THERMISTORRaymond R. RaolasBSECE-IIIMark Francis Orcullo BSECE-III

THERMISTORThermistor is a combination of the words Thermal and Resistor. A thermistor is a type of resistor used to measure temperature changes, relying on the change in its resistance with changing temperature.The first NTC thermistor was discovered in 1833 byMichael Faraday. A commercially viable thermistor was invented by Samuel Ruben in 1930.

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

Lead Coated Thermistor

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

Lead Coated Thermistor

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

Lead Coated Thermistor

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

Lead Coated Thermistor Glass Encased Thermistor

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

Lead Coated Thermistor Glass Encased Thermistor

THERMISTORThermistors are made of semiconductor materials (metallic compounds including oxides such as manganese, copper, cobalt, and nickel, as well as single-crystal semiconductors silicon and germanium).

Lead Coated Thermistor Glass Encased Thermistor Surface Mount Thermistor

THERMISTOR Assuming, as a first-order approximation, that the relationship between resistance and temperature islinear, then:

R = k TWhere

R = change in resistance T = change in temperature k = first-order temperature coefficient of resistance

THERMISTORThermistors can be classified into two types depending on the sign of k.

If k is positive, the resistance increases with increasing temperature, and the device is called a positive temperature coefficient (PTC) thermistor, Posistor.

If k is negative, the resistance decreases with increasing temperature, and the device is called a negative temperature coefficient (NTC) thermistor.

THERMISTORResistors that are not thermistors are designed to have akas close to 0 as possible, so that their resistance remains nearly constant over a wide temperature range.

THERMISTORAdvantages:High sensitivity to small temperature changesTemperature measurements become more stable with useCopper or nickel extension wires can be used

Disadvantages:Limited temperature rangeFragileDecalibration if used beyond the sensors temperature ratingsLack of standards for replacement

THERMISTORApplications:Temperature measurement.NTC thermistors can be also used to monitor the temperature of an incubator.Most are seen in medical equipment markets.Thermistors are also used are for engine coolant, oil, and air temperature measurement in the transportation industry.Used as electrical circuit components for temperature compensation, voltage regulation, circuit protection, time delay, and volume control.

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