2.  Allthe refrigerators are incorporated with a
temperature controller
 The electronic temperature controller
 Concept of Freon gas
 How compressor on and off ?

3. IC LM335 3
TEMPERATURE COMPARATOR
SENSOR
AMPLIFIER
CIRCUIT Switching
Darlington Circuit O/P
I/P 12 V IC CA 3140
pair
ZENER 2
DIODE AND
POT
CIRCUIT

5.  Apply 12 volt supply.
 Set the reference voltage.
 Compare ref. voltage and voltage generated
by LM335.
 Output of comparator to Darlington pair.
 RELAY act.

6.  Easily replaceable and repairable.
 Circuit complexity is less
 IC
lm335 temperature, senser IC easily sense
the small changes in the temperature.
 Accuracy is more

7. In all temperature controller device such as
 In refrigerator for controlling on and off of
compressor
 In AC motors
 In temperature controller fan

8.  Make this circuit by using µcontroller.
 Make Protection circuit for this temperature
controller device
 IC’sare available for temp. controller which
give more sensitivity and accuracy than
LM335

9.  Reference book - R.S. Siddha
 Simple Project Make At Home (page no 138
– 140)
 Applied Electronics -R.S. Siddha
 www.efy.com
 www.datasheetcatlog.com