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IntroductionIn electronics, a pinout (sometimes written "pin-out") is a cross-reference between the contacts, or pins, of an electrical connector or electronic component. It describes the functions of transmitted signals and the circuit input/output (I/O) requirements. The number of pins is divided into 8-pin, 14-pin, 16-pin, etc. Every pin must be properly matched to a connector that has the same function. Pinout types include Universal Serial Bus (USB) pinout, PS/2 pinout, ATX power supply pinout, VGA pinout, and Digital Visual Interface (DVI).How to Read Pinouts?CatalogIntroductionⅠ Pinout Arrangement DescriptionⅡ Arduino Pinout and Raspberry Pi Pinout2.1 Arduino Nano Pinout and Arduino Uno Pinout2.2 Arduino Pinout Series2.3 Raspberry Pi Pinout and Diagram2.4 Difference between an Arduino and a Raspberry PiⅢ Example: AT89S52 PinoutsⅠ Pinout Arrangement DescriptionA pinout generally has descriptions in a diagram or table, which specifically indicates whether it is the back-side or front-side view, or if it is the mating face of the connector, or it stands for? Generally speaking, the more pins, the larger the size of the IC chip, the stronger the circuit function, and of course, the higher the price.What these pins stand for? Look at the following Common PIC Pin Descriptions:Pin NumberSymbolDescription1AUDIOAudio Signal Output2FM OUTFM Detection Output3IF AGCIF Signal Input4RF AGCRF AGC Voltage Output5IF INIF Signal Input6IF GNDIF Circuit Ground7IF VccIF Circuit Power Supply8FM FILTERFM Detector Filter Terminal9AFT OUTAFT Control Power Output10SDAI2C Bus Data Terminal11SCLI2C Bus Clock Terminal12ABLAutomatic Brightness Control13R INRed Character Input14G INGreen Character Input15B INBlue Character Input16BLACK INCharacter Blanking signal Input17RGB VccDecoding Circuit Power Supply18R OUTRed Primary Color Signal Output19G OUTGreen Primary Color Signal Output20B OUTBlue Primary Color Signal Output21IDWhite Balance Adjustment Signal Input22VER OUTField Sawtooth Wave Output23V RAMP ALCField Sawtooth Wave Formation24H/BUS VccLine Start Power25AFC FILTERLine AC Low-pass Filtering26HOR OUTLine Excitation Pulse Output27FBP INLine and Reverse Pulse Input28REFReference Current Formation29CLK OUT4MHz Clock Signal Output Pin NumberSymbolDescription301H DL VccBuilt-in Baseband Delay Line +5V Power Supply311H DL Vcc OUTBaseband Delay Line Boost Circuit Output Terminal321H DL GNDBaseband Delay Line Ground33SECAM INComponent Signal Input34C APC FILTERChroma Subcarrier Phasedetector (APC1) Low-pass Filter35SECAM INTERFACE4.43MHz CW Signal Output or SECAM Achromatic Signal Input36X TAL4.43MHz Crystal Terminal37SEL VIDEO OUTVideo Output38V/C/DEF GNDGround39EXT V IN/Y INAV Video or Y Signal Input Terminal40V/C/DEF VccVideo/Chroma/Scan Part Power41INT V IN/C INAV Video or C Signal Input Terminal42BLACK STECHFilter End of Black Level Extension Circuit43VIDEO OUTVideo Detector Output44VCO FILTERIF Lock Detection Filter45VCOExternal VCO Resonant Network46PIF APCIF APC Filter47EXT AUDIO INAV Audio Signal Input48SIF OUTAudio Accompanying Sound IF Output49SIF INAudio Accompanying Sound IF Input50SND APCAccompanying Sound Discrimination Filter Pin NumberSymbolDescription1BASSBass Control Output2MUTEMute (High Level) Control Output350/6050Hz/60Hz Identification Output4SECAMSECAM Recognition5VOLVolume Control6COMB.FDigital Filter on/off Control7POWERPower On/Standby Control8TUNEPWM Tuning Voltage Output9GNDGround10XTAL132kHz Crystal Connection Terminal11XTAL232kHz Crystal Connection Terminal12VDDPower Supply13KEY-IN1Key Scan Signal Input 114KEY-IN2Key Scan Signal Input 215AFT-INAFT Control Voltage Input16RESETReset Terminal17FILTERCharacter Oscillation Low Pass Filter18NCEmpty Pin19V-SYNCCharacter Vertical Positioning Pulse Input20H-SYNCCharacter Horizontal Positioning Pulse Input21OSD-BLKCharacter Blanking Pulse Output22SDAI2C Bus Data Terminal23SCLI2C Bus Clock End24SAFTYOverload Detection Terminal25CSProduction Debugging Chipselect Signal Input Terminal26REM INRemote Control Signal Input27SIFAudio IF Switching Control28TV/AV1AV/TV Switch29TV/AV2AV/TV Switch303.58/4.433.58/4.43 Control31UHFUHF Band Control32VHVHF-H Band Control33VLVHF-L Band ControlⅡ Arduino Pinout and Raspberry Pi Pinout2.1 Arduino Nano Pinout and Arduino Uno PinoutThe Arduino Nano is a small, complete, and breadboard-friendly board. It is based on the ATmega328 8-bit microcontroller by Atmel. It has a total of 36 pins. Out of these 8 are analog input pins and 14 digital input/output pins (of which 6 can be used as PWM outputs). Nano has a 16 MHz SMD crystal resonator, a mini USB-B port, an ICSP header, 3 RESET pins and, a RESET button. The Arduino digital pins can read/output only two states: when there is a voltage signal and when there is no signal.Figure 1. ATMEGA328 PinoutArduino UNO is based on the ATMEGA328 by Atmel. The Arduino UNO pinout consists of 14 digital pins, 6 analog inputs, a power jack, USB connection and ICSP header. The function of Analog pins is to read the value of the analog/digital input used in the connection.Figure 2. Arduino UNO Pinout2.2 Arduino Pinout SeriesDigital PinsPower:  Mini USB  VinICSP:  MISO (Master In Slave Out)  Vcc (Supply Voltage)  SCK (Clock from Master to Slave)  MOSI (Master Out Slave In)  RST (Reset (Active Low)  GND (Supply Ground)Serial Communication PinsPWM (Pulse Width Modulation) PinsExternal InterruptsSPI (Serial Peripheral Interface) pinsBlinking LED Analog PinsRESETI2C ProtocolAREF (Analog Reference) PinsPower2.3 Raspberry Pi Pinout and DiagramThe Raspberry Pi is a tiny and affordable computer that you can use to learn programming through fun, practical projects, which is the go-to microcomputer for all ages and abilities. You can plugs it into a computer monitor or TV, and uses a standard keyboard and mouse. Over the years the header has expanded from 26 pins to 40 pins while maintaining the original pinout. As you can see, the Pi not only gives you access to the bi-directional I/O pins, but also Serial (UART), I2C, SPI, and even some PWM ("analog output").Figure 3. Raspberry Pi GPIO PinoutRaspberry Pi is as small as the size of a credit card, and works as if a normal computer at a relatively low price. It is possible to work as a low-cost server to handle light internal or web traffic. What’s more, grouping a set of Raspberry Pi to work as a server is more cost-effective than a normal server. Although Raspberry Pi board has so many advantages, it also has the following disadvantages:1) Not able to run Windows Operating system2) Impractical as a Desktop Computer3) Graphics Processor Missing4) Missing eMMC Internal Storage2.4 Difference between an Arduino and a Raspberry PiThe main difference between them is: Arduino is microcontroller board, while Raspberry Pi is a microprocessor based mini computer (SBC). The Microcontroller on the Arduino board contains the CPU, RAM and ROM. ... Raspberry Pi needs an Operating System to run. Arduino doesn't need any operating system.If you're coming to the Raspberry Pi as an Arduino user, you're probably used to referencing pins with a single, unique number. Programming the Pi's hardware works much the same, each pin has its own number...and then some.Ⅲ Example: AT89S52 PinoutsThe pin functions of AT89S52 are diverse. For example, the intermediate frequency signal can be demodulated from the pin to the internal FM circuit in an unbalanced manner. At the same time, it is also the control pin for AV\TV conversion and PAL, NTSC, SECAM chroma system conversion in the block, and its input impedance is about 3.4K.Figure 4. AT89S52 Pinouts1) For Recognition OutputThe pin outputs image recognition signal in OC gate mode. When the video TV signal has been received, this pin presents high impedance to the outside, and a high level signal can be obtained through an external pull-up resistor; when no signal is received, this pin presents a low impedance and outputs a low level.2) As APC1 Filter TerminalThe chip generates a 38MHz switching signal in an oscillating manner to complete the demodulation of the image IF signal. Whether the generated switching signal is accurate depends on the automatic phase control circuit (APC) control. Among them, the filtering of the APC1 error signal is completed on this pin.3) As APC2 Filter TerminalThe filter terminal of the second-stage APC circuit4) An external pin for the quartz crystal oscillatorThe external quartz crystal and internal circuit will oscillate in the form of series resonance. The oscillation frequency is a quarter of the carrier frequency of the image intermediate frequency signal. The frequency of the quartz crystal required is different under different signal systems.5) For AFT Signal OutputThe image IF signal compare with the internal frequency, and then the pin outputs AFT error signal.6) Full TV Signal OutputThe signal in the image is demodulated, and finally the video signal and the accompany audio intermediate frequency signal are output from the pin, and the output signal level is 2V.7) Radio Frequency AGC Delay AdjustmentBy adjusting the external potentiometer, the AGC delay amount can be adjusted.8) For the Input of Internal and External Video SignalsThe signal input needs to be separated from the DC. The coupling capacitor capacity is 1uF. When the internal input level is the peak, the max value is 2V. And when the external input is the peak and the peak is 1V. The input impedance is about 50kΩ. Inside the integrated circuit, the blanking level is fixed at 4.5V.9) The Output of Contrast Control Voltage can also be used to control ACL.10) The pin is the standard level of the built-in filter and the switch of S-VHS. It needs a 1Uf capacitor to be grounded to set the standard level. When it is in the S-VHS mode, the pin voltage must be led by an external circuit is set below 2V. When it is in the normal AV state, the voltage level should be set above 2V.11) Input Pin for S-VHS Chroma Signal and DC ControlWhen inputting chroma signal, a 0.01Uf capacitor should be used to cut off the DC input. At PAL format, the chroma signal level should be 300mV peak-to-peak, and should be 286mV peak-to-peak under the NTSC system.12) As a Delayed Video Signal OutputIt can also achieve ABL control. The output video signal level is 2V peak-to-peak, and a current of 0.5mA or more is necessary.13) The Output of the Decolorization ControlAfter the internal decolorization circuit is activated, a low-level signal will be output from the pin.14) Address Input for Analog Bus Control15) Data Input of Analog Bus Control16) The Output of the Internal Field Scanning PulseThe external resistance value can set the sensitivity of the internal field synchronization separation. If you don't need the internal field pulse, you can also input other field pulse signals from the pin, and the internal field output is automatically cut off at this time. The pin can also be an automatic trigger mode release switch and a row AFC strobe release switch.17) To connect the oscillating quartz crystalThe crystal frequency should be 500Hz.18) Separate power supply pins for line oscillation and line pre-excitation circuits. A higher voltage provides a DC voltage to the pin through a resistor, which is stabilized to 7V by the internal voltage regulator circuit for use by the above circuits. The selection calculation of resistance is: R1=(+B1－7.0V)/13mA.19) The output of line pre-excitation pulse is output in push-pull mode.20) Line and Reverse Pulse InputThe line and reverse pulse signal is output from this pin after forming a sand castle pulse internally. As a unified working sequence of some circuits, this pin is also the output of the integrated circuit pulse in the SECAM system.21) Character Background Blanking Pulse InputThe standard control voltage is 1V, when the input voltage is higher than 1V, the image display stops, and the character is displayed at the current position. When the pin voltage is lower than 1V, the image is displayed at the current position.22) The input of the three-color signal of the on-screen character display (OSD). When using the analog character display mode, the DC input needs to be cut off. When using the digital character display mode, the high level needs to be set to a certain value.23) Negative brightness signal output, and at the same time the input of the de-trap signal.24) Color difference signal output, respectively output the R-Y, G-Y, B-Y of the TV image or the R, G, B three-color screen character display dot matrix after character display conversion.25) After the input of the ALC amplifier (CCD delay adjustment) is delayed and calculated by the integrated one-line delay line, the two color difference signals return to the LA7687 from these two lead pins.26) Output the Color Difference Signal to the Integrated Delay Line.In the PAL system, the two incompletely demodulated color difference signals are output from two pins to the delay line for further processing. When in the SECAM system, the color difference signal does not come from LA7687. Therefore, the two pins present a high impedance state under this system, and the output dc voltage is 3.6V.27) The subcarrier recovery circuit needs to be connected to 4.43MHz and 3.58/MHz quartz crystals.28) For the Color Demodulation Circuit APC FilterThe filter composed of the external resistance container can set the synchronization range of the subcarrier oscillation.29) The AGC Filter Pin of the First Stage Mid AmplifierThe AGC detection circuit separates the synchronization signal by detecting the peak value of the video signal, and filters it into the AGC voltage at the pin. The second stage AGC filter is hidden inside the integrated circuit.30) Image IF Signal InputThrough the surface acoustic filter to form a specific image IF signal, in a balanced way from  two lead pins amplify the collector circuit. Inside the integrated circuit, there are a total of three amplifiers, and the total amplification gain is above 60dB.31) The output of the radio frequency AGC is output in an open-collector mode.32) Audio Signal OutputThe integrated circuit completes the demodulation of the FM signal, and the audio signal is output from the pin, and there should be a de-emphasis circuit composed of resistive components on the outside.33) Audio Filter PinIt is used to eliminate the DC feedback of the preamplifier, in addition, a 1uF capacitor is required to be connected externally. In addition, when this pin is set to high level, the image IF gets into the SECAM mode. Frequently Asked Questions about Electronic Pinout1. What does pinout mean?In electronics, a pinout (sometimes written "pin-out") is a cross-reference between the contacts, or pins, of an electrical connector or electronic component, and their functions. "Pinout" now supersedes the term "basing diagram" that was the standard terminology used by the manufacturers of vacuum tubes and the RMA. 2. What is pin configuration?Devices support both analog input and digital I/O line modes on several configurable pins. The following table provides typical parameters for the pin configuration commands (D0 - D9, P0 - P2). 3. What is a pinout cable?Pinout or pin-out is a term used in electronics to describe how an electrical cable is wired, or the function of each wire (pin) in a connector. An electrical connector typically consists of several electrical contacts or pins that can be used to carry electrical power or signals. 4. What are the pins on Arduino Uno?Arduino/Genuino Uno is a microcontroller board based on the ATmega328P (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header and a reset button. 5. How many digital and analog pins are in Arduino Uno?Microcontrollers

IntroductionA voltage regulator is a circuit that generates a fixed output voltage of a preset magnitude that remains constant regardless of changes to its input voltage or load conditions. It converts an unstable dc voltage into a stable dc voltage. Its power supply composed of discrete components has the advantages of large output power and wide adaptability. In recent years, integrated regulated power supplies have been widely used. Among them, three-terminal series regulators are the most common for low-power regulated power supplies. The commonly used integrated voltage regulators in the circuit mainly include 78xx series, 79xx series, adjustable integrated voltage regulator, precision voltage reference integrated voltage regulator, etc.What is a Voltage Regulator and How Does It Work?CatalogIntroductionⅠ Voltage Regulator ClassificationⅡ Main ParametersⅢ Applying NotesⅣ Typical Examples: LM317 & LM7805Ⅰ Voltage Regulator ClassificationVoltage regulators are generally divided into linear voltage regulator and switching voltage regulator. Linear voltage regulator is a circuit used to maintain a steady voltage, which is divided into low dropout type and general dropout type. Switching voltage regulator is a type of switch mode power supply circuit that is designed to efficiently reduce dc voltage from a higher voltage to a lower one, which is divided into step-down type, step-up type and integrated type with opposite input and output polarity.According to the number of outlet terminals and usage of the voltage regulator, it can be roughly divided into three-terminal fixed type, three-terminal adjustable type, multi-terminal adjustable type and single-chip switch type.The three-terminal fixed type voltage regulator integrates sampling resistors, compensation capacitors, protection circuits, high-power adjustment tubes, etc. on a chip. So that the entire integrated circuit block has only 3 terminals: input, output and public. It is very convenient to use. Its disadvantage is that the output voltage is fixed, so a series of products with various output voltages and current specifications must be produced to match.The three-terminal adjustable integrated voltage regulator only needs two external resistors to obtain various output voltages.The multi-terminal adjustable type is an early integrated voltage regulator. With small output power and many pins, it is not convenient to use, but the precision is high and the price is cheap.The monolithic switch type integrated regulated power supply develops in recent years, and its efficiency is particularly high. Its working principle is different from the above three types. It is a converter that converts DC to AC (high frequency) and then DC. Usually there are two types of pulse width modulation and pulse frequency modulation, and the output voltage is adjustable.Ⅱ Main Parameters1) Voltage Regulation RateIt is an important indicator that characterizes the voltage regulation performance of the integrated voltage regulator, also known as the voltage regulation coefficient or stability. It represents how stable the output voltage V0 of the regulator is when the input voltage V1 changes.2) Current Regulation RateIt is also known as current stability coefficient, and shows the ability of the regulator to suppress output voltage fluctuations caused by changes in load current (output current) when the input voltage remains unchanged.3) Ripple Rejection RatioIt reflects the ability of the regulator to suppress the mains ripple voltage introduced at the input.4) Output Voltage Temperature CoefficientIt is also known as the output voltage temperature change rate, and refers to when the input voltage and output current (load current) remain unchanged, the output voltage of the regulator changes with temperature.5) Long-term Stability of the Output VoltageIt refers to the magnitude of the change in the output voltage value over time (when the output current, input voltage and ambient temperature remain unchanged). It is usually the maximum amount of change in the output voltage of the regulator within a specified time.6) Output Noise VoltageIts absolute value represents the noise performance of the regulator directly. There is also a percentage value of the output noise voltage Vn and the output voltage V0 of the regulator to characterize the noise performance.7) Thermal StabilityIt refers to the thermal stability of the voltage regulator. It is usually the percentage value of the relative change in the output voltage caused by its unit power consumption.8) Temperature StabilityIt is the percentage value of the relative change of the regulator's output voltage within the specified maximum change range of operating temperature. Ⅲ Applying Notes① There are many types of integrated voltage regulator. According to the adjustment method there are linear and switch type. Based on the output method, there are fixed and adjustable types. Because of the obvious advantages of the three-terminal voltage regulator, it is more convenient to use and operate.② Before connecting to the circuit, it is necessary to distinguish the pins and their functions to avoid damage to the integrated block. The input and output ends of the three-terminal integrated voltage regulator with an output voltage greater than 6v need to be connected with protective diodes to prevent the rapid discharge of the output capacitor, which will cause damage to the three-terminal integrated voltage regulator when the input voltage drops suddenly.③ In order to ensure the stability of the output voltage, the minimum input voltage difference should be guaranteed. For example, the minimum pressure difference of the three-terminal integrated voltage regulator is about 2v, and it should be kept above 3v during general use. At the same time, it should be noted that the maximum voltage difference of input and output does not exceed the specified range.④ In order to expand the output current, the three-terminal integrated voltage regulator is allowed to be used in parallel.⑤ When using, the welding should be firm and reliable. If a heat dissipation device is required, it should meet the required size.If you have a bad regulator, it may cause many components such as the fuel pump, ignition system, or other parts which require a minimum amount of voltage to not function correctly. You may experience the engine sputtering, a rough idle, or simply a lack of acceleration when you need it. Ⅳ Typical Examples: LM317 & LM7805The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25V to 37V. It serves a wide variety of applications including local, on card regulation. This device can also be used to make a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM317 can be used as a precision current regulator.LM317 Specifications Adjustable output voltage as low as 1.2VOutput voltage: 1.25-37V DCGuaranteed 1.5A output currentOutput current: 5mA-1.5ATypical linear adjustment rate: 0.01%Max input-output voltage difference: 40V DCTypical load regulation rate: 0.1%Min input-output voltage difference: 3V DCRipple rejection ratio: 80dBOperating temperature: -10± 85℃Output short circuit protectionStorage temperature: -65± 150℃Over-current, overheat protectionOutput voltage: 1.25-37V DCAdjusting tube safe working area protectionOutput current: 5mA-1.5A The linear voltage regulator LM7805 has over-voltage protection, over-current protection, and over-heat protection functions, which makes its performance very stable. It is a 5V regulator, and is able to achieve output current above 1A, and has a good temperature coefficient. So the product has a wide range of applications. Have a look to get more specific info by the following video:Why is the LM7805 is a very Popular Voltage Regulator?As a member of 78xx series of fixed linear voltage regulators, the following is a very good summary of the basics on linear voltage regulator 7805:ParameterSymbolConditionsMinTypicalMaxUnitOutput VoltageVoTj=25℃4.85.05.2V5.0mA<Io<1.0APo<15WVi=7v to 20v4.755.05.25VLinear Adjustment rate△VlineTj=25℃, Vi=7V to 25V 3.0100mVTj=25℃Vi=8V to 12V 1.050mVLoad Adjustment Rate△VloadTj=25℃,lo=5.0mA to 1.5A  100mVTj=25℃lo=250mA to 750mA  50mVStatic CurrentIqTj=25℃  8mAStatic Current Rate△Iqlo=5mA to 1.0A  0.5mAVi=7V to 25V  0.8mAOutput Voltage Drift△Vo/△Tlo=5mA -1.1 mV/℃Output Noise VoltageENf=10Hz to 100KHzTj=25℃  40μV/VoRipple Rejection RatioSVRf=120Hz,Vi=8V to 18V62  dBVoltage DifferentialVdlo=1.0ATj=25℃ 2.0 VOutput ImpedanceRof=1KHz 17 mΩShort-circuit CurrentIscVi=35VTj=25℃ 750 mAPeak CurrentIscpTj=25℃ 2.2 AIf you want to make a 5V power supply with a 7805, output currents up to 1A can be drawn from the IC provided that there is a proper heat sink. A 9V transformer steps down the main voltage, 1A bridge rectifies it and capacitor C1 filters it and 7805 regulates it to produce a steady 5V DC. Then you can test it, turn on the DC power supply and adjust the output voltage of about 8V or slightly larger. Or alternatively you can use a battery 9V-12V as voltage source. Look at the voltmeter panel when you set the voltage. Prepare a DC voltmeter readings on voltage range 50V to measure the output voltage of the IC 7805. Frequently Asked Questions about Voltage Regulator1. What is voltage regulator and how it works?A voltage regulator generates a fixed output voltage of a preset magnitude that remains constant regardless of changes to its input voltage or load conditions. ... A switching regulator converts the dc input voltage to a switched voltage applied to a power MOSFET or BJT switch. 2. What is a voltage regulator used for?Voltage regulator, any electrical or electronic device that maintains the voltage of a power source within acceptable limits. The voltage regulator is needed to keep voltages within the prescribed range that can be tolerated by the electrical equipment using that voltage. 3. What are the three 3 basic types of voltage regulators?There are three types of Switching voltage regulators: Step up, Step down, and Inverter voltage regulators. 4. What happens when voltage regulator goes bad?If you have a bad regulator, it may cause many components such as the fuel pump, ignition system, or other parts which require a minimum amount of voltage to not function correctly. You may experience the engine sputtering, a rough idle, or simply a lack of acceleration when you need it. 5. Where are voltage regulators used?Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators control the output of the plant.

IntroductionThe operational amplifier is an integrated circuit that has two input pins and one output pin. It is used to amplify and output the voltage difference between the two input pins. Based on its characteristics, operational amplifier has different functions in different circuits. Here introduces common and fundamental op amp circuits examples with descriptions.A Basic Introduction to Op Amp CircuitsCatalogIntroductionOp Amp Diagram and Circuit Analysis1.1 What is the Inverting & Non-inverting Amplifier?1.2 Differential Amplifier1.3 Summing Amplifier1.4 Practical Differentiator1.5 Op-amp Integrator1.6 Converter, Detector, Bias Current Compensation, Voltage Comparator1.7 Offset Voltage Adjustment1.8 Sine Wave Generator1.9 Op-Amp Voltage Reference1.10 Instrumentation Amplifier1.11 Precision Current Sink & Source1.12 Precision Diode & Clamp1.13 Notch Filter Amplifier1.14 Capacitance Multiplier2 Other Op-amp Circuit ApplicationsOp Amp Diagram and Circuit AnalysisHow do you build an op amp circuit? This part introduces the most basic operational amplifier circuits. Understand the role of op amp in different circuits, and do reference design for your own amplifier circuit through the description of the op amp equations. What’s more, you can handle the most common op amp applications through these circuits.1.1 What is the Inverting & Non-inverting Amplifier?Figure 1. Inverting AmplifierIn an inverting amplifier circuit, the operational amplifier inverting input receives feedback from the output of the amplifier. Assuming the op-amp is ideal and applying the concept of virtual short at the input terminals of op-amp, the voltage at the inverting terminal is equal to non-inverting terminal. Figure 2. Inverting Amplifier with High Input ImpedanceIn electronics, high impedance means that a point in a circuit (a node) allows a relatively small amount of current through. For an inverting amplifier, the input impedance is approximately equal to the input resistance. This is because the input resistor is connected to “virtual ground” in the inverting configuration.Another Example:Figure 3. Fast Inverting Amplifier with High Input Impedance Figure 4. Non-inverting AmplifierA non-inverting amplifier is an op-amp circuit configuration which produces an amplified output signal. This output signal of non-inverting op amp is in-phase with the input signal applied. In other words a non-inverting amplifier behaves like a voltage follower circuit.Another Example:Figure 5. Non-inverting AC AmplifierRecommended Readings: Inverting and Non-inverting Amplifier and Their Basics......(1)Op Amp High Input Impedance and Low Output Impedance......(2)1.2 Differential AmplifierFigure 6.The differential amplifier circuit is a very useful op-amp circuit and by adding more resistors in parallel with the input resistors. It usually has two outputs and two inputs, which is a special purpose amplifier designed to measure differential signals, otherwise known as a subtractor. 1.3 Summing AmplifierThe Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.Example Explained:Figure 7. Fast Summing Amplifier with Low Input Current Figure 8. Inverting Summing AmplifierThe inverting summing amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage. When the summing point is connected to the inverting input of the op-amp the circuit will produce the negative sum of any number of input voltages. Figure 9. Non-inverting Summing AmplifierThe non-inverting summing amplifier is a similar configuration to the inverting summing amplifier. In other words, it is based around the configuration of a non-inverting operational amplifier circuit in that the input (either ac or dc) is applied to the non-inverting (+) terminal, while the required negative feedback and gain is achieved by feeding back some portion. 1.4 Practical DifferentiatorFigure 11.A practical differentiator amplifier is basically a high pass filter and are used in wave shaping circuits, frequency modulators etc. Because differentiators have frequency limitations while operating on sine wave inputs; the circuit attenuates all low frequency signal components and allows only high frequency components at the output. In other words, the circuit behaves like a high-pass filter. 1.5 Op-amp IntegratorAn op-amp integrator is an electronic integration circuit that performs the mathematical operation of Integration, that is we can cause the output to respond to changes in the input voltage over time as the op-amp integrator produces an output voltage which is proportional to the integral.Figure 12. Fast Integrator Figure 13. Fast Integrator with Low Input Current Figure 14. Low Drift IntergratorIn Low Drift Intergrator circuit, the output of an operational amplifier always contains signals that could not have been predicted, even with knowledge of the input and an accurately. 1.6 Converter, Detector, Bias Current Compensation, Voltage ComparatorFigure 15. Current to Volatge ConverterA current to voltage converter will produce a voltage proportional to the applied input current. This circuit is required if your measuring instrument is capable only of measuring voltages and you need to measure the current output. Figure 16. Precision AC to DC ConverterA simple full wave precision rectifier using a single supply operational amplifier in saturation mode, which is to insure precision half wave rectification and unidirectional current flow. Figure 17. Temperature Compensated Logarithmic ConverterA temperature compensated logarithmic amplifier for signal strength indicator or automatic gain control applications is presented.  Figure 18. Double-Ended Limit DetectorThe circuit in see a differential Input to single ended output amplifier will convert a differential (double ended) signal. Figure 19. Fast Zero Crossing DetectorA zero-crossing detector whose input is a sign wave has been converted into a train of positive pulses at interval T by adding a RC network and a clipping. It can be used to detect phase anomalies, or even as a 'loss of AC' detector, purposes of synchronization, fast and accurate frequency. Figure 20. Low Drift Peak DetectorOp-amp based peak detector circuit is the modification of basic peak detector circuit, used to remove the voltage drop across the diode. It stores the peak value of input voltages for infinite time duration until it comes to reset condition. Figure 21. Op Amp Integrator with Bias Current CompensationThe operational amplifier integrator is an electronic integration circuit, where the resistor producing a compensating current flow through the series capacitor to maintain the virtual ground. Figure 22. Voltage Comparator for Driving DTL or TTL Integrated CircuitHigh frequency performance at any gain as a comparator the output can be drived DTL or TTL integrated circuit. Figure 23. Threshed Detector for PhotodiodesUse operational amplifiers or op-amps to convert the photodiode current to a measurable voltage. 1.7 Offset Voltage AdjustmentThe input offset voltage is defined as the voltage that must be applied between the two input terminals of the op amp to obtain zero volts at the output. Ideally the output of the op amp should be at zero volts when the inputs are grounded. The presence of offset can be encapsulated by assuming that the real Op Amp input/output transfer characteristic is y = A (V + – V – + e ) where e is the error in the differential input to the ideal Op Amp.Figure 24. Offset Voltage Adjustment for Inverting Amplifiers Using Any Type of Feedback Element Figure 25. Offset Voltage Adjustment for Non-inverting Amplifiers Using Any Type of Feedback Element Figure 26. Offset Voltage Adjustment for Voltage Followers Figure 27. Offset Voltage Adjustment for Differential Amplifiers Figure 28. Offset Voltage Adjustment for Inverting Amplifiers Using 10kΩ Source Resistance or Less 1.8 Sine Wave GeneratorSine Wave Generator Using Op AmpThe Sine Wave Generator is a type of electronic equipment that generates an oscillating frequency in a sinusoidal pattern. One of the popular methods of generating a sine wave with an operational amplifier is to use the Wien bridge configuration.Figure 29. Low Frequency Sine Wave Generator with Quadrature Output Figure 30. High Frequency Sine Wave Generator with Quadrature Output 1.9 Op-Amp Voltage ReferenceA voltage reference, or a VREF, is a precision device designed to maintain an accurate, low noise, constant output voltage. Ideally, the output should remain constant even as parameters, such as ambient temperature, supply voltage, or the load current change.Figure 31. Positive Voltage ReferenceIn a positive voltage reference a non-inverting op-amp buffer is often included to scale the output voltage and supply any current needed. Figure 32. Negative Voltage ReferenceA common way to generate a negative voltage has been to use an operational amplifier (op amp) to invert the output of a positive precision voltage reference. This approach typically requires a positive reference, the op amp, and two supply rails to generate the negative output. 1.10 Instrumentation AmplifierInstrumentation amplifier is a kind of differential amplifier with additional input buffer stages. It is a differential op-amp circuit providing high input impedance with ease of gain adjustment. Basically, a typical Instrumentation Amplifier configuration consists of three Op-amps and several resistors.Figure 33. Differential-input Instrumentation Amplifier Figure 34. Variable Gain, Differential-input Instrumentation Amplifier Figure 35. Instrumentation Amplifier with ±100V Common Mode Range Figure 36. Instrumentation Amplifier with ±10V Common Mode Range Figure 37. High Input Impedance Instrumentation Amplifier 1.11 Precision Current Sink & SourceOp Amp can source or sink current.Sourcing current means that current is flowing out of the op-amp into the load. Sinking current means that current is flowing in to the op-amp.Figure 38. Precision Current SinkFor a current sink circuit, opamp are designed to be used in both positive and negative voltages. The op-amp connection is changed, that is the negative input is connected to a shunt resistor. Figure 39. Precision Current SourcePrecision current sources have traditionally been built using op amps, resistors, and other discrete components—with limitations due to size, accuracy. Figure 40. Bilateral Current Source 1.12 Precision Diode & ClampFigure 41. Precision DiodeIn this circuit , the op-amp circuit is required to work as an ideal diode. That is, an ideal op-amp wants to make its two inputs equal in voltage through the negative feedback path. Figure 42. Precision ClampPrecision Op-Amp Clamp Circuit is the same circuit as the classic simple precision rectifier (set to pass the negative half-sine), but with the non-inverting input of the op-amp. 1.13 Notch Filter AmplifierNotch filter is a useful circuit to suppress middle- and high-frequency resonance to improve control precision. It work on only a narrow band of frequencies. To be useful, the notch filter must be tuned to the frequency of resonance or of noise generation.Figure 43. Adjustable Q Notch Filter Figure 44. Easily Tuned Notch Filter 1.14 Capacitance MultiplierCapacitance Multiplier uses an op-amp and a small capacitor to simulate a much larger capacitor instead of a transistor.Example Explained:Figure 45. Negative Capacitance Multiplier Figure 46. Variable Capacitance Multiplier Figure 47. Analog MultiplierIn electronics, an analog multiplier is a device which takes two analog signals and produces an output which is their product. Analog multipliers take two or more analog signals and produce an output which is their product or the sum of multiple products. 2 Other Op-amp Circuit DesignFigure 48. Free-Running MultivibratorThe Op-amp Multivibrator is an astable oscillator circuit that generates a rectangular output waveform using an RC timing network connected to the inverting end. An astable multivibrator uses an op-amp. It generates square waves of its own i.e. without any external excitation. Figure 49. Op Amp Function GeneratorFunction generator system can be readily synthesized using operational amplifiers on an approach which uses full when the need for a special need. Figure 50. Pulse-width Modulator (PWM)Pulse-width Modulator is a way to control analog devices with a digital output. It uses digital signals to control power applications, as well as being fairly easy to convert back to analog with a minimum of signal. High-frequency op amps can be used for a high-frequency PWM, because op amps are used for the modulator. Bridge AmplifierThe bridge amplifier is to generate both an inverted and a noninverted output signal. When the amplifier is switched into bridge-mode operation, the signal at the output of the first stage of amplification of channel A is attenuated. In addition, bridging an amplifier refers to the process of combining two of four channels into one or two channels with half the ohms.Figure 51. Bridge Amplifier with Low Noise Compensation Figure 52. Wien Bridge Sine Wave OscillatorA Wien bridge oscillator is a simple circuit that can be set to continuous oscillation, which outputs a sine wave. It acts as a useful reference oscillator for analog circuits, and the output signal can then be manipulated with other analog circuits. It is an excellent circuit for generating a sine wave signal at audio frequencies. Figure 53. Low Power Supply for Intergrated Circuit TestingOp-amp IC Testing Circuit basically has voltage comparator inside, which has two inputs, one is inverting input and second is non-inverting input. In normal, putting a good op-amp into the circuit, and they will generate a low frequency in the square wave. Figure 54. Fast Half Wave RectifierPrecision half-wave rectifiers are commonly used with other op amp circuits such as a peak-detector or bandwidth limited non-inverting amplifier to produce a DC output voltage. For the positive half cycle of the sinusoidal input, the output of the op-amp will be negative. Figure 55. Absolute Value Amplifier with Polarity DetectorAbsolute Value Amplifier with Polarity Detector Circuit breaks an input voltage signal down into its components. It will handle direct input voltages as well as alternating voltages up to several kHz. Figure 56. Sample and Hold Circuit Using Op AmpIn electronics, a sample and hold (also known as sample and follow) circuit is an analog device that samples (captures, takes) the voltage of a continuously varying analog signal and holds (locks, freezes) its value at a constant level for a specified minimum period of time. It consists of switching devices, capacitor and an operational amplifier. Figure 57. Tuned CircuitA tuned circuit has a very high impedance at its resonant frequency (ideally = infinity). At other frequencies, its impedance is lower. Tuned circuits are used to select or tune in radio stations on a particular frequency and reject all the others. When an amplifier circuit has its load replaced by a tuned circuit, such an amplifier can be called as a tuned amplifier circuit. It is generally referred to as active filters.Another Example:Figure 58. Two-Stage Tuned Circuit Figure 59. Simulated InductorA simulated inductor is an active circuit for generating an equivalent inductive reactance, which is implemented with active and passive components. It is used in the design of filters, amplifiers, oscillators and tuned amplifiers. Figure 60. High Pass Active FilterA high-pass filter (HPF) is an electronic filter that passes signals with a frequency higher than a certain cutoff frequency and attenuates signals with low frequencies. Active High Pass Filter uses inverting operational amplifier with high voltage gain. Figure 61. Low Pass Active FilterA simple active low pass filter is formed by using an op-amp. The operational amplifier will take the high impedance signal as input and gives a low impedance signal as output. The circuit uses an op-amp for amplification and gain control. Figure 62. Nonlinear OP AMP with Temperature Compensated BreakpointsAs long as the gain of the operational amplifier is large enough, the amplification of the circuit is determined by the external feedback resistance network. Figure 63. Current MonitorA current monitor amplifier is a special purpose integrated circuit differential amplifier that is designed to sense the voltage developed across a current shunt and output a voltage proportional to the measured current. Figure 64. Power Booster AmplifierA power booster amplifier is typically a hybrid circuit with thick film resistors, ceramic capacitors. A novel power booster amplifier is based on a modified half-bridge topology using separated switches and a floating bridge capacitor. Figure 65. Long Interval TimerWith the help of high gain high impedance operational amplifier, we can build a long time delay with resistor-capacitor (RC) circuit. Figure 66. Amplifier for Piezoelectric TransducerThe charge sensitive amplifiers employed for piezo electric sensors cover quite wide range. Piezoelectric transducers used as sensors, typically, the high impedance of the sensor requires an amplifier. Figure 67. Temperature ProbeAn inverting op amp operates with a noise gain of two, which produces twice as much output offset voltage as does a unity-gain buffer. This is a fantastic solution to temperature monitoring. Figure 68. Photodiode AmplifierPhotodiode amplifier circuit pedance amplifier for amplifying the light- dependent current of a photodiode. The high gain of the op-amp keeps the photodiode current equal to the feedback current. Some are ideally suited for ultra low noise amplification of very small photodiode currents. Figure 69. High Input Impedance AC FollowerOperational amplifiers have a very high input impedance, which means that they don't suck in much current (ideally, none) at the inputs, typically above 1MΩ as it is equal to that of the operational amplifiers input resistance. Low output impedance and extremely high input impedance make it a simple and effective solution to problematic impedance. Figure 70. Root ExtractorThe proposed extractor is based on the use of two operational amplifiers (op amps) as only active elements. Figure 71. Basic Log AmplifierA logarithmic amplifier, or a log amplifier, is an electronic circuit that produces an output that is proportional to the logarithm of the applied input. The simple logarithmic amplifier uses a junction diode as a nonlinear element. In addition, the basic log amplifier can also be constructed by replacing diode by a transistor. The output is proportional to the logarithm of the input given by. Figure 72. Circuit for Operating the LM101 without a Negative Supply Figure 73. Circuit for Generating the Second Positive Voltage Figure 74. Multiple Aperture Window Discriminator Figure 75. Neutralizing Input Capacitance to Optimize Response Time Figure 76. Saturating Serve Preamplifier with Rate FeedbackFrequently Asked Questions about Op Amp Circuits1. What is an op amp circuit?An operational amplifier is an integrated circuit that can amplify weak electric signals. An operational amplifier has two input pins and one output pin. Its basic role is to amplify and output the voltage difference between the two input pins. 2. Why use an op amp in a circuit?To convert the current into voltage, a simple circuit with an operational amplifier, a feedback loop through a resistor on the non-inverting, and the diode connected between the two input pins allows you to get an output voltage proportional to current generated by the photodiode, which is evident by the light. 3. How do op amp circuits work?An operational amplifier, or op amp, generally comprises a differential-input stage with high input impedance, an intermediate-gain stage, and a push-pull output stage with a low output impedance. ... That is, the output gets fed back to the inverting input through some impedance. 4. What are the advantages of op amps circuit?An op-amp circuit buffers the sensor and allows gain or attenuation circuits to be developed. The output of the sensor is non-linear. An inverting op amp circuit gives you a more linear output than a non-inverting op-amp circuit does. 5. What are the ideal characteristics of op amp?The so-called ideal op amp is to idealize various technical indicators of op amps, and it must have the following characteristics.1) Infinite Input Resistance2) Zero Output Impedance3) Infinite Open-loop Gain4) Infinite Common-mode Rejection Ratio5) Infinite Bandwidth

IntroductionA voltage divider is a passive linear circuit used to create a voltage less than or equal to the input voltage. It is a conversion device composed of a high-voltage arm and a low-voltage arm. The measured high voltage acts on the device, and the output voltage is got from the low voltage arm. The components of the high and low voltage arms are usually resistors and capacitors. The corresponding devices are called resistor dividers, capacitor dividers, and resistance-capacitance voltage divider. Voltage dividers are one of the most fundamental circuits in electronics.What is Voltage Divider? (voltage divider rule)CatalogIntroductionⅠ Overview of Voltage Divider1.1 Voltage Divider Structure1.2 Voltage Divider CircuitⅡ Types of Voltage DividerⅢ Voltage Divider Characteristics3.1 Voltage Divider Basic3.2 Two Major Points in the Voltage Divider Circuit3.3 Common Voltage Divider Features3.4 Voltage Divider FormulaⅣ Voltage Divider RulesⅤ Voltage Divider PotentiometerⅥ Main Differences between Voltage Divider and TransformerⅠ Overview of Voltage Divider1.1 Voltage Divider StructureThe voltage divider is a special instrument for on-site measurement, measuring DC high voltage and AC high voltage. The voltage divider adopts a balanced equipotential shielding structure, and high-quality electronic components are used inside the body. So that it has the characteristics of accurate test, good linearity, stable performance, reasonable structure, easy to carry, simple operation, intuitive display, etc.Figure 1. Voltage Divider Circuit1.2 Voltage Divider CircuitVoltage usually contains two important terms: electromotive force (EMF) and potential difference (PD). When something provides a voltage, such as a battery, it provides the force required to pull electrons along the circuit because of emf. When a component consumes the voltage in the circuit, the amount of voltage drop on it called potential difference. Some rules about voltage can help circuit design, including:1) Series voltages accumulate.2) The parallel voltage is always the same.3) The PD in the component is proportional to its resistance.4) Polarity is decisive.5) Sum EMF around the circuit is equal to the sum of PD.The rule that voltages in series always accumulate affects both EMF and PD. If the batteries are connected in series, their voltages will add up. If there are series-connected components, then you can apply this rule, whose combined PD is the output voltage. Although it is easy to identify potential differences, make sure to pay close attention to the polarity of the power source. Because the battery reverses minus the combined voltage.Figure 2. An Example of a Series of Voltages Added Up Parallel voltages are always the same. It is one of the reasons why it is not a good idea to connect batteries in parallel with different voltages. For example, when two batteries with different voltages are connected in parallel, the battery with the larger voltage will try to charge the smaller battery, which may damage it.Figure 3. An Example of Parallel Voltage Circuit We have known that the series voltages add up and the voltages in parallel are the same. There are also some questions. How does the voltage separate between the elements in the series circuit? What determines the voltage of each component? The voltage division (called potential difference) is determined by the ratio of the resistance of the element to the resistance of the series circuit. This is directly related to the voltage rule:The value of the PD on the component is proportional to its resistance.Basically, this means that the greater the resistance of the component (compared to the series circuit), the greater its potential difference. In fact, the voltage on the component is equal to When considering the classic divider circuit, the formula is usually written as The following is a typical voltage divider circuit with approximately 3.3V from a 5V power supply:(This circuit can be used to connect a 5V output device to the 3.3V input on the microcontroller, such as particle photon.)Figure 4. An Example of a Classic Voltage Divider Circuit When a voltage (EMF) is applied to the circuit, the sum of all potential differences on the series elements will equal the EMF. For example, the voltage provided by the battery will be divided among the components connected in series, and the sum of all these divided voltages will be equal to the voltage of the battery.Figure 5. Series Voltage Circuit Ⅱ Types of Voltage Divider1. According to the applicationa) For laboratoryb) For power system2. According to the measured voltagea) AC voltage dividerThere are two types: resistive type and capacitive type. The resistive type is composed of non-inductive resistance elements suitable for measuring AC voltages with low frequency. The capacitive type is composed of capacitive elements. It basically does not consume power and can be used for higher voltage measurement. The measurement voltage ranges from thousands of volts to millions of volts. So it has a wide rang applications.b) Impulse voltage dividerImpulse voltage is a non-periodic pulse voltage with fast changes and many harmonic components. To accurately measure its waveform and amplitude, the impulse divider is required to have good response characteristics. There are three types: resistive, capacitive, and resistance-capacitance.c) DC voltage dividerIt is composed of two (groups) resistance elements, and a high-impedance voltmeter is usually used to measure the voltage on the low-voltage arm.Figure 6. High-voltage Divider3. According to the principle of voltage dividera) Capacitor dividerThe capacitor divider used to measure the pulse voltage can be divided into two types. One’s high-voltage arm of a voltage divider is composed of multiple high-voltage capacitors stacked, and the high-voltage arm of the other voltage divider has only one capacitor.The former voltage divider is mostly assembled with an oil-paper-insulated pulse capacitor with an insulating shell, which requires that the inductance of this capacitor is relatively small and can withstand short circuit discharge. A high-voltage oil-paper capacitor is assembled by multiple components in series and parallel. Each component not only has capacitance, but also has inherent inductance and contact resistance in series, as well as parallel insulation resistance. Of course, each component has stray capacitance to ground. This kind of voltage divider should be regarded as a distributed parameter, so it is called a distributed capacitor divider.The distributed capacitor divider is formed by stacking multiple pulse capacitors, with only amplitude error and no waveform error. As for the amplitude error, it can be completely eliminated after calibration with a standard voltage divider. However, when measuring steep waves, since the capacitance of the capacitor divider is much larger than the stray capacitance of the shielding ring of voltage divider, the response time is also much longer. So in terms of measuring steep waves, the response characteristics of the capacitor voltage divider are not as good as the shielded resistor divider. The single-capacitor divider does not consume energy and has no trouble of heating. For measuring waves with a longer wavefront and half-peak time, a capacitor divider is better than a resistor divider. In addition, the capacitor divider can also be used as a load capacitor for adjusting the waveform.The high-voltage arm of the centralized capacitor divider can use a standard capacitor charged with compressed gas. The capacitance value of this capacitor is very accurate and stable, and the dielectric loss is small. Because it is shielded, the capacitance value is not affected by surrounding objects. In power frequency measurement, it has been used very commonly. However, when it is used as an impact capacitor voltage divider, some problems will occur. That is, superimposed high-frequency oscillation.b) Resistor dividerIts internal resistance is pure resistance, with characteristics of simple structure, easy to use, good stability, etc. The error generated by it when measuring the transient pulse voltage is related to the product of the resistance value and the stray capacitance to the ground, so the size and impact of the stray capacitance to the ground should be minimized, and the resistor divider should reduce inductance.c) Resistance-capacitance dividerThe resistance-capacitance voltage divider can be divided into a series-type voltage divider and a parallel-type voltage divider according to the connection mode.The resistor-capacitor series voltage divider is also called the damping capacitor voltage divider. Recently, the high-voltage divider belongs to this type. It overcomes the residual inductance of the capacitor circuit and prevents the voltage divider from oscillating, and has excellent performance. According to the difference of the added damping, the RC series voltage divider can be divided into two types: high damping divider and low damping divider. The high damping capacitor voltage divider cannot be used as the load (wave modulation) capacitor of the impulse voltage generator. It is only used as a conversion device for measuring voltage. The series damping resistance of the low damping capacitor voltage divider is very small, and its connection will not make it difficult to generate standard waves in the test circuit. It can also be used as a load capacitor and is a general voltage divider. From the point of view of ease of use, it has more advantages than the high damping capacitor voltage divider. From the response characteristics, it is not as good as the high damping capacitor voltage divider because it also contains oscillation.Theoretically speaking, when the voltage changes rapidly, the voltage divider ratio is mainly determined by the capacitance; when the change is slow, it is determined by the resistance. The device resistance wire is tightly wound on the porcelain tube positively and negatively, and connected in parallel with each capacitor. Practice has proved that the selected resistance value cannot be too small, otherwise it will affect the output load of the generator, so it is generally selected to be relatively large. However, the effect is small. It is similar to a pure capacitive voltage divider without resistance.Figure 7. Voltage Divider CurrentⅢ Voltage Divider Characteristics3.1 Voltage Divider Basic1) The voltage divider adopts high-precision resistor and capacitor assembly, special process potting, and dry seal, so there is no oil leakage problem. 2) High input impedance: the test current is reduced, the power consumption is small, the product is small and light, the performance is stable, and the measurement accuracy is high. 3) The voltage divider, multi-value kilovolt meter and special cables are all placed in an aluminum alloy box, which is safe and reliable, easy to carry and transport. 4) The multi-value kilovolt meter can directly read the DC average value, AC peak value, effective value, peak value and other voltage values.5)The organic composite insulating jacket is used above 150KV, which increases the surface creeping distance, and greatly reduces the height of the product. So the device is more convenient to use and carry.3.2 Two Major Points in the Voltage Divider Circuit1) Input terminalIt is necessary to analyze where the input signal voltage is input to the voltage divider circuit, and what is the specific input current loop. The method of determining the current loop in circuit analysis is as follows: Start from the input end of the signal voltage, follow at least two components (not necessarily resistors) to the ground.2) Output terminalThe signal voltage output by the voltage divider circuit must be sent to the next level circuit. Theoretically, the input of the next level circuit is the output terminal. However, sometimes it is difficult to analyze the input end of the next-level circuit. So you can use a simpler method to analyze: find all the components in the voltage divider circuit, analyze from the ground line to the upper end, and then find a certain component connects with other circuits. This connection point is the output terminal of the voltage divider circuit, and is also the output voltage of the voltage divider circuit.In the process of analyzing the voltage divider circuit, it is often necessary to figure out the size of the output voltage.The calculation method of the output voltage: Uo=R2/R1+R2·Uiwhere Ui is the input voltage, Uo is the output voltage.The output voltage is less than the input voltage, because the voltage divider circuit attenuates the input signal voltage. That is, changing the size of Rl or R2 resistance can change the output voltage Uo.3.3 Common Voltage Divider FeaturesResistor Divider(1) When it is wound by constantan wire with a small temperature coefficient or kama wire with a small temperature coefficient and high resistance, its temperature stability is high, and the long-term stability is also high during operation. (2) Using a compressive resistor divider structure, its response characteristics may be relatively high.Capacitor Divider(1) The distributed capacitor divider is formed by stacking multiple pulse capacitors, with only amplitude error and no waveform error.(2) The high-voltage arm of the centralized capacitor divider can use a standard capacitor filled with compressed gas. The capacitance value of this capacitor is very accurate and stable, and the dielectric loss is small. Because it is shielded, the capacitance value is not affected by surroundings.Resistance-capacitance DividerThe high damping capacitor voltage divider cannot be used as the load (wave modulation) capacitor of the impulse voltage generator. It is only used as a conversion device for measuring voltage. The series damping resistance of the low damping capacitor voltage divider is very small, and its access will not make it difficult to generate standard waves in the test circuit. It can also be used as a load capacitor, which is a general voltage divider.3.4 Voltage Divider FormulaHow do you calculate voltage divider? In a series circuit, the voltage distribution is proportional to the size of the resistance, that is, the larger the resistance is, the greater the voltage is distributed; on the contrary, the smaller the resistance is, the smaller the voltage is distributed. Voltage divider produces an output voltage (Vout) that is a fraction of its input voltage (Vin).In a series circuit, the voltage across the conductors is proportional to their resistance.By I1=I2, U1/R1=U2/R2 is Using Apogee’s Voltage Divider Calculator helps determine the output voltage of the divider circuit given the input (or source) voltage and the resistor values. Simply enter a few values, and this tool will show the illustrated results for you immediately. Ⅳ Voltage Divider RulesWhen use and test voltage divider, you should take care of the following rules:1) There should be no debris on the test site, so as not to affect the measurement accuracy.2) The ground wire must be connected firmly to ensure a safe operating distance.3) After the test, it must be fully discharged.4) It is strictly prohibited to use over-rated voltage.5) Ensure that the surface of the equipment is clean and stored in a cool, dry place. Ⅴ Voltage Divider PotentiometerThe potentiometer is a varistor that can be used to create an adjustable voltage divider. Its  absolute resistance value will not affect the output voltage, and the output voltage is proportional to the input voltage. Commonly used potentiometers have poor resistance accuracy and temperature coefficient. However, as long as the resistance of the potentiometer is uniform, the voltage will be divided evenly. Assuming that the slider is connected to a high-impedance circuit, the contact resistance of the slider will not affect the output voltage. The sliding sheet contact resistance is a value at the contact point of the sliding sheet.When the potentiometer acts as a variable resistor, its resistance accuracy and temperature coefficient will affect the circuit. The contact resistance of the slide will affect the resistance of the circuit, and the contact resistance of the slide will change with changes in position, temperature, vibration and time. Ⅵ Main Differences between Voltage Divider and Transformer1) The transformer changes the ac voltage of by causing the induced electromotive force through the change of the magnetic flux. The capacitor divider changes the alternating voltage through the capacitive reactance during the charging and discharging process.2) The transformer can step up or step down; the capacitor divider cannot step up.3) The input power of the ideal transformer changes with the change of the output power; while the input power of the voltage divider does not change when there is no load.4) When an ideal transformer works, the magnetic flux passing through the iron core is constant. The voltage across the coil follows Faraday's law of electromagnetic induction, in addition, when the voltage divider works, its loop current is a constant value. Frequently Asked Questions about Voltage Divider Rule and Formula1. What is voltage divider rule formula?Using the voltage divider ratio rule, we can see that the largest resistor produces the largest I*R voltage drop. Thus, R1 = 4V and R2 = 8V. Applying Kirchhoff's Voltage Law shows that the sum of the voltage drops around the resistive circuit is exactly equal to the supply voltage, as 4V + 8V = 12V. 2. What is the purpose of a voltage divider?A voltage divider can be used to scale down a very high voltage so that it can be measured by a volt meter. The high voltage is applied across the divider, and the divider output—which outputs a lower voltage that is within the meter's input range—is measured by the meter. 3. What is the voltage divider equation?Voltage Divider Formula / EquationR2 / R1 + R2 = Ratio determines scale factor of scaled down voltage. For example, Vin = 100, R1= 20, R2= 10. 4. What is a voltage divider rule?In electronics, the voltage divider rule is a simple and most important electronic circuit, which is used to change a large voltage into a small voltage. ... When the i/p voltage is applied across the pair of the resistor and the o/p voltage will appear from the connection between them. 5. How does a voltage divider work?A voltage divider can be used to scale down a very high voltage so that it can be measured by a volt meter. The high voltage is applied across the divider, and the divider output—which outputs a lower voltage that is within the meter's input range—is measured by the meter.

IntroductionIn electronics, a comparator is an electronic circuit that compares two voltages (or currents) and outputs a digital signal indicating which is larger. Comparing two or more data to determine the number size and arrangement order between them. In addition, it is a circuit that compares an analog voltage signal with a reference voltage. The two inputs of the comparator are analog signals, and the output is a binary signal 0 or 1, and the output is ideally. When the difference of the input voltage changes and the positive and negative sign remains constant, the output remains unchanged. Comparators play an essential role in designing electrical and electronic projects.What is A Comparator?CatalogIntroductionⅠ Working PrincipleⅡ Main Parameters2.1 Hysteresis Voltage2.2 Bias Current2.3 Super Power Swing2.4 Drain-source Voltage2.5 Output Delay TimeⅢ Comparator Classification3.1 Voltage Comparator3.2 Window Comparator3.3 Hysteresis ComparatorⅣ Comparator ICsⅤ How Do You Select a Comparator?Ⅵ Comparator Applications6.1 Zero-crossing Comparator 6.2 Relaxation Oscillator (ROSC)6.3 A/D Converter6.4 Voltage ComparatorⅦ Op Amp ComparatorⅠ Working PrincipleGenerally, in electronics, the comparator is used to compare two voltages or currents which are given at the two inputs of the comparator. A comparator circuit compares two voltages and outputs either a 1 (the voltage at the plus side; VDD in the illustration) or a 0 (the voltage at the negative side) to indicate which is larger. The operational amplifier can be used as a comparator theoretically without negative feedback. However, the open-loop gain of the operational amplifier is very high, so it can only process signals with a very small input differential voltage. Moreover, in general, the delay time of the op amp is long, which cannot meet the actual requirements. The comparator can be adjusted to provide a very small time delay, but its frequency response characteristics will be limited. To avoid output oscillation, many comparators also have internal hysteresis circuits. The threshold of the comparator is fixed, some have only one threshold, and some have two thresholds.Comparator SymbolⅡ Main Parameters2.1 Hysteresis VoltageThe voltage between the two input terminals of the comparator will change the output state when it crosses zero. Because the input terminal is often superimposed with a small voltage fluctuation, the differential mode voltage generated by it will cause the comparator output to change frequently.  In order to avoid output oscillation, the new comparator usually has a hysteresis voltage of several mV. The existence of it requires two switching points of the comparator: one is used to detect the rising voltage, the other is used to detect the falling voltage. The difference of the voltage threshold (VTRIP) is equal to the voltage hysteresis (VHYST). The offset voltage of hysteresis comparator is the average of TRIP and VTRIP-. The input voltage switching point of the comparator without hysteresis is the input offset voltage, not the zero of the ideal comparator. In addition, the offset voltage generally varies with temperature and power supply voltage. And the power supply rejection ratio is usually employed to express the influence of power supply voltage changes on the offset voltage.2.2 Bias CurrentThe input impedance of an ideal comparator is infinite. Therefore, there is no effect on the input signal theoretically. However, the actual input impedance of the comparator cannot be infinite. There is a current at the input end that flows through the internal resistance of the signal source and flows into the comparator, thereby generating an additional voltage difference. The bias current (Ibias) is defined as the median of the input currents of the two comparators and is used to measure the effect of input impedance.2.3 Super Power SwingTo further optimize the operating voltage range of the comparator, Maxim uses the parallel structure of the NPN tube and the PNP tube as the input stage of the comparator. Thus the input voltage of the comparator can be expanded. In this case, the lower limit can be lower to the lowest level, and the upper limit is 250mV higher than the power supply voltage to reach the Beyond-the-Rail standard. The input of this comparator allows a larger common-mode voltage.2.4 Drain-source VoltageThe comparator has only two different output states (zero level or power supply voltage). Its output stage of the comparator with full power swing characteristics is an emitter follower, which makes its voltage difference smaller between input and output signals. The voltage difference depends on the emitter junction voltage under the saturation state of the internal transistor of the comparator, which is equal to the drain-source voltage of the MOSFFET.2.5 Output Delay TimeIt includes the transmission delay of the signal through the components and the rise time and fall time of the signal. For high-speed comparators, such as MAX961, the typical value of the delay time can reach 4.5ns and the rise time is 2.3ns. Pay attention to the influence of different factors on the delay time when designing, including the influence of temperature, capacitive load, input overdrive and so on.Although the comparator has different types. The design and construction of each should take care of ordinary uses without affecting its measuring accuracy. The instrument should be very sensitive and withstand a reasonable ill usage without permanent harm.Ⅲ Comparator ClassificationComparators are classified into various kinds, such as electronic, electrical, mechanical, optical, sigma, digital and pneumatic comparators. These are used in various applications. Here we are talking about electronic comparator.3.1 Voltage ComparatorA voltage comparator is a circuit that discriminates and compares input signals, and is a basic unit that forms a non-sine wave generating circuit. Voltage comparators are commonly used including single-limit comparators, hysteresis comparators, window comparators, and three-state voltage comparators. Voltage comparator can be used as an interface between analog circuits and digital circuits, as well as waveform generation and conversion circuits.3.2 Window ComparatorCombine two comparators to form a "window comparator", which is widely used. The window comparator can set the upper limit voltage and lower limit voltage of the input at the same time, within limited voltage range, or outside the range, which we need. When the potential level of the high-level signal is higher than a certain specified value VH, it is equivalent to the positive saturation output of the comparator circuit. When the potential level of the low-level signal is lower than a certain specified value VL, it is equivalent to the negative saturation output of the comparator circuit. The comparator has two thresholds, and the transmission characteristic curve is window-shaped, so it is called a window comparator.3.3 Hysteresis ComparatorIt is a comparator with hysteresis loop transmission characteristics, and can be understood as a single-limit comparator with positive feedback. When the input voltage vI gradually increases from zero and VI is less than VT, the comparator output is a positive saturation voltage, and VT is called the upper threshold (trigger) level. When the input voltage VI>VT, the comparator output is a negative saturation voltage, and VT is called the lower threshold (trigger) level.Ⅳ Comparator ICsCommon chips are LM324, LM358, uA741, TL081\2\3\4, OP07, OP27, which can all be made into voltage comparators (without negative feedback). LM339 and LM393 are professional voltage comparators with fast switching speed and small delay time, which can be used in special voltage comparison occasions. Ⅴ How Do You Select a Comparator?The working principle of a comparator is simple and straightforward. It has a positive pin and a negative pin. When the voltage on the positive pin is high, the output drives a signal. When using open-collector output, the output pin of the comparator is the collector of a transistor or the drain of a FET. When using push-pull output, the comparator has a complementary NPN/PNP stage, like in an operational amplifier. The open-collector output is used when the load and the comparator use different power supplies. This kind of scheme can realize the solenoid of 12V, although the comparator may only work at 3.3V. Another function of the open-collector output is to minimize the quiescent current when the output is turned off. Among them, no base current flows in the N-type output transistor, and some base current always flows through one of the two output transistors.However, open-collector output also has some disadvantages. For example, they require external pull-up resistors. These resistors must complete the pull-up task during the high-impedance period, so that when the output is lower than turn-off, the comparator can switch faster, and the pull-up resistor makes the output high. Therefore, when you need a symmetrical waveform, it is not suitable to use an open collector output, such as a clock recovery circuit. If your circuit does not require level conversion, you should choose push-pull output, such as ALD2321APC, it can provide 24mA output drive capacity, quiescent current is 90μA.The high-speed comparator may also have a latched output, so that the output can be kept in a known state to meet the set-up and hold time requirements of the digital input behind it. Once the digital part has read the output of the comparator, the latch pin can be released and the output can track the input.High-speed comparators may also use ECL (emitter coupled logic) levels from -5V to 0V. PECL (positive emitter coupled logic) outputs have the same voltage swing, from 0V to 5V. There is also RSPECL (reduced amplitude PECL) output. The two output pins of some high-speed comparators use LVDS (low-voltage differential signaling) output, which converts 300mV around a 1.2V common-mode voltage in a complementary manner. You can send these outputs directly to the LVDS input pins of FPGA (field programmable gate array) and other digital circuits.In production, CMOS technology is generally used to build low-power devices, while bipolar devices are used to build high-speed devices. This represents a basic compromise: high-power high-speed, accurate devices, and low-power, low-speed devices. Another compromise is gain and high speed. The low-power comparator may take 70µs conversion time and consume less power. The response time of the high-speed comparator is 150ps. Some devices can overcome the trade-off between speed and power consumption. When converting at the highest rate, the power consumed by the comparator is much higher than its static power consumption. In the static state, the current is low. When the comparator is operated at a higher speed, it must be able to charge the capacitor. In dynamic mode, the current increases as the working speed increases. Another factor in power consumption is the load on the chip. For a switching current, the capacitance will also become a load, and the capacitive and resistive components in the load must be considered. Many devices are related to broken pins, which can reduce the power consumption to less than 1µA.As with all simulation, the declared propagation delay is meaningful only under strictly defined conditions, because the degree to which the input pin is driven directly affects the propagation delay. The greater the overdrive, the faster the device. Dispersion is the range of propagation delay values of a device under various overdrive levels. The relationship between overdrive and speed is one reason why some engineers are reluctant to consider comparator speed as a function of slew rate. It necessary to define the output level that is quantized as a valid transition, usually the maximum output level is 10% to 90%. The slew rate also represents a requirement for overdrive, that is, to keep the propagation delay as short as possible.Another parameter to consider when choosing a comparator is noise. However, manufacturers often omit noise specifications of the comparators and instead use random jitter to measure noise. In addition to the noise signal passing through the device gain, the input aperture error and the output rise and fall time can also affect jitter. A clock-driven device is nothing but a lower gain comparator optimized for noise. Designers can use larger input transistors in a CMOS device to reduce flicker noise, but this method increases the input capacitance.The next consideration should be the rated voltage of the comparator. One factor related to the power supply interval is the allowable common-mode voltage at the input pins of the comparator. Some devices allow you to pull the output to a voltage range higher or lower than the power supply. For other devices, when you pull the input pin below the negative power rail, the output will be inverted. Comparator with rail-to-rail input stage expands the range of input common-mode mode. These devices have a dual-input stage, using N-type transistors or FETs in parallel with the P-type input stage. The input voltage of the P-type input stage operates at near the ground or the negative voltage rail, and the N-type input stage works when the input swings to the positive voltage rail. IC designers generally make the device switch between level 1 or 2V below the positive voltage rail. When sweeping over the rail-to-rail devices, some structures can minimize the offset voltage.Another important specification of the comparator is the input offset current, that is, the amount of current flowing into or out of the input pin when the device is working. CMOS products have a low offset current, which represents a mismatch in the leakage of the input pin ESD (electrostatic discharge) structure. For every 10°C increase in temperature, the input offset current doubles. The offset current of high-speed comparators can be obvious, but it is not a problem because low-impedance circuits are generally used to drive these high-speed comparators. The input offset current of a bipolar device depends on the relationship between the two inputs. In a comparator, a 60mV difference in the base voltage of a differential input pair will get a 10 times higher difference between the pair's collector current and the input offset current. Therefore, one pin can pull or sink twice the rated input offset current, while the other pins have almost no input offset current, depending on which pin has a higher voltage.Ⅵ Comparator Applications6.1 Zero-crossing Comparator The zero-crossing comparator is used to detect whether an input value is zero. The principle is using a comparator to compare two input voltages. One of the two input voltages is the reference voltage Vr and the other is the voltage to be measured Vu. Generally, Vr is connected from the non-inverting input terminal, and Vu is connected from the inverting input terminal. According to the result of comparing the input voltage, the forward or reverse saturation voltage is output. When the reference voltage is known, the measured result of the voltage can be obtained. When the reference voltage is zero, it is a zero-crossing comparator.The zero-crossing comparator has a small measurement error. When the product of the voltage difference between the two input terminals and the open-loop magnification is less than the output threshold, the detector will give a zero value. For example, when the open-loop magnification is 106 and the output threshold is 6v, if the voltage difference between the two input stages is less than 6 microvolts, the detector outputs zero. This can also be considered the uncertainty of measurement.6.2 Relaxation Oscillator (ROSC)Comparators can construct relaxation oscillators by using positive feedback and negative feedback. Positive feedback is a Schmitt trigger, which forms a multivibrator. The RC circuit adds negative feedback to it, which causes the circuit to start to oscillate spontaneously, making the entire circuit from a latch to a relaxation oscillator.Level shifting uses open-drain comparators (such as LM393, TLV3011, and MAX9028) to construct a level shifter to change the signal voltage. Choosing an appropriate pull-up voltage can flexibly get the converted voltage value. For example, use the MAX972 comparator to convert ±5V signals into 3V signals.6.3 A/D ConverterThe function of the comparator is to compare whether an input signal is higher than a given value. So it can convert the input analog signal into a binary digital signal. Almost all digital-to-analog converters (including delta-sigma modulation) contain comparators circuit to quantize the input analog signal.6.4 Voltage ComparatorThe voltage comparator can be regarded as an operational amplifier with an infinite amplification factor. The function of the voltage comparator: compare the magnitude of two voltages (using the high or low level of the output voltage to indicate the magnitude relationship between the two input voltages): When the voltage at the "+" input terminal is higher than the "-" input terminal, the voltage comparator output is high level; when the "+" input terminal voltage is lower than the "-" input terminal, the voltage comparator output is low level.It can be used as an interface between analog circuits and digital circuits, and can also be used as a waveform generation and conversion circuit. A simple voltage comparator can change the sine wave into a square wave or rectangular wave with the same frequency. The simple voltage comparator has a simple structure and high sensitivity, but its anti-interference ability is poor, so people have to improve it. The improved voltage comparators include: hysteresis comparator and window comparator. Operational amplifiers are used to determine "operational parameters" through feedback loops and input loops, such as magnification. The feedback amount can be part or all of the output current or voltage. The comparator does not need feedback and directly compares the quantity of the two input terminals. If the non-inverting input is greater than the inverted phase, the output is high, otherwise it outputs low. The input of the voltage comparator is a linear quantity, and the output is a switch (high and low level). In typical applications, a linear op amp can sometimes be used to form a voltage comparator without negative feedback. Ⅶ Op Amp ComparatorIn principle, operational amplifier can be used as comparator without negative feedback. However, because of its high open-loop gain, it can only process signals with very small input differential voltage. Moreover, in this case, the response time of the operational amplifier is much slower than that of the comparator, and it also lacks some special functions, such as hysteresis, internal reference and so on. Comparator usually can not be used as an operational amplifier. Comparator can provide minimal time delay after adjustment, but its frequency response characteristics are limited to some extent. Operational amplifier makes use of the advantage of frequency response correction to become a flexible and versatile device. In addition, many comparators also have internal hysteresis circuit, which can avoid output oscillation, but it can not be used as an op amp. Frequently Asked Questions about Comparator Electronics1. What is a comparator and its application?A comparator is an electronic component that compares two input voltages. Comparators are closely related to operational amplifiers, but a comparator is designed to operate with positive feedback and with its output saturated at one power rail or the other. 2. How does a comparator circuit work?The comparator circuit work by simply taking two analog input signals, comparing them and then produce the logical output high “1” or low “0“. ... When the analog input on non-inverting is less than the analog input on inverting input, then the comparator output will swing to the logical low. 3. What is the purpose of a comparator in op amp?Op-amp window comparators are a type of voltage comparator circuit which uses two op-amp comparators to produce a two-state output that indicates whether or not the input voltage is within a particular range or window of values by using two reference voltages. An upper reference voltage and a lower reference voltage. 4. How do you use comparator electronics?A comparator circuit compares two voltages and outputs either a 1 (the voltage at the plus side; VDD in the illustration) or a 0 (the voltage at the negative side) to indicate which is larger. Comparators are often used, for example, to check whether an input has reached some predetermined value. 5. What is comparator and its types?Comparators are classified into various kinds, such as electronic, electrical, mechanical, optical, sigma, digital and pneumatic comparators, these are used in various applications. Comparators play an essential role in designing electrical and electronic projects.

CatalogⅠ What is a Thermal Fuse?Ⅱ What is the structure of Fuse?Ⅲ How can Thermal Fuses be classified?Ⅳ What are the characteristics of the Thermal Fuse?Ⅴ What are the types of Thermal Fuse?Ⅵ How does a Thermal Fuse work?Ⅶ Precautions for Thermal FuseⅧ Some Frequently Asked Questions about Thermal Fuse Ⅰ What is a Thermal Fuse?A thermal fuse is a new type of electrical overheating protection element. This kind of element is usually installed in heat-prone electrical appliances. Once the electrical appliance fails and generates heat, when the temperature exceeds the abnormal temperature, the thermal fuse will automatically fuse to cut off the power supply to prevent the electrical appliance from causing a fire. The thermal fuse is the same as the fuse we are familiar with. It usually only serves as a powerful path in the circuit. If it does not exceed its rated value during use, it will not fuse and will not have any effect on the circuit. It will fuse and cut off the power circuit only when the electrical appliance fails to produce abnormal temperatures. This is different from a fused fuse, which is blown by the heat generated when the current exceeds the rated current in the circuit.Ⅱ What is the structure of Fuse?Generally, a fuse is composed of three parts: one is the melted part, which is the core of the fuse, which cuts off the current when it is blown. The melt of the same type and specification of the fuse must have the same material, the same geometric size, and the resistance value. It should be as small as possible and consistent. The most important thing is to have the same fusing characteristics. Household fuses are usually made of lead-antimony alloys.  The second is the electrode part, usually two. It is an important part of the connection between the melt and the circuit. It must have good electrical conductivity, should not produce obvious installation contact resistance; third is the bracket part, the melt of the fuse is generally slender and soft, the function of the bracket is to fix the melt and make the three parts a rigid whole for easy installation and use, It must have good mechanical strength, insulation, heat resistance, and flame resistance, and should not be broken, deformed, burned, or short-circuited during use.Ⅲ How can Thermal Fuses be classified?The thermal fuse can be divided into:According to the material: it can be divided into the metal shell, plastic shell, oxide film shellAccording to temperature: it can be divided into 73 degrees 99 degrees 77 degrees 94 degrees 113 degrees 121 degrees 133 degrees 142 degrees 157 degrees 172 degrees 192 degrees... • Commonly used fuse specifications Ⅳ What are the characteristics of the Thermal Fuse?Thermal fuse has the characteristics of accurate melting temperature, high withstand voltage, small size and low cost. The thermal fuse shell is marked with the rated temperature value and the rated current value, it is not difficult to identify, and it is very convenient to use. It can be widely used in electrical equipment, electric heating equipment and practical electrical appliances for overheating protection. Thermal fuse mainly has the following parameters: ①Rated temperature: Sometimes called the operating temperature or fusing temperature, it refers to the temperature at which the temperature rises to the fusing temperature at a rate of 1°C per minute under no-load conditions. ②Fusing accuracy: refers to the difference between the actual fusing temperature of the thermal fuse and the rated temperature. ③Rated current and rated voltage: Generally, the nominal current and voltage of thermal fuse have a certain margin, usually 5A and 250V. Thermal fuse is a one-time-use protection element. Its use affects not only depends on the performance of the element itself but more importantly, on how to select and install the thermal fuse correctly. The thermal fuse is generally connected in series in the circuit when it is used. Therefore, when choosing a thermal fuse, its rated current must be greater than the current used in the circuit. Never allow the current through the thermal fuse to exceed the specified rated current. Before selecting the rated temperature of the thermal fuse, you must understand and measure the temperature difference between the temperature to be protected and the location where the planting fuse is installed.  In addition, the length of the fusing time and the availability of ventilation are also closely related to the selection of the rated temperature of the thermal fuse. Ⅴ What are the types of Thermal Fuse?There are many ways to form a thermal fuse. The following are three common ones:• The first type: Organic Thermal FuseIt is composed of a movable contact (sliding contact), a spring (spring), and a fusible body (electrically nonconductive thermal pellet). Before the thermal fuse is activated, the current flows from the left lead to the sliding contact and flows through the metal shell to the right lead. When the external temperature reaches a predetermined temperature, the organic melt melts and the compression spring becomes loose. That is, the spring expands, and the sliding contact is separated from the left lead. The circuit is opened, and the current between the sliding contact and the left lead is cut off.  • The second type: Porcelain Tube Type Thermal FuseIt is composed of an axisymmetric lead, a fusible alloy that can be melted at a specified temperature, a special compound to prevent its melting and oxidation, and a ceramic insulator. When the ambient temperature rises, the specific resin mixture begins to liquefy. When it reaches the melting point, with the help of the resin mixture (increasing the surface tension of the melted alloy), the molten alloy quickly shrinks into a shape centered on the leads at both ends under the action of the surface tension. Ball shape, thereby permanently cutting off the circuit. • The third type: Square Shell-type Thermal FuseA piece of fusible alloy wire is connected between the two pins of the thermal fuse. The fusible alloy wire is covered with a special resin. Current can flow from one pin to the other. When the temperature around the thermal fuse rises to its operating temperature, The fusible alloy melts and shrinks into a spherical shape and attaches to the ends of the two pins under the action of surface tension and the help of special resin. In this way, the circuit is permanently cut off. Ⅵ How does a Thermal Fuse work?When the current flows through the conductor, the conductor will generate heat because of the resistance of the conductor. And the calorific value follows this formula: Q=0.24I2RT; where Q is the calorific value, 0.24 is a constant, I is the current flowing through the conductor, R is the resistance of the conductor, and T is the time for the current to flow through the conductor. According to this formula, it is not difficult to see the simple working principle of the fuse. When the material and shape of the fuse are determined, its resistance R is relatively determined (if the temperature coefficient of resistance is not considered). When current flows through it, it will generate heat, and its calorific value will increase with the increase of time. The current and resistance determine the speed of heat generation. The structure of the fuse and its installation status determines the speed of heat dissipation. If the rate of heat generation is less than the rate of heat dissipation, the fuse will not blow. If the rate of heat generation is equal to the rate of heat dissipation, it will not fuse for a long time. If the rate of heat generation is greater than the rate of heat dissipation, then more and more heat will be generated.And because it has a certain specific heat and quality, the increase in heat is manifested in the increase in temperature. When the temperature rises above the melting point of the fuse, the fuse blows. This is how the fuse works. We should know from this principle that you must carefully study the physical properties of the materials you choose when designing and manufacturing fuses, and ensure that they have consistent geometric dimensions. Because these factors play a crucial role in the normal operation of the fuse. Similarly, when you use it, you must install it correctly. Ⅶ Precautions for Thermal FuseThe following items must be observed to ensure the normal operation of the fuse:1 Each thermal fuse has rated current and voltage, melting temperature (Tf), operating temperature (Th), and maximum temperature (Tm), which must be used under specified parameters. 2 When selecting the fuse installation location, be careful not to shift the stress to the fuse due to the vibration in the finished product and the displacement of other accessories. 3 It must be installed in a place where the temperature will not rise above the maximum operating temperature after the thermal fuse is blown. 4 Can not be used in liquids or in machines where the humidity is maintained above 95%. 5 The thermal fuse should be installed in a place that can only sense the heat source of the thermal fuse. When it is unavoidable in the structure, a thermal barrier should be installed. For example, when installing on a heater, be careful not to connect directly to prevent the hot wire from heating to the thermal fuse 6 To increase the current flow of the thermal fuse, if it is connected in parallel or continues to pass overcurrent and overvoltage, the internal contact of the thermal fuse will be damaged, which will affect its normal operation. Therefore, it cannot be used under the above conditions. Although the thermal fuse has high reliability in design, the abnormal situation that a single thermal fuse can deal with is limited after all. Coupled with man-made or unpredictable force majeure, the thermal fuse is damaged and cannot function normally, and the circuit cannot be cut off in time when the machine is abnormal. Therefore, when the machine is overheated, when the wrong action directly affects the human body, when there is no circuit cut-off device other than the fuse, and when a high degree of safety is required, two or more thermal fuses with different fusing temperatures should be used. Ⅷ Some Frequently Asked Questions about Thermal Fuse1. How is a thermal fuse different from an electric fuse?An electric fuse is a common name of a thermal fuse. The thermal fuse is of two types.The one which melts at a certain high temperatureThe one which disconnects due to sub-zero temperature as required.Hypo thermal fuse is made of Biometal but a simple electric thermal fuse can be of any metal or alloy.There is another fuse that does not blow but disconnects the electric circuit. This is called a magnetic fuse. This used in circuit breaker. 2. Are thermal fuses universal?If by “universal” you mean “one size fits all”, then no. Thermal fuses come in a range of temperatures. The only ones I’ve bought are to replace failed ones in coffee makers, and I picked ones rated at around 110*C with an appropriate current capacity. Did not search for anything else, but higher current capacity units must exist.For those who have not run into these devices, they operate like any other fuse in that they are installed in series with the power source, but are designed to be relatively insensitive to current and to open when their temperature exceeds the design point. A valuable safety device in heated appliances. 3. How do I test a dryer thermal fuse?First of all, understand that once a certain amount of current goes through any kind of fuse, the fuse blows and can only be replaced, not repaired. So then, the only test you really want to do is to see if the fuse can still conduct electricity. Unplug the power cable and disconnect either end of the thermal fuse. Connect any cheap ohm meter to the loose end and the other end. If you get a reading, you may consider the fuse to be good. Don’t have a meter? In that case, you can use an old flashlight bulb (not LED), along with a battery and a piece of wire to test the fuse. Press the base of the bulb against one node of the battery while pressing the opposite end of the battery to one of the 2 fuse connections. At the same time, hold a test wire between the side of the bulb and the other fuse wire. If the fuse is good, the light will turn on. 4. How do I know if my thermal fuse is blown?Using a digital or analog multimeter, or other resistance-measuring instruments, check the resistance across the thermal fuse (preferably when it’s out of the circuit, which can affect the reading), If you read continuity (in the range of several ohms or less, depending on its rating), the fuse is still functional. If you read an open circuit, the fuse is blown, and has to be replaced. 5. How do you test a fuse using a multimeter?Testing connectivity is the best way of testing a fuse. A fuse works as long as its two terminals are connected by wire i.e. the two terminals of the fuse are shorted. If the connectivity test fails then it is sure that the fuse isn’t working. However, there might arise a case if the fuse isn’t using proper material. There might not be any connectivity, however, testing the resistance between the two terminals would give a small non-zero value. Even in such cases, we say that the fuse is working. However, such cases rarely exist and if they do we don’t consider as a good fuse (at least for the small power applications like a household) 6. What is the function of the thermal fuse of an electric fan?When the oil in the cheap sleeve bearings in the cheap shaded pole motor gets gummy, the motor will start drawing more current and run hotter. If the motor is not re-lubricated in a timely manner, eventually the sleeve bearings will get stuck and the rotor will fail to turn. This results in a locked-rotor condition and the windings draw more current and produce more heat than they can dissipate with no airflow over them to provide cooling. Eventually, the enamel insulation degrades and gets hot enough to smoke, possibly producing shorted turns that draw even more current.  The thermal fuse is a safety device to prevent the cheap motor from actually catching on fire. Sometimes the fuse can be replaced and the bearings can be relubricated to get another year or two of service if the windings haven’t discolored from overheating, but you can be sure that the end is near. You are better off getting a fan motor with sealed ball bearings. They cost more but last much longer, and usually give you a warning by making a rattling noise when the bearings start to wear out rather than seizing silently. 7. What material is used for making electrical fuses and why?Electrical fuses are generally made from materials having low melting. It acts as a low resistance path when the current flowing through it exceeds its rating by even a small amount. This is done to protect an electrical device from getting damaged. Thus, it acts as an overcurrent protection device. During faults, especially short circuit faults, when heavy currents suddenly flow, the fuse wire gets heated up and melts down, thereby preventing damage and fires from occurring. The fuse wires in general are made of nichrome, etc. 8. What is a fuse?It’s a safety device used to provide overcurrent protection of a circuit. Its main component is a metal wire/strip that melts when there’s too much current flowing through it and thus interrupts the current. This element can be made of zinc, copper, silver, aluminum, or some alloys. Fuse body is made of ceramic, glass, fiberglass, molded mica laminates or molded compressed fiber. 9. What is the difference between fuse and circuit breaker?Fuse-it is such a type of device which breaks the circuit one time when overcurrent in the circuit. you cannot break the circuit or open-close according to your choice.Breaker-it is such type of electrical equipment which breaks when overcurrent, other faulty conditions in the circuit. you can easily control the breaker for opening and closing the circuit ut is such a type of automatic switch. Mainly the big breakers are mainly run with the help of a relay. 10. What causes fuses to blow?A fuse is a safety device that should protect the rest of the circuit from (more) damage when there is a FAULT in the circuit. This can be caused by:component failurewiring failureplacing a load in the circuit that exceeds the Circuits safe level.Note that some circuits (example: motors) can have a very large starting current and special (slow blow) fuses are designed for this type of load.