This document describes a student project to design a temperature sensor circuit. It discusses different types of temperature measurement devices such as thermocouples, resistance temperature detectors, and infrared sensors. The objectives are to design a bridge circuit to simulate a temperature sensor and create a printed circuit board considering design rules. Calculations are shown for a differential amplifier and the output waveform. The circuit diagram lists components used, including resistors, an RTD sensor, and op-amps. Potential applications mentioned include food industries to maintain constant temperatures. The result is a circuit that senses temperature changes and outputs a corresponding voltage.

1. ELECTRICAL MEASUREMENTS LAB
PROJECT
15EEE286
PREPARED BY:
S M SHREYAS
SANGITA GURIA
VINAY

2. INTRODUCTION
Temperature plays an important role in many industries both
electrical & non-electrical for analyzing properties and behavior of
various objects.
Industrial Instrumentations.
Hot Wire Anemometers.
Lab Quality Measurements.
Air, Gas & Liquid Monitoring.
Different Types of Temperature Measurement Devices
There are a number of devices that are used to measure
temperature. Let us have a look at each one of them:
 Temperature Transmitters: The temperature
transmitters are electrical instruments featuring interface
sensors that measures temperature by sensing change in a
physical characteristic.
 Thermocouple Temperature Measurement
Devices Thermocouples consist of two wires or strips that are
made of different metals. These wires are joined at one end. As
the temperature changes at the juncture, the thermocouple
induces a change in Electromotive Force (EMF) between the
ends. The EMF of the thermocouple increases with
temperature rise.
 Change-of-State Temperature Measurement Devices: The
change-of-state temperature devices comprise pellets, labels,
pellets, lacquers or liquid crystals, which display a change in
appearance at a certain temperature. These types of devices
are used in applications such as steam traps. A sensor label is

3. attached to the trap. When the trap exceeds a specific
temperature, a white dot on the sensor label turns black. As
these devices do not have a good response time, hence they
don’t respond to transient temperature changes. In addition,
the change in state of these devices is permanent, except in the
case of Liquid-Crystal Displays (LCDs). Nonetheless, these
devices can be handy when one needs to confirm that the
temperature of an equipment or a material has not crossed a
certain level.
 Resistance Temperature Devices (RTD): As the name
suggests, the resistance temperature devices rely on the
change in resistance change of a metal. The resistance rises
more or less linearly with temperature. Two key types of the
RTDs are the metallic devices, and thermistors. Thermistors
rely on the change of resistance in a ceramic semiconductor. As
the temperature rises, there is a non-linear drop in the
resistance.
 Fluid-Expansion Temperature Measurement Devices:
The fluid-expansion temperature measurement devices are
represented by the household thermometer. These devices are
mainly classified into two types, namely, the organic-liquid
type and the mercury type. Also, there are several versions
using gas instead of liquid. As mercury is not an
environmentally friendly material, there are certain
regulations that govern the shipment of devices containing
mercury. Fluid-expansion temperature measurement devices
do not pose explosion hazards, do not require electric power,
and maintain their stability during repeated usage.
 Bimetallic Temperature Measurement Devices: Bimetallic
temperature measurement devices capitalize on the difference

4. in rate of thermal expansion between different metals. In these
devices, strips of two different metals are joined together.
When the device is heated, one side of the strip will expand
more than the other. The resultant bending is converted into a
temperature reading by a pointer. Usually, they are not as
precise as RTDs or thermocouples, and do not lend themselves
to temperature recording. Nonetheless, these devices do not
require power supply, and are portable.
 Infrared Temperature Measurement Devices: The infrared
temperature measurement devices are non-contacting. They
measure temperature from the thermal radiation emitted by a
material. The infrared device consists of a lens that focuses the
infrared (IR) energy onto a detector. The energy is then
converted into an electrical signal by the detector. This signal
is then displayed in units of temperature after it is
compensated for ambient temperature changes.
OBJECTIVE
 To Design a Bridge circuit and to simulate temperature sensor.
 To design a PCB considering all the given design rules

5. CALCULATIONS:

6. DIFFERENTIAL AMPLIFIER CALCULATION:

7. OUTPUT WAVEFORM:

8. CIRCUIT DIAGRAM:
COMPONENTS USED:
SL.NO COMPONENTS SPECIFICATION QUANTITY
1 Resistors 100,220 OHM 5,2
2 RTD PT100 1
3 OPAMP IC741 3
4 DC VOLTAGE SUPPLY 10V 1

9. FUTURE SCOPE: (APPLICATIONS)
Temperature sensors are widely used in engineering and scientific
applications, especially measurement systems. They are found
within roadways in cold weather climates in order to help
determine if icing conditions exist. Indoors, temperature sensors are
used in several climate control systems including refrigerators,
freezers, air conditioners, heaters and water heaters. Aircrafts use
temperature sensors to determine if there are any atmospheric icing
conditions along their flight path and to initialize weather forecast
models.

10. RESULT:
Hence the circuit as been designed to sense the change in
temperature and give the output voltage at that particular time. We
can use this in Food Parks, Food industries for maintaining certain
constant temperature.