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IntroductionA p-n junction is an interface or a boundary between n-type and p-type semiconductor materials, inside a semiconductor. One of the crucial keys to solid state electronics is the nature of the P-N junction. For example, a PN Junction Diode is one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. And the p-side or the positive side of the semiconductor has an excess of holes and the n-side or the negative side has an excess of electrons. Why pn junction exists? and How does it work? What is p-n junction diode?PN Junction IntroductionCatalogIntroductionIntroductionⅠ PN Junction Basic1.1 PN Semiconductor1.2 PN Junction ReviewⅡ PN Junction Characteristic2.1 Unidirectional Conductivity2.2 Reverse Breakdown2.3 Volt-Ampere Characteristic2.4 Capacitance CharacteristicⅢ Typical Example: Transistor PN JunctionⅠ PN Junction Basic1.1 PN SemiconductorN-type SemiconductorIn silicon crystal (or germanium crystal) doped with a small amount of impurity phosphorus element (or antimony element), since semiconductor atoms (such as silicon atoms) are replaced by impurity atoms, among the five outer electrons in the outer layer of phosphorus atoms four of them form covalent bonds with the surrounding atoms, and the extra electron is almost unbound and becomes a free electron more easily. Therefore, the N-type semiconductor has become a semiconductor with a higher concentration of electrons, and its conductivity is mainly due to the conduction of free electrons.P-type SemiconductorIn silicon crystal (or germanium crystal) doped with a small amount of impurity boron element (or indium element), since semiconductor atoms (such as silicon atoms) are replaced by impurity atoms, the three outer electrons in the outer layer of boron atoms and a semiconductor atom form a covalent bond, at this time, a "hole" is generated. This hole may attract bound electrons to "fill", making the boron atom a negatively charged ion. In this way, this type of semiconductor has a higher concentration of "holes" ("corresponding to" positive charges) and becomes a substance capable of conducting electricity.1.2 PN Junction ReviewP-N junction is formed by joining n-type and p-type semiconductor materials, which is a two terminal device that allows electric current in one direction and blocks electric current in another direction.Figure 1. How is PN Junction FormedOn a silicon wafer, different doping processes are used to form an N-type semiconductor on one side and a P-type semiconductor on the other side. We call the area near the interface of the two semiconductors a PN junction.After the P-type semiconductor and the N-type semiconductor are combined, since the free electrons in the N-type region are more and the holes are less, the concentration difference between electrons and holes appears at their junction. Due to the difference in the concentration of free electrons and holes, some electrons will diffuse from the N-type region to the P-type region, and some holes will diffuse from the P-type region to the N-type region. As a result of their diffusion, the P region loses holes, leaving negatively charged impurity ions, and the N region loses electrons, leaving positively charged impurity ions. The ions in the semiconductor cannot move arbitrarily in an open circuit, so they do not participate in conduction. These immovable charged particles form a space charge zone near the interface between the P and N zones. The thickness of the space charge zone is related to the concentration of dopants.After the space charge region is formed, due to the interaction between the positive and negative charges, an internal electric field is formed in the space charge region, the direction of which is from the positively charged N region to the negatively charged P region. Obviously, the direction of this electric field is opposite to the direction of carrier diffusion, which used to prevent diffusion.On the other hand, this electric field will cause the minority carrier holes in the N region to drift to the P region, and the minority carrier electrons in the P region to drift to the N region. The direction of the drift movement is just opposite to the diffusion movement. The holes drifting from the N region to the P region supplement the holes lost in the P region on the original interface, and the electrons drifting from the P region to the N region supplement the electrons lost in the N region on the original interface, which makes the electric charge is reduced and the internal electric field is weakened. Therefore, the result of drift motion is to narrow the space charge region and strengthen the diffusion motion.Finally, the diffusion of multiple carriers and the drift of minority carriers reach a dynamic balance. On both sides of the junction surface of the P-type semiconductor and the N-type semiconductor, a thin ion layer is left. The charge area formed by this thin ion layer is called a PN junction. The direction of the internal electric field of the PN junction points from the N to the P. It is also called the depletion layer, because lack of electrons.Figure 2. PN Junction Depletion RegionⅡ PN Junction Characteristic2.1 Unidirectional Conductivity(1) The PN junction is turned on when the forward voltage is applied.If the positive pole of the power supply is connected to the P area and the negative pole is connected to the N area, a part of the applied forward voltage is in the PN junction area, at this time, the PN junction is in a forward bias. The current flows from the P to the N, and the holes and electrons move to the interface, which narrows the space charge area. In addition, the current can pass smoothly. Its direction is opposite to the direction of the electric field in the PN junction, which weakens the internal electric field. As a result, the resistance of the internal electric field to the diffusion movement of the multitons weakens, and the diffusion current increases. The diffusion current is much larger than the drift current, and the influence of the drift current can be ignored, and the PN junction is in low resistance.(2) PN junction is cut off when reverse voltage is applied.If the positive pole of the power supply is connected to the N zone, the negative pole is connected to the P zone, and a part of the applied reverse voltage applies in the PN junction zone, and it is in reverse bias. Then the holes and electrons move away from the interface, which widens the space charge area, and the current cannot flow. The direction is the same as the direction of the electric field in the PN junction, which strengthens the internal electric field. The resistance of the internal electric field to the multiton diffusion movement is enhanced, and the diffusion current is greatly reduced. At this time, the drift current formed by the minority carriers in the PN junction region under the action of the internal electric field is greater than the diffusion current. The diffusion current can be ignored, and the PN junction exhibits high resistance.2.2 Reverse BreakdownWhen a reverse voltage is applied to the PN junction, the space charge region becomes wider and the electric field in the region strengthens. When the reverse voltage increases to a certain level, the reverse current will suddenly increase. If the external circuit cannot limit the current, the current will be so large that it will burn the PN junction. At this time, it is called the breakdown voltage. There are two basic breakdown ways, namely tunnel breakdown (also called Zener breakdown) and avalanche breakdown. The former has a breakdown voltage of less than 6V and has a negative temperature coefficient, and the latter has a breakdown voltage of greater than 6V and a positive temperature coefficient.2.3 Volt-Ampere CharacteristicThe volt-ampere characteristics of the PN junction are shown in the Figure 3, which visually shows the unidirectional conductivity.Figure 3. Volt-Ampere Curve of the PN JunctionThe volt-ampere characteristic shows by Where iD is the current passing through the PN junction, VD is the applied voltage at both ends of the PN junction, and VT is the voltage equivalent of temperature.2.4 Capacitance CharacteristicWhen a reverse voltage is applied to the PN junction, the positive and negative charges in the space charge region constitute a capacitive device. Its capacitance changes with the applied voltage, mainly including barrier capacitance (CB) and diffusion capacitance (CD). Both of them are non-linear capacitors. Ⅲ Typical Example: Transistor PN JunctionTransistors are one of the basic building blocks of modern electronics. In the diode tutorials we saw that simple diodes are made up from two pieces of semiconductor material to form a simple pn-junction. While the transistor is a three terminal solid state device which is formed by connecting two diodes back to back. Hence it has got two PN junctions.Transistor NPN-Type and PNP-Type JunctionsTransistor Working StateThe transistor works like an electronic switch. It can turn a current ON and OFF. The basic idea behind a transistor is that it lets you control the flow of current through one channel by varying the intensity of a much smaller current that's flowing through a second channel.1) Cut-off State (C): The base current is zero.2) Amplified State (A): The transmitter junction is forward biased (that is, the voltage direction is P->N), and the collector junction is reverse biased.3) Saturation State (S): Both the emitter junction and the collector junction are forward biased.Working StateNPN-Type TransistorPNP-Type TransistorVb<Ve (C)Vc>Vb>Ve (A)Vb>Ve Vb>Vc (S)Vb>Ve (C)Vc<Vb<Ve (A)Vb<Ve Vb<Vc (S)In Figure (a), when there is no voltage input at b of the NPN transistor, no current flows between c and e, and the triode is in the cut-off state.In Figure (b), when a positive voltage is input to b of the NPN transistor, the negative electrons in the N region of e are attracted by the positrons of P region in b. Due to the effect of the power plant, and they rush (diffuse) to the base region, however, only part of the negative electrons collide with the positive electrons (recombination) to generate the base current, and the other part of the negative electrons gather near the collector junction. The negative electrons gathered in the collector junction pass through (drift) the collector junction due to the action of the electric field. After reaching the collector area, it collides with the positrons gathered in c (N-type semiconductor terminal) to generate a collector current.It can be seen from this that the greater the base current, the greater the collector current. That is, when a small current is input to the collector, a large current can be obtained by the collector, and now the transistor is in an amplified state.It should be noted that when the base current reaches a certain level, the collector current no longer rises. At this time, the transistor loses its current amplification effect, and the voltage between the collector and the emitter is very small. The collector and emitter are equivalent to the on-state of the switch. At this moment, the transistor is in a saturated state.The working principle of the PNP transistor is the same as that of the NPN transistor, except that the direction of the bias voltage and the current are opposite, and the roles of electrons and holes are reversed. The PNP transistor uses Veb to control the positrons incident on the collector area from the emitter area through the base area, while the NPN transistor uses Vbe to control the negative electrons that enter the collector area from the emitter area through the base area.In addition, in a low-power design, the transistor control circuit will have a certain impact on the circuit. No matter it is NPN or PNP, there will be leakage current in the PN junction of the transistor. When the I/O controls the base voltage, in order to stabilize the base voltage, a pull-down resistor is generally added to the base of the NPN switch circuit. In the design of the PNP switch circuit, a pull-down resistor is added to the base. The pull-up and pull-down resistors are selected according to the control chip, transistor and circuit voltage. Frequently Asked Questions about PN Junctions Formed1. What is PN junction and how it is formed?P-n junctions are formed by joining n-type and p-type semiconductor materials, as shown below. ... However, in a p-n junction, when the electrons and holes move to the other side of the junction, they leave behind exposed charges on dopant atom sites, which are fixed in the crystal lattice and are unable to move. 2. What is p-type and n-type?In silicon doping, there are two types of impurities: n-type and p-type. In n-type doping, arsenic or phosphorus is added in small quantities to the silicon. ... In p-type doping, boron or gallium is used as the dopant. These elements each have three electrons in their outer orbitals. 3. What is a PN junction diode?A PN Junction Diode is one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. ... By applying a negative voltage (reverse bias) results in the free charges being pulled away from the junction resulting in the depletion layer width being increased. 4. What happens in a PN junction?A forward-biased PN junction conducts a current once the barrier voltage is overcome. The external applied potential forces majority carriers toward the junction where recombination takes place, allowing current flow. A reverse-biased PN junction conducts almost no current. 5. What is a PN junction used for?A p-n junction diode is a two terminal device that allows electric current in one direction and blocks electric current in another direction. In forward bias condition, the diode allows electric current whereas in reverse bias condition, the diode does not allow electric current.

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 AVTV 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.

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, TL081234, 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.

IntroductionIn electronics and electrical circuits, a Fuse is an electrical safety device that operates to provide overcurrent protection. In order to stop the damaging effects of overcurrent, when too much current flows through the low resistance element of the fuse, the element melts and breaks the circuit, because a special feature of the fuse is that it contains a piece of wire that melts easily. Fuses are widely used for the protection of electric motor circuits of different types. Before you read the following note, you can think about a question: what are the types of fuses and their uses?What is an Electric Fuse? and How to Prevent Short Circuit with Fuses?CatalogIntroductionⅠ Fuse Basic Overview1.1 What Are Fuses1.2 Fuse Working Principle1.3 Electrical Fuse Symbol1.4 Fuse MaterialsⅡ Electric Fuse Classification2.1 DC Fuses Basic2.2 AC Fuses BasicⅢ ConclusionⅣ Frequently Asked Questions about Fuse Types Basics and Its ApplicationsⅠ Fuse Basic Overview1.1 What Are FusesAn electrical fuse is a protection device built around a conductive strip that is designed to melt and separate in the event of excessive current. In other words, what are fuses for? The fuse breaks the circuit if a fault in an appliance causes too much current to flow. Except that, fuses are essentially temperature-sensitive devices. Even small variations from the controlled test conditions can greatly affect the predicted life of a fuse.1.2 Fuse Working PrincipleThe primary task of a fuse is to split the circuit if the circuit draws a current higher than desired, thus avoiding the harm due to short circuits.The simplest fuse type consists of a resistive part, carefully chosen for its melting point. A slight voltage drop (small enough so that the circuit downstream will not be impacted) is generated across the element when a current passes through this element, and some power is dissipated as heat. Thus, the element's temperature increases. This temperature rise is not necessary for normal currents to melt the filament. However, the melting point is easily reached if the current draw reaches the nominal current of the fuse. The resistive part melts and is disrupted by the circuit. The nominal current is determined by the thickness and length of the resistive material.To provide predictable trip currents, fuse components are made of zinc, copper, silver, aluminum, or other alloys. Over time, the element must not oxidize or corrode.1.3 Electrical Fuse SymbolWhat is the symbol of fuse? different fuse symbols in the electrical circuit diagram showed below.Electronic Symbols of Fuse1.4 Fuse MaterialsWhat are fuses made of? The material used for making fuse elements has a low melting point such as tin, lead, or zinc. A low melting point is, however, available with a high specific resistance metal shown in the table below. The material mainly used for fuse elements are tin, lead, silver, copper, zinc, aluminum, and an alloy of lead and tin. Ⅱ Electric Fuse ClassificationAfter you know what is a fuse in a circuit, the following are the types of fuse. There is a wide selection of PCB fuses in the market. Here introduce two major types: AC fuses, and DC fuses. The following note describes different types of fuses and their constriction, working characteristics.Types of Fuse Explained2.1 DC Fuses BasicCartridge FusesThis is the fused form that is the most common. In a glass envelope that is terminated by metal caps, the fuse part is encased. In a suitable holder, the fuse is mounted. As the glass envelope is transparent, whether the fuse is blown, it is easy to visually determine.This style has many versions, including the slow blow fuse and the quick blow fuse. Slow blow fuses have a larger element that can handle overcurrent and are unaffected by spikes in the appliance for a relatively short period of time. Quick blow fuses respond to existing spikes instantly.To withstand elevated temperatures, some versions of this fuse are encased in ceramic. Sand or oil is packed with fuses for high voltage applications. This is to stop arcing after it has blown between the two ends of the fuse. For direct PCB mounting, SMD variants of cartridge fuses also exist. Automotive, Blade Type & Bolted Type FusesThese fuses are designed especially for automotive systems running up to 32V and 42V at times. They come in the form of a 'sword' (a transparent plastic envelope with flat contacts) and are color-coded according to the nominal current. In other high-power circuits, some of these types are also used. Resettable Fuses/PolyfuseThese fuses are self-resetting, much as their name suggests. They contain black particles of carbon embedded inside organic polymers. The carbon black usually renders the mixture conductive. Heat, which expands the organic polymer, is created when a large current flows. The black particles of carbon are pulled apart, and conductivity decreases to the point that there is no flow of current. As temperatures decrease, conductivity is restored. The fuse does not, however, have to be replaced physically. This type of fuse is often referred to as a PTC, which means a positive temperature coefficient since the temperature rises with resistance.For computer power supplies and phone chargers, the PTC Fuse is ubiquitous. They are particularly handy here because it is difficult to replace them. They are used in aerospace devices for the same purpose.In their through-hole variants, PTCs are easily recognized by their yellow-orange colour and disc (and sometimes rectangular) form. With white markings, SMD poly fuses normally come in green or with gold markings in black. Virtually every current rating offers PTCs. Semiconductor FusesWith current flow, the power dissipated by a semiconductor increases exponentially, and semiconductors are thus used for ultrafast fuses. These fuses are commonly used to secure devices that are susceptible to even minor current spikes from semiconductor switching. Overvoltage Suppression FusesVoltage spikes may also often be dangerous to circuits, and with a fuse, an overvoltage safety system is also used to protect against both voltage and current spikes.There are NTCs (negative coefficient of temperature) put in parallel with the supply. NTC Fuses minimize resistance due to higher current flow and absorb spikes when the supply voltage spikes.Semiconductor-like devices that bidirectionally absorb voltage spikes are metal oxide varistors (MOVs). Using the linked post, you can learn more about MOV and its work.2.2 AC Fuses BasicHigh Voltage FusesIn high voltage AC transmission lines, these fuses are used where voltages can exceed several hundred kilovolts.1) HRC (High Rupture Current) FusesHRC fuses are fuses of a cartridge type consisting of a transparent steatite envelope (magnesium silicate). The fuse is packed with quartz powder that serves as an arc extinguishing agent (and, in the case of a liquid-filled HRC fuse, a non-conducting liquid like mineral oil).2) Expulsion FusesThese fuses are packed with chemicals such as boric acid, which creates heating gases. The arc is extinguished by these gases and ejected from the ends of the fuse. Copper, tin, or silver are made of fuse material. Low Voltage FusesThe low voltage fuses are divided into five types and those are rewirable, cartridge, drop out, striker, and switch fuses.1) Rewireable FusesThey are a quick fuse used in homes and offices that is reusable. A carrier and a socket are composed of them. The carrier is taken out, rewired and placed back in the socket when the fuse is blown, to restore normal service. They are slightly less effective than fuses from HRC.2) Cartridge FusesThey are very similar to DC fuses for cartridges. A transparent envelope covering the part of the fuse consists of them. It is possible to plug them in (blade type) or screw them into a fixture (bolt type).3) Drop Out FusesThey contain a spring-loaded lever arm that retracts when a fault occurs and must be rewired to restore normal service and put back in place. They are a form of fuse for expulsion.4) Striker Fuses A spring-loaded striker is provided with these fuses that can serve as a visual indication that the fuse has exploded and other switchgear is also triggered.5) Switch FusesHigh current fuses can be attached or disconnected by a handle that is manually controlled.Ⅲ ConclusionIn the field of electronics or electrical, the fuse is a small safety part in an electrical device or piece of machinery. It is considered the most crucial device which is employed in various electrical circuits. Many types of fuses with stock availability in the business can meet various circuit requirements. Ⅳ Frequently Asked Questions about Fuse Types Basics and Its Applications1. What are fuses?Fuses are sacrificial devices used to protect much more expensive electrical components from the damaging effects of overcurrent. They consist of a low-resistance metal or wire that is used to close a circuit. 2. What are the types of fuses?Different Types of Fuses – Constriction, Working & CharacteristicsDC FusesAC FusesCartridge FusesD – Type Cartridge FuseHRC (High Rupturing Capacity) Fuse or Link Type Cartridge FuseHigh Voltage FusesAutomotive, Blade Type & Bolted Type FusesSMD Fuses (Surface Mount Fuse), Chip, Radial, and Lead Fuses 3. Where are fuses used?Fuses are widely used for protection of electric motor circuits; for small overloads, the motor protection circuit will open the controlling contactor automatically, and the fuse will only operate for short circuits or extreme overload. 4. How many types of fuses are there?Fuses can be divided into two major categories, AC fuses, and DC fuses.5. What is the difference between Fuse and MCB (miniature circuit breaker)?Fuse is an electrical device that self-destructs and stops the current flow in a circuit whenever the current exceeds the predefined value. MCBs are resettable circuit protection devices that, on the occurrence of faults, stops the current flow in a circuit. 6. How do I know what fuse to use?You'll usually find the fuse rating on the side of your fuse, which will be given in amps. The fuse rating is the amount of current needed for the fuse to blow or break. When this happens, it stops the electrical power from flowing through the electrical circuit. 7. What are the different types of fuses?The fuse is the current interrupting device that breaks or opens the circuit by fusing the element and thus removes the faulty device from the main supply circuit. The fuses are mainly classified into two types, depends on the input supply voltages they are the AC fuses and the DC fuses. 8. What is the difference between AC and DC fuses?With AC circuits, the current is crossing the zero potential at 60 or 50 cycles a second. This helps in breaking the arc that forms when the fuse element melts and creates a gap. In dc circuits, the voltage does not go to a zero potential, making it more difficult to suppress the arc in the melting element's gap. 9. What is the difference between T and TL fuses?The difference between SL and TL fuses is their bases. An SL is a rejection base, while a TL is your typical edison base. The difference between S and T fuses is the same. SL and TL fuses are Loaded Link and are normally used in special, lighter applications, while S and T are used in heavier applications. 10. How do fuses protect us?The fuse breaks the circuit if a fault in an appliance causes too much current to flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit. 

Executive Summary: Active vs. Passive Components (2026 Update)The Core Difference: Active components (like transistors and ICs) require an external power source to function and can inject power into a circuit (amplification). Passive components (like resistors and capacitors) do not require external power; they consume, store, or release energy but cannot amplify signals.Key Takeaway: Modern 2026 electronics rely on the interaction between active devices (for logic and control) and passive devices (for stability and energy management).Introduction to Electronic Components in 2026Electronic components are the fundamental building blocks of modern circuits, functioning as the discrete physical entities that manipulate electrons and their associated fields. As of 2026, these components are critical for everything from IoT sensors to high-performance AI processors. They connect to form specific functions like amplifiers, radio receivers, and oscillators, typically welded onto a Printed Circuit Board (PCB). While components come in standardized package sizes (ranging from the microscopic 008004 metric size to large power modules), they all fall into two primary categories: active components and passive components. This guide clarifies the definitive technical differences between them for engineers and hobbyists alike.Figure 1: Visual breakdown of Active vs Passive circuit elements.Ⅰ. What Are Active Components?An active component is an electronic device that relies on an external source of energy to control, modify, or amplify electrical signals. Unlike passive devices, active components can inject power into a circuit, providing a "gain" in voltage or current. They are the "decision makers" in a circuit, acting as switches, amplifiers, and memory cells.1.1 How Active Components FunctionActive components function by using a DC power source to manipulate an AC signal. They include amplifying components such as transistors, Triode vacuum tubes (valves), Tunnel diodes, and Silicon Controlled Rectifiers (SCRs). In 2026, wide-bandgap semiconductors (like GaN and SiC) represent the cutting edge of active component technology, offering higher efficiency than traditional silicon.1.2 Examples of Active ComponentsTransistors (The Backbone of Modern Tech)A transistor is an active semiconductor component used for amplifying, controlling, and generating electrical signals. It acts as a variable switch or amplifier. Structurally, it consists of PN junctions and typically has three terminals: emitter, base, and collector (BJT) or source, gate, and drain (FET). Today, Field Effect Transistors (FETs) are the dominant architecture in microprocessors.Vacuum Tubes (Legacy High-Fidelity)A vacuum tube (electron tube or valve) controls electric current flow in a high vacuum between electrodes using an applied potential difference. While largely replaced by semiconductors in the 1960s, they remain relevant in 2026 for high-end audio amplification, military RF applications, and microwave transmitters due to their robustness against electromagnetic pulses (EMP).Silicon Controlled Rectifiers (SCRs)A Silicon Controlled Rectifier (SCR) is a four-layer solid-state current-controlling device. Functioning as a latching switch for high-power operations, SCRs operate in three modes: forward blocking (off), forward conduction (on), and reverse blocking (off). They are essential in industrial power control systems.Ⅱ. What Are Passive Components?A passive component is an electrical device that consumes, stores, or releases energy but cannot generate power or amplify a signal. These components operate without an external power source (beyond the signal passing through them) and utilize physical properties to restrict current, filter signals, or store energy.2.1 How Passive Components FunctionPassive elements dissipate energy (resistors), store energy in an electric field (capacitors), or store energy in a magnetic field (inductors). While they cannot add gain to a circuit, they are vital for stability, filtering noise, and managing voltage levels.2.2 Examples of Passive ComponentsResistorsA resistor is a linear passive component designed to oppose current flow. By restricting the passage of electrons, it creates a voltage drop according to Ohm's Law (V=IR). Standard values follow the E-series (E12, E24, E96) to ensure manufacturing consistency. In 2026, precision thin-film resistors are standard for high-accuracy electronics.CapacitorsA capacitor is a passive component that stores electrical energy in an electrostatic field between two conductive plates. They function as temporary batteries or frequency filters. Common types include Multilayer Ceramic Capacitors (MLCCs) found in smartphones and Aluminum Electrolytic capacitors used in power supplies.Diodes (The Passive/Active Hybrid)A diode is a two-terminal component that allows current to flow in only one direction (rectification). While constructed from semiconductor material, diodes are generally classified as passive because they cannot amplify a signal—they result in a power loss (voltage drop).InductorsAn inductor is a passive component consisting of a coil of wire that stores energy in a magnetic field when electric current flows through it. They resist changes in current flow, making them crucial for power management in Switched-Mode Power Supplies (SMPS) and RF filtering.Ⅲ. Key Differences: Active vs. Passive Components (2026 Comparison)To clearly understand the operational distinctions, we compare these components across six critical engineering parameters.ParameterActive ComponentsPassive ComponentsPower SourceRequires an external DC source to function.Does not require an external power source.Energy FunctionProduces power gain (amplifies voltage/current).Stores, releases, or dissipates energy.LinearityNon-linear (output is not directly proportional to input).Linear (responds linearly to voltage/current, e.g., Resistors).Power GainCapable of providing power gain ($P_{out} > P_{in}$).No power gain ($P_{out} < P_{in}$ due to losses).Flow ControlCan control current flow via an external signal.Cannot control flow via external signals.ExamplesTransistors, ICs, SCRs, Logic Gates.Resistors, Capacitors, Inductors, Transformers.Ⅳ. ConclusionIn 2026 circuit design, the distinction between active and passive components remains fundamental. Active components provide the intelligence and power control, acting as the brain of the system, while passive components provide the necessary environment for signals to travel efficiently, acting as the nerves and support structure. Successful electronic engineering requires the precise integration of both types to meet modern requirements for size, efficiency, and speed. Frequently Asked Questions (FAQ)1. Are diodes considered active or passive components?Diodes are technically classified as passive components because they cannot amplify a signal (they have no power gain). However, because they are made of semiconductor materials and have non-linear IV characteristics, some older texts occasionally group them with active devices. In 2026 standards, they are passive.2. Can a circuit work without active components?Yes, but its functionality is limited. A circuit with only passive components (like a light bulb connected to a battery via a switch) can dissipate or store energy, but it cannot compute data, amplify weak signals, or perform automated control logic.3. What is the ratio of passive to active components in modern devices?In modern devices like smartphones (2026 models), passive components vastly outnumber active ones. A typical smartphone may contain 15-20 active ICs but over 1,000 passive components (mostly MLCC capacitors and resistors) to filter noise and stabilize power delivery.4. Why do resistors not require external power?Resistors operate based on the physical properties of their material (carbon, metal film). They simply restrict electron flow by converting kinetic energy into heat. 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