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INDEPENDENT PROJECT

INDEPENDENT PROJECT. RITAMBHARA CHAUHAN-ES12B1015 SAVIT VARCHASVI ALURI-ES12B1017. Temperature Controlled Switch. Temperature controlled switch. Temperature controlled switch.

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INDEPENDENT PROJECT

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  1. INDEPENDENT PROJECT RITAMBHARA CHAUHAN-ES12B1015 SAVIT VARCHASVI ALURI-ES12B1017

  2. Temperature Controlled Switch

  3. Temperature controlled switch

  4. Temperature controlled switch • When the LM35DZ(An IC included in a circuit) detects a temperature higher than a preset level, the LED is switched on. • So basically the circuit can be used in circuits where a device can be made operational or non-operational when temperature variations occur. • This is a circuit which can be used in applications where automatic temperature control is needed.

  5. Components used • IC1 : LM35DZ  Precision Celsius (Centigrade) Temperature sensor  IC2 :TL431  +2.5V precision voltage reference IC3 :LM358  Dual single supply Op-amp. LED1 -- 3mm or 5mm LED Q1 -- General purpose PNP transistor ( A1015,...) with E-C-B pin-out)D1, D2  -- 1N4148 silicon diodes (or 1SS133)D3, D4  -- 1N400x (x=2,,,,.7) rectifier diodesZD1 --- Zener diode,  13V, 400mWPreset(trim pot) :  2.2K   (Temperature set point)(# 222 or  2k2)

  6. Components used • Resistor  : ( 1/4W or 1/6W)R1 -- 10K    • R2 -- 4.7M • R3 -- 1.2K • R4 -- 1K • R5 -- 1K • R6 -- 33Ω • Capacitors : • C1  -- 0.1 µF ceramic or mylar cap         (# 104 or 100n)

  7. Working….. • The heart of the circuit is the LM35DZ temperature sensor which is factory-calibrated in the Celsius (or Centigrade) scale with a linearDegree->Volt conversion function. • The output voltage (at pin 2)  changes linearly with temperature from 0V  (0oC)  to  1000mV (100oC). This greatly simplifies the circuit design as we only need to provide a precision voltage reference (TL431) and an accurate comparator (A1 of LM358) in order to construct a complete thermal-controlled switch.

  8. Working…. • The preset (VR1) & resistor (R3) from a variable voltage divider which sets a reference voltage (Vref) form 0V ~ 1.62V. The op-amp (A2) buffers the reference voltage so as to avoid loading the divider network (VR1 & R3).  The comparator (A1) compares the reference voltage Vref  (set by VR1) with the output voltage of LM35DZ and decides whether to switch on or switch off the LED. • We can set a specific temperature according to our wish with the help of voltage across the variable resistor. • When the temperature in the surroundings is higher then a specific value, then it gets switched on. And when temperature is again low it is switched off.

  9. Temperature controlled switch…

  10. Thank You!!!!!!

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