48828741 Automatic Room Ight Controller

8/12/2019 48828741 Automatic Room Ight Controller

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Usually when we enter in our room in darkness, we find it difficult to

locate the wall mounted switchboard to switch on the light, for a stranger, it

is tougher still as he has no knowledge of the correct switch to be turned on.

Here is a reliable circuit that takes over the task of switching on and

switching off of the lights automatically, when somebody enters or leaves

the room during darkness. This circuit has the following features.

The lights turns off only when the room is vaccent, or in other words, when

all the persons who entered the room have left.

A seven segment display shows the number of persons currently inside the

room.

In this project we use two infra red sensors. oth connected in the door. Two

photodiode!s are also connected to the receiver circuit to detect the infra red

signal. oth the infra red sensor is connected to the I" ### as a monostable

timer. In attach with the sensor and ### we use one up down counter circuit.

Up down counter increment and decrement the input pulses and display it

on the seven segment display. $ne logic circuit to compare the total number

of person in the room is also involved in this project. %or this purpose we

use I" &'(# ' bit binary comparator to compare the total number of person

in the room.


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$ne relay driver circuit to interface the main lights or fan with this unit.

)elay provide a high voltage to the fan and lights for proper working.

In this monostable timer we use I" ### . *in no ( of this I" is connected to

the positive supply. *in no + is connected to the negative supply. *in no Is

connected to the photodiode. In this project we use two

### I". -orking of this project is just like this when -hen any body enter

in the room then one infra red sensor is active and one I" is enable and at

this time second ### is disable. -hen any person came out from the room

then other ### is on and disable first I" and enable this second one. ote

that only one sensor is on at a time. -ith the help of this I" we give a up

and down pulse to the up / down counter.

*hotodiode is connected to the pin no via k ohm reistor. k ohm is

grounded from the . In normal way when we switch on the circuit both the

infra red sensor is on and light is fall on the photodiode. ow when any

body enter in the room then circuit sense the intruption and at this time ###

gives its output. $utput from the this ### is connected to the up0down

counter through npn transistor. Here we get this output from the collector

of the transistor. This collector point is also connected to the pin no ' of

second I". $utput available on the collector point is negative and due to

this pin no ' of the ne1t I" is become negative and hence this ### is off.


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-ith the help of this logI" at a time we switch on one I" and off the

second one by controlling a pin no ' by giving a negative voltage on pin

no'.

$ur ne1t circuit is I" &'+2. I" &'+2 is a up down counter. *in no +3 and

++ is connected to the positive supply. *in no +,(,2 is connected to the

ground voltage4 *in no ' and # is clock input for up and down pulses. This

up and down pulse is from the two I" ###. *in no +' of this circuit is

connected to the master reset pin +'. . *in no ,3,&,5 is output pin of this I".

These output are in bcd output and in flip flop mode. *in no +# and +6 of

this I" is connected to the ground pin.

$utput of this up7down counter is further connected to the ' bit binay

comparator circuit. "8 output from the up down counter is connected to

the I" &'(# and I" &''&. I" &&'(# compare the magnitutde of this output

and compare this output to the ground pin 2.++.+'.+. when there is any

single output on the &'(# then pin no # of this comparator is high and and

switch on the relay coil.relay further switch on the output bulb to on. -hen

"8 is connected to the &'(# and at the same time this bcd is connected to

the I" &''& to display the seven segment code.


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ow when any body enter in the room then I" ### sense the signal through

photodiode and then this signal is further connected to the I" &'+2 for

clock up signal . this I" gives its output in "8 form and then this output is

now connected to the two I" no + I" &'(# and I" &''&. $utput of the I"

&''& is connected to the common anode segment display. I" &'(# compare

the bcd signal to the ground potential when all the bcd is 9ero then there is

no output on the pin no #. If single bcd is high then pin no # become high

and output bulb is on.


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"I)"UIT 8IA:)A;.


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Working of infra red transmitter and receiver circuit.

This type of infrared pro1imity circuit is widely used as an electric switch

where physical contact is not desired for hygiene purpose. %or e1ample, we

commonly see use of infrared pro1imity sensors on public drinking

fountains and in public washrooms. The simple circuit presented here can be

operated by moving your hand in front of it. This is achieved by detecting

the infrared light reflected by your hand onto a receiver device.

%ig. + shows the circuit of the touch0free timer switch. It has two sections?

transmitter and receiver. The I) transmitter is built around timer >;"###

@I"+, which is wired as an astable multivibrator. The multivibrator produces

5(kH9 pulses @at low duty cycle that drive an infrared >=8 @>=8+. This

freBuency can be tuned using a +60kilo0ohm preset @C)+. A 60ohm series

resistor @)5 ensures that the current consumption of the I) transmitter is not

out of arrangement.

The receiver section is built around I) receiver module T;"### @I" and a few discretecomponents. The T


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designed as an I) filter.

-hen a short I) burst is received by I)D+ @as you wave your hand in front

of the switch, the demodulated pulses are fed to the trigger input @pin of

the second >;"### @I". This, in turn, triggers the monostable wired

around I" and its output pin 5 goes high for a period determined by the .0

mega0ohm potentiometer and capacitor "#. This turns off the standby

indicator @>=8+ and transistor T+ conducts to drive the #C relay @)>+.

>=8+ enables you to locate the switch in the dark. A" mains supply to the

load to be switched0on is routed through the pole and normally0opened

contacts of )>+ as shown in the diagram. The circuit works off regulated #C

8".

%ig. shows the pin configurations of T=8+ and transistor

"#'&. Assemble the circuit on a general0purpose*"and enclose in a

small plastic cabinet. %it I) >=8+ with a reflecting hood at a recessed

position on the front panel of the enclosure. The dome0shaped face of the

T=8+ inside a suitable >=8 holder such that it slightly protrudes
http://kitsnspares.com/user1/buyproduct.asp?id=76http://kitsnspares.com/user1/buyproduct.asp?id=76


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from the front panel. To prevent unwanted reflection of the I) beam, the

finished unit should be mounted such that it does not face a nearby wall.

Using high0precision linear potentiometer C) and capacitor "# @+66E%,

the time length can be set from nearly + second to +6 seconds. Attach a

small paper dial on the front panel of the enclosure and mark various

positions of the control knob of C) as shown in %ig. 5. The accuracy of the

timer depends mainly upon the Buality @and value of timing capacitor "#. In

practice, most electrolytic capacitors are rated on the basis of minimum

guaranteed value and the real value may be higher.


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Photo Transistor

A phototransistor is in essence nothing more than a normal bipolar

transistor that is encased in a transparent case so that light can reach the

ase0"ollector diode. The phototransistor works like a photodiode, but with

a much higher sensitivity for light, because the electrons that tunnel through

the ase0"ollector diode are amplified by the transistor function.

*hototransistors are specially designed transistors with the base region

e1posed. These transistors are light sensitive, especially when infrared

source of light is used. They have only two leads @collector and emitter.

-hen there is no light the phototransistor is closed and does not allow a

collector0emitter current to go through. The phototransistor opens only with

the presence of sufficient light

An opto electronic device that conducts current when e1posed to light is the

*H$T$T)A


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Infrared

Infrared@I) radiation is electromagnetic radiation of a wavelength longer

than visible light, but shorter than microwave radiation. The name means

Fbelow redF @from the >atin infra, FbelowF, red being the color of visible

light of longest wavelength. Infrared radiation has wavelengths between &66

nm and + mm.

I) is often subdivided into near0I) @I), 6.&0# Em in wavelength, mid0I)

@;I) @also intermediate0I) @II), # 0 56 Em and far0I) @%I), 56 0 +666

Em. However, these terms are not precise, and are used differently in the

various study. Infrared radiation is often linked to heat, since objects at room

temperature or above will emit radiation mostly concentrated in the mid0

infrared band

Uses

Infrared is used in night0vision eBuipment, when there is insufficient visible

light to see an object. The radiation is detected and turned into an image on a

screen, hotter objects showing up brighter, enabling the police and military

to chase targets.


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=8s to emit infrared radiation which is focused by a

plastic lens into a narrow beam. The beam is modulated, i.e. switched on and

off, to encode the data. The receiver uses a silicon photodiode to convert the

infrared radiation to an electric current. It responds only to the rapidly

pulsing signal created by the transmitter, and filters out slowly changing

infrared radiation from sunlight, people and other warm objects.

The light used in fiber optic communication is typically infrared.


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Diode

A diode functions as the electronic version of a one0way valve. y

restricting the direction of movement of charge carriers, it allows an electric

current to flow in one direction, but blocks it in the opposite direction.

A diodeGs current0voltage, or I0C, characteristic can be appro1imated by two

regions of operation. elow a certain difference in potential between the two

leads, the diode can be thought of as an open @non0conductive circuit. As

the potential difference is increased, at some stage the diode will become

conductive and allow current to flow, at which point it can be thought of as a

connection with 9ero @or at least very low resistance

Light-emitting diode

A light-emitting diode (LD! is a semiconductor device that emits

incoherent monochromatic light when electrically biased in the forward

direction. This effect is a form of electroluminescence. The color depends on

the semiconducting material used, and can be near0ultraviolet, visible or

infrared. ick Holonyak r. @+2( 0 developed the first practical visible0

spectrum >=8 in +23.


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Light-emitting diodes

@various

LD Technolog"

A >=8 is a special type of semiconductor diode. >ike a normal diode, it

consists of a chip of semiconducting material impregnated, or doped, with

impurities to create a structure called a pn junction. "harge0carriers

@electrons and holes are created by an electric current passing through the

junction, and release energy in the form of photons as they recombine. The


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wavelength of the light, and therefore its colour, depends on the bandgap

energy of the materials forming the pn junction. A normal diode, typically

made of silicon or germanium, emits invisible far0infrared light, but the

materials used for a >=8 have bandgap energies corresponding to near0

infrared, visible or near0ultraviolet light.

Unlike incandescent bulbs, which can operate with either A" or 8", >=8s

reBuire a 8" supply of the correct polarity. -hen the voltage across the pn

junction is in the correct direction, a significant current flows and the device

is said to beforward biased. The voltage across the >=8 in this case is fi1ed

for a given >=8 and is proportional to the energy of the emitted photons. If

the voltage is of the wrong polarity, the device is said to be reverse biased,

very little current flows, and no light is emitted.

"onventional >=8s are made of inorganic minerals such as?

aluminium gallium arsenide @Al:aAs 0 red and infrared

gallium arsenide7phosphide @:aAs* 0 red, orange and yellow

gallium nitride @:a 0 green

gallium phosphide @:a* 0 green

9inc selenide @n


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silicon carbide @


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Available with gains from +66 to over +66,666

;oderately fast response times

Available in a wide range of packages including epo1y coated,

transfer molded, cast, hermetic packages and in chip form

Usable with almost any visible or near infrared light source such as

>=8s, neon, fluorescent, incandescent bulbs, laser, flame sources,

sunlight, etc....


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arrow band of emitted wavelengths

;inimal generation of heat

Available in a wide range of packages including epo1y coated,

transfer molded, cast and hermetic packages

>ow cost

"an be specially selected to meet the reBuirements of your particular

application

Applications

*hototransistors can be used as ambient light detectors. -hen used with a

controllable light source, typically and >=8, they are often employed as the

detector element for optoisolators and transmissive or reflective optical

switches. Typical configurations include?

$ptoisolator

The optoisolator is similar to a

transformer in that the output is

electrically isolated from the

input.


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$ptical %&itch

An object is detected when it

enters the gap of the optical

switch and blocks the light path

between the emitter and detector.

#etro %ensor

The retrosensor detects the

presence of an object by

generating light and then looking

for its reflectance off of the object

to be sensed.

Phototransistors and I#Ds have 'een used in the follo&ing

applications.

omputer)*usiness +uipment

track 9ero detector 0 floppy

drive

margin controls 0 printers

onsumer

coin counters

position sensors 0 joysticks

remote controllers 0 toys,


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read finger position 0 touch

screen

detect holes 0 computer

card

monitor paper position 0

copiers

Industrial

>=8 light source 0 light

pens

security systems

safety shields

encoders 0 measure speed

and direction

photoelectric controls

appliances, audio7visual eBuipment

games 0 laser tag

,edical

provide electrical isolation between

patient and eBuipment

monitor intravenous injection rates


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asic of the ic ### as a monostable timer.


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The ### timer I" was first introduced around +2&+ by the

48828741 Automatic Room Ight Controller

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