Temperature Sensor

Temperature is a physical property that finds its usefulness in every field of science, and also of great importance to mankind. For this utility of temperature in the day to day activities, its measurement is important. Gauging of temperature is helpful in many technical procedures like assessing the performance of jet engine, smelting of steel, in measuring the approach of an experiment, and also in determining the consequences of global warming.

Thus, the temperature sensors found its way to existence. These sensors are actually specific devices which are implanted, and surrounded by insulating materials. To electrically isolate the delicate sensors, this insulation is employed. For the purpose of electrical insulation, good insulators are used, which, in turn, also acts as thermal insulator. This results in a sluggish functioning of the sensor.

How temperature sensors work?

The voltage that is read across the diode is actually the working base for the sensor. When the voltage increases, the temperature also rises. There is a voltage drop between the emitter and base of the transistor which is recorded. If the voltage difference is amplified, an analog signal is generated. This signal and the temperature are proportional. Even though the technique has improved, this remains the basic working principle of the temperature sensors.

What is a temperature sensor?

Analog temperature sensors are actually chips that record the surrounding temperature. A solid state method is used for its determination. Unlike age old thermometers, mercury is not used in the temperature sensor. Neither bimetallic strips, nor thermistors are used (as in stoves or thermometers). The simple relation between voltage and temperature is applied using a diode. A power supply is the only required commodity.


  • Size: three leads in the TO-92 package (0.2” x 0.2” x 0.2”)
  • Range of Temperature: Starts at -40 degree F and ranges up to 320 degree F. Or, -40 degree C till 150 degree C.
  • Range of Output: After 125 degree C, accuracy declines. 2.0 V at 150 degree C and 0.1 V at -40 degree C.
  • Power Required: Very less current is drawn. Maximum of 5.5 V supply. 0.05 A current.

Temperature Sensor

Temperature Sensor Installation

The installation process is very easy, and hassle free.

  • The left pin is connected to the power. The right pin is brought in contact with the ground.
  • The pin at the middle is fitted with an analog voltage which is linearly proportional to the temperature. This voltage is not affected by the power supply.
  • A power supply, preferably 2-4 AA battery, is connected. According to the setup, pin 3 is connected to the ground and pin 1 to the power supply.
  • The multimeter is set in the DC voltage, and is connected to both ground and the pin at the middle.
  • When the sensor’s plastic cover is pressed with a finger, the voltage range is altered. Subsequently, voltage as well as the temperature rises.
  • The TO-92 package resembles a semi cylinder made of plastic, with three legs and a chip embedded inside. To accommodate the sensor in a breadboard, the legs are made flexible. The pins can also be soldered for connection of long wires.


The chips installed inside the sensors might not be very delicate, but is also not meant for rough handling. Static electricity should be cautiously maintained and all the connections should be done properly to avoid accidents. The power supply should be chosen wisely.

Cost of Temperature Sensors

The temperature sensors are generally tagged at $10. However, it might be pulled down to $3. The RIFD temperature sensors are priced high at $25. Availability of such sensors in the market serves some very useful purposes.

Why use temperature sensors?

If you want to record the temperature at any place, this device comes very handy. It even goes easy on your pocket. Your daily plans can also be easily settled with this device. Pick up one and feel the pride.

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