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CatalogHistory and Basics of Polymer CapacitorsTypes and Comparison of Polymer CapacitorsAdvantages and Use of Polymer CapacitorsConclusionFAQs History and Basics of Polymer CapacitorsPolymer capacitors came into the game way back, making a big splash with their fancy science words like "conductive polymers". They started as simple parts in our gadgets but grew up to have major roles, helping keep things like power supplies steady and happy. Definition and classificationPolymer capacitors are a type of electrolytic capacitor that uses a solid conductive polymer as the electrolyte. This design sets them apart from traditional capacitors, which often rely on liquid or gel-like electrolytes.These devices come in various styles, including rectangular chips and cylindrical SMDs (V-chips), making them versatile for different electronic applications. They are further divided into categories such as polymer tantalum, polymer aluminum, hybrid polymer, and polymer niobium electrolytic capacitors.Each type offers unique benefits and is suited for specific roles in electronics.Among these classes, the polymer tantalum capacitors shine in compact power supply circuits due to their excellent performance and reliability under high temperatures. Polymer aluminum types also garner attention because they combine low equivalent series resistance (ESR) with high ripple current handling capabilities—traits beneficial for smoothing voltage fluctuations in dc/dc converters.Capacitors are like batteries; just as water towers store water, capacitors store electrical energy. - Analogous to understanding how essential water storage is for managing supply needs during demand spikes, recognizing the value of polymer capacitance is key to stabilizing voltage and current flows within electronic systems. Application basicsPolymer capacitors are like power lifelines for integrated circuits. They sit quietly inside gadgets, keeping the electricity flowing just right. Imagine them as tiny traffic cops on your phone or computer, directing energy where it needs to go.These components can handle high frequency switching power supplies without breaking a sweat. That’s because of their low ESR (equivalent series resistance), a fancy term for they don’t waste much energy.Using polymer electrolytic capacitors means your devices work smoother and last longer. Whether it’s in a smartphone or on a spaceship, these capacitors make sure the power is just right.And since they compete with MLCC (multilayer ceramic chip) capacitors, manufacturers always try to one up each other. This competition means better products for everyone. From personal experience, swapping an aluminum capacitor with a polymer one in an old radio made it sound new again — no more hums or buzzes, just music. Role of ESR, ESL, and capacitanceESR, or equivalent series resistance, plays a key role in how well capacitors handle sudden demands for power. Think of it as the throttle control on your car; lower ESR means you can go from 0 to 60 faster and smoother.For polymer aluminum electrolytic capacitors, their ESR values are really low, about 1/10 of those with traditional manganese dioxide electrolyte. This low ESR helps your devices perform better by allowing quicker response times during power surges.Capacitance is like the fuel tank capacity; higher capacitance holds more charge for later use. Engineers achieve this larger "tank" through techniques that roughen up or sinter the anodes inside aluminum and tantalum electrolytic capacitors.ESL, or equivalent series inductance, affects how fast the capacitor can release its stored power—think of it as the size of your car's exhaust pipe: bigger pipe, faster power flow.By using multi-anode designs and laying components face-down on circuits (face-down construction), modern capacitors minimize ESL so your electronic gadgets work more efficiently during high-speed operations. Types and Comparison of Polymer CapacitorsPolymer capacitors come in many shapes and sizes. Some look like tiny tubes, while others are shaped like small boxes. Rectangular chip styleRectangular chip style polymer capacitors are big in power in a small package. 7.3x4.3x4.3 mm and 1000 μF, they are space savers on the board.They handle 2.5 to 63 V and run cool from -55 °C to +125 °C. Perfect for tight spaces where power needs to be smooth, like smoothing circuits or backup capacitors.I used these little giants in my latest project, going for minimalism without losing performance. The rectangular shape made soldering them to the board a breeze, leaving more room for other components.The electrical specs were impressive too; low ESR means less energy wasted as heat, so my device will be more efficient and reliable over its life.These little rectangles are mightier than they look – good things do come in small packages. Cylindrical (radial) styleCylindrical (radial) style polymer capacitors are the choice for hybrid devices. They come in a sleek tube like shape that fits into electric circuits. Think of them as the marathon runners of electronic components, built to last and perform under pressure.With sizes up to 10×13 mm, they are compact but big on capacitance 3900 μF×2.5 V. They withstand -55 °C to +125 °C, so they are tough cookies no matter the weather.I had to swap out capacitors in an old radio during a cold winter project. The cylindrical ones were my lifesavers — easy to handle and even easier to solder onto the crowded board.Their cold weather performance made me appreciate their temperature range firsthand. And their performance didn’t falter when I turned up the volume on my restored radio — a testament to their design and high capacitance value in changing conditions. Comparison of polymer familiesPolymer capacitors come in different families, each with its own set of features. Let's compare them, shall we?TypeAnode MaterialElectrolyteCapacitance RangeRated VoltageMax Operation TempSolid Polymer AluminumAluminumSolid PolymerVaries2.5 to 63 VUp to +125 °CSolid Polymer TantalumTantalumSolid PolymerVaries2.5 to 63 VUp to +125 °CHybrid PolymerAluminum, Tantalum, NiobiumHybrid (Solid + Liquid)Varies2.5 to 63 VUp to +125 °C Each family shines in its own way. Solid Polymer Aluminum capacitors are great for their stability. Tantalum versions offer precision. Hybrid Polymer mixes solid and liquid electrolytes for an all-around performance boost. Your choice depends on your needs. Comparison of electrical parametersJumping right into the nuts and bolts of polymer capacitors, let's talk about how they stack up against each other based on their electrical parameters. Think of this as the showdown in the capacitor world, where only the best features shine.Here's a quick, no-fluff comparison in HTML Table format:ParameterRectangular Chip StyleCylindrical (Radial) StyleESR (Equivalent Series Resistance)LowerComparatively higherLeakage CurrentHigher than manganese dioxideAlso higher, but varies with materialImpedance (Measured at 100 kHz)LowSlightly higherRipple CurrentCan handle high levelsGood, but watch the heat. It's not just about picking a capacitor willy-nilly. It's about finding the right fit. Low ESR means less heat and more efficiency. But, keep an eye on that leakage current; it can be a sneaky troublemaker, leading to higher power consumption. Also, impedance at 100 kHz? That's your golden number for comparing how these components will behave in your circuit.Choosing between rectangular chip and cylindrical styles? Think about your space and how you're going to fit everything into your design puzzle. Rectangular might save you some precious real estate on the board.And about that ripple current - it's like the treadmill test for capacitors. Push too hard, and you're asking for trouble. Keep it in the safe zone to ensure reliability without turning your project into a mini toaster.No fluff, just the facts. This table is your cheat sheet to making an informed choice without getting lost in the technical jungle. Straightforward, to the point, and just a little bit of fun. Advantages and Use of Polymer CapacitorsPolymer capacitors are like superheroes in electronics. They keep devices running smoothly by controlling power flow and reducing energy hiccups.Electrical characteristicsPolymer capacitors pack a punch with their electrical characteristics. They excel in performance, making your gadgets run smoother and longer. Here's a breakdown of what sets them apart:Capacitance measurement follows the AC method, using 0.5 V at 100/120 Hz at a cozy 20 °C. This method is like finding out how much electricity these capacitors can hold and use.Ripple current really puts these capacitors to the test, heating them up and challenging their reliability. Think of it as the amount of traffic a bridge (capacitor) can handle before it gets too jammed (hot).Surge voltage for polymer aluminum electrolytic capacitors (Al-e-caps) is 1.15 times their rated voltage, while polymer tantalum electrolytic capacitors (Ta-e-caps) handle 1.3 times their rated voltage without breaking a sweat.Low Equivalent Series Resistance (ESR) means they barely put up a fight against electricity flow, letting your devices work without unnecessary stress.Near-zero Equivalent Series Inductance (ESL) ensures that little energy is wasted as heat, keeping things cool under pressure.High capacitance values packed into small sizes make them perfect for slim gadgets needing big power.Impressive tolerance to voltage fluctuations keeps your devices safe even when power supply gets wild.With low failure rates, these champions show up every day without fail, promising long-term reliability.These points highlight how polymer capacites bring efficiency and reliability to the table in a compact package. Rated capacitance and voltageCapacitance and voltage are like a capacitor's ID card. They tell you how much electric charge it can hold and the maximum voltage it can handle without trouble. Think of rated capacitance like a bucket's size, measured in microfarads (μF), where more μF means a bigger bucket for electrical charge.For example, capacitors come with capacitances up to 1000 μF – that’s quite a large bucket.Rated voltage, on the other hand, tells us the highest volt line it can work with safely.This ranges from 2.5 to 63 V, sort of like choosing the right pressure hose so our bucket doesn’t explode.Knowing these numbers is crucial for making sure your electronic devices work smoothly without any hiccups or fireworks shows from overloaded capacitors. Just imagine hooking up a small toy car battery to your home's power system.It’s all about finding the perfect match to avoid any sparks flying in places they shouldn't be. Impedance and ESRPolymer capacitors shine because they have really low Equivalent Series Resistance (ESR), 1/10th of a tantalum capacitor with manganese dioxide electrolyte.Think of ESR as the capacitor’s internal friction - lower ESR means your device runs smoother and cooler, especially at high frequencies. Some models have an ESR as low as 5mΩ, no wonder they’re the go to for smoothing out ripple in power supplies.Impedance is how much the capacitor opposes AC and is important to understand how a capacitor will perform at different frequencies. Think of impedance like trying to walk against a strong wind – the stronger the wind (or higher the impedance), the harder it is to walk (or for electricity to flow).Polymer capacitors have their impedance measured at 100 kHz to show their performance across a wide range of applications from filtering to bypassing in circuits.This makes them incredibly versatile components in both audio and power management systems.Lower ESR and optimal impedance make polymer capacitors essential heroes in our electronic world. Reliability and lifetimeCapacitors like the solid tantalum and hybrid polymer aluminium electrolytic types are built to last. They keep your gadgets going longer than traditional aluminium capacitors.It’s not just luck, it’s all about how they handle heat and power. For example they can work in -55 °C or +125 °C without breaking a sweat.The key players here are ripple current and ESR (Equivalent Series Resistance). Think of them as the stamina and heart rate of your capacitor. The better they handle these two the longer your electronics will run without a hitch.This makes them perfect for smoothing out bumps in power supplies or keeping your favorite gizmos humming along smoothly for years to come. ConclusionWe zipped through the wonders of polymer capacitors together. These marvels keep our gadgets running smoothly by managing power supply like champs. From their impressive low internal resistance to their knack for handling high currents without breaking a sweat, they're tough cookies in the electronics world.Companies are always cooking up new tech to make them even better. So, keep your eyes peeled; the future of these components looks brighter than a LED bulb. FAQs1. What's the big deal about polymer capacitors?Polymer capacitors, like solid tantalum or aluminium electrolytic capacitors, are a type of capacitor that uses conducting polymers as an electrolyte. They're known for their low ESR and ESL values and high capacitance.2. How do these polymer guys stack up against ceramic capacitors?Well, compared to ceramic or MLCC capacitors, they have a lower dielectric absorption rate which means less soakage effect. Plus, they can handle more humidity.3. Can you tell me more about how these things work?Sure. Polymer capacitors use materials such as polythiophene or Baytron P in their dielectric layer. This makes them great for roles requiring high breakdown voltage like smoothing and filter applications.4. So what types of polymer capacitors are there?There's quite a range. You've got your hybrid ones which combine elements of non-solid electrolytic and solid types; then there are series and parallel versions too.5. And how long will these bad boys last?That depends on many factors including temperature and applied voltage but generally speaking, they have better 'mean time between failures' than other fixed capacitor types.6. Any special care instructions I should know about?Just remember that unlike some other capacitor types such as polarized ones, polymer caps aren't ideal for rectifying circuits due to half-wave rectification issues.

CatalogOverview of Temperature SensorsAnalog Temperature SensorsDigital Temperature SensorsComparing Analog vs Digital Output in Temperature SensorsApplications and Benefits of Analog and Digital Temperature SensorsConclusion FAQsEver had trouble choosing the right thermometer for your project? Well, you’re not alone. This post will go through both analog and digital thermometers, showing you their benefits.Hang on tightly to yourself; This will be exciting. Overview of Temperature SensorsTemperature sensors like thermometers for your appliances. They monitor how hot or cold devices are, be it a computer chip or a car engine. Analog Temperature SensorsAnalog temperature sensors shine in their simplicity. These sophisticated devices translate heat into electrical signals. This makes them super easy to read straight-up temperatures without having to make fine adjustments.They’re like thermometers in the tech world, but instead of raising the mercury, they use electrical signals to tell us how hot or cold something is.These sensors handle critical temperature, freezing and cooling, and operate anywhere from -55°C to 175°C. That’s the extreme! Whether it’s cooling a car engine or making sure chocolate doesn’t melt, they’re ready for action.And if you have an AEC-Q100 qualified vehicle and grades, you know these features mean performance when accuracy matters."In a world where accuracy is everything, analog temperature sensors hold their ground by converting degrees of data."From power supplies to temperature monitoring systems, these sensors are everywhere. They move effortlessly into things that require simple temperature controls—no extra fluff.Imagine trying to cook a perfect steak without knowing the temperature of the grill; That’s where analog enters – it sets things right. Digital Temperature SensorsDigital temperature sensors excel in a wide range of environments. They operate from extreme cold at -55°C to really hot at 175°C. This makes them perfect in many situations, whether in the comfort of home or outside in the harsh outdoors.They come packed with cool features like different output types, voltage supply options and accuracy levels. With over 3,850 models on the market, it’s easy to find one that fits your needs like pie.These sensors are not just about measuring temperature; They also involve smart technology. Many use I2C connections, making them easy to integrate with microcontrollers and other digital systems.This feature allows smartphones, computers and other devices to read the ambient temperature without breaking a sweat. It’s all about getting accurate data faster, and using less energy while doing so.The fate behind digital temperature sensors lies in their accuracy and efficiency. They can tell you exactly how hot or cold something is, without requiring much power from batteries or electricity.Imagine trying to charge your phone faster or trying to save electricity in your home - these sensors help make that happen by making everything run more smoothly. Comparing Analog vs Digital Output in Temperature SensorsLet’s dive in and break down the two star temperature sensors: analog and digital output sensors. Each has a light level, depending on what the game requires.AspectAnalog OutputDigital OutputSignal TypeContinuousDiscreteConversion NeededYes, to digital for most usesNo, already in digital formSusceptibility to NoiseMore proneLess proneCost ImplicationsHigher, due to extra processingLower, simpler data handlingBest Fit forHigh accuracy needsQuick, reliable data transmissionAnalog sensors, like old school vinyl, give you all the subtle tonal information but can get hissy and interference. Digital sensors, think MP3s, make the music clearer but can lose subtlety. Got a tight budget and hate fudge? Digital is your friend. Craving details and willing to tweak the layout? Analog is your go to. Choose based on what your project is jamming. Applications and Benefits of Analog and Digital Temperature SensorsAnalog and digital temperature sensors play an important role in our daily lives. From beautifying homes to optimizing industrial gadgets, these little tools are everywhere.Analog sensors are like the old school way of measuring temperature. It is always shown to change smoothly with increasing or decreasing temperature. This makes them perfect for use in HVAC systems to make buildings feel right or in car engines where precise temperature control keeps things running smoothly.On the flip side, digital sensors speak in numbers and this makes them easier for computers and machines to understand. They are built into smart home appliances, allowing you to control your temperature from your phone no matter where you are.In practice, they help monitor equipment health through predictive maintenance or target systems to monitor asset health without missing a beat. In addition, with the ability to quickly send accurate data to programmable logic controllers or data-acquisition systems, quick decision making is a breeze.Both types of sensors offer unique perks based on needs - analog smoothness over accuracy and sharp communication skills with digital. Whether it’s to optimize the power supply with µModule regulators and LED driver ICs or to keep delicate electronics safe with heaters and cooling systems, these sensors ensure that everything does work without interruption.For any gadget enthusiast or anyone involved in industrial automation technology looking for reliable ways to accurately measure temperature change – analog and digital temperature sensors have it covered! ConclusionChoosing between analog and digital temperature sensors can feel like choosing your favorite ice cream flavor – both have their advantages! Analogs shine in simplicity and cost, perfect for when you just need the basics.Digital sensors, on the other hand, bring precision to the table without breaking a sweat on the noise barrier. From keeping cars cool to making sure devices don’t overheat, these young tech giants play a big part in a variety of areas. FAQs1. What's the deal with temperature sensors?Temperature sensors are like your home thermostat but way cooler (pun intended). They can sense how hot or cold an object is, and there are two types: analog and digital. Think of them as never-ending spies in a tropical world. 2. Analog vs Digital Output: Which team are you on?The analog band transmits vibes (signals) that change smoothly as the temperature rises or falls. In other words, Team Digital communicates the code - ones and zeros - to give you the lowdown on temperature changes. Both have a secret handle for dealing with the heat! 3. Can these sensors play nice with other gadgets?exactly! These sensors are like social bees; They integrate with many gadgets like light sensors, accelerometers and those fancy wireless charging systems. It’s like having a party where everyone is invited – from PCBs to LED lighting. 4. Is hooking up these sensors harder than building a rocket ship?No! No need to be a rocket scientist here. Whether you insert a terminal block or solder on a PCB (with your trusty soldering iron), installation is more like putting LEGO bricks together than launching a satellite. 5. Do I need to break my piggy bank to afford one?Not at all! Temperature sensors won't mess up a wallet faster than you can say "Google Pay." They’re very affordable, which means keeping things cold (or warm) won’t freeze your pockets. 6. Will using these make me look like a mad scientist?Only if you want to! Playing with temperature sensors will make you feel like a genius inventor without crazy hairstyles – unless that’s your style, no judgement here!

IntroductionThe Temperature Sensor, a measuring instrument, uses various physical properties of a substance to convert the thermal quantity into the physical quantity, including expansion, resistance, capacitance, electromotive force, magnetic properties, frequency, optical characteristics and thermal noise. Many materials and components change with temperature, so there are quite a few materials that can be used as temperature sensors. Here are four temperature sensors in detail.Temperature Sensors ExplainedCatalogIntroductionⅠ Temperature Sensor Types Overview1.1 What is Thermocouple?1.2 What is Thermistor Sensor?1.3 What is Resistance Temperature Detector (RTD)?1.4 What is IC Sensor?1.5 Temperature Sensor Cons and ProsⅡ How to Test: Measuring IndexesⅢ FAQⅠ Temperature Sensor Types OverviewThere are many types of temperature sensors, which can be divided into contact type and non-contact type according to the measurement method; thermistor and thermocouple according to the characteristics of sensor materials and electronic components.The contact temperature sensor needs to maintain thermal contact with the measured medium, so that the two can perform sufficient heat exchange to reach the same temperature. This type of sensor mainly includes resistance type, thermocouple, PN junction temperature sensor and so on. The non-contact temperature sensor does not need to be in contact with the measured medium, but achieves the purpose of temperature measurement through the heat radiation or convection of the measured medium.Here is a detailed introduction to the commonly used four: Thermocouples, Thermistors, Resistance Temperature Detector (RTD), IC Sensor.Figure 1. Temp Sensors (Resistance Changes with Temperature)1.1 What is Thermocouple?Thermocouples are the most commonly used temperature sensors in measurement. Its main advantages are wide temperature range and adaptability to various atmospheric environments, and it is strong, low in price, does not require power supply, and is also the cheapest. The thermocouple consists of two different metal wires connected at one end. When one end of the thermocouple is heated, there is an electric potential difference in the thermocouple circuit, and the measured electric potential difference can be used to calculate the temperature.Figure 2. Metal JunctionsThe thermocouple sensor has two contacts. The measurement end (sometimes called the hot end) is where the two metals connect. The reference junction (also called the cold end) is connected to the measurement circuit. When there is a temperature difference between two ends, an mV signal proportional to the temperature difference is generated. The mV value increases with increasing temperature. The relationship between mV and temperature is non-linear.The thermocouple connector can be constructed by connecting the thermal junction to the outer sheath for grounding or ungrounding (insulating from the sheath). A grounded thermocouple responds faster, but the thermocouple will contact the processing voltage. Therefore, it is important to isolate the measurement circuit to prevent the formation of ground loops and to avoid measurement errors.Figure 3. Thermocouple for Temperature MeasurementInside the temperature component, the thermocouple is usually embedded in magnesium oxide (MgO) and a metal sheath, then insert it into the thermowell or protective tube. This helps protect the sensor from environmental pollution. When magnesium oxide is contaminated with water and salt, even thermocouples that are not grounded will eventually be grounded.As above mentioned, the relationship between voltage and temperature is nonlinear, so it is necessary to make a second measurement for the reference temperature (Tref), and use the test equipment software or hardware to process the voltage-temperature conversion inside the instrument to finally obtain the thermocouple temperature (Tx). Thermocouple is the simplest and most versatile temperature sensor, but its sensitivity is relatively low, which is easy to be affected by environmental interference signals, and the temperature drift of the preamplifier. So it is not suitable for measuring small temperature changes, that is, it is not suitable for high-accurate measurement and application.In actual use, the thermocouple measuring circuit can measure any temperature except 0°C. The measuring circuit must measure the temperature of the cold junction and restore the temperature to 0°C. This kind of electrical compensation is called cold junction compensation (or reference junction compensation). Most thermocouple measurement circuits do this.If the application requires a thermocouple instead of a thermistor, a higher-grade thermocouple is better. In addition, their cost difference is small, and high-quality wire can provide higher stability.🔺Table 1: Thermocouple Types and Application RangesThermocouple TypeApplication Range (℃ / ℉)E95-900℃ (200-1650℉)J95-760℃ (200-1400℉)K95-1260℃ (200-2300℉)N95-1260℃ (200-2300℉)R870-1450℃ (1600-2640℉)S980-1450℃ (1800-2640℉)T0-350℃ (32-660℉) 1.2 What is Thermistor Sensor?The main component of the thermistor sensor is the thermistor, which absorbs heat radiation around.Thermistors are made of semiconductor materials, mostly with a negative temperature coefficient, that is, the resistance decreases with increasing temperature. Temperature changes will cause large resistance changes, so it is the most sensitive temperature sensor. However, the linearity of the thermistor is extremely poor and has huge effects with the production process. So the manufacturer cannot give a standardized thermistor curve.The thermistor is very small and responds quickly to temperature changes. But it needs to use a current source, and its small size also makes it extremely sensitive to self-heating errors.Figure 4. Thermistor SensorThe thermistor measures the absolute temperature on the two lines, with better accuracy, but it is more expensive than a thermocouple, and the measurable temperature range is also smaller than that of a thermocouple. A commonly used thermistor has a resistance value of 5kΩ at 25°C, and a temperature change of 1°C causes a resistance change of 200Ω. Note that the lead resistance of 10Ω only causes a negligible error of 0.05°C. It is very suitable for current control applications that require fast and sensitive temperature measurement. Small size is benefit for applications with space requirements, but care must be taken to prevent self-heating errors.Figure 5. Resistance-TemperatureThe thermistor also has its own measurement tips. With small size, it can quickly stabilize, and will not cause thermal load. However, it is not strong enough, and large currents can cause self-heating. Since the thermistor is a resistive device, any current source will cause heat on it due to power. Power is equal to the product of current squared and resistance. Therefore, a small current source must be used. If the thermistor is exposed to high heat, it will cause permanent damage. 1.3 What is Resistance Temperature Detector (RTD)?RTD is a precision temperature sensor, made of high-purity conductive metal (such as platinum, copper or nickel) or alloy. Its resistance increases with increasing temperature and decreases with decreasing temperature, similar to a thermistor. RTD is like a thermoelectric converter, converting temperature changes into voltage changes. By passing a constant temperature current through the temperature sensor, an output voltage that increases linearly with temperature can be obtained. The most suitable metal for RTD is a pure metal that remains stable within a given temperature range. The resistance-temperature change relationship is preferably linear. The larger the temperature coefficient (it is defined as the resistance change caused by unit temperature), the better, and it must be able to resist thermal fatigue and respond sensitively to temperature changes. A typical RTD has a protective sleeve and a probe. The protective sleeve is mainly used to protect the RTD from being damaged by the measured medium, which is usually made of stainless steel, carbon steel, inconel or cast iron, and its use temperature can reach 1100°C.Figure 6. Resistance Temperature Detector (RTD)It is currently the most accurate and stable sensor, and its linearity is better than thermocouples and thermistors. However, RTD is also a temperature sensor with slow response speed and more expensive price. So it is most suitable for applications that have strict requirements on accuracy, but speed and price are not critical. 1.4 What is IC Sensor?IC sensors can work in a temperature range of -55°C to +150°C, and precise one can operate at temperatures up to +200°C. It is commonly used in fitness tracking applications, wearable products, computing systems, data loggers, and automotive applications. The most common integrated IC temperature sensors are analog output devices, digital interface devices, remote temperature sensors, and those integrated ICs with thermostat functions.Figure 7. IC Sensors (Thermometer)Analog output devices (usually output voltage, but some also output current) are most like passive solutions when they need an ADC to process the output signal. Digital interface devices most often use a two-wire interface (I2C or PMBus) and have a built-in ADC. In addition to including a local temperature sensor, remote temperature sensors also have one or more inputs to monitor the remote diode temperature—they are most often placed in highly integrated digital ICs (for example, processors or field programmable gate arrays FPGA). When reached the temperature threshold, the thermostat can provide a simple alarm.Here are the details of two common types:🔺Analog Output Temperature SensorThe integrated sensor is made using silicon semiconductor integration process, so it is also called a silicon sensor or a monolithic integrated temperature sensor. It is a dedicated IC that integrates a temperature sensor on a chip and can take temperature measurement and then output analog signals. The main features of this sensor are single function (only measuring temperature), small temperature measurement error, low price, fast response speed, long transmission distance, small size, micro power consumption, etc., which are suitable for long-distance temperature measurement, control and measurement. What’s more, non-linear calibration doesn’t required, and the peripheral circuit is simple.🔺Digital Output SensorDigital temperature sensor is the product of microelectronics technology, computer technology and automatic test technology (ATE). The intelligent temperature sensor contains temperature sensor, A/D converter, signal processor, memory (or register) and interface circuit. Some products also come with multiplexers, central controller, random access memory and read-only memory. The characteristic of the intelligent temperature sensor is that it can output temperature data and related temperature control quantities, adapts to various microcontrollers (MCU). It realizes the test function through software on the basis of hardware, and its intelligent harmony also depends the level of software development.1.5 Temperature Sensor Cons and Pros🔺Table 2: Advantages and Disadvantages of thermocouples, RTDs, thermistors and IC sensors.CriteriaThermocoupleRTDThermistorIC SensorTemperature-250℃ to +750℃-100℃ to +500℃-267℃ to +2316℃-55℃ to +200℃AccuracyBestDepends on calibrationGoodGoodLinearityGoodWorstGoodBestSensitivityLessBestWorstGoodCircuityComplexDepends on accuracy/power requirementsComplexSimplestPower ConsumptionHigh when takingLow-highLowest Ⅱ How to Test: Measuring Indexes1) Measurement accuracy: 0.01 level2) Resolution 0.1uV and 0.1mΩ3) Scan switch parasitic potential: ≤0.4μV4) Temperature range: Water tank: (room temperature +5~95)°C; Oil tank: (95 ~ 300)°C; Low & constant temperature bath: (-80 ~ 100)°C; High temperature furnace: (300~1200)°C5) Temperature control stability: better than 0.01℃/10min (oil tank, water tank, low temperature constant temperature tank); 0.2℃/min (tube type verification furnace)6) Total uncertainty: For thermocouple verification, measurement uncertainty is better than 0.7 ℃, repeatability error <0.25 ℃; For thermistor verification, measurement uncertainty is better than 50 mk, repeatability error <10 mk7) Working power supply: AC220V±10%, 50Hz, and well protected grounding.8) High temperature furnace power: about 2kW9) Constant temperature bath power: about 2kW10) Power of microcomputer measurement and control system: <500 Ⅲ FAQ1. What is temperature sensor and how it works?How do temperature sensors work? They are devices to measure temperature readings through electrical signals. The sensor is made up of two metals, which generate electrical voltage or resistance once it notices a change in temperature. ... Temperature is the most common physical measurement type in industrial applications. 2. What happens when a temperature sensor goes bad?If the coolant temperature sensor goes bad it can send a false signal to the computer and throw off the fuel and timing calculations. ... This will cause the computer to think the engine is cold, even when it is not, and as a result will use more fuel than necessary. 3. Which temperature sensor is best?The most well-known are Pt100 (with a resistance of 100 ohms at 0°C) and Pt1000 (with a resistance of 1,000 ohms at 0°C). The Pt1000 offers better accuracy and a larger tolerance to long wire lengths than the Pt100. Compared to thermocouples, resistance sensors offer better accuracy and a more linear response. 4. What is the application of temperature sensor?Within our homes, temperature sensors are used in many electrical appliances, from our refrigerators and freezers to help regulate and maintain cold temperatures as well as within stoves and ovens to ensure that they heat to the required levels for cooking, air confectioners/heaters. 5. How do I know if my temperature sensor is bad?What Signs May Signal Your Coolant Temperature Sensor May Be Failing.Poor Fuel Economy.Irregular Temperature Readings.Black Smoke from Your Exhaust.Your Engine is Overheating.Your Check Engine Light is On. 6. How important sensors are nowadays?Intelligent sensor systems are omnipresent in our everyday lives. They provide security, save lives and improve our quality of life. As more and more areas of life are automated and networked, the importance of innovative sensor technologies will also increase in the future. 7. What should I consider when choose a temperature sensor?Several factors must be considered when selecting the type of sensor to be used in a specific application: temperature range, accuracy, response time, stability, linearity, and sensitivity. 8. What is the value range of a temperature sensor?The effective operating range is -50 to 250 °C for glass encapsulated thermistors or 150°C for standard thermistors. 9. What are the pros and cons thermocouple?Advantages and disadvantages of thermocoupleAdvantages of thermocouple: Simple working principle, Short response time, Low price, Wide temperature ranges, Rugged construction, Self-powered, Small size.Disadvantages of thermocouple: Nonlinearity, Accuracy, Interference can cause errors. Old technology, Needs calibration, Corrosion. 10. What is difference between PT100 and RTD?There is no difference a PT100 is a version of a RTD (resistance temperature detector). What is an RTD? A resistance temperature detector, also known as an RTD or resistance thermometer, is a type of temperature sensor. ... A PT100 sensor is the most common type of Resistance Thermometer (RTD).

CatalogⅠ What is Coolant Temperature SensorⅡ Function and Structure of Coolant Temperature SensorⅢ The Working Principle of Coolant Temperature SensorⅣ Application of Coolant Temperature Sensor in Vehicles  4.1 Location on Automobiles  4.2 Ways of Testing Coolant Temperature SensorⅤ How to Replace the Faulty Coolant Temperature  SensorⅥ Frequently Asked Questions about Coolant Temperature Sensor Analysis Ⅰ What is Coolant Temperature SensorEvery driver is aware that coolant/antifreeze is applied to keep an engine operating at peak efficiency. However, how do cooling systems recognize when the engine is at the proper operating temperature? We take a closer inspection at coolant temperature sensors in this guide, providing information on what they do and how they work, as well as step-by-step instructions for diagnosing and replacing a faulty sensor. A coolant temperature sensor (CTS) (also known as an ECT sensor or ECTS (engine coolant temperature sensor)) measures the temperature of the coolant/antifreeze mix in the cooling system, indicating how much heat the engine is producing. The sensor communicates with the vehicle's ECU and continuously monitors coolant temperature to ensure that the engine is operating at the proper temperature. Ⅱ Function and Structure of Coolant Temperature Sensor The coolant temperature sensor is installed on the water jacket of the engine block or cylinder head, contracting with the coolant directly. The CTS is applied to detect the temperature of the engine coolant. The internal part is equipped with a negative thermistor with negative temperature characteristics. The feature of a negative thermistor is that the higher the temperature, the smaller the resistance, the lower the temperature, the greater the resistance.Figure1: the circuit image of coolant temperature sensor The signal of the coolant temperature sensor is a correction signal, and its function is to inspect the temperature of the engine coolant. The temperature of the engine coolant transmit the signal to the ECU, and the ECU  measured temperature and correct the fuel injection volume according to the signal indication. When the cold car starts or the engine warms up, the ECU will correct the fuel injection.When the car is hot, the ECU will correct to inject the leaner mixture; the same way, when the engine coolant temperature signal is detected, the ECU controls the cooling and the fan is turned on and off. Ⅲ The Working Principle of Coolant Temperature Sensor Generally, the structure of the coolant temperature sensor seems to be a negative thermistor. Therefore, its temperature is inversely proportional to resistance, and its voltage is also inversely proportional to resistance. The range of temperature changes: -40 to 195°C. When the engine cools down from the start of the cold car to the hot car, the parameters of the fluid temperature sensor gradually increase, and the vehicle is idling when the engine is completely warmed up. The coolant temperature should be 85～105℃ when operating, if the parameter of CTS is  -40℃, it indicates that there is a short-circuit in CTS. If the parameter is higher than 185℃, it means that there was the same failure as-40℃. The voltage change range is 0 ~ 5V. When the temperature parameter is -40℃, the corresponding voltage is 4.98V，while the temperature parameter is 185℃, the corresponding voltage is 0.02V. The cooling system in a car with an internal combustion engine keeps the engine at the proper temperature and prevents it from overheating.  The temperature of the liquid coolant is measured by an engine coolant temperature sensor or ECT. A Negative Temperature Coefficient (NTC) thermistor is a type of engine cooling temperature sensor in which the electrical resistance decreases as the temperature rises. The ECT sensor's tip protrudes into a cooling system passage and is submerged in coolant.This vedio show that how coolant temperature sensor works Ⅳ Application of Coolant Temperature Sensor in Vehicles4.1 Location on Automobiles Many automobiles have multiple coolant temperature sensors. The primary ECT sensor (ECT sensor 1) is usually located near the thermostat in the cylinder head or block, or on the thermostat housing. Sensor for electrocardiography (ECT) the engine computer, or PCM, is connected to the ECT sensor. A second coolant temperature sensor could be installed in the radiator or in another part of the engine. Instead of or in addition to the ECT sensor, some cars use a cylinder head temperature or CHT sensor. The CHT sensor (shown in the photo) works in the same way, but it measures the temperature of the cylinder head metal rather than the coolant temperature. This enables the CHT sensor to accurately measure the temperature of the engine even when coolant is lost. This may help prevent overheating in some cases. The main computer is connected to an ECT sensor (powertrain control module or PCM). The PCM provides a constant reference voltage (typically 5 volts) and monitors the ECT sensor signal. When the temperature reaches a pre-determined level, the PCM adjusts the engine performance and operates the electric radiator fans based on this signal. If the sensor signal is missing or outside of the expected range, the PCM illuminates the Check Engine light and records the associated trouble code. 4.2 Ways of Testing Coolant Temperature SensorTesting the ECT/CHT Sensor Resistance: One method is to measure the sensor's resistance at various engine temperatures and compare the results to the service manual's specifications.We tested the resistance of the ECT sensor in this car, for example. Only when the sensor is disconnected from the circuit can the resistance be measured. The reason for this is that measuring the resistance of any electrical component that is still connected to the circuit will result in inaccurate results. When the engine was cold, the resistance was 2,953 Ohm. After the engine was fully warmed up, it dropped to 248.5 Ohm; see photo. This sensor complies with the manufacturer's specifications. Of course, the resistance specifications differ from car to car. Figure2:one way to test the resistance of senser  Checking the ECT/CHT Sensor Voltage:With the ignition on, another way to test the sensor is to measure the voltage across the sensor terminals. The voltage of the engine coolant temperature (ECT) sensor is measured. The voltage of the ECT sensor is being checked. The engine computer is linked to the sensor (PCM). The reference voltage (typically 5 volts) is supplied by the PCM, and the sensor ground is provided by another wire. The ground as well as the reference voltage must be checked first. The voltage drops as the sensor's resistance decreases as the engine warms up. We probed the ECT sensor inversely in this photo to keep it connected to the circuit. We measured 3.96 Volt when the car was cold. The voltage dropped to 0.988 Volt on a fully warmed-up engine. The multimeter will read 5 volts when the sensor is disconnected. If you don't see any voltage, the circuit is either open or shorted to the ground. One of the wires in the sensor harness, for example, could break or rub against a metal part, causing a short. Figure3: another way to test sensor Voltage  4.3  Symptoms of a bad or failing coolant temperature Poor fuel economy Poor fuel economy is one of the first signs of failure with the coolant temperature sensor. If the coolant temperature sensor fails, it can send a false signal to the computer, causing fuel and timing calculations to be thrown off. It's not uncommon for the coolant temperature sensor to fail and send a signal to the computer that's always cold. This will trick the computer into thinking the engine is cold when it isn't, causing it to consume more fuel than is necessary. The poor fuel economy will suffer as a result, and engine performance may suffer as a result. Black smoke from engine Black smoke from the vehicle's exhaust is another sign of a possible problem with the coolant temperature sensor. If the coolant temperature sensor fails and sends a cold signal to the computer, the computer may become confused and enrich the fuel mixture unnecessarily. If the fuel mixture becomes too rich, it will burn up in the exhaust pipes, resulting in black smoke. In severe cases, the black smoke may be so awful that the vehicle can not be started. Overheating engine An overheating engine is another sign of a problem with the coolant temperature sensor. The coolant temperature sensor can also fail in such a way that it sends an always-hot signal. This can cause the computer to compensate for a lean signal incorrectly, resulting in overheating, misfires, and even engine ping. Check Engine Light comes on Another sign of a problem with the coolant temperature sensor is an illuminated Check Engine Light. If the computer detects a problem with the sensor's signal or circuit in some vehicles, the Check Engine Light will illuminate. The Check Engine Light will stay illuminated until the trouble is resolved. Ⅴ How to Replace the Faulty Coolant Temperature SensorBegin with a cold engine. Drain the cooling system by jacking the car up and using jack stands. Wear safety glasses and glovesMterials:1. coolant collection pan2. flat head screwdriver3. new coolantTools:1. eyewear and golves 2. pliers3. funmel4. jack standsTip: Only do this job when the engine is completely cold and hasn't been running for at least an hour. Because you'll be underneath the car and the risk of coolant splashing in your face is high, it's a good idea to protect your face with a safety shield. If the engine is not cold, wear safety glasses and gloves to protect your hands from the hot coolant.  Step1: Locate the SensorThe CTS is usually found near the radiator or thermostat housing in the front of the engine. You may need to use a light or torch to locate it because it's a small component that's often found lower down inside the engine bay. If it's near the thermostat housing, removing the engine cover can also help you find it.Figure4: firstly, locate the coolant sensor   Step2: Remove the Connector Cable from the Terminal A connector connects the CTS to the ECU, which you must unfasten and remove. Do this with caution, as the plastic connector and wiring can be brittle and require replacement if they break. Remove the connector and place the cable somewhere out of the way.Figure5: release the connector   Step3: Loosen and Remove the Old Sensor Coolant sensors are installed similarly to spark plugs, so they must be unscrewed to be removed. Carefully loosen the sensor in an anticlockwise direction with a deep socket and ratchet, without applying too much pressure. A squirt of release spray can aid in the unsticking of stuck sensors. Remove the sensor from the socket by unscrewing it by hand once it is loose. Because coolant is likely to leak at this point, have a new one on hand or consider draining the coolant if necessary.Figure6: Remove the clip and old sensor   Step4: Install the New Sensor Clean the area with a rag or cloth to remove any dust or debris that could influence the new CTS' performance. Set the new sensor in the threads and hand-twist clockwise to ensure it is securely seated in the socket. Tighten the sensor with a torque wrench to the amount specified in the manufacturer's instructions.Figure6: install the new coolant sensor  Step5 : Reinstate the Connector Cable The only thing left to do now is reconnect the cable after the new sensor has been installed. Make sure the connector is clean and free of debris before carefully plugging it into the new sensor and tightening any clips to ensure a good connection. Start the engine to ensure the new sensor is working, and as it warms up, keep an eye on the temperature gauge on the dash to ensure the correct temperature is maintained.Figure7: reconnect the cableⅥ Frequently Asked Questions about Coolant Temperature Sensor Analysis1. Can you drive with a bad coolant sensor?It is possible to drive a vehicle with a faulty coolant temperature sensor as the management system defaults to a static reading. A vehicles coolant sensor is a critical component used by the engine management system. It directly effects, cooling and fueling of the engine and therefore effects how the engine performs. 2. What does the coolant temperature sensor do?A coolant temperature sensor (CTS) (also known as an ECT sensor or ECTS (engine coolant temperature sensor) is used to measure the temperature of the coolant/antifreeze mix in the cooling system, giving an indication of how much heat the engine is giving off. 3. What causes a coolant temperature sensor to fail?The engine may run in fail-safe mode:Many Check Engine light codes related to the (ECT) sensor; could also be caused by other reasons. Such as a bad thermostat or issues with the cooling system; including even a leaking head gasket. Therefore, The problem must be properly diagnosed. 4. How long do coolant temp sensors last?About 100,000 miles. Often, the engine coolant temperature sensor must be replaced at about 100,000 miles. If you don't properly maintain the engine cooling system, the sensor could fail much earlier. 5. Do you need to drain coolant to change coolant temperature sensor?Open the radiator valve and drain about two to three quarts of coolant. You only need to remove enough to drop the level below the sensor. Then close the drain valve. This will minimize coolant waste when you remove the sensor. 6. Can you run a car without a temperature sensor?Generally it should be ok to drive without the thermostat fitted, as it will only cause the engine to take longer to reach operating temperature. The thermostat is designed to allow the engine to reach ideal operating temperature as quickly as possible, so it would not be recommended to drive without it. 7. Can a bad coolant temp sensor cause rough idle?A faulty coolant sensor that always reads cold may cause the fuel control system to run rich, pollute and waste fuel. A coolant sensor that always reads hot may cause cold drive ability problems such as stalling, hesitation and rough idle. ... This also affects engine performance and fuel economy. 8. Does coolant temp sensor affect AC?In a properly operation system the engine coolant temperature should not affect the cooling of the air conditioner. The A/C condenser is located in front of the radiator and is first to receive the incoming airflow.    

Ⅰ IntroductionInvented by Boykin in 1959, resistors are today commonly used in almost all electronic circuits. Resistors can be described as a device that resists the flow of current flowing through itself, back when the resistor size was very huge and the tolerance value reached as high as 10 percent when it was implemented. Besides, they are usually made of compressed carbon. Resistors are mostly made from metal films and are available in small SMD packets with a tolerance value of as little as 2%, or even less, in the case of precision resistors. Carmet, KWK, Epcos India Pvt Ltd. and more are some of the leading manufacturers of resistors in India. If you didn't know, India accounts for some 34% of the market for passive components such as resistors by importing them, the remainder being imported. If you are interested in learning more about the work and characteristics of resistors, then you can try reading this article. We will address the difference between carbon film resistors and metal film resistors in this article.CatalogⅠ IntroductionⅡ Brief Intro to the ResistorsⅢ Carbon Film ResistorsⅣ Metal Oxide Film ResistorsⅤ Carbon Film Resistors VS Metal Oxide Film ResistorsⅥ Voltage and Temperature CoefficientⅦ SizeⅧ FAQⅡ Brief Intro to the ResistorsThe word "resistor" is born from the word "resist," meaning to withstand the impact. A resistor resists the movement of electrons that move through it, guides it, or controls it. With the support of the conductive material that it is made of, this is achieved. Now, the name makes sense, does it not? In parallel and series, resistors are connected according to the specifications for current and voltage. These small devices monitor, attenuate or decrease voltage and current, but do not have a power source of their own. The current flows through them in a controlled manner, resulting in a heat-like loss of energy. Only when there is a potential difference do two resistors bind and carry on a current between them. Yeah, they obey the Rule of Ohm. You must have heard, we're sure, of this statute. Oh, in the field of electronics and electrics, it is something to swear by. Moving on, depending on their characteristics, there is an infinite list of various types of resistors including composition form, film type, and wire-wound type of resistors. Physical size, durability, temperature rating, noise, temperature coefficient, and voltage coefficient, to name a few of these features. Well, the drill is known to you. We are here, however, to address two very significant types of resistors that are capable of transforming your electronic circuits.Ⅲ Carbon Film ResistorsLet us first contemplate what film resistors are before we begin talking about this. Well, after depositing oxide film or pure metals on a substrate or some insulating ceramic, these are simply those resistors that are formed. The layer is extremely thin and sputtering is known as the entire process. By depositing carbon film on the ceramic substrate that is an insulator, the carbon film resistor is prepared. The electric current is blocked by the carbon film to a certain degree. The insulating ceramic, on the other hand, does not allow heat to move through it, which in turn allows the carbon film resistor to withstand massive temperatures without being harmed. Carbon film resistors have a good tolerance rating, available from 1 ohm to 1 megaohm. Speaking of the resistance coefficient of negative temperature - the property of observing a decrease in resistance in response to a rise in temperature, these have a high coefficient of negative temperature that makes them susceptible to decreasing resistance as the temperature increases.These resistors are also available and have a very low tolerance at a low cost. They have a large variety of activities. Carbon film resistor applications are commonly used in X-Rays, power supplies and RADAR.Ⅳ Metal Oxide Film ResistorsMetal oxide film resistors use thin metal oxide films to coat an insulating ceramic rod, in contrast to carbon film resistors. Informing a coating film, the compound made from oxygen atoms and other atoms performs wonders. Using tin oxide, however, metal oxide film resistors are made. To produce better resistance, antimony oxide is also added. Because of the existence of an insulating ceramic rod that does not let heat pass through itself, these resistors are capable of withstanding high temperatures. Metal oxide resists the current at the same time. The greater the sum of antimony, the greater the resistance. But that doesn't even stop here, for good resistance metal oxide film resistors rely heavily on the thickness of the metal oxide and the width of the helical metal oxide film cut. The helical metal oxide film cut width and metal oxide thickness are inversely proportional to the resistance.Wondering what makes them special? Resistors come at a very low cost and withstand high temperatures while making much less sound. Also, along with high reliability and stability, they are small in scale.Ⅴ Carbon Film Resistor VS Metal Oxide Film ResistorWell, engineers are still in a dilemma about which to use one. Whether to use the resistor for the carbon film or the resistor for the metal oxide film. All right, let us break it down, bit by bit, for you. You want your experiments, after all, to go spot on. According to our contrast between Metal Film and Carbon Film Resistors, due to certain properties they possess that are listed below, we feel that metal-oxide film resistors prevail over carbon film resistors.Ⅵ Voltage and Temperature CoefficientThere are a stronger voltage coefficient and temperature coefficient for Metal Oxide film resistors than for carbon film resistors. The coefficient of voltage is the change in resistance concerning the change in voltage. In short, it is the ratio of the resistance change to the voltage change. Metal oxide film resistors operate in a wide range of resistors and can withstand a higher temperature than the resistors of the carbon film. Noise Design In contrast to carbon film resistors, metal oxide film resistors has a low noise design. They keep the minimum current. Therefore, it ensures less noise. If you didn't know, metal oxide film resistors, relative to carbon film resistors, make up for stronger resistors for radio frequency or high-frequency applications. Tolerance The 2 percent minimum carbon film resistor tolerance level does not stand a chance against metal oxide film resistors that can go as low as 0.1 percent.Ⅶ SizeFinally, compared to the carbon film resistors, the size of the metal oxide film resistors is smaller, making them a safer choice to go for. Now that we've done our bit to make you see the complexities of the resistors of both kinds, you can take your pick.Ⅷ FAQ1. What is a carbon film resistor?The resistive film deposited on the glass or ceramic rod is of pure carbon that is why they are called carbon film resistors. The thickness of the film will decide the value of the resistor. Spiralling is done on it in order to adjust the value of resistance.Some important features:• Tolerance =0.5% to 10%• Negative temperature coefficient of resistivity.• Wide temperature range from 55°c to 155°c• These are low power resistors typically of 1/8W, 1/4W, or 1/2W capacity. 2. What are the advantages of using metal film resistors versus carbon composition resistors?Metal film resistors produce less thermal noise than carbon composition resistors. Metal film resistors also typically have a much lower inductance/capacitance than carbon comp resistors so they (metal film) work better at higher frequencies. Carbon composition resistors have no real performance advantage over metal film resistors except that they are cheaper. 3. Are carbon film and metal film resistors interchangeable?No. They simply have less noise and do not drift in value. In short, they behave more like an ideal resistor. You can find metal films in 1% tolerance so the amps with those are very consistent in sound from amp to amp. 4. What is the advantage of a metal film resistor over a carbon resistor?The advantages that a metal film resistor has over a carbon composition resistor is that they don't change their value with age and their tolerance is better than the carbon resistor. 5. How do you identify a metal film resistor?Common carbon film resistors are mostly yellow or pink due to their low accuracy and low production costs, while most metal film resistors are blue. There is a layer of black protective paint on the surface of carbon film resistors, while metal film resistors are usually coated with bright white protective films. 6. What is the advantage of a metal film resistor?Metal film resistor has a low-temperature co-efficient of resistance. The rate at which the resistance of the material changes with a change in temperature is called the temperature coefficient of resistance. Metal film resistors have a low-temperature coefficient of resistance. 7. What is a carbon film resistor used for?The carbon film resistor is a type of fixed resistor that uses carbon film to restrict the electric current to a certain level. These types of resistors are widely used in electronic circuits. 8. Are metal film resistors inductive?Film resistors may be approximately classified as follows: values < 100Ω are inductive. values between 100Ω and 470Ω are practically true resistive. 9. What is a film resistor?Film Resistor is a general term referring to different types such as Carbon Film, Metal Film, and Metal Oxide Film resistors. They are generally manufactured by depositing pure metals (e.g., nickel) or oxide film (e.g., tin-oxide) onto an insulating ceramic or substrate. 10. What are carbon film resistors made of?Carbon film resistors are a fixed form type resistors. They are constructed out of a ceramic carrier with a thin pure carbon film around it, that functions as resistive material.

IntroductionThe humidity sensor is a sensor that measures relative humidity, absolute humidity, or dew point. At present, such sensors are widely used, and are gradually developing in the direction of excellent environmental resistance, long life, and low price. This article will introduce the working principle, type, classification, application of humidity sensor, and an Arduino tutorial on real-time temperature and humidity monitor. In addition, some basic knowledge like the calculation of relative humidity and absolute humidity is also covered. Let’s waste no more time! The humidity sensor is a sensor that measures relative humidity, absolute humidity, or dew point. At present, such sensors are widely used, and are gradually developing in the direction of excellent environmental resistance, long life, and low price. This article will introduce the working principle, type, classification, application of humidity sensor, and an Arduino tutorial on real-time temperature and humidity monitor. In addition, some basic knowledge like the calculation of relative humidity and absolute humidity is also covered. If you are only interested about the Arduino guide, you can jump to that part from the category, and the video below is about the accuracy test of different temperature and humidity sensor for arduino, which can help you to choose the best one. Let’s waste no more time!Check this video to look for the best temperature and humidity sensor for ArduinoCatalogIntroductionCatalogI How do Humidity Sensors Work?1.1 Humidity1.2 Absolute Humidity and Relative Humidity1.3 How Humidity Sensors WorkII Classification and Common Types of Humidity Sensors2.1 Classification2.2 Comparison of Resistive and Capacitive Humidity Sensors2.3 Four Types of Humidity Sensors with More Applications2.4 Commonly Used Humidity Sensor ModelsIII Application of Humidity Sensors3.1 Typical Uses3.2 Application FieldsIV Arduino Entry Project: Real-time Temperature and Humidity Detector4.1 Hardware Preparation4.2 Software Preparation4.3 Circuit Connection4.4 Implementation CodeⅤ FAQI How do Humidity Sensors Work?1.1 HumidityBefore learning the humidity sensor, let's take a look at what humidity is. Humidity, a physical quantity indicating the degree of air dryness. At a certain temperature, the less water vapor contained in a certain volume of air, the drier the air; the more water vapor, the more humid the air. The degree of air humidity is called "humidity". In this sense, it is often expressed by physical quantities such as absolute humidity, relative humidity, comparative humidity, mixing ratio, saturation difference, and dew point; if it represents the percentage of the weight of water vapor in the wet steam to the total weight (volume) of the steam, it is called the humidity of the steam. The humidity that the human body feels comfortable with is: the relative humidity is lower than 70%. So the question comes again, what is the relative humidity?Figure1. What is Humidity?1.2 Absolute Humidity and Relative HumidityThe degree of dryness and humidity of the air, or the physical quantity that indicates how much water vapor it contains, is called humidity. The mass of water vapor contained in a unit volume of air is called absolute humidity. Because it is difficult to directly measure the density of water vapor, it is usually expressed by the pressure of water vapor. The absolute humidity of the air does not determine the speed of water vapor on the ground and the perception of humidity. People call the absolute humidity of air at a certain temperature and the percentage of saturated air pressure at the same temperature as relative humidity. To be more specific, absolute humidity refers to the mass of water vapor contained in a certain volume of air, and its unit is generally g/m3. The maximum absolute humidity is the highest humidity undersaturation. Absolute humidity is only meaningful together with temperature, because the amount of humidity that can be contained in the air varies with temperature, and the absolute humidity is also different at different temperatures, because the volume of air also changes with temperature. But the closer the absolute humidity is to the highest humidity, the smaller its change with temperature. The following is the formula for calculating absolute humidity:The symbols are:e-vapor pressure, the unit is Pascal (Pa)-The gas constant of water = 461.52J/(kg K) T-Temperature, the unit is Kelvin (K)m-the mass of water dissolved in the air, in kilograms (kg)V-The volume of air, in cubic meters (m). Relative humidity (RH)A hygrometer is recording relative humidity. The relative humidity is the ratio between absolute humidity and maximum humidity. Its value shows how high the saturation of water vapor is. Air with a relative humidity of 100% is saturated air. Air with a relative humidity of 50% contains water vapor that reaches half the saturation point of air at the same temperature. Water vapor in the air with a relative humidity of more than 100% generally condenses.  As the temperature increases, the air can contain more water, that is to say, the relative humidity will decrease when the temperature increases with the same amount of water vapor. Therefore, while providing relative humidity, temperature data must also be provided. The dew point can also be calculated from the relative humidity and temperature. The following is the formula for calculating relative humidity:The symbols are:ρw-absolute humidity, in grams/cubic meterρw,max-the highest humidity, the unit is g/m3e-water vapor pressure, the unit is PascalE-saturated vapor pressure, the unit is Pascals-specific humidity, the unit is g/kgS-the highest specific humidity, the unit is g/kg 1.3 How Humidity Sensors WorkGenerally, humidity sensors use the following four methods to detect humidity or condensation:(1) Measure the change in electrical impedance or capacitance caused by moisture absorption, separation, or condensation of moisture-sensitive materials.(2) Measure the difference in gas thermal conductivity due to changes in humidity.(3) Measure the change in the resonance frequency of the crystal vibrator due to changes in humidity or condensation.(4) Measure the attenuation and light absorption and reflection caused by alpha rays passing through water droplets due to changes in humidity.For example, the characteristic of a humidity-sensitive resistor is to cover a film made of moisture-sensitive material on the substrate. When water vapor in the air is adsorbed on the moisture-sensitive film, the resistivity and resistance value of the element will change. One characteristic can measure humidity.Figure2. How a polymeric membrane humidity sensor worksII Classification and Common Types of Humidity Sensors2.1 ClassificationAt present, there are many types of humidity sensors on the market, and their application ranges are also different. They are roughly divided into the temperature and humidity ranges used, which can be listed in the following table.IndustryScope of applicationOperating temperature and humidity rangeUsesTemperature(℃)Humidity(%PH)Home appliancesAir conditioning machine5~40 40~70 Air conditioning equipmentDryer800~40Clothes dryingElectronic range5~1002~100Food heating and conditioning controlVTR-5~6060~100Prevent condensationCarAutomatic anti-fog-20~8050~100Prevent condensationMedical treatmentTreatment device10~3080~100Respirator systemIncubator10~3050~80Air conditioning equipmentIndustryFiber10~3050~100SilkDryer50~1000~50Kiln industry, wood dryingPowder moisture5~1000~50Ceramic raw materialsDry food50~1000~50Food preservationElectronic Components Manufacturing5~400~50Magnetic head, LSI ICAgriculture, Forestry and LivestockHouse air conditioning5~400~100Air conditioning equipmentTea smoke anti-frost-10~6050~100Prevent condensationReptile feeding5~400~50Increase humidity, health managementTestConstant temperature and humidity tank-5~1000~100Precision measurementRF detector-50~400~100High-precision meteorological measurementHygrometer5~1000~100Control recording deviceOtherSoil moisture-20~500~100Plant cultivation, soil and sand collapseIn the above, we have introduced four methods for detecting humidity or condensation. These measurement methods must be selected according to the different test environments. The most commonly used measurement method on the market is the first one because its measurement and signal selection methods are quite simple and cheap. It can be divided into the following six categories if it is distinguished by the difference of its manufacturing materials:(1) Electrolytes such as LiCl.(2) Semiconductor materials such as Se and Ge.(3) MgCr2O4, ZnCr2O4, TiO2, SnO2 and other metal oxide fusion products.(4) Porous metal oxide film such as Al2O3.(5) A material made by dispersing conductive powder in a polymer material such as nylon.(6) Organic or inorganic polymer electrolyte membrane. Sensors made of moisture-sensitive materials can be roughly divided into 7 categories:(1) Electrolyte humidity sensor(2) Polymer humidity sensor(3) Ceramic humidity sensor(4) Crystal oscillator humidity sensor(5) Semiconductor humidity sensor(6) Thick-film humidity sensor(7) Condensation humidity sensorClassificationMoisture Sensitive MaterialDetection methodElectrolyteLiCl+Polyviny1 Alcho1 PolystyreneResistorSulfated filmResistorPotassium sulfate membraneResistorLiC1 saturated solutionResistorSemiconductorSe (Ge or Si) vapor deposition filmResistorSi+SiO2+PAPA (Polyamino Phenylacetylene)ResistorMetal oxides (ceramics)Fe3O4 Colloid coating filmResistorCr2O3 Ni2O3 Fe2O3ResistorGlass ceramic filmCapacitorFe2O3-K2O ceramicResistorZnO-Li2O-V2O5 ceramicResistorMg Cr2O4 type ceramicCapacitorPolymersAl2O3+ epoxy resinResistor or CapacitorMulti-emulsion resin filmCapacitor Organic materialCelluloid+CarbonResistorButyr CellaloseCapacitorResin carbonResistorPolyamid+ crystal oscillatorResonance frequency2.2 Comparison of Resistive and Capacitive Humidity Sensors(1) Resistive humidity sensorThe resistive humidity sensor is a sensor that uses the electrical characteristics of the humidity sensor (such as resistance value) to change with humidity to measure humidity. The humidity sensor is generally immersed in an insulating material with a hygroscopic substance, or through evaporation, It is made by coating and other processes to prepare a layer of metal, semiconductor, polymer film and powdered particles.  During the moisture absorption and dehumidification process of the moisture-sensitive element, the conduction state of the ion H+ decomposed by water molecules changes, so that the resistance value of the element changes with humidity.Figure3. Resistive humidity sensorAdvantage1) Compared with the capacitive type, the structure is simpler, and it is easier to achieve mass production and low price.2) There is no need to consider the capacity between the leads like capacitive sensors, so the sensor can be stretched at will, with greater design freedom.3) Since the characteristic is a logarithmic change (the degree of change is large), the humidity change is small for the resistance change. (According to this point, for example, the degree of influence of the deviation of the electrode on the characteristics is small, and the instability is also small. Even if there is a slight change, it is difficult to show when converted to humidity.) Disadvantages1) The temperature characteristic is larger than that of the capacitive type (0.5%rh/℃), and temperature compensation is usually required.2) Since the characteristic is a logarithmic change, if the logarithmic conversion is not processed, the linear characteristic will not be obtained.3) The low humidity range is difficult to detect due to high resistance. (About 20% rh is the limit) In addition, it is easily affected by interference. (2) Capacitive humidity sensorA capacitive humidity sensor is a commonly used instrument in humidity sensors. It uses polymer humidity and humidity-sensitive capacitors as the basic humidity-sensing component, and uses a single-chip microcomputer to analyze, process, display and remotely transmit the measurement results. The measurement accuracy is ±2.5 %. The capacitive humidity sensor is mainly composed of a glass substrate, a lower electrode, a humidity-sensitive material, and an upper electrode. The two lower electrodes are connected in series with the humidity-sensitive material and the two capacitors formed by the upper electrode. Humidity-sensitive material is a high molecular polymer whose dielectric constant changes with the relative humidity of the environment.  When the environmental humidity changes, the capacitance of the humidity sensor changes accordingly, that is, when the relative humidity increases, the humidity sensitive capacitance increases, and vice versa (the capacitance is usually between 48 and 56 pf). The sensor's conversion circuit converts the humidity-sensitive capacitance change into a voltage change, which corresponds to a change in relative humidity from 0 to 100% RH, and the output of the sensor changes linearly from 0 to 1v.Figure4. Capacitive soil moisture sensorAdvantage1) Generally speaking, low humidity starting from 0% rh can be detected.2) The capacitance value is relatively close to linear, and no logarithmic change is required.3) The temperature characteristic is smaller than that of the resistance type (about 0.05～0.1%rh/℃), and temperature compensation is not required for general use.4) In order to increase the capacitance value, the structure is made into a thin film, and there are more products with a faster response speed than the resistance type. Disadvantage1) If the sensor is extended with a lead wire, the capacitance value will change, so it is not suitable to extend the sensor alone. Also, if it is assembled into the device, it is difficult to change the position by the lead wire, so the design freedom is small.2) The amount of change is relatively small, but a small change in capacitance will cause a large error. Therefore, inexpensive sensors have a large deviation. (The sensors used for measurement also have very high accuracy, but these estimation formulas have been processed.)3) The fact that the amount of change is small can be said in terms of dependence. But a small change in capacitance will produce a large error. Therefore, a sensor with poor reliability will have a large humidity change.4) Although the amount of change is small, the deviation and temperature characteristics of other circuit parts will have a greater influence, so be careful when selecting circuit parts. 2.3 Four Types of Humidity Sensors with More Applications(1) Lithium chloride humidity sensor● Resistive lithium chloride hygrometerCertain metal salts (such as lithium chloride LiCI) have strong moisture absorption properties in the air, and their moisture absorption is a certain function of the relative humidity of the air, that is, the greater the relative humidity in the air, the more the moisture absorbed by the lithium chloride. At the same time, the electrical conductivity of lithium chloride, that is, the size of the resistivity changes with the amount of moisture absorption, the more water absorbed, the smaller the resistivity, and vice versa.  Therefore, the relative humidity of the air can be determined according to the change in resistivity of lithium chloride. Lithium chloride resistance hygrometer is a meter made of the characteristics of resistivity change after lithium chloride absorbs moisture. The first lithium chloride electric humidity sensor based on the principle of resistance-humidity characteristics was developed by F.W.Dunmore of the American Bureau of Standards. This kind of element has high precision, simple structure, low price, suitable for a series of advantages such as measurement and control of normal temperature and humidity. ● Dew point lithium chloride hygrometerThe dew-point lithium chloride hygrometer was first developed by Forboro Company in the United States. This type of hygrometer is similar to the above-mentioned resistive lithium chloride hygrometer, but its working principle is completely different. In short, it uses the saturated vapor pressure of a saturated aqueous solution of lithium chloride to work with temperature. (2) Carbon humidity sensorThe carbon humidity sensor was first proposed by EKCarver and CWBreasefield in the United States in 1942. Compared with commonly used sounding elements such as hair, casing and lithium chloride, the carbon humidity sensor has a fast response speed, good repeatability, The advantages such as no erosion effect and narrow hysteresis ring are eye-catching. The uncertainty of measurement using carbon humidity sensor does not exceed ±5%RH, the time constant is 2～3s at positive temperature, the hysteresis is generally about 7%, and the specific resistance stability is also better. (3) Alumina hygrometerThe outstanding advantage of alumina sensor is that the volume can be very small (for example, the humidity sensor used in the radiosonde is only 90μm thick and 12mg weight), high sensitivity (the lower limit of measurement reaches -110℃ dew point), and the response speed is fast (generally 0.3 s to 3s), the measurement signal is directly output in the form of electrical parameters, which greatly simplifies the data processing program, and so on. In addition, it is also suitable for measuring moisture in liquids. (4) Ceramic humidity sensorCeramic humidity sensor is also called metal oxide humidity sensor, because its humidity sensing material is made of metal oxide powder through pressure molding and sintering into ceramics. Due to the degree of sintering, many porous objects can be obtained, and water vapor will be adsorbed on the porous surface to form an adsorption layer, and the H+ ions in the adsorption layer will form current carriers due to the adhesion of water vapor. When the humidity is high, the current attached to the layer of water vapor in the adsorption easily flows. The ceramic humidity sensor utilizes this property to convert the humidity change into the output of the impedance value change.Figure5. Heating purification type ceramic humidity sensor2.4 Commonly Used Humidity Sensor ModelsAt present, the main manufacturers and typical products producing integrated humidity sensors are Honeywell (HIH-3602, HIH-3605, HIH-3610), Humirel (HM1500, HM1520, HF3223, HTF3223), Sensiron (SHT11, SHT15) type). These products can be divided into the following four types: Linear voltage output integrated humidity sensorTypical products are HIH3605/3610, HM1500/1520. Its main feature is the use of constant voltage power supply, built-in amplifier circuit, can output a volt-level voltage signal proportional to the relative humidity, fast response, good repeatability, and strong anti-pollution ability. Linear frequency output integrated humidity sensorThe typical product is HF3223 type. It adopts a modular structure and is a frequency output integrated humidity sensor. The output frequency is 8750Hz (type value) at 55%RH. When the relative humidity changes from 10% to 95%, the output frequency is reduced from 9560Hz to 8030Hz . This kind of sensor has the advantages of good linearity, strong anti-interference ability, easy to be equipped with digital circuits or single-chip computers, and low price. Frequency/temperature output integrated humidity sensorThe typical product is HTF3223. In addition to the functions of HF3223, it also adds a temperature signal output terminal and uses a negative temperature coefficient (NTC) thermistor as a temperature sensor. When the ambient temperature changes, the resistance value changes accordingly and is drawn from the NTC terminal, and the temperature value can be measured with a secondary meter. Single-chip intelligent humidity/temperature sensorIn 2002, Sensiron took the lead in the world to successfully develop the SHT11 and SHT15 intelligent humidity/temperature sensors. The overall dimensions are only 7.6 (mm) × 5 (mm) × 2.5 (mm), and the size is similar to that of a match head. Before leaving the factory, each sensor has been precision-standardized in the temperature room, and the standard coefficients are compiled into corresponding programs and stored in the calibration memory.  The relative humidity can be automatically calibrated during the measurement process. They can not only accurately measure relative temperature, but also temperature and dew point. The measurement range of relative temperature is 0-100%, the resolution is up to 0.03%RH, and the highest accuracy is ±2%RH. The measuring temperature range is -40℃～+123.8℃, and the resolution is 0.01℃. The accuracy of measuring dew point is <±1℃. When measuring humidity and temperature, the digits of the A/D converter can reach 12 and 14 bits respectively.  Using the method of reducing the resolution can increase the measurement rate and reduce the power consumption of the chip. The products of SHT11/15 have good interchangeability, fast response speed, strong anti-interference ability, do not need external components, adapt to various single-chip microcomputers, and can be widely used in medical equipment and temperature/humidity adjustment systems.Figure6. HTS221 Capacitive Digital Humidity SensorIII Application of Humidity Sensors3.1 Typical UsesWork in any industry is inseparable from the air, and the humidity of the air is directly related to work, life, and production, making the monitoring and control of humidity more and more important. The main applications of humidity sensors are as follows: (1) Climate monitoringWeather measurement and forecasting are of great significance to industrial and agricultural production, military and people’s lives, and scientific experiments. Therefore, humidity sensors are essential humidity measuring equipment. For example, resin swelling humidity sensors have been used in meteorological balloon humidity measuring instruments. on. (2) Greenhouse breedingModern agriculture, forestry, and animal husbandry industries have a considerable number of greenhouses. The humidity control of the greenhouse is as important as temperature control. Controlling the humidity in a suitable range for the growth of crops, trees, livestock and poultry is one of the conditions for reducing pests and diseases and increasing yield. (3) Industrial productionIn the textile, electronics, precision machinery, ceramic industry and other sectors, air humidity directly affects the quality and output of products, and must be effectively monitored and regulated. (4) Storage of goodsVarious items have certain adaptability to the environment. If the humidity is too high or too low, the product will lose its original performance. For example, in high-humidity areas, electronic products are seriously damaged in the warehouse, non-metal parts will become moldy, and metal parts will corrode and rust. (5) Use protection of precision instrumentsMany precision instruments and equipment have higher requirements for the working environment. The environmental humidity must be controlled within a certain range to ensure their normal operation and improve work efficiency and reliability. For example, the working humidity of the telephone program-controlled switchboard is better at 55% ±10%. Too high temperature will affect insulation performance, and too low temperature will easily generate static electricity and affect normal operation.3.2 Application Fields(1) Humidity measurement system● When the temperature is below 70°C (usually above -40°C), if the environment is clean, use a polymer sensor, and use a ceramic sensor (heating cleaning regeneration type) for serious pollution. Because of its heating and cleaning process, it cannot be measured continuously and consumes a lot of energy (1-10W). However, it has a long life and can choose a sensor with a longer heating and cleaning cycle during use, such as a chloroapatite ceramic sensor, which is washed once every 2 to 3 months. In addition, the internal heating type consumes less energy than the external heating type. ● Measure the humidity in the range of 70～100℃, use ceramic sensors with heating and cleaning, and perform linearity and temperature compensation to improve accuracy. In order to achieve higher accuracy, a microcomputer is required. Frequent heating and cleaning are required at high temperature and humidity. For example, when the RH is above 80%, it needs 30S cleaning once. It is best equipped with an automatic heating cleaning device. ● Measure the humidity in the range of 100～150℃. In the world, ceramic humidity sensors are mostly used to make high temperature humidity meters. (2)Automatic control of industrial processesIn order to improve product quality and energy-saving, ceramic humidity sensors are usually used for control in product drying systems, reactor humidity control, boiler water vapor leakage detection, integrated circuits, or air conditioning in magnetic head processing plants; the humidity control of various air conditioning systems, medical systems can be carried out with polymer or ceramic humidity sensors. (3) Steam leak detection systemIn thermal power stations, nuclear power plants, steam locomotives, boilers and other high-temperature and high-pressure equipment, in order to prevent gas leakage and prevent personal accidents, humidity sensors can be used for leak detection. (4) Other systemsIn-home appliances, the humidity sensor can be used for humidity measurement of humidifiers, dehumidifiers, air conditioners, wine cabinets, clothes dryers, etc.IV Arduino Entry Project: Real-time Temperature and Humidity Detector4.1 Hardware PreparationArduino UNO oneA temperature and humidity sensorOne PCF8574T adapter board1602LCD oneA piece of breadboardSeveral connecting lines4.2 Software PreparationArduino IDE4.3 Circuit ConnectionThis project directly uses the PCF8574T adapter board to drive the 1602 LCD display, which will save a lot of Arduino IO ports and save a lot of wiring troubles. PCF8574T adapter board contains four interfaces: VCC, GND, SDA and SCL. Make these connections respectively: VCC - 5V, GND - GND, SDA - A4, SCL - A5. The temperature and humidity sensor contains 3 pins, viewed from the side with the mesh, from left to right are DATA, VCC, and GND. Make connections like this: DATA - A0, VCC - 3.3V, GND - GND.Figure7. Circuit Connection4.4 Implementation CodeFigure8. Experiment Result/** Use temperature and humidity sensor to detect information and display it on the LCD*/#include "Wire.h" // Import libraries needed to drive LCD#include "LiquidCrystal_I2C.h"#include "dht.h" // Import dht library for temperature and humidity sensor#define dht_pin A0 // Connect the data port of the temperature and humidity sensor to A0dht DHT;// Set up LCDLiquidCrystal_I2C lcd(0x27,16,2); // 0x27 is the address of the I2C busvoid setup() {// Delay waiting for system initializationdelay(1000);// Initialize LCDlcd.init();// Turn on the screen backlightlcd.backlight();// LCD screen displays Humidity(%):lcd.print("Humi(%): ");// LCD screen displays Temp(C):lcd.setCursor(0, 1);lcd.print("Temp(C): ");}void loop() {// Read the data of the temperature and humidity sensorDHT.read11(dht_pin);// LCD displays the collected temperature and humidity datalcd.setCursor(8,0);lcd.print(DHT.humidity,1);lcd.setCursor(8,1);lcd.print(DHT.temperature,1);delay(1000);} After the code is compiled without any problem, click the button to upload it to the Arduino UNO board. After the programming is no problem, you can observe the result on the LCD. If there is no change in the humidity, you can try to breathe a sigh of relief at the sensor and you can observe the change in value.Ⅴ FAQ1. What are humidity sensors?A humidity sensor (or hygrometer) senses, measures and reports both moisture and air temperature. The ratio of moisture in the air to the highest amount of moisture at a particular air temperature is called relative humidity. Relative humidity becomes an important factor when looking for comfort. 2. How do humidity sensors work?Humidity sensors work by detecting changes that alter electrical currents or temperature in the air. ... A capacitive humidity sensor measures relative humidity by placing a thin strip of metal oxide between two electrodes. The metal oxide's electrical capacity changes with the atmosphere's relative humidity. 3. How many types of humidity sensors are there?There are three primary types of humidity sensors employed which are defined around what approach is used to sense humidity and deliver an electrical signal that can be used to establish the value. These types of humidity sensors include Capacitive humidity sensors. Resistive humidity sensors. 4. Is a humidity sensor analog or digital?Humidity sensors measure and report moisture levels in two distinct ways - analog or digital (aka discrete). Digital sensors are able to monitor conditions for operation within a specified range. ... Analog sensors are more advanced and provide continuous visibility to current conditions through accurate measurements. 5. Why is a humidity sensor used?Humidity sensors are electronic devices that measure and report the moisture and air temperature of the surrounding environment where they are deployed e.g., in air, soil, or confined spaces. Humidity measurements indicate the concentration of water vapor present in the air. 6. What is an absolute humidity sensor?The ABS-300 is a thermal conductivity absolute humidity sensor. This sensor measures absolute humidity by quantifying the difference in thermal conductivity of dry air and air containing water vapor. ... If temperature and pressure are known the absolute humidity easily converts to relative humidity. 7. How accurate is a humidity sensor?Digital relative humidity sensors are typically accurate to plus/minus 3% relative humidity throughout the entire 0-100% RH range, but closer to plus/minus 2% at 50% RH. ... The simplest way to calibrate a relative humidity sensor is with table salt and water in an airtight container. 8. What is a humidity transducer?Humidity transducers are normally used in laboratories connected to a controller to keep a constant humidity there. ... Humidity transducers can transform a physical quantity of air humidity into a standard signal which is transferred to a controller. 9. How does the humidity sensor sense the moisture in the air?A capacitive humidity sensor measures relative humidity by placing a thin strip of metal oxide between two electrodes. The metal oxide's electrical capacity changes with the atmosphere's relative humidity. These types of sensors are used for weather, commercial and industrial applications. Resistive humidity sensors utilize ions in salts to measure the electrical impedance of atoms. As humidity changes, so do the resistance of the electrodes on either side of the salt medium. State-of-the-art resistive humidity sensors use ceramics to overcome areas where condensation occurs. Thermal conductivity sensors measure changes in heat to detect humidity. Two thermal sensors conduct electricity based upon the humidity of the surrounding air. One sensor is encased in dry nitrogen as a comparison to the other sensor which measures the ambient air. The difference between the two measures the humidity. 10. What is the difference between a Temperature sensor and a Humidity sensor?Temperature Sensor: Temperature is the most common environmental parameter. Temperature plays an important role in our homes and industries. Over the past few years, we are able to monitor and control environmental parameters with the help of temperature sensing devices. A temperature sensor is an electronic device that is used to detect and measure accurate temperature levels in different environmental conditions. There are many affordable temperature sensors are available in the market to measure the accurate temperature level. Humidity Sensor: Humidity is another most measurable environmental parameter. The high humidity levels in our homes and warehouses increase the chances of damaged products and things. In the past, we were not able to detect the accurate humidity level due to a lack of sensing devices. The humidity sensor is an electronic device uses to measure the humidity level and make changes in the humidity level through our mobile phone from anywhere. The humidity sensor detects the humidity level in the water, air and in soil. We can easily access humidity sensors in our homes and business.