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IntroductionAs the most popular open-source hardware in the world, Arduino is not only an excellent hardware development platform, but also a trend in hardware development. Its simple development method makes developers pay more attention to creativity and realization, complete their own projects and get experiments faster, which greatly saves the cost of learning and shortens the development cycle. There are too many want to say, in short, arduino provides a lot of convenience for many electronics enthusiasts and creators, and also provides a platform for sharing their results. So what exactly is it? How does it work?CatalogIntroductionⅠ What is Arduino?Ⅱ Who Make the Arduino?Ⅲ Why Use Arduino?Ⅳ What Does Arduino Have?Ⅴ Arduino Programming LanguageⅥ Arduino Basic ArchitectureⅦ Copyright and PaymentⅧ Simple Arduino Projects8.1 Video Demonstration8.2 Examples and Programming CodesⅨ FAQⅠ What is Arduino?Arduino is a tool that can be used to sense and control the physical world more than your desktop computer. It consists of an open source-computer platform based on a simple single-chip microcomputer, and a development environment for writing programs for the Arduino board.Arduino can be used to develop interactive products. For example, it can read a large number of switches and sensor signals, and can control a variety of lights, motors, and other physical devices. The Arduino project can be a standalone project, or it can communicate with programs running on your computer (for example: Flash, Processing, MaxMSP) at runtime. You can choose to manually assemble the Arduino board yourself or buy a productthe, because open-source IDE can be downloaded for free.The Arduino programming language seems to be correspondingly connected to a physical computing platform, which is based on a programming environment that handles multimedia.Learn Arduino in 15 MinutesⅡ Who Make the Arduino?Massimo Banzi was a teacher at a high-tech design school in Ivrea, Italy. His students often complain about not being able to find cheap and easy-to-use microcontrollers. In the winter of 2005, Massimo Banzi discussed this problem with David Cuartielles. He is a Spanish chip engineer who was a visiting scholar in this school at the time. The two decided to design their own circuit boards and introduced David Mellis (Banzi student) to design a programming language for the circuit boards. Two days later, David Mellis wrote the code. After another three days, the circuit board was completed. Massimo Banzi likes to go to a bar called di Re Arduino, which was named after the Italian king Arduin 1,000 years ago. To commemorate this place, he named this circuit board Arduino.Figure 1. The Making Arduino Core Team Ⅲ Why Use Arduino?There are many single-chip microcomputers and their platforms that are suitable for the design of interactive systems. For example: Parallax Basic Stamp, Netmedia's BX-24, Phidgets, MIT's Handyboard and others provide similar functions. With all these tools, you don't need to care about the cumbersome details of MCU programming. Arduino provides you a set of easy-to-use toolkits. Arduino also simplifies the process of working with a single-chip microcomputer, but compared with other systems, it has many advantages in many places. In fact, it is especially suitable for teachers, students and some amateurs:0️⃣Cheap1️⃣Cross-platform2️⃣Simple programming environment3️⃣The software is open-source and expandable.4️⃣Hardware is open-source and expandable. Ⅳ What Does Arduino Have?At the beginning of Arduino development, its application environment was clarified, and an open-source platform was designed to facilitate its secondary development. The main features of Arduino are as follows:1) Open-source circuit diagram design. The program development interface is free to download, or you can modify it according to your needs. Arduino carries low-priced microcontrollers (ATmega8 or ATmega128). It can be powered by a USB interface, no external power supply, and an external 9VDC input can also be used.2) Support ISP online programming, making the Bootloader firmware into the chip. The Arduino controller contains the Bootloader program, which is the first piece of code that runs after the system is powered on. It is like the program in the BIOS of the PC. It performs self-check after startup, configures the port, and so on. Of course, the microcontroller relies on programming the fuse. Set the startup from the boot area after power-on, and use this program to directly store the program sent from the serial port in the flash area. Therefore, when using the Arduino compilation environment to download the program, first reset the microcontroller and start the Boodoader program to guide the program sent from the serial port to be successfully written into the flash area. The flash can be programmed repeatedly, so it is very convenient to update the software. After having Bootloader, you can update the firmware through the serial port or USB to RS232 line.3) According to the official PCB and SCH circuit diagrams, the Arduino module can be simplified to complete independent micro-processing control.4) It can be easily connected with sensors and various electronic components, such as infrared, ultrasonic, thermistor, photoresistor, servo motor, etc.5) Support a variety of interactive programs, such as Flash, Max/MSP, VVVV, PurEDAta, C, Processin, etc.In terms of application, the use of Arduino can break through the interactive content of devices that can only use mouse, keyboard, CCD and other input devices in the past. For example, it can achieve single-player or multi-player game interaction more simply. The functional characteristics of Arduino make it more and more widely used. Ⅴ Arduino Programming LanguageUsually, the Arduino language we say refers to a collection of various application programming interfaces (APIs) provided by the Arduino core library files. Arduino uses C/C++ to write programs. Although C++ is compatible with C language, these are two languages. C language is a process-oriented programming language, and C++ is an object-oriented programming language. The early Arduino core library was written in C language, and later object-oriented ideas were introduced. At present, the latest Arduino core library is written in a mixture of C and C++.The Arduino language is a program framework that starts with setup() and loop() as the main body. setup() is used to initialize variables, pin modes, call library functions, etc. This function only runs once, and its function is similar to "main()" in C language. For the loop() function, the statements in the function are executed in a loop.Arduno language modularizes some parameter settings related to AVR microcontroller, including EEPROM, Ethernet, LED matrix, steering gear, stepping and TWI/I2C control library. It does not require the user to directly deal with the underlying system, which can improve the efficiency of application development. Ⅵ Arduino Basic ArchitectureThe Arduino system has also developed different versions based on different application environments. The "Arduino Duemilanove" version is used as an example to introduce the Arduino system. This version was developed in 2009 and is based on the atmega328 microcontroller board. During use, connect the computer with a USB cable or use a power adapter to power it.1) One 9V DC input provides external power output for the Arduino board, so that the Arduino control board has the ability to drive high-power external devices such as steering gear.2) One USB port used to connect the computer. The Arduino IDE uploads the control program written by the user to the control board, and at the same time, it can also supply power to the circuit board and drive low-power external devices through this port.3) 14 digital input/output terminals, among which ports 0 (RX) and 1 (TX) are respectively connected to the serial pins of the main control chip to receive and send TTL serial data. Among them, ports 2 and 3 can receive external signals to realize external interrupt function. Ports 3, 5, 6, 9, 10, 11 are used as PWM ports, which can be used for motor PWM speed regulation or music playback. Port 10 (SS), 11 (MOSI), 12 (MISO) and 13 (SCK) can provide SPI communication mode with the support of SPI module library. Port 13 is connected with an LED indicator, which can open and close with the change of the level on pin 13.4) 6 analog input/output ports, of which port 4 (SDA) and port 5 (SCL) can realize I2C communication.5) One 5V DC output and one 3.3V DC output, which can provide 3.3V and 5V DC power supplies for other circuits.6) One reset interface.The Arduino system is developed based on a single-chip microcomputer, and a large number of common and standard electronic components are used on it. The entire design, including hardware and software, is released in an open source manner. Therefore, the cost of procurement is relatively low. In various electronic production competitions, Arduino is used as a development platform for creative design of electronic artwork.Figure  2. Arduino Board Terminals🔺Arduino Hardware✔️There are many motherboard, such as:Arduino UnoArduino NanoArduino LilyPadArduino Mega 2560Arduino EthernetArduino DueArduino LeonardoArduinoYún✔️There are many expansion boards for Arduino, such as:Arduino GSM ShieldArduino Ethernet ShieldArduino WiFi ShieldArduino Wireless SD ShieldArduino USB Host ShieldArduino Motor ShieldArduino Wireless Proto ShieldArduino Proto Shield Ⅶ Copyright and PaymentIn order to maintain the open-source concept of the design, Arduino decided to adopt the Creative Commons license, which is a license similar to GPL that appears to protect open copyright activities. Because copyright law can regulate open-source software, but it is difficult to use it on hardware. Having this license, anyone is allowed to produce copies of circuit boards, redesign, and even sell copies of the original design. You don't need to pay royalties, or even get permission from the Arduino team. However, if you republish the reference design, you must sign the original Arduino team. In addition, if you adjust or modify the circuit board, your latest design must use the same or similar license to ensure that the new version of the Arduino circuit board will be free and open. In other words, only the name Arduino is reserved, and it is a trademark now. If someone wants to sell a circuit board under this name, they must pay a small trademark fee to the Arduino core development members. Ⅷ Simple Arduino Projects8.1 Video DemonstrationBasic Projects with Arduino8.2 Examples and Programming Codes🔺Water Lamp ControlInsert 6 LED lights on the breadboard, among which the long pins are assigned to the 6, 7, 8, 9, 10, 11 ports of arduino respectively, the short pins are all connected to the blue wire of the breadboard, and then one port of the blue wire is connected to the GND port of the arduino. Figure  3. Water Lamps ConnectionCode:void setup(){ pinMode(6,output);pinMode(7,output);pinMode(8,output);pinMode(9,output);pinMode(10,output);pinMode(11,output);}void loop(){digitalWrite(6, LOW);digitalWrite(7,HIGHT);delay(200);digitalWrite(7, LOW)；digitalWrite(8,HIGHT);delay(200);digitalWrite(8,LOW);digitalWrite(9,HIGHT);}🔺Using the Buzzer to Realize the AccordionThe buzzer is set according to different frequencies, so set the corresponding buzzer frequency based on the level of the switch interface.void setup(){pinMode(8,INPUT);  //switch setdigitalWrite(8, HIGH);pinMode(9,INPUT);digitalWrite(9, HIGH); piMode(10,INPUT);digitalWrite(10, HIGH); pinMode(11,OUTPUT) //light setpinMode(12, OUTPUT)pinMode(13,OUTPUT)}void loop(){if(digitalRead(8)==LOW){tone(7,2093);  //the buzzer frequency is set to 2093digitalWrite(11, HIGH);}else{notone(7);digitalWrite(11,LOW);}Repeat 2 switch values down;;; 🔺Breathing LightThe so-called breathing is relatively stable, so it cannot flicker and go off like a flashing LED. So analog output is used, and the current changes continuously.Figure  4. Breathing Light ConnectionCode:void setup(){pinMode(11,OUTPUT);  }void loop(){for(int i=0;i<30;i++){analogWrite(11,i);   //analog signal input, the range of i is [0,255];delay(10);}for(int j=29;j>0;j--){analogWrite(11,j);delay(10);}} Among them, the corresponding relationship between the analog signal voltage and the digital signal voltage:How is the analog signal realized to control the voltage within a range in a cycle?Figure  6. PWMAs shown in the figure, “on” belongs to 5V, and “off” belongs to 0V. In a time period, that is, when a pulse is sent, the duration of “on” in the previous figure is 25%, and the “off” is 75%. The voltage value calculated like this: v0=5*25%+0*75%=1.25(v). It can be simply understood like this. 🔺Breathing Water Lampvoid  setup(){pinMode(3, OUTPUT);pinMode(5, OUTPUT);pinMode(6, OUTPUT);pinMode(9, OUTPUT);pinMode(10, OUTPUT);pinMode(11, OUTPUT);}int  ports[6]=[3,5,6,9,10,11];int i=0，level=0; set loop(){ analogWrite(ports[i], level);delay(10);++level %=7;++i %=6;  i is incremented first, and then modulo 6, that is, i is always in the range of 0~5；}🔺Vibrating LEDPhotoresistor, resistor, LED are required;Connect one end of the photoresistor to 5V, the other end to the resistor, and the resistor to GND. Pull out a wire between the two and connect to analogIn;Figure  7. Vibrating LED ConnectionCode:void setup(){Setrial.begin(9600);}void loop(){Setril.printIn(analogWrite(0));  //the middle wire is connected to port 0, which is the serial output port；delay(200);} 🔺Electric BellWhen energized, electromagnetic induction produces magnetic force, the switch (oscillator) is attracted and pulled down; When the power is cut off, the coil loses its magnetism, the switch is restored, and then energized. That is, repeat the cycle. This is also the principle of crystal oscillator.Figure  8. Electric Bell DiagramCode:void setup(){pinMode(9,OUTPUT);Setrail.begin(9600);}void loop(){Setrail.printIn(analogRead(0));analogWrite(9, map(analogRead(0), 400,700,0,255);   //map(a1,b1,a2,b2), that is, the original range of values [a1,b1] is mapped to [a2,b2];delay(200);} Ⅸ FAQ1. What is an Arduino used for?Arduino is an open-source electronics platform based on easy-to-use hardware and software. Arduino boards are able to read inputs - light on a sensor, a finger on a button, or a Twitter message - and turn it into an output - activating a motor, turning on an LED, publishing something online.2. Is Arduino illegal?The hardware designs of Arduino are open source; it is allowed to copy and further develop the designs. Note that in case a copy uses the Arduino name and/or logo on it, this board is no longer a copy but a counterfeit which is illegal to manufacture and sell.3. Can Arduino run C++?First, the Arduino compiler/IDE accepts C and C++ as-is. In fact many of the libraries are written in C++. Much of the underlying system is not object oriented, but it could be. Thus, "The arduino language" is C++ or C.4. Is Arduino easy to learn?Arduino is cost-effective and easily accessible. Arduino is easier to learn as a programming language as it is a simplified version of the C++ programming language. Arduino is cross-platform which makes it easy to run on any sort of device compared to other microcontrollers which can only run on windows.5. What is the difference between Arduino and Raspberry Pi?The 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. All the additional hardware on Arduino Board is for power supply, programming and IO Connectivity.6. Why is Arduino so popular?So the Arduino hardware is easy, the Arduino IDE is simple, and the code itself is much easier to comprehend (than trying to program an off-the-shelf microcontroller). ... Another reason Arduino is so popular is because there are many people using it which means there's a lot of examples out there to work with.7. Can I sell my Arduino project?Yes, with the following conditions: Physically embedding an Arduino board inside a commercial product does not require you to disclose or open-source any information about its design. ... You may manufacture and sell the resulting product.8. Do you have to use the Arduino IDE?Can I program an Arduino board without the Arduino IDE? Yes, you can use Create web editor to program your board without the need of download the classic IDE.9. Can I use Python in Arduino?Arduino uses its own programming language, which is similar to C++. However, it's possible to use Arduino with Python or another high-level programming language. In fact, platforms like Arduino work well with Python, especially for applications that require integration with sensors and other physical devices.10. What language does Arduino code in?Arduino is programmed with a c/c++ 'dialect'. Most c/c++ will work but much of the standard libraries will not work.11. Which language is best for Arduino?Any language that has a compiler that generates Arduino compatible machine code will be perfect. As of this moment , a subset of C / C++ is the only language that is supported by the Arduino IDE.12. How do I program an Arduino?1) Use your Arduino Uno on the Arduino Web IDE.2) Use your Arduino Uno on the Arduino Desktop IDE. Install the board drivers. Open your first sketch. Select your board type and port. Upload the program. Learn more on the Desktop IDE.3) Tutorials.13. Can Arduino connect to WiFi?Connect your Arduino to the internet by adding ESP8266 WiFi Module ... Adding this module to your Arduino UNO will open you to more and exciting projects.14. Can an Arduino run Linux?Arduino have a couple of boards that support running a variant of Linux called Linino: The Arduino Yún is a microcontroller board based on the ATmega32u4 and the Atheros AR9331. The Atheros processor supports a Linux distribution based on OpenWrt named Linino OS.15. What should I learn before Arduino?Before learning Arduino you need to have knowledge of basic programming. You can choose any language like C, C++ or Java. And apart from that you need to have basic idea about electronic devices like which part it is?, How it works? etc.16. Where do I program Arduino?Arduino programs are written in the Arduino Integrated Development Environment (IDE). Arduino IDE is a special software running on your system that allows you to write sketches (synonym for program in Arduino language) for different Arduino boards.17. How many types of Arduino are there?Top 6 Different Types of ArduinoArduino UNO. The development of Arduino UNO board is considered as new compared to other Arduino boards.LilyPad ArduinoArduino MegaArduino LeonardoArduino Red BoardArduino Shields18. Is Arduino good for beginners?Arduino is easily accessible - even for those who don't know much about electronics. Arduino boards are simple a type of microcontroller. They are able to read inputs from the sensors and turn those inputs into output. Arduino is the best for beginners looking to get started with electronics for the first time.19. Which is more powerful Raspberry Pi or Arduino?Given those differences you might think a Raspberry Pi is so much more powerful and capable than Arduino, so you should use that. ... Raspberry Pi has 8. Individual I/O pins in Arduino can drive 40mA while Raspberry Pi GPIO pins can each drive a maximum of 16mA.

ⅠIntroduction RTC is an abbreviation for Real-Time Clock. RTC modules are simply TIME and DATE remembering systems with a battery setup that keeps the module running in the absence of external power. This keeps the TIME and DATE current. As a result, we can get accurate TIME and DATE from the RTC module whenever we want. Catalog ⅠIntroduction Ⅱ RTC Module Explaintion 1.1 What is RTC module？ 1.2 Timing Ⅲ DS1302 RTC Module Basics 3.1 DS1302 RTC Module Pinout 3.2 DS1302 Pin Configuration 3.3 Features 3.4 Technical Specifications  3.5 Block Diagram of DS1302 RTC Chip Ⅳ DS1302 RTC Module with Arduino 4.1 Setting up the Hardware 4.2 Making the Code Ⅴ FAQ   Ⅱ RTC Module Explaintion 1.1 What is RTC module？ A real-time clock (RTC) is an electronic device that measures the passage of time (typically in the form of an integrated circuit). Although the term is most commonly associated with devices found in personal computers, servers, and embedded systems, RTCs can be found in almost any electronic device that requires an accurate time of day. A real-time clock mechanism and a long-lasting battery are used by an RTC module to keep track of the time. On a small board with five pins, the module contains a 3V lithium-ion battery, a 32 kHz crystal, and a DS1302 chip. The DS1302 chip is extremely power efficient and can run for up to 5 years on a 3V lithium battery. Figure1:RTC Module     The power supply voltage  is 5 volts. The serial  I2C  communication protocol is used by the RTC module.  which makes interfacing with the microcontroller very simple. Aside from VCC and GND, only two pins (CLK and DAT) are required for interfacing with  Arduino . CLK and DAT are the required SCL and SDA pins for  I2C communication, respectively, while RST is the reset pin (optional).   1.2 Timing The majority of RTCs use a crystal oscillator,[8][9] but some can use the power line frequency.  The crystal frequency is typically 32.768 kHz, which is also the frequency used in quartz clocks and watches. It is a convenient rate to use with simple binary counter circuits because it is exactly 215 cycles per second. The low frequency saves power while remaining above the range of human hearing. The temperature has little effect on the size of these crystals' quartz tuning forks, so the temperature has little effect on their frequency. Some RTCs employ a micromechanical resonator on the RTC's silicon chip. This reduces the size and cost of an RTC by reducing the number of parts. Micromechanical resonators are much more temperature-sensitive than quartz resonators. So, using an electronic thermometer and electronic logic, compensate for temperature changes. Typical crystal RTC accuracy specifications range from 100 to 20 parts per million (8.6 to 1.7 seconds per day), but temperature-compensated RTC ICs are available with accuracy as low as 5 parts per million. In practice, this is adequate for celestial navigation, the traditional function of a chronometer. Chip-scale atomic clocks became available in 2011. Despite being significantly more expensive and power-hungry (120 mW vs. 1 W), they keep time to within 50 parts per trillion.   Ⅱ RTC Module Related Video: What is RTC and how it is working || real time clock|| diyproject || graspelectronics RTC Module Video Description: what is rtc ? and how it is working ? RTC stands for real tme clock. RTC module code  is ds3231 the code is given in the datasheet for all components  . it is work in 3.3v  5v may kill the module. it is used to maintain accurate time keeping when main power to the device is interrupted. The rtc maintan maintains second,hours, day,date, month and year information. Real time clockThe date at end of the month is automatically adjusted for month with fewer then 31 days including corrections for leap years.   Ⅲ DS1302 RTC Module Basics Before we start this project, we will have a look at basics of DS1302 RTC Module. 3.1 DS1302 RTC Module Pinout Figure2: Pinout   3.2 DS1302 Pin Configuration Pin No. Pin Name Description 1 Vcc2 Second supply input, when Vcc2 is greater than Vcc1 + 0.2V, DS1302 powers through this pin 2,3 X1 and X2 For connecting external crystal oscillator of 32.768kHz 4 GND Ground 5 CE This pin set to HIGH during a Read or a Write 6 I/O (Data Line) This is the bi-directional data pin to 3-wire interface 7 SCLK(Serial Clock) Used to synchronize data movement on the serial interface 8 Vcc1 Rechargeable energy source connected to this pin   3.3 Features Minutes, seconds, date, hours, month, day of the week, year, and leap-year compensation up to 2100 are all counted in real-time.Single and multiple (Burst mode) data transfers for Clock or RAM data read and write31*8 general-purpose battery-powered RAMSimple interface based on three TTL-compatible wiresFull operation from 2V to 5.5VSmall sizepin DIP and 8-pin SO packages are available. 3.4 Technical Specifications 3.3V is the typical supply voltage.Voltage range (concerning ground) on any pin: -0.5V to 7.0°CTemperature range (commercial): 0°C to +70°CTemperature range (Industrial): -40°C to +85°CTemperature range for storage: -55°C to +125°CTemperature for Soldering: 260°C Note: The DS1302 Datasheet, which is linked at the bottom of this page, contains all of the technical information.  3.5 Block Diagram of DS1302 RTC Chip Figure3:Diagram   3.6 How to Use a DS1302 Chip？ A typical DS1302 operating circuit is shown below. The DS1302 has two power inputs, one from the cell and one from the controller. To generate the required frequency, a crystal oscillator with a frequency of 32.768 kHz is used. The data line, reset pin, and serial-clock pins of the DS1302 are connected to the microcontroller for interfacing. Figure4:Example   Ⅳ DS1302 RTC Module with Arduino 4.1 Setting up the Hardware Pins A4 and  A5  on the  Arduino are dedicated to I2C communication. However, with the assistance of software code, any pin can be used to serve the purpose. This is known as a software I2C bus. For our purpose, we will use the "Rtc by Makuna" library, which can be found in the Arduino IDE's Tools -> Manage Libraries... menu. Following installation, the examples provided with the library can be used to learn more about the functions and initialization methods. Figure5:Library Manager Arduino  To use the following code, connect the RTC module's DAT, CLK, and RST pins to Arduino's digital pins 6, 7, and 8. 4.2 Making the Code Now we must write the C code to set the current date and time in the RTC module, read from the module, and write to the serial monitor every second.   Figure6 :Code for connection with RTC Module The line ThreeWire DatClkRst (6,7,8); creates a bundle of three wires that will be used to initialize the object Rtc from the RtcDS1302 class using the command RtcDS1302ThreeWire> Rtc(DatClkRst); The function SetDateTime resets the DS1302 chip's date and time. The date and time at the time of Arduino's C code compilation are saved in the RtcDateTime object "compiled." The loop() method has a one-second delay. Date and time are read from the RTC module and displayed on the serial monitor in each iteration. To learn how to use this RTC module, remove the line and flash the Arduino with the updated code again. Even if the Arduino's power is turned off or the RTC module is disconnected and reattached, the Arduino will be able to read and display the correct real-time.   Ⅴ FAQ 1. Which RTC module is best? Choosing The Right RTC For Your Project The DS-1307 is often the default choice for an RTC. ...The DS3234 has the distinction of using an SPI interface instead of I2C. ...The RV-1805 draws so little power that this Sparkfun module gets by without a backup battery at all. 2. What is RTC module DS3231? The DS3231 is a low-cost, extremely accurate I2C real-time clock (RTC) with an integrated temperature- compensated crystal oscillator (TCXO) and crystal. The device incorporates a battery input, and maintains accurate timekeeping when main power to the device is interrupted. 3. What is RTC in mobile phone? A real-time clock (RTC) is an electronic device (most often in the form of an integrated circuit) that measures the passage of time. 4. What is RTC in laptop? The real-time clock, or RTC, maintains the internal clock … in real time. That is how the laptop knows the time as well as the date whenever you turn it on. ... Or you can keep the laptop plugged into an AC source. 5. Does RTC work without battery? The RTC module accurately keeps time with a precise oscillator and is maintained with a small battery (not included). 6. How does RTC module work? An RTC maintains its clock by counting the cycles of an oscillator – usually an external 32.768kHz crystal oscillator circuit, an internal capacitor based oscillator, or even an embedded quartz crystal. Some can detect transitions and count the periodicity of an input that may be connected. 7. What is the difference between DS1307 and DS3231? The main difference between the DS3231 and DS1370 is the accuracy of time-keeping. DS1307 comes with an external 32kHz crystal for time-keeping whose oscillation frequency is easily affected by external temperature. This usually results with the clock being off by around five or so minutes per month.  

ⅠIntroductionA direct current (DC) motor is a type of rotary electrical motor that converts direct current electrical energy into mechanical energy. The most common types are based on magnetic field forces. Almost all types of DC motors have an internal mechanism, either electromechanical or electronic, that changes the direction of current in a portion of the motor on a regular basis.  CatalogⅠIntroductionⅡ Dc Motor Related VideoⅢ What is a DC Motor?Ⅳ How DC Motors Work？Ⅴ Types of DC Motors5.1 Shunt Wound DC Motor5.2 Series Wound DC Motor5.3 Compound Wound DC MotorⅥ Applications of DC MotorsⅦ Popular DC Motor BrandsⅧ What is the Difference Between an AC and DC Motor?8.1 AC Motor and It’s Mechanism8.2 Difference Between AC and DC MotorⅨ FAQ Ⅱ Dc Motor Related VideoDC Motor, How it works? Dc Motor Video Description：The working of a DC motor is well explained in this video with the help of animation. Construction details of DC Motor, Shunt & Series motor, concept of back EMF are also explained in this video. Ⅲ What is a DC Motor?A DC motor is an electric motor that runs on direct current (DC) (unlike an induction motor that operates via an alternating current). A direct current motor converts direct current electrical energy into mechanical energy.A direct current (DC) motor is a type of rotary electrical motor that converts direct current electrical energy into mechanical energy. The most common types are based on magnetic field forces. Almost all types of DC motors have an internal mechanism, either electromechanical or electronic, that changes the direction of current in a portion of the motor regularly. Figure1：What is a DC Motor?Ⅳ How DC Motors Work？Any rotary electrical machine that shifts direct current electrical energy into mechanical energy is referred to as a 'DC motor.' Small motors in toys and appliances to large mechanisms that power vehicles, pull elevators and hoists, and drive steel rolling mills are examples of DC motors. But how do direct current motors work?A stator and an armature are the two main components of a direct current motor. The stator is the motor's stationary component, while the armature rotates. In a direct current motor, the stator generates a rotating magnetic field that causes the armature to rotate.A simple DC motor generates an electromagnetic field aligned with the center of the coil by using a stationary set of magnets in the stator and a coil of wire with a current running through it. To concentrate the magnetic field, one or more windings of insulated wire are wrapped around the core of the motor.Insulated wire windings are connected to a commutator (a rotary electrical switch), which applies an electrical current to the windings. The commutator enables each armature coil to be energized in turn, resulting in a consistent rotating force (known as torque).When the coils are on and off in sequence, a rotating magnetic field is created that interacts with the varying fields of the stator's stationary magnets to produce torque, which causes it to rotate. These key operating principles of direct current motors enable them to convert electrical energy from direct current into mechanical energy via rotating movement, which can then be used for object propulsion. Figure2：working principleⅤ Types of DC MotorsDirect motors are classified based on how the field winding is connected to the armature.There are 3 main types of DC Motors: 5.1 Shunt Wound DC MotorFigure3：Shunt Wound DC Motor A DC shunt motor (also known as a shunt wound DC motor) is a type of self-excited DC motor in which the field windings are shunted to or paralleled with the motor's armature winding. The armature and field windings are exposed to the same supply voltage because they are connected in parallel. Though, as shown in the figure below, there are separate branches for the flow of armature current and field current.Figure4：DC shunt motor    5.2 Series Wound DC MotorFigure5：Series Wound DC Motor A series wound DC motor like a shunt wound DC motor or a compound wound DC motor, is a type of self-excited DC motor that gets its name from the fact that the field winding is connected internally in series to the armature winding. As a result, unlike a shunt motor, the field winding is exposed to the entire armature current.  Figure6：wound DC motor circuit 5.3 Compound Wound DC Motor A compound wound DC motor (also known as a DC compound motor) is a type of self-excited motor that is composed of both series and shunt field coils connected to the armature winding, as shown in the figure below.  Figure7：DC compound motor Both field coils provide the required amount of magnetic flux, which connects with the armature coil and produces the torque required to allow rotation at the desired speed. As we can see, a compound wound DC motor is created by combining a shunt wound DC motor and a series wound DC motor to achieve the best of both types. A shunt-wound DC motor, like a shunt-wound AC motor, has an extremely efficient speed regulation characteristic, whereas a DC series motor has a high starting torque.As a result, the compound wound DC motor strikes a balance between these two characteristics, offering a good combination of proper speed regulation and high starting torque.Though its starting torque is lower than that of a DC motor, and its speed regulation is not as good as that of a shunt DC motor. The overall characteristics of a DC shunt motor fall somewhere between these two extremes. Studying our electrical MCQs will help you learn more about motors.Types of Compound Wound DC Motor：Long Shunt Compound Wound DC MotorShort Shunt Compound Wound DC MotorCumulative Compounding of DC Motor  Ⅵ Applications of DC MotorsBecause of the various types of DC motors available, DC motors have a wide range of applications. The preceding section discussed some of the various applications and circumstances in which DC motors are used, as well as the advantages of the various types of motors.While each type has advantages, a DC motor can be used in a variety of ways. Small DC motors are used in tools, toys, and various household appliances at home. Conveyors and turntables are examples of DC motor applications in retail, while large DC motor applications in the industry include braking and reversing.Here are a few more specific uses for DC motors:DC motors for fansDC motors for pumpsDC motors for toysDC motors for electric carsDC motors for robotsDC motors for bikes Ⅶ Popular DC Motor BrandsPlease search the below online to view DC motors produced by some of our most popular brands.                                                                                  RS PRO                                                                               Crouzet                                                                                   Maxon  Ⅷ What is the Difference Between an AC and DC Motor?Electric motors are broadly classified into two types. They are the alternating current (AC) motor and the direct current (DC) motor. The AC motor is powered by alternating current, whereas the DC motor is powered by direct current.Figure8：Difference Between an AC and DC Motor 8.1 AC Motor and It’s MechanismA hoop of electromagnets is organized across the outside of an AC motor (making up the stator). Which can be configured to generate a rotating magnetic field. An axle made of solid metal, a wire loop, a coil, a squirrel cage made of metal bars, and interconnections are all found inside the stator. Other freely rotating metal parts that can conduct electricity are also present.The rotor, which is suspended within the magnetic field, acts as an electrical conductor. The magnetic field is constantly changing as a result of its rotation. The magnetic field generates (or induces) an electric current inside the rotor, according to Faraday's law of electromagnetism. If the conductor is a ring or a wire, the current flows in a loop around it. Instead, eddy currents swirl around a solid piece of metal if the conductor is simply a solid piece of metal.In any case, the induced current generates its magnetic field and, according to another electromagnetism law (Lenz's law), attempts to stop whatever is causing the rotating magnetic field by rotating as well. AC motors provide a relatively efficient way of generating mechanical energy from a simple electrical input signal.  Figure9：AC motor and DC notor 8.2 Difference Between AC and DC MotorAC MotorDC MotorAC motors do not require current conversion.Current is converted from alternative (AC) to direct (DC) output in DC motors.AC motors are available in two-phase, single-phase, and three-phase configurations.DC motors are all single phase.Armatures in alternating current motors do not rotate in tandem with the continuous rotation of magnetic fields.The armature rotates while the magnetic field rotates in DC motors.Repairing is not expensive.Repairs are quite expensive.Have a longer life expectancy.Have a shorter life expectancy.To begin operation, AC motors require effective starting equipment such as a capacitor.DC motors do not require any external assistance to begin operation.There are three input terminals.You should have two input terminals.When the load changes, AC motors are slow to respond.DC motors respond quickly to changes in load.AC motors are suitable for applications requiring high speed and variable torque.DC motors are appropriate for applications requiring high torque and variable speed.The speed of an alternating current motor is simply controlled by varying the frequency of the current.The speed of a direct current motor is controlled by varying the current of the armature winding.Implemented for large-scale industrial use.Intended for small-scale domestic use.The distinction between AC and DC motors is significant not only from a technical standpoint. It is also required for practical demonstrations. Whether you're an engineer or a business enthusiast, you can't choose the right one for your needs unless you understand the fundamental technical differences. Ⅸ FAQ1. How can you tell if a motor is AC or DC?Look for the stator core construction and rotor. If there is no commutator, then it is a AC motor. If there is a commutator and brushes, it may be either a DC motor or an AC commutator motor (Universal motor).2. Which motor is powerful AC or DC?AC motors are generally considered to be more powerful than DC motors because they can generate higher torque by using a more powerful current. However, DC motors are typically more efficient and make better use of their input energy.3. Why starter is used in DC motor?Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor's armature winding and restricts the current to an acceptable level.4. What is the voltage of a DC motor?Typical DC motors may operate on as few as 1.5 Volts or up to 100 Volts or more. Roboticists often use motors that operate on 6, 12, or 24 volts because most robots are battery powered, and batteries are typically available with these values. Operating Current.5. Is a brushless motor AC or DC?There are two types of commonly used DC motors: Brushed motors, and brushless motors (or BLDC motors). As their names imply, DC brushed motors have brushes, which are used to commutate the motor to cause it to spin. Brushless motors replace the mechanical commutation function with electronic control.6.Does Tesla use DC or AC motors?Tesla, for example, uses alternating current (AC) induction motors in the Model S but uses permanent-magnet direct current (DC) motors in its Model 3. There are upsides to both types of motor, but generally, induction motors are somewhat less efficient than permanent-magnet motors at full load.7. Are Tesla motors brushless?Today, all the hybrids are powered by DC brushless drives, with no exceptions. The only notable uses of induction drives have been the General Motors EV-1; the AC Propulsion vehicles, including the tzero; and the Tesla Roadster. Both DC brushless and induction drives use motors having similar stators.

Introduction   If you've heard much about furnaces and their components, you've almost certainly heard the term "blower." Because the blower is an important component of the furnace, we'll explain what it is, how it works, and what to expect if it develops problems.   The blower is one of your furnace's most aptly named components: its sole purpose is to blow hot air through the ducts and into your home.   There is an important distinction to be made between a blower motor and a blower fan. Although they are frequently referred to as the "blower," the majority of problems you will encounter will be with the blower motor itself. After all, the blower fan is merely an accessory to the motor.   Figure1: Blower motors are able to move large volumes of air since they use fan cages in enclosed spaces.   Catolog Introduction Ⅰ What Is a Blower Motor? Ⅱ How does a Blower Motor Works? Ⅲ Why Blower Motor need Maintenance? Ⅳ Types of Blower Motors Ⅴ What is the Components of a Blower Motor? Ⅵ Where is a Blower Motor Located? Ⅶ How to test the blower motor? Ⅷ What are Some Of The Symptoms of a Failing Blower Motor? Ⅸ Can I Change Out The Blower Motor Myself? Ⅹ What Steps DO I need to take for this DIY Blower Motor Replacement? Ⅺ FAQ     Ⅰ What Is a Blower Motor?   A blower motor is a motor that drives the fan in a car's heating and air conditioning system.   A blower motor is a part of a home's HVAC system. When the heating system is operated, the motor blows heated air through vents. When the air conditioning system is on, some blower motors blow cold air. Blower motors are classified into two types: single-speed motors and variable-speed motors. Single-speed blower motors only produce one speed of airflow. Variable-speed motors change their speed to blow air at different levels. A properly functioning blower motor is still a significant part of your home's HVAC system. The blower motor is critical in keeping your home at a comfortable temperature.       Understand Blower Motor Circuits to Better Diagnose Problems (Season 5/E12)       Ⅱ How does a Blower Motor Works?     ostats cooperated with the home's heating and cooling systems to monitor the temperature. When the temperature falls below the thermostat setting, the furnace activates. The furnace generates hot (or cold) air, which must then circulate throughout your home. This is when the blower motor kicks in.   A blower motor circulates the heated or cooled air produced by the furnace throughout the home to ensure the temperature meets the temperature set on the thermostat. It accomplishes this by spinning a fan, which blows air through your home's ventilation system. Even a small blower motor can move a significant amount of air.       Figure2: motor circuit   When in use, single-speed motors operate at one speed and full energy capacity. The thermostat controls the operation of your blower motor by telling it when to turn on and off. Single-speed motors can cause cold spots because they only run when the thermostat signals them to. Variable-speed motors, on the other hand, blow air at higher and lower speeds as needed. As a result, this motor contributes to a more evenly distributed temperature throughout your home. Furthermore, variable-speed motors are typically more energy-efficient than single-speed motors, allowing you to save money on your monthly energy bills.       Ⅲ Why Blower Motor need Maintenance?   One of the most obvious signs that your blower motor has failed is that your furnace is persistently working while the house remains cool. You can ensure your family's year-round comfort by properly maintaining your furnace's blower motor. When each heating season is coming, clean the fan blades, inspect the motor belt for wear and tear, and lubricate the motor adequately.   Even with proper maintenance, some problems can cause your blower motor to stop working. Common problems, for example, involve the resistor, fan relay, and climate control switches. An experienced HVAC professional, on the other hand, evaluates and repairs any problems with these components.     Figure3: blower motor in HVAC     Blower motor failure can also be caused by a worn-out bearing, a broken or worn-out motor, or an obstructed fan cage. However, routine maintenance, such as regular cleaning, keeps the motor clean. Furnaces are frequently found in basements and laundry rooms. As a result, dirt and even small lint particles frequently find their way into the engine, causing burnouts. In addition, dirt or debris falling down the ventilation system frequently obstructs the blower motor fan cage.       Ⅳ Types of Blower Motors   There are two types of blower motors. The first option is a single-speed transmission. When the thermostat indicates that the temperature in your home has dropped or increased beyond the desired setting, single-speed blower motors will activate.   The variable-speed blower motor is the second type of blower motor. Variable-speed blower motors are distinguished from single-speed blower motors by their ability to move at different speeds, allowing them to better command the flow of air in your home. Variable-speed blower motors use less energy. They consume 2-4 amps, whereas older-style motors consume 12 amps. The amount of electricity consumed by the motor is measured in amps. The slower speed also contributes to efficiency.   Variable motors also circulate the air in your home more frequently, preventing cold spots. Finally, variable speed blower motors are quieter than single-speed blower motors.       Ⅴ What is the Components of a Blower Motor?   The components of a blower motor can vary depending on the application, but they typically include:   a direct current motora fan housing that can be bolted down (also known as a wheel or cage)Some blower motors are wired differently than others, but the majority of systems use a few other components to control their operation, such as:a fan relay and a blower motor resistor   Figure4: components of a blower motor         Ⅵ Where is a Blower Motor Located?     A blower motor is typically found in the heater box, though each vehicle is slightly different. Some blower motors are easily accessible, while others are hidden beneath the dash. Blower motors are commonly found inside the passenger compartment for most passenger cars and trucks, but in some cases, the heater box, blower motor, or both are located in and accessed from, the engine compartment.       Figure5: Mazada3     Large vehicles, such as large SUVs and vans, may have multiple blower motors. In those cases, one blower motor is typically located in the front heater box and another somewhere in the rear of the vehicle. These vehicles may also have an additional heater core located in the passenger compartment's back end.       Ⅶ How to test the blower motor?   If the blower motor does not function properly, the blower motor has to be diagnosed preferentially. When the blower motor is on, the voltage at the blower motor connector is typically measured. If there is a voltage at the motor (at least 4-6 Volts at low speed and 12 Volts at high speed), but the motor does not run, the motor is defective or jammed. Voltage testing of the blower motor The voltage at the blower motor is being tested. If there is a voltage at the motor (at least 4-6 Volts at low speed and 12 Volts at high speed), but the motor does not run, the motor is defective. Leaves, twigs, nuts, and pieces of a ripped cabin filter can all jam the blower motor's blade. This is a common occurrence in many automobiles.   If there is no voltage at the motor, the entire blower motor circuit, beginning with a fuse, has to be tested. See also: how to test a fuse in a car.     Figure6 : Testing the voltage at the blower motor. If there is a voltage at the motor (at least 4-6 Volt at low speed and 12 Volt at high speed), but the motor doesn't run, the motor is bad.       Ⅷ What are Some Of The Symptoms of a Failing Blower Motor? When the blower motor is faulty , it will come out some of the symptoms of a bad or a failing blower motor.   Low Or Inadequate Airflow From the Vents Low or shaky airflow from the vents is one of the most noticeable signs of a faulty blower motor. When you turn on the A/C or heat, the vents will blow out air, but it will be much lower or fainter than you're used to. This is a good indication that your blower motor is either broken or starting to wear out. A faulty blower motor will not properly cool or heat a vehicle. The temperature in the car's cabin will also be uncontrollable.     The Fan Will Only Blow At Specific Speeds Another sign of a faulty blower motor is a motor that only operates at certain speeds. Many blower motors are designed and built to operate at different speeds. Their design allows for the control of various cabin temperatures. You have a faulty blower motor if it does not push air at any of its specific settings.     There is No Air Coming From The Vents When there is no air flow from your vehicle's vents when the A/C or heat is turned on, this indicates that you have a faulty blower motor. If your blower motor fails or short circuits, there will be no airflow produced for the system. This type of situation necessitates a complete replacement of the blower motor in order to restore proper system operation.   Figure67: No Air Coming From The Vents     Smoke Is Being Blown At You Have you noticed a burning odor while driving your car? Then you should pull over as soon as possible. You could have a blown-out blower motor. Your blower motor may also have bad wiring or a short circuit. That burned or short-circuited blower motor could be emitting burning odors and smoke that you should not inhale or endure. If you inspect your blower motor and discover a blown fuse in the blower motor circuit, you have proof that the circuit was overloaded.       Ⅸ Can I Change Out The Blower Motor Myself?   You certainly can. You can successfully replace the blower motor if you have the patience, the right tools, and the energy.   What tools are required for a blow motor replacement? The following tools are required for a successful blow motor change out:   Set of Rachet and SocketService manual for a small flat heat screwdriverNew cabin air filter and blower motorCleaning cloths and flashlights       Ⅹ What Steps DO I need to take for this DIY Blower Motor Replacement?   Check that you're parked on a level surface and that your parking brake is engaged. Remove your car's hood and disconnect the battery.     Step1: Find the blower-motor service manual. Important Note: If your vehicle was built prior to the mid-late 1990s, your blower motor may be located inside the engine bay, on the firewall on the passenger side. It should be easy to find.     Step2: Remove the lower trim from your glove box. This may necessitate the removal of a few bolts.Examine your supplies for clips and plastic connectors. Please be gentle and mild with them if you do. You want them to fit back together properly.     Step3:  Take a look in your glove box. Then take it out. This usually only necessitates a push of the retaining clips to the side, allowing you to unlatch the glovebox from its housing. With your flashlight, enter the footwell.   Step4: Then, raise your eyes to the ceiling until you see the blower motor. Look for three or six bolts that keep it together.   Step5: Use your sockets and ratchet kit to remove the bolts. These bolts are almost certainly metric-sized bolts.The motor assembly for your blower should easily slide out. This should also allow you to disconnect the HVAC vent connections. It is now time to disconnect the electrical power connector. You can dislodge the clips by hand or by using a small flathead screwdriver.   Step6: Use your old blower as a template for installing the new blower. Allow plenty of time to install the new blower. You may also need to replace a gasket.You can now connect the vehicle's power supply. After that, it's time to reinstall the HVAC vents. Then, carefully slide the blower motor into the bracket. You can now secure your new blower.     Step7:  The next step is to replace your glovebox and lower trim panel. After that, you can reconnect the battery in your vehicle. You are now ready to start your engine and test the blower motor's operation. You can accomplish this by selecting a few different levels of A/C and heat.   Step8: Check to see if there is a strong blow coming from the vents and if there are any unusual noises.     Ⅺ FAQ   1. How Does A Blower Motor Work in a Vehicle? Once you turn on the vehicle’s heater, the blower motor will blow that heat across the core. Then it will send that heat through the vents, so that you stay warm as you drive your vehicle. The same is true once you turn on your vehicle’s air conditioning. The same process will happen, except the cold air will blow through the vents, to keep you cool as you drive your vehicle.     2. What is The Average Blower Motor Replacement Cost? The average cost of a blower motor replacement can fall between $340 and $400. Labor alone for a blower motor replacement can cost up to $300. Of course, these figures are approximate. You will have to visit a mechanic so that he or she can look at your vehicle and give you an exact value.   3. What causes blower motor failure? Like other components in your HVAC system, the blower motor can wear down over time. Some of the reasons a blower motor might fail are overheating, and excessive moisture. ... Blower motors that are clogged with debris, or that become saturated with moisture can fail due to overworking or electrical shorts.     4. What does a bad blower motor sound like? A defective blower motor will make a continuous sound noticeable by the passengers in the vehicle. It can manifest as a knocking, whirring, clunking, vibrating, squealing, or whining noise that persists until the blower motor is replaced.       5. How long do blower motors last? 10 to 20 years The blower motor in your home or office should last anywhere from 10 to 20 years. Modern sealed bearings and sealed bushings can push the lifespan to its maximum of 20 years.     6. How long does it take to replace a blower motor? DIY or Pro Installation: It's going to take a furnace repair technician between 45 minutes and 90 minutes to replace the motor, clean the fan, adjust the motor, test it and put the furnace back together. The biggest factor is how easy it is to get the assembly out.     7. Can you drive a car with a bad blower motor? A bad heater blower motor will not affect the safety of your car, with the possible exception of you not being able to clear the windshield of snow, ice, or condensation if the defrosters don't work. But you won't be comfortable inside your car, especially during the cold of winter and the heat of summer.          

 This article is a brief introduction to contactor.  Catalog  I. What is a Contactor?II. Differences Between Contactor and RelaysIII. Contactor Working PrincipleIV. About Arc SuppressionFAQ I. What is a Contactor? As an essential part of the motor control gear, the most widespread switching device used in a starter is the a,c. airbrake contactor which consists of contact assemblies actuated by electromagnetic action. An operating coil is enclosed by the magnetic yoke, as well as when energized attracts an armature to which is attached a set of moving contacts which make with a set of stationary contacts. Modern contractors use a silver alloy contact tip, normally silver–cadmium oxide or silver–tin oxide alloy attached to a brass or copper backing strip. The choice of tip material is critical and is normally established after many types of tests.  Note: The rating of the contactor depends on the size, shape, and material of the contacts and on the efficiency of the arc extinction method used. An electrical contactor is an electromagnetic switch similar to a relay. It is a switch that can be controlled with the current/pulse to switch over an electrically powered circuit. II. Differences Between Contactor and Relays Let me put forward a basic question firstly:If you see in industrial control panels, both relays and contractors are used for the same purpose, so why different names? Both of them perform the same task. The relay is usually used in low voltage paths such as switching tube-light or small LEDs. The contactor is used in electrical circuits of industrial motors or other heavy applications. So, the difference is from an application point of view. The basic working principle is the same for both. The relay behaves similarly to how a contractor works. If you want to switch circuits with high voltages, use contactors and if you want to switch light voltages then the relay is ready for you.  It is important to note here the difference between protection and switching. A relay is a protection device whereas a contactor cannot assure you about protection. The relay can differentiate between normal & abnormal conditions and give command accordingly which contactor cannot. Switching means to break and make a circuit and a contactor is mainly used for that purpose. III. Contactor Working Principle When the contactor coil is de-energized, gravity or a spring returns the electromagnet core to its initial position and opens the contacts. For contactors energized with alternating current, a small part of the core is surrounded by a shading coil, which slightly delays the magnetic flux in the core. The following video will help you understand the working principle of contactor more intuitively:  IV. About Arc Suppression Most motor control contactors at low voltages (600 volts and less) are air brake contactors; air at atmospheric pressure surrounds the contacts and extinguishes the arc when interrupting the circuit. Modern medium-voltage AC motor controllers use vacuum contactors. High voltage AC contactors (greater than 1,000 volts) may use a vacuum or an inert gas around the contacts. High voltage DC contactors (greater than 600V) still rely on air within specially designed arc-chutes to break the arc energy. High-voltage electric locomotives may be isolated from their overhead supply by roof-mounted circuit breakers actuated by compressed air; the same air supply may be used to "blow out" any arc that forms.Without adequate contact protection, the occurrence of electric current arcing causes significant degradation of the contacts, which suffer significant damage. An electrical arc occurs between the two contact points (electrodes) when they transition from a closed to an open (break arc) or from an open to a closed (make arc). The break arc is typically more energetic and thus more destructive. Without adequate contact protection, the occurrence of electric current arcing causes significant degradation of the contacts, which suffer significant damage. An electrical arc occurs between the two contact points (electrodes) when they transition from a closed to an open (break arc) or from an open to a closed (make arc). The break arc is typically more energetic and thus more destructive.FAQ 1. What is the main function of contactor?Function of contactor, generally used for connected and disconnected of electric current supply. Usually in use for applications: motors, heater, lighting or electric power distribution. 2. Why do we need contactors?Contactors are used for high power applications. They allow a lower voltage and current to switch a much higher power circuit, so they are generally larger and more heavy-duty than control relays, enabling them to switch higher power loads on and off for many thousands of cycles. 3. How a contactor is wired?Break your circuit, L N E through your contactor. Link a permanent live and a neutral from your supply to your coil (Al + A2) then use your switch feed to your photocell from A1, and switch the wire to the switched phase of your contactor load. This should now open when light, close when dark. 4. What is NO and NC In Contactor?Normally Open (NO) and Normally Closed (NC) terms refer to type of dry contact or wet contact. Put very simply, a Normally Open sensor will have no current when in a normal state but when it enters an alarm state it will have +5V applied to the circuit. 5. How many types of contactors are there?The contacts are classified as power contact, auxiliary contact, and contact spring. There are two types of power contact; stationary contact and movable contact. The material used for the contacts has stable arc resistance and high welding resistance. 6. Why contactor is used?Contactors are used for high power applications. They allow a lower voltage and current to switch a much higher power circuit, so they are generally larger and more heavy-duty than control relays, enabling them to switch higher power loads on and off for many thousands of cycles 7. What is the difference between a relay and a contactor?A contactor joins 2 poles together, without a common circuit between them, while a relay has a common contact that connects to a neutral position. Additionally, contactors are commonly rated for up to 1000V, while relays are usually rated to only 250V. 8. What are the types of contactors?There are different types of contacts in a contactor, and they are; auxiliary contact, power contact, and contact spring. The power contact has two types that are; stationary and movable contact. Material for making contacts must have a high welding resistance and stable arc resistance. 9. What are the three major parts of a contactor or relay?There are three major parts of a contactor or relay: the coil, mechanical linkage and contacts. The coil is used to create a magnetic field and is rated based on voltage (24 V, 120 V, 208/204 V, 480 V). The mechanical linkage connects the armature to the contacts when the coil is energized, completing the circuit. 10. How contactor is connected?A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch. Unlike general-purpose relays, contactors are designed to be directly connected to high-current load devices. 

This article introduces stepper motor at full length.There are five parts of this article--the definition of stepper motor; types of steppers; how a stepper motor work; how to select and the basic wiring.  CatalogI. What is a Stepper Motor?II. Types of Stepper MotorsIII. How Does a Stepper Motor WorkIV. How to Select a Stepper motorV. Basic Wiring of Stepper MotorFAQI. What is a Stepper Motor? A Stepper Motor or a step motor is a brushless, synchronous motor which divides a full rotation into a number of steps. Unlike a brushless DC motor which rotates continuously when a fixed DC voltage is applied to it, a step motor rotates in discrete step angles. The Stepper Motors therefore are manufactured with steps per revolution of 12, 24, 72, 144, 180, and 200, resulting in stepping angles of 30, 15, 5, 2.5, 2, and 1.8 degrees per step. The stepper motor can be controlled with or without feedback.   II. Types of Stepper MotorThere are a wide variety of stepper types, some of which require very specialized drivers. By construction the step motors come into three broad classes: 1.Permanent Magnet StepperPermanent magnet motors tend to "cog" as you twist the rotor with your fingers, while variable reluctance motors almost spin freely (although they may cog slightly because of residual magnetization in the rotor). You can also distinguish between the two varieties with an ohmmeter. Variable reluctance motors usually have three (sometimes four) windings, with a common return, while permanent magnet motors usually have two independent windings, with or without center taps. Center-tapped windings are used in unipolar permanent magnet motors. 2.Variable Reluctance StepperJust as resistance determines the flow of electric current, reluctance determines the flow of magnetic flux. In a variable reluctance (VR) stepper, the rotor turns at a specific angle to minimize the reluctance between opposite windings in the stator. The primary advantage of VR steppers is that they have an excellent angular resolution. The primary disadvantage is low torque. 3. Hybrid Step MotorHybrid stepper motors provide excellent performance in areas of torque, speed, and step resolution. This type of motor provides a combination of the best features available on both the PM and VR types of stepper motors. Permanent magnet and hybrid stepper motors are two types of the most commonly used stepper motors. Permanent magnet and hybrid stepper motors are two types of the most commonly used stepper motors. III. How Does a Stepper Motor Work Stepper motors consist of a permanent magnetic rotating shaft, called the rotor, and electromagnets on the stationary portion that surrounds the motor called the stator. Figure above illustrates one complete rotation of a stepper motor. At position 1, we can see that the rotor is beginning at the upper electromagnet, which is currently active (has voltage applied to it). To move the rotor clockwise (CW), the upper electromagnet is deactivated and the right electromagnet is activated, causing the rotor to move 90 degrees CW, aligning itself with the active magnet. This process is repeated in the same manner at the south and west electromagnets until we once again reach the starting position.  In the above example, we used a motor with a resolution of 90 degrees for demonstration purposes. In reality, this would not be a very practical motor for most applications. The average stepper motor's resolution -- the number of degrees rotated per pulse -- is much higher than this. For example, a motor with a resolution of 5 degrees would move its rotor 5 degrees per step, thereby requiring 72 pulses (steps) to complete a full 360-degree rotation. You may double the resolution of some motors by a process known as "half-stepping". Instead of switching the next electromagnet in the rotation on one at a time, with half-stepping you turn on both electromagnets, causing an equal attraction between, thereby doubling the resolution. As you can see in Figure 2, in the first position only the upper electromagnet is active, and the rotor is drawn completely to it. In position 2, both the top and right electromagnets are active, causing the rotor to position itself between the two active poles. Finally, in position 3, the top magnet is deactivated and the rotor is drawn all the way right. This process can then be repeated for the entire rotation.  IV. How to Select a Stepper Motor Selecting between a servo motor and a stepper motor can be quite a challenge involving the balancing of several design factors. Cost considerations, torque, speed, acceleration, and drive circuitry all play a role in selecting the best motor for your application.  At first, we need to know the basic differences between stepper and servo motors.   Stepper and servo motors differ in two key ways, in their basic construction and how they are controlled.  Stepper motors have a large number of poles, magnetic pairs of north and south poles generated either by a permanent magnet or an electric current, typically 50 to 100 poles. In comparison, servo motors have very few poles, often 4 to 12 in total. Each pole offers a natural stopping point for the motor shaft.  Driving a stepper motor to a precise position is much simpler than driving a servo motor. With a stepper motor, a single drive pulse will move the motor shaft one step, from one pole to the next. Since the step size of a given motor is fixed at a certain amount of rotation, moving to a precise position is simply a matter of sending the right number of pulses. In contrast servo motors read the difference between the current encoder position and the position they were commanded to and just the current required to move to the correct position.The greater number of poles allows a stepper motor to move accurately and precisely between each pole and allows a stepper to be operated without any position feedback for many applications. Servo motors often require a position encoder to keep track of the position of the motor shaft, especially if precise movements are required. Note that with today's digital electronics, stepper motors are much easier to control than servo motors. All in all, Selecting the best motor for your application depends on a few key design criteria for your system including cost, positional accuracy requirements, torque requirements, drive power availability, and acceleration requirements. Overall, servo motors are best for high speed, high torque applications while stepper motors are better suited for lower acceleration, high holding torque applications. V. Basic Wiring of Stepper Motor  Stepper motors are available in two basic wiring configurations, bipolar and unipolar. Unipolar motors have one winding with a center tap for each phase. This allows the motor direction to be reversed easily by changing which section of the phase is powered rather than reversing the flow of current. This allows the control circuitry to be very simple. Unipolar motors typically have six leads, three for each phase, but can also be found with five leads, with the center tap of both phases internally connected. Unipolar motors can be easily controlled with a microcontroller or stepper motor controller and are very affordable.  Bipolar motors have one or two windings without a center tap for each phase. In order for the direction of rotation to be reversed on a bipolar motor, the current direction needs to be reversed. This requirement makes the driving circuitry more complicated and is generally implemented with an H-bridge control arrangement or an H-bridge motor driver. While more complicated to drive, bipolar motors are much stronger for the same weight and size. Bipolar motors can be configured with series or parallel windings, allowing them to be driven with the lower current in series or higher inductance and greater torque in parallel. Bipolar motors generally have four or eight leads, two or four per phase, allowing them to be distinguished from the five and six-lead unipolar motors. FAQ 1. What is a stepper motor used for?The stepper motor is used for precise positioning with a motor, such as hard disk drives, robotics, antennas, telescopes, and some toys. Stepper motors cannot run at high speeds, but have a high holding torque. 2. What is a stepper motor and how does it work?Stepper motors are DC motors that move in discrete steps. They have multiple coils that are organized in groups called "phases". By energizing each phase in sequence, the motor will rotate, one step at a time. With a computer controlled stepping you can achieve very precise positioning and/or speed control. 3. What is the working principle of stepper motor?The basic working principle of the stepper motor is the following: By energizing one or more of the stator phases, a magnetic field is generated by the current flowing in the coil and the rotor aligns with this field. 4. Are stepper motors AC or DC?Stepper motors are DC motors that move in discrete steps. They have multiple coils that are organized in groups called "phases". By energizing each phase in sequence, the motor will rotate, one step at a time. With a computer controlled stepping you can achieve very precise positioning and/or speed control. 5. How long do stepper motors last?4.8 yearsThe typical lifetime for a stepper motor is 10,000 operating hours. This approximates to 4.8 years; given the stepper motor operates one eight-hour shift per day. The lifetime of a stepper motor may vary in regards to user application and how rigorous the stepper motor is run. 6. Do stepper motors need drivers?Stepper motors require a driver. There are usually 200 steps per revolution or 1.8 degrees per step (but they also can be “micro-stepped”). In general, you use an H-driver to reverse a DC motor, but it can also be done with a DPDT relay. 7. Do stepper motors go bad?Stepper motors very rarely go bad. It's possible, like a bearing fails. More often the wiring goes bad, or the stepper driver, or the driver overheats. 8. Why is it called stepper motor?Stepper motors are so named because each pulse of electricity turns the motor one step. Stepper motors are controlled by a driver, which sends the pulses into the motor causing it to turn. 9. What are the three types of stepper motor?There are three main types of stepper motors:Permanent Magnet Stepper. Variable Reluctance Stepper.Hybrid Syncronous Stepper. 10. How is stepper motor different from DC motor?The stepper motor operates in open loop whereas Direct current motor operates in closed loop. Stepper are are easy to control with the help of microprocessors and other controlling devices. Control of DC motor is not easy. ... DC motor has a continuous displacement and can be controlled accurately and positioned exactly.  11. Do stepper motors have brushes?Stepper motors are different from ordinary DC motors in at least four important ways. The first difference you notice is that they have no brushes or commutator (the parts of a DC motor that reverse the electrical current and keep the rotor—the rotating part of a motor—constantly turning in the same direction). 12. What voltage is a stepper motor?Stepper motors have a rated voltage and current. A typical stepper motor like our NEMA 17 might have a rated voltage of 2.8 Volts and a maximum current of 1.68 Amps. This basically means if you hook it up to 2.8 Volts it will draw 1.68 Amps. 13. Why do stepper motors fail?One of the major problems with a stepper motor is complete motor failure. This problem is caused by excessive current being sent to the device by the power supply. A short circuit in the wiring from the power supply to the motor cause this problem with the stepper motor. Some application will cause this short circuit. 14. Can stepper motors run continuously?Stepper motors fall somewhere in between a regular DC motor and a servo motor. They have the advantage that they can be positioned accurately, moved forward or backwards one 'step' at a time, but they can also rotate continuously. 15. How do I choose a stepper motor driver?A simple way to choose a stepper drive is to look for four things — voltage, current, microstepping, and maximum step pulse rate. Ensure that the drive can handle a wide range of current so that you can test the system at different voltage levels to fit your application.