocessor applications).

The PIC16C505 device has Power-on Reset, selectable Watchdog Timer, selectable code

protect, high I/O current capability and precision internal oscillator.

The PIC16C505 device uses serial programming with data pin RB0 and clock pin

3.2.2 PIN DIAGRAM WITH COMPARISION OF 16F505 vs

12F50X


Fig.23

Here are some differences between the 12F50X and the 16F505:

12F508

512 words (12 bit), 25 bytes SRAM, 5 I/O ports + 1 Input pin.

one 8-bits timer, Max speed: 4Mhz and 33 instructions.

12F509

1024 words (12 bit), 41 bytes SRAM, 5 I/O ports + 1 Input pin. one 8-bits timer, Max speed:

4Mhz and 33 instructions.

16F505

1024 words (12 bit), 72 bytes SRAM, 11 I/O ports + 1 Input pin. one 8-bits timer, Max speed:

20Mhz and 33 instructions.

The only difference on this PIC is: more speed, more ports and more SRAM. Basically it can

replace a 12F508 or 12F509 if the project is already made. A good idea to take advantage of this,


is to replace a 12F509 with a 16F505 and use a 20Mhz Xtal. In that way, you can break the

4Mhz barrier of the 12F50X.

An important feature of the 16F505 is the register file Map. It is fully compatible with the

12F509. With four banks, the 16F505 can address more memory. Microchip also shows a sample

how to clear ram using indirect addressing.

As all microchip PICs, the INF register is not a physical register. Addressing INDF actually

addresses the register whose address is contained in the FSR register. Remember: FSR is a

pointer.

CHAPTER 4

POWER SUPPLY UNIT

The circuit needs two different voltages, +5V & +12V, to work. These dual voltages are supplied

by this specially designed power supply.


CIRCUIT DIAGRAM OF +5V & +12V FULL WAVE

REGULATED DC POWER SUPPLY

Fig.24

POWER SUPPLY

Parts List:SEMICONDUCTORS

IC1

IC2

7812 Regulator IC

7805 Regulator IC

1

1

D1& D2 1N4007 Rectifier Diodes 2

CAPACITORS

C1 1000 µf/25V Electrolytic 1

C2 to C4 0.1µF Ceramic Disc type 3

MISCELLANEOUS

X1 230V AC Pri,12-0-12 1Amp Sec Transformer 1

230AC

X1

C1

7812

D21

C2 C3

IC1

D11 9V

7805

C4

IC1

7805

+12V

+5V


CIRCUIT DESCRIPTION:

A d.c. power supply which maintains the output voltage constant irrespective of a.c. mains

fluctuations or load variations is known as regulated d.c. power supply. It is also referred as full-

wave regulated power supply as it uses four diodes in bridge fashion with the transformer. This

laboratory power supply offers excellent line and load regulation and output voltages of +5V &

+12 V at output currents up to one amp.

1. Step-down Transformer: The transformer rating is 230V AC at Primary and 12-0-12V,

1Ampers across secondary winding. This transformer has a capability to deliver a current of

1Ampere, which is more than enough to drive any electronic circuit or varying load. The 12VAC

appearing across the secondary is the RMS value of the waveform and the peak value would be

12 x 1.414 = 16.8 volts. This value limits our choice of rectifier diode as 1N4007, which is

having PIV rating more than 16Volts.

2. Rectifier Stage: The two diodes D1 & D2 are connected across the secondary winding of the

transformer as a full-wave rectifier. During the positive half-cycle of secondary voltage, the end

A of the secondary winding becomes positive and end B negative. This makes the diode D1

forward biased and diode D2 reverse biased. Therefore diode D1 conducts while diode D2 does

not. During the negative half-cycle, end A of the secondary winding becomes negative and end B

positive. Therefore diode D2 conducts while diode D1 does not. Note that current across the

centre tap terminal is in the same direction for both half-cycles of input a.c. voltage. Therefore,

pulsating D.C. is obtained at point ‘C’ with respect to Ground.

3. Filter Stage: Here Capacitor C1 is used for filtering purpose and connected across the rectifier

output. It filters the a.c. components present in the rectified d.c. and gives steady d.c. voltage. As

the rectifier voltage increases, it charges the capacitor and also supplies current to the load.


When capacitor is charged to the peak value of the rectifier voltage, rectifier voltage starts to

decrease. As the next voltage peak immediately recharges the capacitor, the discharge period is

of very small duration. Due to this continuous charge-discharge-recharge cycle very little ripple

is observed in the filtered output. Moreover, output voltage is higher as it remains substantially

near the peak value of rectifier output voltage. This phenomenon is also explained in other form

as: the shunt capacitor offers a low reactance path to the a.c. components of current and open

circuit to D.C. component. During positive half cycle the capacitor stores energy in the form of

electrostatic field. During negative half cycle, the filter capacitor releases stored energy to the

load. The result of the addition of a capacitor is a smoothing of the FWR output. The output is

now a pulsating dc, with a peak to peak variation called ripple. The magnitude of the ripple

depends on the input voltage magnitude and frequency, the filter capacitance, and the load

resistance.

To describe the source of the voltage ripple, consider the performance of the filtered full

wave rectifier above. The input to the rectifier is a sine wave of frequency f. Let Vi be the full

wave rectified signal input to the filter stage of the rectifier and Vo be the output. Vi can be

approximated as the absolute value of the rectifier input, with frequency 2f.


Fig. 25: Output (Vi) and input (Vo) of a filtered full wave rectifier

In the time period from T0 to T1, the diode D1 (or D3, depending on the phase of the

signal) is forward biased since Vi > VC1 (approximate the forward biased diode as a short

circuit). The capacitor C1 charges and the voltage across the load R increases. From T1 to T2,

the diodes D1 and D2 are reverse biased (open circuit) because Vcap > Vi, and the capacitor

discharges through the load R with a time constant of RC seconds.

4. Voltage Regulation Stage: Across the point ‘D’ and Ground there is rectified and filtered d.c.

In the present circuit KIA 7812 three terminal voltage regulator IC is used to get +12V and KIA

7805 voltage regulator IC is used to get +5V regulated D.C. output. In the three terminals, pin 1

is input i.e., rectified & filtered D.C. is connected to this pin. Pin 2 is common pin and is

grounded. The pin 3 gives the stabilized D.C. output to the load. The circuit shows two more

decoupling capacitors C2 & C3, which provides ground path to the high frequency noise signals.

Across the point ‘E’ and


‘F’ with respect to ground +5V & +12V stabilized or regulated d.c output is measured, which

can be connected to the required circuit.

Note: While connecting the diodes and electrolytic capacitors the polarities must be taken into

consideration. The transformer’s primary winding deals with 230V mains, care should be taken

with it.

CHAPTER 5.

SENSOR’S

5.1 LX16C PASSIVE INFRARED SENSOR (PIR):

The product is an energy saving device automatic switch, it adopt integrated circuit and

precise detecting components.

It can be ON when one comes in the detection field and will off automatically after one

leaves the detection field..


It can identify day and night automatically.

Its performance is very stable.

Can identify day and night automatically.

Ambient-light can be adjusted. so it will work at night and stops in the day time. The

consumer can adjust it freely.

Detection distance can be adjusted according to the local place.

Time delay can be adjusted vary to the place.

The light- time can be added automatically.

When one moves in the direction of the field when the lamp is lighting: it can compute

time once more and delay the light – time automatically after the sensor detects signal

once again.

Installation diversify: we can fit connection-line box,

connection-mouth,1/2″spiraling connection hand.SPECIFICATIONS:

Detection distance(<24 ˚c) : 2-11m(adjustable)

Detection range : 180˚

Power source : 180-240v/AC, 50-60 Hz

Rated load : 1200w (220v/ACMax)

Working temperature : -20˚ - +40˚c

Working humidity : < 93% RH

Time delay : 5 sec – 7 min, ±2 min

Ambient- light : < 10-2000

Lux adjust Installation height : 1.8m-2.5m

OPERATION:


Sensitivity: turn the knob clock wise to raise its sensitivity and turn it anti clock wise to reduce

its sensitivity. Turn the knob to clock wise to last operating time and turn it anti clock wise to

shorten it.

Light control: turn the knob then this product can oprate in different ambient-light.(see the Fig.

23 given below)

Fig. 26


5.2 LM35

PRECISION CENTIGRADE TEMPERATURE SENSORS GENERAL


DESCRIPTION The LM35 series are precision integrated-circuit temperature sensors,

whose output voltage is linearly proportional to the Cels

ius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature

sensors calibrated in Ê Kelvin, as the user is not required to subtract a large constant voltage

from its output to obtain convenient Centigrade scaling. The LM35 does not require any

external calibration or trimming to provide typical accuracies of ±1¤4 ÊC at room temperature

and ±3¤4 ÊC over a full -55 to +150ÊC temperature range. Low cost is assured by trimming

and calibration at the wafer level. The LM35’s low output impedance, linear output, and

precise inherent calibration make interfacing to readout or control circuitry especially easy.

It can be used with single power supplies, or with plus and minus supplies. As it draws only

60 µA from its supply, it has very low self-heating, less than 0.1 ÊC in still air. The LM35 is

rated to operate over a -55Ê to +150ÊC temperature range, while the LM35C is rated for a -

40Ê to +110ÊC range (-10Ê with improved accuracy). The LM35 series is available pack-aged

in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also

available in the plastic TO-92 transistor package. The LM35D is also avail-able in an 8-lead

surface mount small outline package and a plastic TO-220 package.

FEATURES

Calibrated directly in Ê Celsius (Centigrade)

Linear + 10.0 mV/ÊC scale factor

0.5ÊC accuracy guaranteeable (at +25ÊC)

Rated for full -55Ê to +150ÊC range

Suitable for remote applications


Low cost due to wafer-level trimming

Operates from 4 to 30 volts

Less than 60 µA current drain

Low self-heating, 0.08ÊC in still air

Nonlinearity only ±1¤4 ÊC typical

Low impedance output, 0.1 for 1 mA load

5.3 IR RECEIVER MODULE FOR REMOTE CONTROL

SYSTEM

DESCRIPTION

The TSOP1 1.. - series are miniaturized receivers for infrared remote control systems. PIN

diode and preamplifier are assembled on lead frame, the epoxy package is designed as IR filter.

The demodulated output signal can directly be decoded by a microprocessor. The main benefit is

the operation with short burst transmission codes and high data rates.

FEATURES

· Photo detector and preamplifier in one package

§ Internal filter for PCM frequency

§ Improved shielding against electrical field disturbance

§ TTL and CMOS compatibility


§ Output active low

§ Low power consumption

§ High immunity against ambient light

SPECIAL FEATURES

§ Enhanced data rate of 4000 bit/s

§ Operation with short bursts possible (~ 6 cycles/ burst)

CHAPTER 6.

PROGRAM FOR MICROCONTROLLER ATMEL 89C51

#include<stdio.h>

#include<at89x51.h> //HEADER FILE FOR ATMEL 89C51

sfr port0 = 0x80;

sfr port1 = 0x90;

Part Carrier Frequency

TSOP1130 30 kHzTSOP1133 33 kHzTSOP1136 36 kHz

TSOP1 137 36.7 kHzTSOP1138 38 kHzTSOP1 140 40 kHz


sfr port2 = 0xa0;

sfr port3 = 0xb0;

sbit lrelay1 = port1 ^ 0;




sbit trelay1 = port1 ^ 4;



sbit input = port1 ^ 7;

unsigned char dig, digit;

unsigned char cnt = 0, cnt1 = 0;

unsigned int counter1 = 0, counter = 0;

void delay() // DELAY FUNCTION

unsigned int i;

for (i = 0;i < 5000 ; i++ );

void ldelay() // DELAY FUNCTION

unsigned long int i;

for (i = 0;i < 15000 ; i++ );


void main()

delay ();

delay ();

port1=0x00;

port0=0x00;

//input=1;

while (1) //ENTERS INFINITE LOOP

ldelay ();

cnt = port3;

cnt1 = port2;

if (input==1)

if ((cnt > 1) && (cnt < 16)) lrelay1 = 1; lrelay2 = 0; lrelay3 = 0; lrelay4 = 0;




if ((cnt1 > 0) && (cnt1 < 10)) trelay1 = 1; trelay2 = 0; trelay3 = 0;



else port1=0x00;

counter = counter+1;

if (counter==1 && counter1 < 6) port0 = 0x01;





if (counter==5) counter=0; counter1=counter1+1;

if (counter==1 && counter1 > 6) port0 = 0x08;




if (counter==5) counter=0; counter1=counter1+1;

if (counter1==12) counter=0; counter1=0;

CHAPTER. 8 FLOW CHART FOR MC 89C51

NO

START

GENERATE THE OUTPUT FOR SOLAR TRACKING

SYSTEM

IF PORT 1.8 = 1


YES

NO

YES

FLOW CHART FOR PIC MC 16F505

NO

YES

ACCEPT THE INPUTS FROM PORT2 AND PORT3 DEPENDING ON THE VALUES OF LDR AND

TEMP SENSOR

GENERATE THE OUTPUT AT PORT1 TO DRIVE NO. OF LED’S & SPPED OF FAN

STOP

START

IF PORT 1.8 OF MC= 1

ACCEPT THE INPUTS FROM IR SENSOR MODULE TO PIN NO.4

OF PIC MC

GENERATE THE OUTPUT AT PORT1 TO DRIVE NO. OF DEVICES

CONNECTED TO IT

STOP

IF SYSTEM IS SWITCHED OFF

IF SYSTEM IS SWITCHED OFF


NO

YES

YES

CHAPTER .9

ADVANTAGES

1. Walking up to the regulators board to change the fan speed is avoided.

2. Fan regulators are eliminated.

3. Unnecessary wastage of electricity can be controlled to a greater extend.

4. Maximum power can be saved.

5. Electrical safety is designed to prevent device damage & electrical shocks.

6. Selectable Sensitivity, Sensitivity can be adjusted to match installation requirements.

7. Wide supply voltage range: 3.0V to 15V in COMPARATOR.

8. Photo detector and preamplifier in one package.

DISADVANTAGES


In this project usage of relays leads to consume more power.

FUTURE DEVELOPMENT

Instead of using relays if we replace it by IC 4066 (QUAD BILATERAL SWITCH)

then there will be drastically power consumption can be reduced to an greater extent.

CHAPTER .10 BIBLOGRAPHY

BOOKS REFERED:

For Hardware and Programming.

The 8051 Microcontroller and Embedded Systems

By. Muhammad Ali Mazidi

Janice Gillespie Mazidi

Hardware detail

Power Electronics

By. J. S. Chitode

Circuit Designing

IC Design Projects

By. Stephen Kamichik

WEB SITES:


http://www.atmel.com

http://www.vsnl.com

http://en.wikipedia.org/wiki/Solar_energy

[email protected]

www.google.com

www.efy.com

http://www.iccatalog.com

IC DETAILS & DATASHEETS

ANALOG TO DIGITAL CONVERTOR:

CS VCC

RD CLK R

WR D0

CLK IN D1

INTR D2

1 20

2 19

3 18

4 17

5 COMPARATOR 0804 16

6 15

7 14

8 13

9 12

mailto:[email protected]

http://en.wikipedia.org/wiki/Solar_energy

http://www.vsnl.com/

http://www.atmel.com/


VIN(+) D3

VIN(-) D4

A GND D5

VREF/2 D6

D GND D7

Fig.27

COMPARATOR convertors are among the most highly used devices for data acquisitition digital

computer use binary values , but in the physical world everything is analog temperature,

pressure, humidity and velocity are free examples of physical quantities.

A physical quantity is converted in to electrical signals using a device called transducer (sensor).

Although there are sensors for temperature, light, velocity, pressure,they produce an output that

is voltage or current. Therefore we need COMPARATOR which translate analog signal to digital

numbers that microcontroller can read them.

PIN DESCRIPTION FOR COMPARATOR0804 IC:

COMPARATOR Works with +5v and has a resolution of 8 bits. In addition to resolution,

conversion time is another major factor in judging an COMPARATOR. Conversion time is

defined as the time it takes the COMPARATOR to convert analg input to digital number. The

conversion varies depending on the clocking signal applied to the CLK R and CLK IN pins bit it

cannot be faster than 110µs.

CS: chip select is an active low input used to activate the COMPARATOR0804 chip. To access

the COMPARATOR 0804 this pin must be LOW.


RD( READ): This is input signal active LOW. It is used to get the converted data using

COMPARATOR chip. When CS=0 & if a HIGH to LOW pulse is applied to the RD pin 8-bit

digital output shows up at the D0-D7 (Data pin)

WR(Write): this is an active LOW input used ti inform the COMPARATOR to start the

conversion process. If CS=0 & WR makes transaction, the COMPARATOR start converting

input analog values of Vin to digital numbers. When data conversion is complete INTR pin is

forced LOW by COMPARATOR.

CLK IN & CLK R: CLK IN is an input pin connected to external clock source when external

clock source is used for timing. To use the internal clock generator of COMPARATOR CLK IN

& CLK R pins are connected to the capacitor and resistors. As shown in fig above. The clock

frequency is determined by equation

F = 1/1.1RC

Typically R = 10kΩ, C=150µF

Putting in above equation we get 6.6 kHz.

INTR (Interrupt): This is an output pin and active LOW. It is normally HIGH pin when the

conversion is finished; it goes to LOW to signal the cpu that converted data is ready to be picked

up. After INTR pin goes LOW we make

CS =0 and sends a HIGH to LOW pulse to the RD pin to get data out of COMPARATOR chip.

Vin+ & Vin-: These are the different analog inputs where Vin = Vin (+) – vin(-), where Vin(-) is

connected to GND and Vin(+) is used as analog input to be converted to digital.

Vcc: This is the +5v power supply. This is also used as reference voltage when the Vreff/2 is

opened.


Vreff/2(pin 9): this pin is used for reference voltage. If this pin is opened the analog input

voltage for COMPARATOR is in the range of 0 – 5V. This is used to implement analog input

voltage other then 0- -5V.

D0-D7: These are the digital data input pins. These are

tristate buffered and converted data is accessed only

when CS=0 & RD forced to LOW. So to calculate the

output voltage we use the fallowing formula:

Dout = Vin / step size

Where Dout = digital data output.

Vin = Analog input voltage and step size is the

smallest change.

Analog ground and Digital ground:

These are the input pins providing the GND for both

analog and digital signal. Analog GND is connected to

the GND of the analog Vin while digital GND is connected to the Vcc pin. The reason is to

isolate the analog Vin signal from the transient voltages caused by the digital switching of the

output D0 – D7. Such isolation contributes the accuracy of the digital data output.

HEX BUFFER / CONVERTER (NON-INVERTER)

CD4050: This circuit accepts eight inputs from the vehicle’s ID Decoder Stage.

These eight inputs are given to eight Darlington drivers for amplification purpose. The

Buffer IC’s 3, 5,7,9,11,14 [of IC2] and 11, 14 [of IC1] pins take the inputs and

1

2

6

3

16

5

15

4

14

10

11

12

13

7

Vcc

Vss 8 9

IC 4050


corresponding buffered outputs are observed at 2, 4, 6, 10, 12 [of IC2] and 12,15 [of

IC1] pins. Fig. 28

GENERAL CHARACTERISTICS:

1. Voltage Rating : 4V to 16V

2. Operating Temperature : 0C -65C

3. Max Power Dissipation : 0.01mW

4. Propagation Delay : 30 nsec typically

5. Max Toggle Speed : 3 MHz

6. Fan Out : > 50

7. Noise Immunity : 3.7V

8. Fig. 29





Fig. 30 ULN 2004: Since

the digital outputs of the some circuits

cannot sink much current, they are not

capable of driving relays directly. So,

high-voltage high-current Darlington

arrays are designed for interfacing low-

level logic circuitry and multiple

peripheral power loads. The series

ULN2000A/L ICs drive seven relays

with continuous load current ratings to

600mA for each input. At an

appropriate duty cycle depending on

ambient temperature and number of

drivers turned ON simultaneously, typical power loads totaling over 260W [400mA x 7, 95V]

can be controlled. Typical loads include relays, solenoids, stepping motors, magnetic print

hammers, multiplexed LED and incandescent displays, and heaters. These Darlington arrays are

furnished in 16-pin dual in-line plastic packages (suffix A) and 16-lead surface-mountable

SOICs (suffix L). All devices are pinned with outputs opposite inputs to facilitate ease of circuit

board layout. The input of ULN 2004 is TTL-compatible open-collector outputs. As each of

these outputs can sink a maximum collector current of 500 mA, miniature PCB relays can be

easily driven using ULN 2004. No additional free-wheeling clamp diode is required to be

connected across the relay since each of the outputs has inbuilt free-wheeling diodes. The Series

Vcc

1 16

2

3

4

5

6

7

8

11

12

14

15

13

10

9

IC ULN 2004


ULN20x4A/L features series input resistors for operation directly from 6 to 15V CMOS or

PMOS logic outputs.




VOLTAGE REGULATOR

GENERAL CHARACTERISTICS:

1. Output voltage : 05 V/12 V

2. Operating Temperature : 0c - 70c Fig. 31

3. Output Current : 100mA


4. Dropout Voltage : 1.7V

VOLTAGE REGULATION : The filtered d.c. output is not stable. It varies in accordance

with the fluctuations in mains supply or varying load current. This variation of load current is

observed due to voltage drop in transformer windings, rectifier and filter circuit. These variations

in d.c. output voltage may cause inaccurate or erratic operation or even malfunctioning of many

electronic circuits. For example, the circuit boards which are implanted by CMOS or TTL

ICs.The stabilization of d.c. output is achieved by using the three terminal voltage regulator IC.

This regulator IC comes in two flavors: 78xx for positive voltage output and 79xx for negative

voltage output. For example 7812 gives +12V output and 7912 gives -12V stabilized output.

These ICs have in-built short-circuit protection and auto-thermal cutout provisions.

IC NE 556

These devices provide two independent timing circuits of the NA555, NE555, SA555, or SE555

type in each package. These circuits can be operated in the astable or the monostable mode with

external resistor-capacitor (RC) timing control. The basic timing provided by the RC time

constant can be controlled actively by modulating the bias of the control-voltage input.

The threshold (THRES) and trigger (TRIG) levels normally are two-thirds and one-third,

respectively, of VCC. These levels can be altered by using the control voltage (CONT) terminal.

When the trigger input falls below trigger level, the flip-flop is set and the output goes high. If

the trigger input is above the trigger level and the

threshold input is above the threshold level, the flip-flop is reset, and the output is low. The reset

(RESET) input can override all other inputs and can be used to initiate a new timing cycle. When


RESET goes low, the flip-flop is reset and the output goes low. When the output is low, a low-

impedance path is provided between the discharge (DISCH) terminal and ground (GND).

FEATURES:

· Two Precision Timing Circuits Per Package

· Astable or Monostable Operation

· TTL-Compatible Output Can Sink or Source up to 150 mA

· Active Pullup or Pulldown

· Designed to Be Interchangeable With Signetics NE556, SA556, and SE556

APPLICATION:

· Precision Timers From Microseconds to Hours

· Pulse-Shaping Circuits

· Missing-Pulse Detectors

· Tone-Burst Generators

· Pulse-Width Modulators

· Pulse-Position Modulators

· Sequential Timers

· Pulse Generators

· Frequency Dividers


· Application Timers

· Industrial Controls

· Touch-Tone Encoders


Documents

Embedded Design for Power Saving Pir,Illum,Tem,Solar