The Kynix Blog

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.  

Introduction Latching relay is a new type of relay and also an automatic switch. Like other electromagnetic relays, it turns on and off the circuit automatically. The difference is that the normally closed or normally open state of it is completely dependent on the action of permanent magnets, and the switching state of it is triggered by a pulse electric signal of a certain width. It has the characteristics of power saving, stable performance, small size, large carrying capacity, and superior performance than general relays. Latching Relay Basics in 2 Minutes Catalog Introduction Ⅰ Working Principle 1.1 Action Principle 1.2 Action Process Ⅱ Main Functions and Advantages 2.1 Average View 2.2 Function Lists 2.3 Application Area Lists 2.4 Latching Relay Advantages Ⅲ Tech Parameters Ⅳ Latching Relay Test 4.1 Measuring Contact Resistance 4.2 Measuring Coil Resistance 4.3 Set Voltage and Current 4.4 Reset Voltage and Current Ⅴ Relay Selection 5.1 The Necessary Conditions 5.2 Relevant Information Search 5.3 Installation Layout Consideration Ⅵ FAQ Ⅰ Working Principle 1.1 Action Principle The on and off state of the latching relay is usually held by the magnetic force generated by the permanent magnet. When the contacts of the relay need to be opened or closed, only the positive (reverse) DC pulse voltage is needed to excite the coil, and the relay completes the state transition between opening and closing in an instant. Usually when the contact is in the holding state, the coil does not need to continue to be energized, and the state of the relay can be maintained unchanged only by the permanent magnet force.   1.2 Action Process When the contacts of the relay need to be set, it is only necessary to excite the coil J2 with a positive DC pulse voltage. The magnetic poles generated by the coil J2 after excitation interact with the magnetic poles of the permanent magnet. As we all known, the same polarities repel each other, but the opposite polarities attract each other. The state transition from reset to set is completed in an instant. The following schematic diagrams demonstrates the specific state transition process. The process of the latching relay changing from the set state to the reset state, which are the same. Figure 1. Reset Latching Relay Figure 2. Constant-Current Pulse Monment Figure 3. Constant-Current Pulse Monment Figure 4. Latching Relay Reset   Ⅱ Main Functions and Advantages 2.1 Average View Latching relay is an automatic switching element with isolation function. It is widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment. It is one of the most important control elements in electricity.Magnetic latching relays generally have an induction mechanism (input part) that can reflect certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.). It has the ability to turn on/off the controlled circuit. In addition, between the input part and output part of the relay, there is an intermediate mechanism (drive part) for coupling and isolating the input, functional processing and driving the output part. 2.2 Function Lists The latching relay has the following functions:1) ExpansionFor example, when the control signal of a multi-contact relay reaches a certain value, multiple circuits can be switched, disconnected, and connected at the same time according to different forms of contact groups.2) AmplificationFor example, magnetic latching relays can control a large-power circuit with a very small control quantity.3) IntegrationFor example, when a plurality of control signals are input to a multi-winding relay in a prescribed form, they will be compared and integrated to achieve a predetermined control effect.4) Automation, remote control and monitoringFor example, on the automatic device and other electrical appliances, magnetic latching relays can form a program control circuit to realize automatic operation. 2.3 Application Area Lists 1) Smart meters: IC card meters, prepaid meters, single-phase meters, three-phase meters.2) Reactive power compensation: synchronous switch, composite switch, smart capacitor.3) Intelligent control: smart home, solar street light control, automation equipment, etc. 2.4 Latching Relay Advantages 1) They only need pulse excitation, and can work with single and double coils.2) Small size, easy installation.3) Low power consumption and strong load capacity.4) Safe and reliable, long service life. Figure 5. General Relay Structure Ⅲ Tech Parameters 1) Rated VoltageIt refers to the voltage required by the coil when the relay is working normally. Depending on the model of the relay, it can be AC voltage or DC voltage.2) DC ResistanceIt refers to the DC resistance of the relay coil, which can be measured by a multimeter.3) Pull-in CurrentIt refers to the minimum current that the relay can produce the pull-in action. In normal use, the given current must be slightly larger than the pull-in current, so that the relay can work stably. As for the working voltage applied to the coil, generally do not exceed 1.5 times the rated working voltage, otherwise it will generate a larger current and burn the coil.4) Release CurrentIt refers to the maximum current that the relay generates to release the action. When the current in the pull-in state of the relay is reduced to a certain level, it will return to the unpowered release state. The current at this time is much smaller than the pull-in current.5) Switch Voltage and CurrentThis refers to the voltage and current that the relay allows to load. It determines the magnitude of the voltage and current that the relay can control, and you cannot be exceeded this value during use, otherwise it is easy to damage the contacts of the relay.6) Coil Resistance RThe resistance produced by winding a T circle with an enameled wire with a diameter of Φ: R=￡*(T/Φ).7) TemperatureThe higher the temperature, the greater the resistance, and the lower the resistance, the smaller the resistance. Generally speaking, the coil resistance refers to the coil resistance at 20°C. When the temperature is higher or lower than 20℃, there is a calculation formula: Rt=R20[1+(T℃-20℃)×0.004].8) Contact Resistance CRIt is the resistance between the contacts of the relay. And it is the sum of the shrinkage resistance Re and the surface film resistance Rf: Rk=Re+Rf.Note:🔺The factors that form shrinkage resistance Re:♦️The size of the contact pressure determines the size of the shrink resistance. The relationship between the two is inversely proportional, the greater the contact pressure, the smaller the shrinkage resistance.🔺The factors that form the surface film resistance Rf:♦️Dust in the air.♦️Harmful gases in the air: H2S, SO2, etc.♦️Organic vapor in the air: plastic, glue and rosin.♦️Oil stains on the contact surface during the production process.9) Pull-in VoltageThe minimum voltage required to close the relay contacts.10) Release voltageThe minimum voltage required to open the relay contacts.11) Insulation ResistanceThe resistance value that appears when measured with a specified DC voltage between conductive parts that are insulated from each other.12) Medium Withstand VoltageAlso known as dielectric degree, it refers to the maximum voltage that can withstand between two conductive parts without breakdown.13) Reversing RetentionThe minimum force applied on the armature assembly handle to open or close the contacts.14) Contact PressureThe interaction force generated between the moving and static contacts is equal to the contact pressure equal to the reaction force generated by the over-travel of the reed head. Figure 6. Latching Relay Product Ⅳ Latching Relay Test 4.1 Measuring Contact Resistance Use the resistance profile of the universal meter to measure the resistance of the normally closed contact and the moving point, which should be 0. The contact resistance can be measured in a more accurate way within 100 milliohms, while the resistances of the normally-open contact and the moving point should infinite. From this, it can be distinguished which is a normally-closed contact or a normally-open contact.   4.2 Measuring Coil Resistance The resistance value of the relay coil can be measured with the universal meter R×10Ω, so as to judge whether there is an open circuit phenomenon in the coil.   4.3 Set Voltage and Current Get an adjustable regulated power supply and an ammeter, input the set voltage to the relay, and insert an ammeter in the power supply loop for monitoring. Slowly increase the power supply voltage, and when you hear the sound of the relay picking up, write down the set voltage and set current. In order to be accurate, you can try several times. Pay attention to, the setting current should be the average value, and the setting voltage should be the maximum value.   4.4 Reset Voltage and Current Repeat the above operation. But there is a little difference that the reset current is the average value, and the reset voltage is the maximum value.   Ⅴ Relay Selection 5.1 The Necessary Conditions ① The power supply voltage of the control circuit, the maximum current that can be provided.② The voltage and current in the controlled circuit.③ How many sets and types of contacts are needed for the controlled circuit. When selecting a relay, the power supply voltage of the general control circuit can be used as the basis for selection. The control circuit should be able to provide enough working current to the relay, otherwise the relay will be unstable when it is closed.   5.2 Relevant Information Search After consulting the relevant information to determine the conditions of use, you can search for the relevant information to find out the model and specification number of the required relay. If you already have a relay on hand, you can check whether it can be used based on the data. Finally, consider whether the size is appropriate.   5.3 Installation Layout Consideration If it is used for general electrical appliances, in addition to considering the volume of the case, it is necessary to consider the installation layout of the circuit board. For small electrical appliances, such as toys and remote control devices, ultra-small relay products should be used.   Ⅵ FAQ 1. What is magnetic latching?The design of a Magnetic Latching Relay is such that when a short pulse of electrical energy is applied to the solenoid coil, sufficient magnetic force is generated to over-come the force of the relay' return mechanism. 2. How does a latching relay work?One latching type has two opposing coils with an over-center spring or permanent magnet hold the contacts in position after the coil is de-energized. A pulse to one coil turns the relay on and a pulse to the opposite coil turns the relay off. 3. Where is latching relay used?This type of relay is most suitable in applications like ON/OFF devices from multiple places with push-button or momentary switch. For example, it is used in a lighting circuit or conveyer to control from different locations. 4. What is a magnetic latching relay used for?A magnetic latching relay is a device in which the solenoid principle is applied to open and close light-current electrical circuits. The same device applied in heavy-current circuits is called a contactor, or circuit breaker. 5. How does a latching relay reset?Resetting is very simple. The coil circuit needs to be opened and shortened to the coils ground potential. The capacitor will be discharged through the coil and drives a current pulse with opposite polarity through the coil.

Ⅰ Introduction RFID is a technology that uses electromagnetic fields to automatically recognize and track tags attached to objects. An RFID system is composed of a small radio transponder, a radio receiver, and a radio transmitter. Catalog Ⅰ Introduction Ⅱ RFID Related Video: Ⅲ RFID Chip 3.1 WHAT IS RFID? 3.2 HOW DOES RFID WORK? 3.3 What Are the Types of RFID Systems  ? Ⅳ RFID Tags 4.1 Definition of RFID Tags 4.2 How RFID Tags Work？ 4.3 Examples of RFID Tags Ⅴ What Does (RFID Reader) Mean? 5.1 What exactly is an RFID Reader  ? 5.2 Readers Types Ⅵ Blocking Wallet 6.1 What Is an RFID-Blocking Wallet? 6.2 How Do RFID-Blocking Wallets Work? 6.3 The 5 Best RFID-Blocking Wallets Ⅶ RFID Asset Tracking  7.1 What Is RFID Asset Tracking  ? 7.2 How Does RFID Asset Tracking  Work? Ⅷ RFID Vs. NFC: The 5 Key Differences Ⅸ FAQ   Ⅱ RFID Related Video:   How RFID Works? and How to Design RFID Chips?     RFID Related Video Description: In this video, we learn about how RFID works and we see how RFID chips are designed. The main concepts such as backscatter modulation and energy harvesting is explained in detail. We start by explaining the RFID technology, in particular passive RFIDs.We discuss the operation of RFID and the magnetic field coupling.Then we look inside the RFID tags and locate the RFID chip and antenna inside the tags.Then we see how RFID chips are designed and explain all different parts of the chip in detail.We discuss the backscatter modulation as well as RF frequencies used in RFID communication.At the end we also provide some information about RFID readers.     Ⅲ RFID Chip 3.1 WHAT IS RFID? RFID is an abbreviation for "radio-frequency identification," and it refers to a technology that uses radio waves to capture digital data encoded in RFID tags  or smart labels (defined below). RFID is similar to barcoding in the sense that data from a tag or label is captured by a device and stored in a database. RFID, on the other hand, has several advantages over systems that use barcode asset tracking software. The most notable difference is that RFID tag data can be read even when the tag is not in direct view, whereas barcodes must be aligned with an optical scanner. If you are thinking about implementing an RFID solution, contact the RFID experts at AB&R® (American Barcode and RFID).   3.2 HOW DOES RFID WORK? RFID systems are made up of three parts: a scanning antenna  , a transceiver, and a transponder. An RFID reader  or interrogator is a device that combines the scanning antenna  and the transceiver. RFID reader  s are classified into two types: fixed readers  and mobile readers  . RFID reader  s are network-connected devices that can be portable or fixed. It transmits signals that activate the tag via radio waves. When activated, the tag sends a wave back to the antenna.  which converts it into data. The RFID tag contains the transponder. RFID tag read range varies depending on factors such as tag type, reader type, RFID frequency, and interference in the surrounding environment or from other RFID tags  and readers,  Tags with a more powerful power source have a greater read range.   3.3 What Are the Types of RFID Systems  ? RFID systems are classified into three types: low frequency (LF), high frequency  (HF), and ultra-high frequency (UHF) (UHF). Microwave RFID technology is also available. Frequencies differ greatly depending on country and region. RFID systems with low frequency. These frequencies range from 30 kHz to 500 KHz, with 125 KHz being the most common.  LF RFID  has relatively short transmission ranges, ranging from a few inches to less than six feet. RFID system with high frequency  These range from 3 MHz to 30 MHz, with 13.56 MHz being the most common HF frequency. The typical range is from a few inches to several feet. RFID  UHF  systems These have a frequency range of 300 MHz to 960 MHz, with a typical frequency of 433 MHz, and can be read from a distance of 25 feet or more. RFID systems that use microwaves These operate at 2.45 Ghz and can be read from a distance of more than 30 feet.   Ⅳ RFID Tags 4.1 Definition of RFID Tags RFID tags are a type of tracking system that uses intelligent barcodes to identify items. RFID stands for "radio frequency identification," and RFID tags  make use of radiofrequency technology. These radio waves send data from the tag to a reader, which then sends the data to an RFID computer program. RFID tags  are commonly used to track merchandise, but they can also be used to track vehicles, pets, and even Alzheimer's patients. An RFID tag is also known as an RFID chip. 4.2 How RFID Tags Work？ An RFID tag transmits and receives data via an antenna  and a microchip, which is also known as an integrated circuit or IC. The RFID reader  's microchip is programmed with whatever information the user desires. What exactly is an RFID tag? RFID tags are classified into two types: battery-powered and passive. Battery-operated RFID tags.  as the name implies, use an onboard battery as a power source, whereas passive RFID tags  do not, instead of relying on electromagnetic energy transmitted from an RFID reader,  RFID tags  powered by batteries are also known as active RFID tags,  Passive RFID tags  transmit data at three different frequencies: 125–134 KHz, also known as Low Frequency (LF), 13.56 MHz, also known as High Frequency (HF) and  Near-Field Communication  (NFC), and 865–960 MHz, also known as Ultra High Frequency (UHF) (UHF). The range of the tag is affected by the frequency used. When a reader scans a passive RFID tag, it sends energy to the tag, which powers it up enough for the chip and antenna  to relay information back to the reader. The reader then sends this data to an RFID computer program for interpretation. Passive RFID tags  are classified into two types: inlays and hard tags. Inlays are typically thin and can be adhered to a variety of surfaces, whereas hard tags are, as the name implies, made of a hard, durable material such as plastic or metal.Transponders are much more battery-efficient than beacons because they only activate when they are close to a reader. Figure1:antenna 4.3 Examples of RFID Tags Because an active RFID is constantly transmitting a signal, it is an excellent choice for those seeking real-time trackings, such as in tolling and real-time vehicle tracking applications. They are a costly product, but they have a long read range, which may be preferred depending on the application. Passive RFID tags.  which cost around 20 cents each, are a much more cost-effective option than active  RFID tags ,  As a result, they are a popular choice for applications such as supply chain management, race tracking, file management, and access control. While a passive RFID tag does not require a direct line of sight to the RFID reader.  its read range is much shorter than that of an active RFID tag. They are small, lightweight, and have the potential to last a lifetime. Active RFID tags are better suited for applications requiring durability because they have a larger, more rugged design than passive RFID tags,  They are commonly used in toll payment transponder systems, cargo tracking applications, and even personal tracking devices. Figure2:Examples of RFID Tags Ⅴ What Does (RFID Reader) Mean? 5.1 What exactly is an RFID Reader  ? A radio frequency identification reader (RFID reader) is a device that collects data from RFID tags that are used to track individual objects. Data is transferred from the tag to a reader using radio waves. RFID is a technology that, in theory, is similar to bar codes. The RFID tag, on the other hand, does not have to be scanned directly, nor does it need to be in direct line of sight of a reader. To be read, the RFID tag must be within the range of an RFID reader.  which can range from 3 to 300 feet. RFID technology allows several items to be scanned quickly and allows for quick identification of a specific product, even when it is surrounded by several other items. RFID tags have not replaced bar codes due to their high cost and the requirement to individually identify each item.   5.2 Readers Types A passive reader in a Passive Reader Active Tag (PRAT) system only receives radio signals from active tags (battery operated, transmit only). A PRAT system reader's reception range can be adjusted from 1–2,000 feet (0–600 m), providing flexibility in applications such as asset protection and supervision.   An active reader in an Active Reader Passive Tag (ARPT) system transmits interrogator signals and receives authentication responses from passive tags. Active tags activated by an interrogator signal from the active reader are used in an Active Reader Active Tag (ARAT) system. A Battery-Assisted Passive (BAP) tag, which acts like a passive tag but has a small battery to power the tag's return reporting signal, could also be used in this system.Fixed readers  are configured to create a specific interrogation zone that is tightly controlled. This allows for a well-defined reading area when tags enter and exit the interrogation zone. Handheld mobile readers  are available, as well as those mounted on carts or vehicles.   Ⅵ Blocking Wallet If you have RFID-enabled cards, passports, or devices, an RFID-blocking wallet may be necessary to protect your data.   6.1 What Is an RFID-Blocking Wallet? Thieves can steal your credit card information just by standing next to you if you don't have an RFID-blocking wallet. It is possible if you carry a credit card with an RFID chip embedded in it. RFID credit cards allow you to make payments by simply touching the card to a scanner rather than swiping it across or inserting it into a terminal. They're made for ease of use. Imagine someone approaching you and "scanning" the wallet in your back pocket without your knowledge. They could theoretically copy the RFID data and create a clone of your credit card unless it is protected by an RFID-blocking wallet.   6.2 How Do RFID-Blocking Wallets Work? RFID chips have been a source of concern for many years, and not just in credit cards. RFID chips in all US passports issued after 2006 track your photo and information. RFID chips are embedded in metro cards for quick swiping, and RFID chips are implanted in dogs for tracking. RFID chips communicate by using radio waves. An RFID tag with information is embedded in the object, such as a credit card, and an RFID reader  uses radio waves to read the information from the tag. The key point is that RFID chips have tiny electromagnetic fields, which allows them to be read without having to "initiate" communications. The RFID reader  only needs to be close enough to the field to work. As a result, someone could theoretically scan a card through your pocket. And, yes, people have been scanned in the real world in this manner. Check out this Reddit anecdote to see what kind of headache RFID hackers can cause. Fortunately, radio waves can be easily interrupted and blocked, which is how an RFID-blocking wallet works. They encase your credit cards in a radio-interfering material. If the wallet is constructed properly as a Faraday cage, it will block all electromagnetic fields and prevent communication between your cards and RFID scanners. But do YOU really require an RFID-blocking wallet? Most likely not. If your credit cards do not have RFID chips, you obviously do not require one. Even if you do have RFID-enabled cards, the chances of being scanned maliciously are extremely low—-less than 1%, according to some. On the other hand, the possibility exists at all times, and the probability is non-zero.   6.3 The 5 Best RFID-Blocking Wallets Saddleback Passport WalletBig Skinny Slimline WalletTrayvax Original WalletSharkk Rugged WalletRadix One Black Steel   Ⅶ RFID Asset Tracking  As a company that depends on the availability of high-value assets to generate revenue, you understand the significance of asset tracking and effective inventory management. Whether it's inventory, tools, IT equipment, vehicles, or even employees. 7.1 What Is RFID Asset Tracking  ? RFID asset tracking is a technique for automating the management and location of physical assets. It works by loading data onto an RFID tag and attaching it to a relevant asset. This information can range from name, condition, amount, and location. An RFID reader  can capture the stored data by using the RFID tag's repeatedly pulsating radio waves. Eventually, it will be collected in a sophisticated asset tracking system, where the data can be monitored and acted upon. The ability to automate your tracking and monitoring processes seeks to eliminate the highly error-prone methods of pen-and-paper and excel spreadsheets.Among other benefits such as: Tracking multiple assets at any one timeEliminating human interventionCollecting data in real-timeImproving asset visibilityLocating lost or misplaced assetsMaximising accuracy of inventory   7.2 How Does RFID Asset Tracking  Work? The basic principles of how an RFID tracking system works are very similar whether it is used in agriculture to track livestock or in a warehouse to monitor a manufacturer's supply chain. First, you'll need the right tools: RFID Tags (Passive, Active, or Semi-Passive)An AntennaAn RFID ReaderA computer database equipped with Asset Tracking Software The RFID asset tracking process can be divided into four stages once the proper equipment is in place: The data is stored on an RFID tag that has a unique  Electronic Product Code  (EPC) and is attached to an asset. An antenna  detects a nearby RFID tag's signal. An RFID reader is wirelessly connected to the antenna  and receives the data stored on the RFID tag. The data is then transmitted by the RFID reader to an asset tracking database, where it is stored, evaluated, and acted upon. The initial process is relatively simple, depending on how you choose to deploy your RFID asset tracking system. However, there are a variety of factors to consider when selecting the right hardware.   Ⅷ RFID Vs. NFC: The 5 Key Differences Even though both technologies appear similar on the surface, there are five key differences between them. The Reading Range NFC technology operates on a limited range, also known as proximity. RFID, on the other hand, can read tags from up to 10 meters away, making it the best solution for vehicle identification and access. Check out our Automatic Vehicle Identification Guide if you want to learn more about long-term solutions. Communication Because NFC is capable of two-way communication, it can provide novel and complex solutions such as card emulation and peer-to-peer. Speed With NFC technology, unlike RFID tags.  only one tag can be read at a time. As a result, RFID tags are often better suited to environments with a high concentration of trackable components. Asset management in a manufacturing facility or tracking fast-moving vehicles is two examples. Data NFC technology stores and transmits a variety of data types. NFC devices, with their larger storage capacity, can store and transmit more data than RFID devices, which can only carry simple ID information. As a result, NFC is better suited to environments where payment details, membership, and ticket information, among other things, must be transferred. The cost-effectiveness NFC-based readers  are less expensive than long-range RFID solutions due to their limited reading range. As a result, NFC is an excellent choice for businesses on a tight budget who still require a high-quality solution. Ⅸ FAQ 1. Can you be tracked through RFID? The answer was an electronic lock, and the company has given its handful of employees the option of using an electronic key or getting an RFID chip implanted in their arm. "It can't be read, it can't be tracked, it doesn't have GPS," Darks said. 2. Can RFID be hacked? RFID hackers have demonstrated how easy it is to get hold of information within RFID chips. As some chips are rewritable, hackers can even delete or replace RFID information with their own data. ... It's easy to purchase the parts for the scanner, and once built, someone can scan RFID tags and get information out of them. 3. Why is RFID bad? The other problem with RFID chips versus, say, embedded smart chips is that as wireless devices they don't need to be near the reader to be read. Smart chips, on the other hand, need to be put next to, or into, a reader, so they aren't as susceptible to being sniffed in the open. 4. How is RFID powered? Active RFID tags have a transmitter and their own power source (typically a battery). ... Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, but communicate by drawing power from the reader. 5. What is RFID example? For example, an RFID tag attached to an automobile during production can be used to track its progress through the assembly line, RFID-tagged pharmaceuticals can be tracked through warehouses, and implanting RFID microchips in livestock and pets enables positive identification of animals. 6. How do I know if I have an RFID chip? The best way to check for an implant would be to have an X-ray performed. RFID transponders have metal antennas that would show up in an X-ray. You could also look for a scar on the skin. Because the needle used to inject the transponder under the skin would be quite large, it would leave a small but noticeable scar. 7. Do credit cards have RFID? RFID-enabled credit cards - also called contactless credit cards or “tap to pay” cards - have tiny RFID chips inside of the card that allow the transmission of information. ... Though many new credit cards are RFID-enabled, not all of them are. On the other hand, all newly-issued credit cards come with an EMV chip.

Introduction Biomedical sensors are conversion devices that convert physiological information of the human body into electrical information that has a definite functional relationship with it. The information it picks up is the physiological information of the human body, and its output is often expressed in electrical signals by sensors. Figure 1. Health Care with Sensors Catalog Introduction Ⅰ Working Principle Ⅱ Biomedical Sensor Characteristics Ⅲ Classifications Ⅳ Biomedical Sensors Functions Ⅴ Biomedical Sensors Applications 5.1 Patient Lift Chair 5.2 Sports Rehabilitation Machine 5.3 Artificial Prosthesis 5.4 Infusion Pump 5.5 Baby Incubator 5.6 Infrared Thermometer Ⅵ Biomedical Sensors Development Ⅶ FAQ Ⅰ Working Principle In modern medicine, biomedical sensors actually replace the doctor’s sensory organs and play an extended role. It has become a key technology that restricts the development of high-level advanced medical equipment. The important technological foundation of the information society. There are two types of human physiological information: electrical information and non-electrical information. In terms of distribution, there are internal (such as blood pressure and other types of pressure), body surface (such as various types of bioelectricity such as ECG) and the external (such as infrared, biomagnetism, etc.).   Ⅱ Biomedical Sensor Characteristics As an important branch of sensors, the design and application of biomedical sensors must consider the influence of human factors, such as the particularity and complexity of biological signals, and the biocompatibility, reliability and safety of biobiomedical sensors.1) The sensor itself has good technical performance, such as sensitivity, linearity, hysteresis, repeatability, frequency response range, signal-to-noise ratio, temperature drift, zero drift, sensitivity drift, etc.2) The shape and structure of the sensor should be adapted to the anatomical structure of the tested part, and the damage to the tested tissue should be small.3) The sensor has a small impact on the measured object. In other words, it will not bring a burden to physiological activities, and does not interfere with normal physiological functions of humans.4) The sensor must have enough firmness so that it will not fall off or be damaged when use it.5) The sensor and the human body must have sufficient electrical insulation to ensure the safety.6) When the sensor enters the human body, it can adapt to the chemical action in the biological body. For example, it is compatible with the chemical composition in the biological body, is not easy to be corroded, has no adverse irritation to the human body, and is non-toxic.7) If the sensor enters the blood or is buried in the body for a long time, it should not cause blood problem.8) The sensor should be simple to operate, easy to maintain, and easy to sterilize in structure. Figure 2. Health Monitoring with Biobiomedical Sensor Ⅲ Classifications 1. According to the working principle:🔺Chemical sensorUse the principle of chemical reaction to convert chemical composition and concentration into electrical signals.🔺Biological sensorUse the selective identification of biologically active substances to determine biochemical substances.🔺Physical sensorTake advantage of physical changes in materials.🔺Bioelectric electrode sensorUse the body's various bioelectricity (cardioelectricity, brain electricity, myoelectricity, neuron discharge, etc.).2. According to the type of detection:Displacement sensor, flow sensor, temperature sensor, speed sensor, pressure sensor, etc. For pressure sensors, including metal strain gauge pressure sensors, semiconductor pressure sensors, capacitive pressure sensors, etc. For temperature sensors, including thermistors, thermocouples, PN junction temperature sensors and other sensors that can detect temperature.3. According to human senses:1) Vision SensorIncluding various optical sensors and other sensors that can replace vision functions.2) Hearing SensorIncluding various pickups, piezoelectric sensors, capacitive sensors and other sensors that can replace auditory functions.3) Olfactory SensorInclude various gas-sensitive sensors, and sensors that can replace the olfactory function.This classification method is conducive to the development of bionic sensors. In addition to the widely used sensor classification methods, there are also multiple classification standards based on sensor materials, structures, energy conversion fractions, etc., all with their own advantages and limitations.   Ⅳ Biomedical Sensors Functions (1) Provide diagnostic information, such as heart sounds, blood pressure, pulse, blood flow, respiration, body temperature and other information for clinical diagnosis and medical research.(2) Monitoring: Long-term continuous measurement of certain parameters, monitoring whether these parameters are within the specified range, in order to check the patient's recovery process, and take actions when abnormalities occur. For example, after a heart operation, it is necessary to monitor changes in a series of parameters such as body temperature, pulse, arterial pressure, venous pressure, respiration, and electrocardiogram of a patient.(3) Human body control: Use the detected parameters to control the physiological process of the human body. For example, an automatic respirator uses a sensor to detect the patient’s breathing signal to control the movement of the respirator to synchronize the breathing of the human. Another example is the electronic prosthesis, which uses the measured electromyographic signal to control the movement of the human prosthesis. What’s more, have the blood flow and blood pressure control of cardiopulmonary bypass.(4) Clinical tests: In addition to collecting information directly from the human body, diagnostic information is often obtained from various body fluids (blood, urine, saliva, etc.) samples. This type of information is called biochemical test information. It is obtained by using chemical sensors and biosensors, and is an indispensable basis for diagnosing various diseases. Figure 3. Tiny Biobiomedical Sensor Ⅴ Biomedical Sensors Applications 5.1 Patient Lift Chair Electric chair lifts can provide a safe and efficient way to transfer patients from one place to another, helping to ensure the safety of patients. These basic equipment can greatly reduce the burden on nursing staff when using other transfer methods to keep on patient safety and comfort. These chairs have a lightweight and portable design and are suitable for many medical care environments. For example, modern versions of these chairs also incorporate load cells to further enhance their performance. The weighing sensor designed to measure the weight of the patient can be connected to an alarm, and when the load exceeds the safety upper limit, an alarm will be issued to the health staff immediately. 5.2 Sports Rehabilitation Machine Usually used in physiotherapy, these machines are usually used to exercise the patient's muscles as part of the therapy to restore the patient's motor skills and mobility after the patient has suffered a stroke or sports injury. With our advanced technology, modern rehabilitation machines can now provide intelligent sensing capabilities to detect the movement of patients. By integrating load cells, we are now able to provide the controller with the real-time feedback needed to predict the patient's next movement. The intelligent resistance control can increase or decrease the resistance of the exercise machine according to the force measured from the patient's actions, thereby promoting the patient's muscle growth in the most suitable way. The load cell can also be used to measure the weight of the patient, so that the rehabilitation machine can estimate the height of the patient, and pre-position the handle of the machine at the correct level in an efficient manner. 5.3 Artificial Prosthesis After a long period of development, artificial prostheses have been improved in many aspects, from the comfort of materials to the integration of electromyographic control using electrical signals generated by the wearer’s own muscles, to the fact that artificial prostheses are extremely realistic in appearance and have the same skin texture. Even match pigments and details such as hair level, nails and texture.With the integration of advanced sensors into artificial prostheses, further improvements can be brought about. They are aimed at enhancing the natural movement of artificial prostheses for arms and legs, and providing the correct amount of strength assistance during exercise. Our solutions include weighing sensors and custom force sensors that can be built into artificial prostheses. These sensors can measure the pressure of each patient's movement, thereby automatically changing the resistance of the artificial prosthesis. This feature allows patients to adapt and perform daily tasks in a more natural way. 5.4 Infusion Pump It is the most commonly used and basic tool in the medical environment and can achieve flow rates from 0.01 mL/hr to 999 mL/hr. Our customized solutions help reduce errors and achieve the goal of providing high-quality and safe patient care. And the solution can provide reliable feedback to the infusion pump to ensure continuous and accurate drug delivery, and the liquid is delivered to the patient in a timely and accurate manner, reducing the supervision workload of medical staff. 5.5 Baby Incubator Rest and reducing bacterial exposure are key factors for newborn care. Therefore, the baby incubator is designed to protect weak babies by providing a safe and stable environment. The load cell is incorporated into the incubator to achieve accurate real-time weight measurement without affecting the baby's rest or exposing the baby to the external environment. 5.6 Infrared Thermometer It is a kind of devices with non-contact temperature sensor, its sensitive element and the measured object are not in contact with each other, also known as non-contact temperature measuring instrument. This kind of instrument can be used to measure the surface temperature of moving objects, small targets and objects with small heat capacity or rapid temperature changes (transient), and it can also be used to measure the temperature distribution of the certain field. In today's outbreak of COVID-19, physical contact has been minimized and the spread of bacteria and viruses has been reduced greatly.   Ⅵ Biomedical Sensors Development Among them, the research and development of the sensor itself has two branches. One is related to the basic research of the sensor, that is, the research on the new technology and new principles required by the sensor.In recent years, the development of medical sensor products has become more and more popular, and the productization of sensor technology in the field of medical equipment products has become increasingly popular. Innovative medical products such as wearables, artificial intelligence AI, surgical robots, etc. are emerging in an endless stream. Modern medical sensor technology has got rid of the technical shortcomings of traditional biomedical sensors such as large size and poor performance, and has formed new development directions such as intelligence, miniaturization, multi-parameter, remote control, and non-invasive detection.The development of biomedical sensors is already one of the key technologies restricting the development of high-end and advanced medical equipment, and it is also one of the main driving forces to promote the development of medicine.   Ⅶ FAQ 1. Why are sensors used in healthcare?Sensors are used in electronics-based medical equipment to convert various forms of stimulation electrical signals for analysis. Sensors can increase the intelligence of medical equipment, such as life-supporting implants, and can enable bedside and remote monitoring of vital signs and other health factors. 2. What sensors are used in patient monitoring system?Thus, different types of sensors can be used (e.g., GPS receiver, accelerometer, ECG, blood pressure, blood glucose, body temperature, and breathing sensor). 3. What are the sensors used in biomedical applications?Biomedical sensor classification. Many different kinds of sensors can be used in biomedical application.Oxygen and carbon dioxide sensor for blood.Heart sound sensor.Blood flow sensor.Respiration sensor.Blood pressure sensor.Electrochemical electrode. 4. What is the main difference between biosensors and biomedical sensors?Biosensors, which can be considered a special subclassification of biomedical sensors, are a group of sensors that have two distinct components: a biological recognition element, such as a purified enzyme, antibody, or receptor, that functions as a mediator and provides the selectivity. 5. Can biomedical sensors be placed anywhere inside the body?Biosensors can be placed inside your body as well. Dr. Natalie Wisniewski, a biomedical engineer at a medical device company in San Francisco called Profusa, is developing miniature sensors that can be injected under the skin. These sensors automatically track chemicals in your body without drawing blood. 6. What are the types of biomedical sensor?While talking about biomedical engineering, we come across biomedical sensor terminology, which is then divided into three types: physical sensors, chemical sensors, and biosensors. Physical sensors are used to evaluate blood pressure, biologic magnetic field, etc. 7. Which sensors are used in biomedical applications?There are different types of physical sensors used for biomedical applications: Radiation sensors address the X-ray and gamma ray-based sensors, Mechanical sensors include ultrasound and pressure sensor Thermal sensors include a range of sensors such as thermocouple, thermistor, thermopile, optical fiber devices, P-N. 8. What are biomedical sensors used for?In medicine and biotechnology, biomedical sensors are used to detect specific biological, chemical, or physical processes, which then transmit or report the monitored data. These sensors can also be components in systems that process clinical samples, such as increasingly common lab-on-a-chip devices. 9. What sensors are used in hospitals?Types of medical sensorsThe primary sensors used within medical devices are pressure, force, airflow, oxygen, pulse oximetry, temperature, and barcode sensing. The above sensors play a critical role in the operation of the equipment. 10. What sensors are used in patient monitoring system?Thus, different types of sensors can be used (e.g., GPS receiver, accelerometer, ECG, blood pressure, blood glucose, body temperature, and breathing sensor). 11. What are the temperature sensors?A temperature sensor is a device used to measure temperature. This can be air temperature, liquid temperature or the temperature of solid matter. There are different types of temperature sensors available and they each use different technologies and principles to take the temperature measurement.

ⅠIntroductionThyristors are high-speed solid-state devices that can control motors, heaters, and lighting. Before we get into Thyristor Circuits. We'll look at the basic construction and operation of the Silicon Controlled Rectifier, also known as a Thyristor. Next, we'll look at how we can use thyristors and thyristor switching circuits to control much larger loads like lamps, motors, or heaters, among other things. CatalogⅠIntroductionⅡ Thyristors Circuits Related VideoⅢ What Is Silicon Controlled Rectifier?Ⅳ Construction of Silicon Controlled RectifierⅤ What is a Thyristor?Ⅵ Thyristor Switching Circuits6.1 Thyristor Circuit in DC6.2 AC Thyristor CircuitⅦ How an SCR Circuit Works with Thyristor Circuits?7.1 DC Thyristor / SCR Circuit7.2 Basic AC Thyristor / SCR Circuit7.3 AC SCR Circuit with Gate Phase ControlⅧ FAQ Ⅱ Thyristors Circuits Related VideoSilicon Control Rectifier SCR Basic AC Circuit Thyristors Circuits Video Description:  Silicon Control Rectifier SCR Basic AC Circuit Ⅲ What Is Silicon Controlled Rectifier?The Silicon Controlled Rectifier (SCR) is one of the most popular devices in the market. SCR can be found in a variety of applications such as rectification, power regulation, and inversion, among others. SCR, like a diode, is a unidirectional device that allows current in one direction but opposes it in the other gate. SCRs have the ability to turn ON or OFF, and their switching is controlled by biasing conditions and the gate input terminal.By varying the ON periods of the SCR, the average power delivered at the load can be varied. It is capable of handling tens of thousands of voltages and currents. Figure depicts the SCR symbol and its terminals.Figure1 :Silicon Controlled Rectifier   Ⅳ Construction of Silicon Controlled RectifierAs shown in the figure, an SCR has three terminals: anode, cathode, and gate. SCRs have the ability to turn ON or OFF, and their switching is controlled by biasing conditions and the gate input terminal.By varying the ON periods of the SCR, the average power delivered at the load can be varied. It is capable of handling tens of thousands of voltages and currents. Figure depicts the SCR symbol and its terminals.Figure2:Construction The SCR is manufactured using three different types of constructions: planar, Mesa, and press pack. Planar construction, in which all junctions in an SCR are diffused, is used for low-power SCRs. In a mesa type construction, junction J2 is formed by diffusion and the outer layers are alloyed to it as a result. This design is primarily used in high-power Silicon Controlled Rectifiers. The SCR is braced with plates made of molybdenum or tungsten to provide high mechanical strength. One of these plates is soldered to a copper stud, which is threaded to connect to the heat sink. Ⅴ What is a Thyristor?A thyristor is a four-layer solid-state semiconductor device made of P and N materials. When a gate receives a triggering current, it begins to conduct until the voltage across the thyristor device is biased forward. In this case, it functions as a bistable switch. To control a large amount of current flowing through the two leads, we must create a three-lead thyristor by combining the small amount of current with that current. This is referred to as control lead. If the potential difference between the two leads is less than the breakdown voltage, a two-lead thyristor is used to turn the device on.Figure3:Thyristor Ⅵ Thyristor Switching CircuitsDC Thyristor CircuitAC Thyristor circuit 6.1 Thyristor Circuit in DCWhen connected to a DC supply, we use a thyristor to control larger DC loads and current. The main advantage of using a thyristor in a DC circuit as a switch is that it provides a high current gain. Because a small gate current can control a large anode current, the thyristor is classified as a current-operated device.Figure4:Thyristor Circuit in DC 6.2 AC Thyristor CircuitWhen connected to an alternating current supply, the thyristor behaves differently because it is not the same as a DC-connected circuit. A thyristor is used as an AC circuit during one half of a cycle, causing it to turn off automatically due to its reverse biased condition. Figure6:AC Thyristor Circuit Ⅶ How an SCR Circuit Works with Thyristor Circuits?7.1 DC Thyristor / SCR CircuitMany applications call for an SCR circuit to control the operation of a DC load. This can be used for switching DC motors, lamps, or any other load.The basic SCR circuit shown below can control power to a load by using a small switch to initiate power application to the load.Figure7:Basic DC thyristor / SCR circuit With S1 closed and S2 open, no current will flow at first. The SCR circuit will turn on and the current will flow in the load only when S2 is closed and it triggers the gate by causing the gate current to flow.Until the anode circuit is broken, the current will continue to flow. S1 can be used for this. Another method is to place the switch S1 across the SCR and briefly close it, causing the voltage across the SCR to disappear and the SCR to stop conducting.Because of their functions in this SCR circuit, S1 and S2 may be referred to as the Off switch and the ON switch, respectively. In this configuration, S1 must be able to carry the full load current, while S2 must only carry the gate current. Once the SCR is turned on, the switch can be released and remain open because the SCR's action maintains the current flow through the device and thus the load.R1 connects the gate to the power supply via the switch. When S2 is closed, current flows through the resistor enters the gate and activates the SCR. The resistor R1 must be calculated to provide enough gate current to turn on the SCR circuit.R2 is included to reduce the SCR's sensitivity so that it does not fire on any noise that is detected. 7.2 Basic AC Thyristor / SCR CircuitWhen using a thyristor circuit with AC, a few changes must be made, as shown below.This is because alternating current reverses polarity throughout the cycle. This means that the SCR will become reverse-biased, effectively lowering the anode voltage to zero and causing it to turn OFF for one-half of each cycle. As a result, there is no need for an off switch because this is accomplished as part of the use of an alternating current supply.When using a thyristor circuit with AC, a few changes must be made, as shown below.This is because alternating current reverses polarity throughout the cycle. This means that the SCR will become reverse-biased, effectively lowering the anode voltage to zero and causing it to turn OFF for one-half of each cycle. As a result, there is no need for an off switch because this is accomplished as part of the use of an alternating current supply.\Figure8: AC thyristor / SCR circuitThe circuit operates in a slightly different manner than the DC SCR circuit. When the switch is turned on, the circuit must wait for sufficient anode voltage to be available as the AC waveform progresses along its path. In addition, the SCR circuit will have to wait until the voltage within the gate section of the circuit is high enough to trigger the SCR. The switch must be in a closed position for this to work.Once triggered, the SCR will remain to conduct for the duration of the positive half of the cycle. As the voltage falls, the anode-cathode voltage will become insufficient to support conduction. At this point, the SCR will come to a halt.The SCR will then not operate during the negative half of the cycle. The process will only be repeated when the next positive half of the cycle returns. As a result, this circuit will only operate when the gate switch is closed.One disadvantage of using this type of SCR circuit is that it cannot supply more than 50% power to the load because it does not conduct during the negative half of the AC cycle because the SCR is reverse biased. 7.3 AC SCR Circuit with Gate Phase ControlBy varying the proportion of the half-cycle over which the SCR conducts, the amount of power reaching the load can be controlled. This can be accomplished by using an SCR circuit with phase control of the input gate signal.Figure9:AC thyristor circuit waveformsThe SCR gate signal is derived from an RC circuit consisting of R1, VR1, and C1 before the diode D1 when using the SCR circuit with phase control.Because the SCR is forward biased, only the positive half cycle of the waveform is of interest, as with the basic AC SCR circuit. During this half-cycle, the capacitor, C1, charges up from the AC supply voltage via the resistor network of R1 and VR1. The waveform at the positive end of C1 is seen to lag behind the input waveform, and the Gate is only triggered when the voltage at the capacitor's high end has risen sufficiently to trigger the SCR via D1. As a result, the SCR's turn-on time is delayed compared to what it would be if the RC network was not present. The VR1 value changes the delay and thus the proportion of the cycle over which the SCR operates. The power into the load can thus be adjusted in this manner. Figure10: AC thyristor circuit with gate phase control R1 is a series resistor that has been included to limit the minimum value for the resistor network to a value that will provide an acceptable gate current level for the SCR. The phase angle of the gate waveform must typically vary between 0° and 180° to provide complete control of the 50% of the cycle available for conduction with an SCR. These circuits demonstrate some of the fundamental concepts underlying the design of SCR thyristor circuits. They show how they work and how they can be used in their most basic form. One of the most important considerations when designing thyristor circuits is power dissipation. Because these circuits frequently handle high voltages and high power levels, power dissipation can be a significant factor in circuit design and operation. Ⅷ FAQ1. What does a thyristor do in a circuit?The primary function of a thyristor is to control electric power and current by acting as a switch. For such a small and lightweight component, it offers adequate protection to circuits with large voltages and currents (up to 6000 V, 4500 A).2. How thyristor acts as a switch?When connected to a direct current DC supply, the thyristor can be used as a DC switch to control larger DC currents and loads. When using the Thyristor as a switch it behaves like an electronic latch because once activated it remains in the “ON” state until manually reset3. What is difference between SCR and thyristor?Thyristor is a four semiconductor layer or three PN junction device. It is also known as “SCR” (Silicon Control Rectifier). The term “Thyristor” is derived from the words of thyratron (a gas fluid tube which works as SCR) and Transistor. Thyristors are also known as PN PN Devices.4. Is thyristor convert AC to DC?A single-phase thyristor rectifier converts an AC voltage to a DC voltage at the output. The power flow is bidirectional between the AC and the DC side.5. What are the advantages of thyristor?Advantages of Thyristor :It is easy to turn on. It is able to control AC power. It can switch high voltage, a high current device. It cost is very low. 

Introduction An oscillator is an electronic component used to generate an oscillating signal. The circuit composed of it is called an oscillating circuit, which can convert direct current into an electronic circuit or device with a certain frequency of alternating current signal. It is widely used in electronics industry, medical treatment, scientific research, etc. Catalog Introduction Ⅰ Oscillator Basics 1.1 Oscillator Meaning 1.2 Classification Rules Ⅱ Examples: RC Oscillator, LC Oscillator and Crystal Oscillator 2.1 RC Oscillator 2.2 LC Oscillator 2.3 Crystal Oscillator Ⅲ Selection Rules Ⅳ FAQ Ⅰ Oscillator Basics 1.1 Oscillator Meaning The oscillator is simply a frequency source and generally used in a phase-locked loop. In detail, it is a device that can convert DC power into AC power without external signal excitation. Generally divided into two types: positive feedback and negative resistance. The so-called oscillation, its meaning alludes to AC, and the oscillator includes a process and function starting from scratch. In other words, it can complete the conversion from DC power to AC power, such a device can be called an oscillator. 1.2 Classification Rules Oscillators are widely used, and there are many types:According to the oscillation frequency: high frequency oscillator, and low frequency oscillator.According to the oscillation waveform: sine wave oscillator, and non-sine wave oscillator.According to the oscillation feedback: positive feedback oscillator, and negative resistance oscillator.   Ⅱ Examples: RC Oscillator, LC Oscillator and Crystal Oscillator Electronic Oscillators || RC, LC, Crystal 2.1 RC Oscillator In a resistance-capacitance oscillator or short for RC oscillator, by using RC components in the feedback branch, a phase shift occurs between the input of the RC network and the output from the same network. The input is again moved through the second inverting stage, giving a phase shift, which is the same as providing the required positive feedback. It is suitable for low frequency oscillation, and is generally used to generate low frequency signals of 1Hz to 1MHz. The circuit is composed of four parts: amplifying circuit, frequency selection network, positive feedback network, and amplitude stabilization. The main advantages of it are simple structure, economic and convenient, and belong to the audio frequency oscillator. Figure 1. RC Oscillator Circuit (1) Vibration ProcessWhen the power is just turned on, there are various electrical disturbances in the circuit, and a relatively large feedback voltage is generated through feedback through the frequency selection network. Passing through the continuous loop of linear amplification and feedback, the oscillation voltage will continue to increase.(2) Oscillation FrequencyThe oscillation frequency is determined by the phase balance condition., Only meets the phase balance condition at f0, the oscillation frequency is .Changing R and C can change the oscillation frequency.(3) Conditions for Start-up and Stable OscillationTaking into account the starting conditions of AuF>1, generally Rt should be selected slightly larger than 2R1. If this value is too large, it will cause serious distortion of the oscillation waveform.The RC series-parallel sine-wave oscillator circuit composed of an op amp does not rely on the transistor inside the op amp to enter the nonlinear region to stabilize the amplitude, but to achieve the purpose of amplitude stabilization by introducing negative feedback from the outside.(4) Stable AmplitudeThe growth process of the oscillation amplitude cannot continue forever, when the amplifier gradually enters the saturation or cut-off zone from the amplification zone. Working in a non-linear state, its gain gradually decreases. When the amplifier gain decreases and the loop gain decreases to 1, the amplitude increase process will stop and the oscillator will reach equilibrium.For the RC oscillator circuit, increasing the resistance can reduce the oscillation frequency, and it does not need to increase the cost. The frequency of the sine wave generated by the commonly used LC oscillation circuit is relatively high. If a low frequency sine oscillation is to be generated, the oscillation circuit must have a larger inductance and capacitance. This will not only cause the components to be bulky, heavy, and inconvenient to install, but also difficult to manufacture with high cost. Therefore, the sinusoidal oscillation circuit below 200kHz generally adopts an RC oscillation circuit with a lower oscillation frequency.   2.2 LC Oscillator LC oscillator is also called LC oscillating circuit, resonance circuit, tank circuit or tuning circuit. It consists of a capacitor and a parallel coil. The circuit has an inductor L and a capacitor C. Capacitors store energy in the form of electrostatic fields and generate potential on their plates, while inductance coils store energy in the form of electromagnetic fields. By placing the switch in a specific position, the capacitor is charged to the DC supply voltage. When the capacitor is fully charged, the switch is switched to a certain position, and the charged capacitor is connected in parallel to the inductor coil, so the capacitor starts to discharge itself through the coil. Figure 2. LC Oscillator Circuit The LC circuit is not only used to generate a specific frequency signal, but also used to separate a specific frequency signal from a more complex signal. They are key components in many electronic equipment, especially radio equipment, used in oscillators, filters, tuners and mixer circuits.The inductive circuit is an idealized model because it assumes that there is no energy dissipated due to resistance. The actual realization of any LC circuit will include the loss caused by the small but non-zero resistance of the components and connecting wires. The purpose of an LC circuit is usually to minimize oscillations, so the resistance is made as small as possible. Although there is no lossless circuit in practice, studying the ideal form of this circuit is beneficial to study physical phenomenon.When electromagnetic oscillation occurs in an oscillating circuit, if there is no energy loss and no external influences, the period and frequency of it at this time are called the natural frequency and natural period of the oscillating circuit. The natural period can be obtained by the following formula: Where, the time constant is L/R. What are LC Oscillations? 2.3 Crystal Oscillator Some electronic devices require an AC signal with a highly stable frequency, but the LC oscillator has poor stability and the frequency is easy to drift (that is, the frequency of the generated AC signal is easy to change). A special component-quartz crystal is used in the oscillator, which can generate a highly stable signal. This kind of oscillator that uses a quartz crystal is called a crystal oscillator. It is mainly composed of a crystal and peripheral components. In a crystal oscillator, the main frequency determining element is a quartz crystal. Due to the inherent characteristics of the quartz crystal oscillator, it has extremely high frequency stability. Temperature compensation may be related to the crystal oscillator to improve the thermal stability. Because it is a fixed frequency oscillator, stability and accuracy are the basic considerations when use it. Figure 3. Crystal Oscillator Circuit The crystal oscillator has a piezoelectric effect, that is, the crystal will deform when a voltage is applied to the two poles of the wafer. Conversely, if an external force deforms the wafer, the metal sheets on the two poles will generate voltage. If an appropriate alternating voltage is applied to the chip, the chip will resonate (the resonance frequency is related to the tilt angle of the quartz slope, etc., and the frequency is constant). The crystal oscillator uses a crystal that can convert electrical energy and mechanical energy into each other. It can provide stable and accurate single-frequency oscillation when working in a resonance state. Under normal working conditions, the absolute accuracy of ordinary crystal oscillator frequencies can reach 50 parts per million. Using this feature, the crystal oscillator can provide a more stable pulse, which is widely used in the clock circuit of the microchip. In addition, the wafers are mostly quartz semiconductor materials, and the shell is encapsulated with metal.The main parameters of the crystal oscillator include nominal frequency, load capacitance, frequency accuracy, frequency stability, etc. These parameters determine the quality and performance of the crystal oscillator. Therefore, in practical applications, an appropriate crystal oscillator should be selected according to specific requirements. For example, systems such as communication networks and wireless data transmission require high-precision crystal oscillators. However, since the higher the performance of the crystal oscillator is, the more expensive it is, so you can choose a crystal that meets the requirements when buying.   Ⅲ Selection Rules Oscillators are used in many electronic products. In order to ensure the normal operation of electronic products, the selection of oscillators is important. The following summarizes the five selection rules for reference.1) Appearance InspectionBy checking the appearance of the product, whether the marking text is clear and standard, whether there are cracks on the surface of the appearance, and whether the pins have been soldered. If the product is found to be imperfect on the outside, it should not be used.2) FrequencyChoose the appropriate frequency according to the actual product requirements. The frequency is the most important, and it cannot be replaced casually. Negotiations must be conducted after passing the qualification verification or professional test. If the frequency required by the actual circuit is 5MHZ, do not replace it with a similar frequency without any original replacement.3) Output ModeWhen choosing a oscillator, consider the type of oscillator output required by the circuit, which generally divided into level output and differential output. As for level output, CMOS is the most commonly used type, and in terms of differential output, LVPECL(Low Voltage Positive Emitter-Couple Logic) and LVDS (Low-Voltage Differential Signaling) are commonly used differential output type. Different output types cannot be changed randomly, especially differential and ordinary oscillators.4) ModelTo use the oscillator, you must see the model mark of the shell. The model number indicates its multiple parameters. According to the product requirements, the corresponding product parameters can be found, and the same model can be found later. If the crystal oscillator model is not selected properly, it will cause errors in the application.5) ReplacementIf an oscillator is damaged, it should be replaced by the original model in principle. When the original model is not available, it is best to consider replacing it with another model or other type of oscillator after testing.   Ⅳ FAQ 1. What is oscillator and its types?An oscillator is a type of circuit that controls the repetitive discharge of a signal, and there are two main types of oscillator; a relaxation, or an harmonic oscillator. This signal is often used in devices that require a measured, continual motion that can be used for some other purpose. 2. What are the types of oscillator in electronics?There are two main types of electronic oscillator – the linear or harmonic oscillator and the nonlinear or relaxation oscillator. 3. How many types of oscillations are there?There are 3 main types of Oscillation – Free, damped, and forced oscillation. When a body vibrates with its own frequency, it is called a free oscillation. 4. What is RC and LC oscillator?The oscillation frequency is proportional to the inverse of the capacitance or resistance, whereas in an LC oscillator the frequency is proportional to inverse square root of the capacitance or inductance. So a much wider frequency range can be covered by a given variable capacitor in an RC oscillator. 5. What is the principle of oscillator?There are many types of electronic oscillators, but they all operate according to the same basic principle: an oscillator always employs a sensitive amplifier whose output is fed back to the input in phase. Thus, the signal regenerates and sustains itself. This is known as positive feedback. 6. What are the three types of oscillator?The main types of Oscillators include: Wien Bridge Oscillator. RC Phase Shift Oscillator. Hartley Oscillator. 7. What is the use of LC oscillator?LC oscillators are used in heating with high-frequency, RF generators, radios, TV receivers, etc. These types of oscillators use tank circuits including the components like a capacitor (C) and an inductor (L). 8. What does RC oscillator do?RC oscillators are a type of feedback oscillator; they consist of an amplifying device, a transistor, vacuum tube, or op-amp, with some of its output energy fed back into its input through a network of resistors and capacitors, an RC network, to achieve positive feedback, causing it to generate an oscillating. 9. What is RC phase oscillator?RC phase-shift oscillators use resistor-capacitor (RC) network to provide the phase-shift required by the feedback signal. They have excellent frequency stability and can yield a pure sine wave for a wide range of loads. ... Further, the circuit also shows three RC networks employed in the feedback path. 10. What are the advantages of RC oscillator?The RC phase shift oscillator gives good Frequency stability. The output of this circuit is sinusoidal that is quite distortion free.. It is suitable for lower frequencies and this lower limit exists in as low as 1Hz. RC phase shift oscillators don't require any negative feedback and stabilization arrangements. 11. What is a crystal oscillator used for?A crystal oscillator is an electronic oscillator circuit that is used for the mechanical resonance of a vibrating crystal of piezoelectric material. It will create an electrical signal with a given frequency. 12. What are the advantages of crystal oscillator?The Advantages of a Crystal OscillatorStability. Stability is one of the most important requirements of any oscillator.High Q. The Q factor or quality factor describes how 'underdamped' oscillators are.Frequency Customization and Range.Low Phase Noise.A Crystal Oscillator Is Compact and Inexpensive. 13. What is crystal oscillator explain?A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a constant frequency. ... Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz.