Now coming on to the 7805 voltage regulator. It is the voltage regulator that outputs +5V belonging to the 78xx series of the fixed linear voltage regulators.The 78 part is just a convention that the chip makers use
The LM7805, like most other regulators, is a three-pin IC.Pin 1 is for input that accepts the incoming DC voltage ranging from 5v-18v according to tested results. But manufacturer claims upto 35v. Pin 2 establishes the ground for the regulator. Pin 3 is Output pin regulated at 5 volts DC.
Now the question arises why should we use this component and why not any other. Because 78 series…………………………………making them easy to use. Secondly they have a protection against overheating and short-circuits making them robust in most applications.
Pot 2.2k ohm used Max operating voltage 150v Rated power 0.08 Watt Total rotation angle 300
LM stands for Linear Monolithic
New microsoft power point slide
The main aims of the design are:
To design a cheap and effective
temperature control systems for rooms
and classes etc.,
To make switching of fan and heater
automatic as per the required preset
temperature of room for the comfortability.
Let us consider the following situation
• Imagine as if u are sitting in a room
• U started feeling temperature is too much and u switch on fan so
that temperature starts decreasing.
• Then assume after some time u start feeling that temperature is
low and u started feeling cold.
• Now u again need to switch on the heater.
Control over Temperature plays an important part when it comes to our
comfortability and hence our project is the best possible solution that
solves such problem. We have design a cheap and effective
Temperature system for class rooms, offices & homes, so as to
maintain the temperature as per our requirements. The system works
by temperature control system which was divided into units and each
unit designed separately before being coupled to form a whole
• It is a voltage regulator that outputs +5V.
• It is a member of 78xx series of fixed linear voltage
• The "78" part is just the convention that the chip makers
use to denote the series of regulators that output positive
• The other series of regulators, the LM79XX, is the series
that outputs negative voltage.
• The xx in 78xx indicates the fixed output voltage it is
designed to provide.
• 7805 provides +5V regulated power supply.
Pin No Function Name
1 Input voltage (5V-18V) Input
2 Ground (0V) Ground
3 Regulated output; 5V (4.8V-5.2V) Output
• 78xx series ICs do not require additional
components to provide a constant,
regulated power supply.
• They have protection against overheating
and short-circuits, making them quite
robust in most applications
A potentiometer (Pot) is a three terminal
resistor with a sliding or rotating contact that
forms an adjustable voltage divider.
It consists of a fixed resistance track having
connections at both ends and a sliding
contact, called wiper, which moves along
this track by turning the spindle.
If only one of the connections and wiper
are used, it behaves as a variable resistor
In case wiper is not used, it will offer fixed resistance across the two
They are specified by their fixed value resistance
LM35 is a precision IC temperature sensor with
its output proportional to the temperature (in oC).
The sensor circuitry is sealed and therefore it is
not subjected to oxidation and other processes.
With LM35, temperature can be measured more
accurately than with a thermistor. It also possess
low self heating and does not cause more than
0.1 oC temperature rise in still air.
The operating temperature range is from -55°C to 150°C. The output voltage
varies by 10mV in response to every oC rise/fall in ambient temperature,
i.e. its scale factor is 0.01V/ oC .
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1 Supply voltage; 5V (+20V to 4V) Vcc
2 Output voltage (+6V to 0V) Output
3 Ground (0V) Ground
• CA3130 is op amplifier..
• It takes the current reading of
temperature from sensor
LM35 (PIN 2) and compares it
with the preset temperature of
rotary potentiometer(PIN 3).
• If input at pin2 is greater than
pin 3 than output is low.
• If input at pin3 is greater than
pin 2 than output is high.
A transistor is a semiconductor
device used to
amplify and switch electronic signal
s and electrical power. It is
composed of semiconductor
material with at least three
terminals for connection to an
external circuit. A voltage
or current applied to one pair of the
transistor's terminals changes the
current through another pair of
terminals. Because the controlled
(output) power can be higher than
the controlling (input) power, a
transistor can amplify a signal.
A relay is an electrically operated switch. Many
relays use an electromagnet to
mechanically operate a switch, but other
operating principles are also used, such
as solid-state relays. Relays are used where
it is necessary to control a circuit by a low-power
signal (with complete electrical
isolation between control and controlled
circuits), or where several circuits must be
controlled by one signal. The first relays
were used in long
distance telegraph circuits as amplifiers:
they repeated the signal coming in from one
circuit and re-transmitted it on another
circuit. Relays were used extensively in
telephone exchanges and early computers
to perform logical operations.
• Cost effective.
• Précised and accurate.
• To sense and measure the current temperature
• To maintain the temperature of classrooms,
offices and homes.
This circuit can be modified to improve it
further and include other features, like
displaying the current temperature using 8 to
7 segment decoder, displaying the preset
temperature in LCD. Some sensors other
actuator and sensors can also be included to
increase the sensitivity and accuracy of the
• Control over Temperature plays an important
part when it comes to our comfortability and
hence our project is the best possible solution
that solves such problem. As such, we have
design a cheap and effective Temperature
system for class rooms, offices & homes, so
as to maintain the temperature as per our
requirements. The system works by
temperature control system which was divided
into units and each unit designed separately
before being coupled to form a whole