PROJECT SLIDES FOR TEMPEATURE CONTROLLED DC FAN USING OP AMP.... AMP ARE USED IN THIS PROJECT TO UNDERSTAND THE THINGS ARE USING IN THIS PROJECT FOR WORKING AND ALSO CIRCUIT DIAGRAM...

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2. APPLIED PHYSICS
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PROJECT PRESENTATION

3. M S . A N A S I B R A R
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SUBMITTED TO

4. ALTAF HUSSAIN (016)
HAMMAD RAFIQUE(008)
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SUBMITTED BY

5. TEMPERATURE CONTROLLED DC FAN
USING OP AMP 741 IC
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PROJECT TITLE

6. INTRODUCATION
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 This circuit can cool your heat generating electronic
devices by operating a DC fan when the temperature in
its vicinity increases above the preset level. Its operation
is fully automatic and turns off when the temperature
returns normal. It uses a small 12V DC brush less fan
used in computers.

7. PURPOSE OF PROJECT
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 Here a 4.7K NTC Thermistor is used. IC uA 741 is used
as a voltage comparator to switch on the DC fan. ...
When the temperature increases above the value set by
VR, resistance of Thermister decreases and the voltage
at pin3 decreases. As a result, output of IC becomes low
to switch on T1.

8. CIRCUIT DIAGRAM ON PROTEUS
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9. Components are used:
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 Op amp IC LM741
 NPN Transistor MJE3055
 NTC Thermistor -10k
 Potentiometer – 10k
 Resistor -47 ohm, 4.7k
 DC Fan(Motor)
 Power supply-5v

10. Op amp IC LM741: NPN Transistor MJE3055:
 An LM741 Operational
amplifier is a DC-coupled
high gain electronic
voltage amplifier. It has
only one op-amp inside
 Power transistors are
transistors which can
handle a lot more power
in compared to BJTs.
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COMPONENTS DETAIL

11. NTC Thermistor -10k Potentiometer – 10k
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 The Thermistor is a solid
state temperature sensing
device which acts a bit like
an electrical resistor but is
temperature sensitive.
 Potentiometers also known
as POT, are nothing but
variable resistors. They can
provide a variable
resistance by simply
varying the knob on top of
its head.

12. DC Fan (motor):
 Resistor is a component
to use to control the
current source don’t over
flow the current.
 The specific type of DC
motor used in ceiling
fans is a brushless DC
motor (aka synchronous
DC motor).
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RESISTOR & DC FAN
Resistor -47 ohm, 4.7k:

13. Application of Temperature controlled DC Fan using op amp 741 IC :
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 Power supply circuits
 Audio amplifier circuits
 Battery chargers
 PC, Laptops etc.

14. Working of project:
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 When the 10K NTC Thermistor senses heat its resistance
will be decreased and it will power the circuit. A 10K
variable resistor is used to set the circuit to activate the
DC fan on your desired temperature.

15. THANK YOU
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