Thermistor

Thermistor
Thermistor (English: thermistor) is a device or component or sensor electronics used to measure temperature. The basic principle of the thermistorm is the change in resistance value (or barriers or werstan or resistance) when mtemperature or the temperature of the thermistor is changed. this thermistor a combination of said thermo (temperature) and resistors (gauges
prisoners). Thermistor was discovered by Samuel Ruben in 1930, and earned the right
in the United States patent number # 2,021,491. There are two kinds of thermistors
in general: Posistor or PTC (Positive Temperature Coefficient), and NTC (Negative Temperature Coefficien). Resistance value at the PTC will rise if temperature rises, while the NTC just the opposite.

Thermocouples

Thermocouples
In the world of electronics, thermocouples are a widely used temperature sensors to turn the heat difference in the measured object to the change potesial temperature / voltage (voltage). Simple thermocouple can be installed, and have the same type of standard connectors, and can measure temperature within a temperature range large enough to limit the measurement error of less than 1 ° C.  In 1821, an Estonian physicist named Thomas Johann Seebeck discovered that a conductor (like metal) that were given different heat gradients will produce an electric voltage. This is called the thermoelectric effect. To measure the heat change is a combination of two kinds of conductors as well as frequently used at the end of a hot object being measured. This additional conductor will then have the temperature gradation, and change the voltage in contrast to the differences in body temperature. Using different metals to complete the circuit will produce a different voltage, leaving little difference in voltage allows us to make measurements, which increases according to temperature. This difference is usually between 1 to 70 microvolt per degrees Celsius for the range of the resulting combination of modern metal. Some combinations are becoming popular as an industry standard, judging from the cost, ketersediaanya, convenience, melting point, chemical capability, stability, and results. It's important to remember that the thermocouples measure the temperature difference between two points, not absolute temperature. In many applications, one of the connections that cold-preserved as a reference temperature, while others are linked to the object of measurement. example, in the picture above, the relationship will be placed on a copper cold on the circuit board. Another temperature sensor will measure the temperature at this point, so the temperature at the tip of the object being examined can be calculated. Thermocouples can be connected in series with each other to make termopile, where each connection that heat is directed to higher temperatures and cold all connections to the lower temperature. Thus, the voltage at each thermocouple rises, allowing it to be used at higher voltages. With the constant temperature in a cold connection, which is useful for measurements in the lab, simply use the thermocouple is not easy for most direct indication of the connection and control instruments. They add cold artificial connection to their circuitry is other equipment that is sensitive to temperature (such as a thermistor or diode) to measure the temperature of the input connection on the equipment, with the specific aim of reducing the temperature gradation in between ujungujungnya. Here, the voltage derived from a known cold relationship can be simulated, and good correction can be applied. This is known as cold relationship compensation. Usually, the thermocouple is connected by means of an indication by a wire called an extension cord or compensation. The goal is clear. Extension cords used with the same amount kawatkawat with kondoktur used in thermocouple itself. Kabelkabel is cheaper than the thermocouple wires, although not too cheap, and usually produced in a form appropriate for transport over long distances - typically as a closed flexible wire or multi-core cables. Kabelkabel usually have a specification for a larger temperature range than the thermocouple wires. These cables are recommended for high accuracy. Cable compensation on the other hand, is less precise, but cheaper. They wear small differences, usually a mixture of cheap conductor material having the same thermoelectric coefficient with thermocouples (working on a limited temperature range), with results that are not as accurate as extension cables. This combination produces output similar to the thermocouple, but the operating temperature range on the cable compensation is limited to keep the small errors obtained. Extension or compensating cable must be selected according to the needs of the thermocouple. This selection generates a voltage proportional to the temperature difference between hot and cold connections, and the poles must be properly connected so that the additional voltage added to the thermocouple voltage, replace the temperature difference between hot and cold connections. The relationship between temperature difference voltage generated by thermocouple is not a linear function but the function of an interpolation polynomial coefficients has n between 5 and 9. In order to obtain accurate measurement results, the equation is usually implemented on a digital controller or stored in a table of observations. Some older equipment using analog filters.  There are several types of thermocouples, depending on application use Type K (Chromel (NiCr alloy) / Alumel (NiAlalloy)) thermocouple for general purpose. Cheaper. Available for the temperature range -200 ° C to +1200 ° C. Type E (Chromel / Constantan (CuNialloy)) Type E has a large output (68 μV / ° C) makes it suitable for use at low temperatures. Other properties of type E is a non-magnetic type. Type J (Iron / Constantan) The range is limited (-40 to +750 ° C) makes it less popular than type K type A has a sensitivity of ~ 52 μV / ° C Type N (Nicrosil (NiCrSi alloy) / Nisil (NiSi alloy)) stability and resistance to high temperature oxidation makes type N suitable for high temperature measurements without platinum. Can measure temperatures above 1200 ° C. Sensitivity is about 39 μV / ° C at 900 ° C, slightly below the type K. Type N is the improvement of K-type thermocouple types B, R, and S is a noble metal thermocouples that have similar characteristics. They are the most stable of all thermocouples, but due to low sensitivity (about 10 μV / ° C) they are usually only used to measure high temperatures (> 300 ° C). Type B (PlatinumRhodium / PtRh) Suitable temperature measurements up to 1800 ° C. Type B gives the same output at 0 ° C to 42 ° C so it can not be used below 50 ° C. Type R (Platinum / Platinum with 7% Rhodium) Suited for high temperature measurements up to 1600 ° C. low sensitivity (10 μV / ° C) and high cost makes them not suitable for general purpose use. Type S (Platinum / Platinum with 10% Rhodium) Suited for high temperature measurements up to 1600 ° C. low sensitivity (10 μV / ° C) and high cost makes them unsuitable for general purposes. Because of its high stability type S is used for standard measurements of the melting point of gold (1064.43 ° C).

Galileo thermometers

Galileo thermometers

Galileo thermometer is a thermometer made ​​from mercury, which placed in a glass tube. Signs are calibrated on the tube make the temperature can be read according to the length of the mercury in the glass, varies according to temperature. To improve accuracy, there is usually a water bulb mercury at the tip of the thermometer which contains most of the mercury; expansion and narrowing of the volume of mercury and then proceed to the tube more narrow. The space between the mercury can be filled or left empty.

Mercury Thermometers

Mercury Thermometers

Mercury in glass thermometer is a thermometer made from mercury placed in a glass tube. Signs are calibrated on the tube make the temperature can be read according to the length of the mercury in the glass, varies according to temperature. To improve accuracy, there is usually a water bulb mercury at the tip of the thermometer which contains most of the mercury; expansion and narrowing of the volume of mercury and then proceed to the tube more  narrow. The space between the mercury can be filled or left empty. In lieu of mercury, some families contain alcohol thermometers with the addition of red dye. This thermometer is safer and easier to
read. A special type of thermometer mercury, called the maximum thermometer, working with the valve on the neck of the tube near the bulb. When the temperature rises, the mercury is driven upwards through the valve by the force of expansion. When the temperature drops of mercury retained on valve and can not return to the bulb make the mercury remains in the  tube. The reader can then read the maximum temperature during the time predetermined. To restore its function, the thermometer should be  swung hard. This thermometer medical thermometer-like design. Mercury will freeze at a temperature of 38.83 ° C (37.89 ° F) and can only be used at temperatures above it. Mercury, unlike water, does not expand when frozen so it does not break the glass tube, making it difficult observed when it freezes. If the thermometer contains nitrogen, the gas may flowing down into the column and trapped there when the temperature rises. If
This happens thermometer can not be used until the return to initial conditions. To avoid this, the mercury thermometer should be inserted into the a warm place at temperatures below 37 ° C (34.6 ° F). In areas where the maximum temperature is not expected to rise above 38.83 ° C (37.89 ° F) thermometer that uses a mixture of mercury and thallium may be used. This thermometer has a freezing point of 61.1 ° C (78 ° F). Mercury thermometers commonly use the Celsius temperature scale and Fahrenhait. Anders Celsius Celsius scale formulation, presented in its publication "The Origin of the Celsius temperature scale" in 1742. Celsius used two important points on the scale: temperature when the ice melts and the temperature
evaporation of water. This is not a new idea, since Isaac Newton first worked with
something similar. Celsius temperature measurements using the melting temperature and
instead of freezing temperatures. Experiment to get a better calibration  on the Celsius thermometer carried out for 2 weeks after that. With perform the same experiment repeatedly, he found the ice melts on the same calibration mark on the thermometer. He found a point similar to the calibration at the boiling of water vapor (when experiments were performed with high accuracy, the variation seen with variations in atmospheric pressure). When he remove the thermometer from the water vapor, the height of the mercury down slowly. This related to the rate of cooling (and the expansion of the glass tube). Air pressure affect the boiling point of water. Celsius claims that height of mercury as water evaporation is proportional to the height of the barometer. When deciding to use the Celsius temperature scale itself, he determine the boiling point at 0 ° C (212 ° F) and freezing at 100 ° C (32° F). One year later Frenchman Jean Pierre Cristin proposed version of the inverse  Celsius scale the freezing point at 0 ° C (32 ° F) and boiling point at 100 ° C (212 ° F). He named it Centrigade.  In the end, proposed the Celsius thermometer calibration method as follows: 1. Place the thermometer in the water cylinder and mark the point of pure melts when fluid in the thermometer is stable. This is the freezing point of water.

2. In the same way mark the point at which the liquid is stable when thermometer placed in boiling water vapor.

3. Divide the length between two points with 100 parts of the same small. Dots was added in a calibration average but both are very depending on air pressure. Currently, three dots are used instead of water (The third point occurs at 273.16 kelvins (K), 0.01 ° C). NOTE: All
heat transfer stops at 0 K, but this temperature is still impossible to achieve because the physics is still not possible to stop the particles. Today mercury thermometers are still widely used in the fields of meteorology, but the fields hand use Another less, because mercury permanently very toxic to the system is fragile and few countries progress have condemned its use for medical purposes. Some companies using a mixture of gallium, indium, and tin (galinstan) instead
mercury.

Infrared Thermometers

Infrared Thermometers
Infrared thermometer offers the ability to detect temperature
optically - for objects observed, radiation infrared ray energy is measured, and
presented as temperature. They offer a quick method of temperature measurement
and accurate with objects from a distance and without being touched - the ideal situation where
fast moving objects, far away, very hot, be in an environment that
hazards, and / or the need to avoid contamination of objects (such as
food / medical equipment / medicines /
product or test, etc..). Product temperature measuring
Infrared available on the market, starting from the flexible to the functions
special / standard thermometer (such as images), up to a more reader system
complex and thermal imaging cameras. This is the image / picture of the thermometer
industry-specific infrared is used to monitor the temperature of liquid material
purpose of quality control in manufacturing processes.
Termometers Infrared radiation to measure temperature using a black box
(Usually infrared) emitted by objects. Sometimes called laser thermometers
if using a laser to assist the work measurement, or thermometer
without a touch to describe the ability of the tool to measure temperature from a distance
far. By knowing the amount of infrared energy emitted by the object
and its emissions, temperature of objects can be distinguished.
The main design consists of a lens pemfokus infrared energy at the detector, which
convert the energy into electrical signals that can be expressed in units
temperature after adjusting for variations in ambient temperature.
Configuration facility temperature gauges are working remotely without touching
object. Thus, the infrared thermometer is useful to measure the temperature at
circumstances where thermocouples or other types of sensors can not be used or
does not produce an accurate temperature for several purposes.
Some common condition is the object to be measured in a condition to move;
object surrounded by electromagnetic fields, as in induction heating; object
is in vacuum or an artificial atmosphere, or in applications where
needed a quick response.
Termometers Infrared can be used for multiple functions of the observations
temperature. Some examples include:
• Detecting clouds for remote telescope operating system.
• Checking mechanical equipment or electrical boxes or conduit sakering hotspots
• Checking heater or oven temperature, for the purpose of control and calibration
• Detecting hot spots / show diagnostics on the circuit board production
electricity
• Checking of hotspots for firefighters
• Detects body temperature of living creatures, like humans, animals, etc.
• Monitor the process of cooling or heating material, for research and
development or quality control in manufacturing

Bimetallic Thermometer Mechanics

Bimetallic thermometer Mechanics
Mechanical bimetal thermometer is a thermometer made ​​of modern day
fruit pieces of metal that has a different coefficient of expansion is riveted
(dipelat) into one. The word itself has a meaning that is bimetallic bi means two
while the word metal is metal, so that the bimetal means "two metal".
Bimetallic pieces intentionally made ​​to have two pieces of metal as pieces
This can be curved if there is a change in temperature. In principle, if the temperature
turned into a high, curved pieces will bimetallic toward metal
keoefisien muainya higher, whereas if the temperature becomes low, the chip
bimetal will bend toward the metal keofisien muainya lower.
Metal with a larger coefficient of expansion (high) will be faster elongated
so that the strip will bend (curve) for the other metals
did not participate again lengthwise. Usually these pieces are made of bimetallic metal
muainya much different coefficients, such as iron and copper.
On the thermometer, bimetal pieces can function as a signpost for
if the pieces received rangsanag of temperature, then the chip will be directly
curved because of the long expansion in the metal.
Besides being used as a thermometer, bimetal pieces are also used in lamps
sein cars, thermostats, irons, etc..