ABSTRACT:
This practical temperature controller
controls the temperature of any device according to its requirement for any
industrial application. It also displays the temperature on an LCD
displays in the range of –55°C to +125°C. At the heart of the circuit is
the microcontroller from 8051 family which controls all its functions. An IC DS1621 is used as temperature sensor.
The DS1621 Digital Thermometer and Thermostat provides 9-bit temperature
readings, which indicate the temperature of the device. User-defined
temperature settings are stored in a nonvolatile memory EEPROM through 8051
series microcontroller .Maximum and minimum temperature settings are entered to
the MC through a set of switches which are stored in the EEPROM -24C02.Maximum
and minimum setting are meant for allowing any hysteresis necessary. Set button
is used first and then the temperature setting by INC and then the enter
button. Similarly for the DEC button. A
relay is driven from the MC through a transistor driver. The contact of the
relay is used for the load, shown as a lamp in the circuit. For high power
heater load a contactor may be used, the coil of which is operated by the relay
contacts in place of the lamp as shown.
Standard
power supply of 12 volt DC and 5 volt through a regulator are made from a step
down transformer along with a bridge rectifier and filter capacitor.
BlockDiagram:
Hardware
requirement Software requirement
1.
Transformer. Keil
compiler
2.
Voltage
regulator. Embedded
C
3.
Diodes
4.
Capacitor.
5.
Resistors.
6.
Microcontroller
(AT89S52).
7.
Temperature
sensor (DS1621).
8.
BC547.
9.
Relay.
1. Lamp.
1 LCD(16x2).
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