The Kynix Blog

Ⅰ IntroductionThis article focuses on the electronic component known as the Optocoupler. (For the fiber-optic networking component, please refer to Optical Isolators). This guide covers the fundamentals of optocouplers, their working principles, specifications, and practical examples of how to implement them in your circuits.Optocoupler Related VideoVideo: How an Optocoupler Works and Example CircuitⅡ Photocouplers, Opto-couplers & Opto-isolatorsThese devices are known by a variety of names, including optoisolator, photocoupler, and optocoupler.An optocoupler is a semiconductor device that transmits an electrical signal between two isolated circuits using light. This process ensures there is no direct electrical connection between the input (source) and the output (load), effectively protecting sensitive low-voltage components.While often used interchangeably, there is a technical distinction in the industry:Optocoupler: Typically refers to devices used to transfer analog or digital information between circuits with voltage differentials below 5,000 Volts.Optoisolator: Often refers to devices specifically designed to withstand very high voltage differentials (5,000V to 50,000V+) for safety isolation in power systems.Optocouplers are typically housed in small packages ranging from standard DIP (Dual Inline Package) to tiny SMD (Surface Mount Device) packages. Despite their small size, they play a massive role in linking data, optical encoding, and detecting position transitions on encoder wheels.They are also the core technology inside Solid-State Relays (SSR), allowing low-power logic signals to switch high-power AC or DC loads without any mechanical parts.Figure 1: Typical Photocouplers in DIP packagingⅢ Photocoupler / Optocoupler BasicsAn optocoupler consists of two main internal elements encased in a light-tight body:The Emitter: Usually a Near-Infrared LED (Light Emitting Diode) that converts the electrical input signal into light.The Detector: A photosensitive device (such as a phototransistor, photodiode, or TRIAC) that detects the light and generates an electrical output.These two components are separated by a transparent dielectric barrier (glass, plastic, or air gap). Because the connection is made via light photons rather than electrons, the input and output sides are electrically isolated. This isolation prevents high voltages or rapidly changing voltage spikes on one side from damaging components on the other.Ⅳ Optocoupler SymbolIn circuit diagrams, the optocoupler symbol illustrates its internal functionality. The left side typically shows the LED (Emitter), and the right side shows the receiver (Detector).Figure 2: Optocoupler circuit symbol (Phototransistor output)Common Variations:Phototransistor: The most common type for DC signal switching (shown above).Photo-Darlington: Uses a Darlington pair transistor for much higher gain (sensitivity) but slower switching speed.Photo-TRIAC / Photo-SCR: Used for controlling AC power mains.Figure 3: Photo-TRIAC circuit symbol (used for AC control)Ⅴ Optocoupler Specifications to WatchWhen selecting a component, consult the datasheet for these critical parameters:1. Current Transfer Ratio (CTR)This is the equivalent of "gain" (Beta) in a standard transistor. It is the ratio of the output collector current ($I_C$) to the input LED forward current ($I_F$), expressed as a percentage.Standard Phototransistor: CTR ranges from 10% to 100%.Photodarlington: CTR can range from 500% to 5000% (high sensitivity).Design Note - CTR Degradation: The efficiency of the internal LED decreases over time (aging). A good engineering practice is to design your circuit assuming the CTR will drop by 50% over the product's lifespan.2. Bandwidth and SpeedThis determines the maximum data rate.Phototransistors: Generally limited to about 250 kHz.Photodarlingtons: Slower, often limited to < 20 kHz due to long turn-off times.High-Speed Optocouplers: Devices like the 6N137 use a photodiode + logic amplifier architecture and can handle 10 MHz or more.3. Input Current ($I_F$)This is the current required to light up the internal LED. You must calculate a series resistor to limit this current, typically between 5mA and 20mA for standard devices.4. Isolation Voltage ($V_{iso}$)The maximum voltage difference the component can withstand between the input and output pins without electricity jumping the gap. Common ratings are 2500V to 5000V RMS.Ⅵ How It WorksThe operation is straightforward:Current is applied to the input side, flowing through the internal infrared LED.The LED emits infrared light inside the package. The intensity of this light is proportional to the input current.The light strikes the photosensitive base of the output transistor (or Triac).The photosensitive device "turns on" and conducts current.Figure 4: The internal light pathWhy is the Base pin unconnected?In many 6-pin optocouplers (like the 4N25), the base of the transistor is broken out to a pin (Pin 6). However, in most applications, this pin is left floating (unconnected) because the light serves as the base current. Connecting a resistor from the base to the ground can reduce sensitivity but increase switching speed.Figure 5: Effective isolation between Input and OutputⅦ Benefits and TypesPrimary Benefits:Ground Loop Elimination: Breaking the ground path between two circuits prevents hum and noise (critical in audio and instrumentation).Safety: Protects low-voltage microcontrollers (3.3V/5V) from high-voltage spikes (110V/220V).Level Shifting: Allows a 3.3V signal to switch a 24V or 48V circuit effortlessly.Common Types:Photo-Transistor: General-purpose DC switching.Photo-Darlington: High gain for very low input currents.Photo-SCR / Photo-TRIAC: Designed for interfacing with AC power mains.Logic Gate Output: (e.g., 6N137, H11L1) Includes internal logic buffers for high-speed digital communications.Figure 6: Common output configurationsⅧ Typical ApplicationsMicroprocessor I/O: Protecting GPIO pins on Arduinos or PLCs.Switch Mode Power Supplies (SMPS): Used in the feedback loop to maintain voltage regulation while keeping the mains side isolated from the low-voltage side.Motor Driving: Isolating the control logic from the noisy high-current motor drivers.Example: Triac Optocoupler for AC LoadsBy using a device like the MOC3020, a 5V digital signal can trigger a large external Triac, which in turn controls an AC motor or lamp. Many Triac optocouplers feature Zero-Crossing Detection, which ensures the device only switches when the AC voltage is at zero, significantly reducing Electromagnetic Interference (EMI).Figure 7: A basic DC switching configurationⅨ Differences Between Optocouplers and Solid State Relays (SSR)While they operate on the same principle, the distinction lies in power capability and integration.Figure 8: Solid State Relays (SSRs)Optocouplers: Low power. Used for signal transmission. Usually requires external components (external Power Triacs or MOSFETs) to switch heavy loads.Solid State Relays: High power. They contain an optocoupler plus the high-power switching components and protection circuitry inside a single, larger block. They can switch tens of Amps directly.Ⅹ How to Use an Optocoupler with ArduinoConnecting a load directly to an Arduino is risky. If the load is a motor or a solenoid, "flyback" voltage spikes can destroy the microcontroller. Using an optocoupler like the 4N25 or PC817 resolves this.The Circuit Concept:The Arduino drives the internal LED of the optocoupler. The optocoupler's output transistor acts as a switch for the secondary circuit.Figure 9: 4N25 OptocouplerWiring Guide (4N25 to Arduino):1. Input Side: Connect Arduino Pin -> 220Ω Resistor -> Optocoupler Pin 1 (Anode). Connect Pin 2 (Cathode) to Arduino GND.2. Output Side: Connect the device you want to control. Important: If you are using the optocoupler to send a signal into another digital pin, you must use a Pull-up Resistor on the collector (Pin 5) because the phototransistor can only pull voltage down to ground; it cannot "source" voltage effectively.Figure 11: Basic wiring diagram for isolating a signalⅪ FAQ1. What are the disadvantages of an optocoupler?The main disadvantages are speed and power handling. Standard optocouplers have a relatively slow frequency response compared to digital isolators. Also, the output phototransistor cannot handle high currents directly; it usually requires an external transistor or relay to switch heavy loads.2. Is an optocoupler the same as a relay?Not exactly. While both isolate circuits, a mechanical relay uses a physical electromagnet and moving contacts (clicking sound). An optocoupler uses light and has no moving parts. Optocouplers are faster and last longer but handle much less current than relays.3. How do you use an optocoupler for analog signals?While mostly used for digital switching, linear optocouplers exist. To send audio or analog data, you set up a specific bias current (standing current) through the LED and modulate that current with your signal. Specialized "Linear Optocouplers" use feedback photodiodes to linearize the output.4. How do I ensure the optocoupler switches fully (Saturation)?To use an optocoupler as a solid switch, you must drive it into "saturation." This means ensuring the input current ($I_F$) is sufficient and the output collector load resistor is high enough so that the phototransistor turns completely on. Always check the CTR curve in the datasheet.5. Are optocouplers analog or digital?They are fundamentally analog devices (light intensity varies with current), but they are most commonly used in digital applications (On/Off switching). Specialized high-speed digital optocouplers (logic-output) are available specifically for data transmission. ul { margin-bottom: 20px; } li { margin-bottom: 10px; } .caption { text-align: center; font-size: 14px; color: #7f8c8d; margin-top: -15px; margin-bottom: 25px; font-style: italic; } .note-box { background-color: #e8f6f3; border-left: 5px solid #1abc9c; padding: 15px; margin: 20px 0; font-size: 16px; } .warning-box { background-color: #fff3cd; border-left: 5px solid #ffc107; padding: 15px; margin: 20px 0; } strong { color: #d35400; } .faq-item { margin-bottom: 20px; background: #fff; padding: 15px; border: 1px solid #eee; border-radius: 5px; } .faq-question { font-weight: bold; color: #e67e23; font-size: 18px; display: block; margin-bottom: 10px; }

Introduction Automotive connectors are a component that very common for electronic engineering technicians. Its function is very simple: it sets up a bridge of communication between the blocked or isolated circuits in the circuit, so that the current flows and the circuit realizes the predetermined function. The form and structure of automotive connectors are ever-changing. They are mainly composed of four basic structural components, namely: contacts, shells (depending on the types), insulators, and accessories. Common Automotive Electrical Connections Catalog Introduction Ⅰ Automotive Connectors Ⅱ Basic Structure Ⅲ Design Criteria Ⅳ Automotive Connector Development Trends Ⅴ Connector Selection Ⅵ Performance Standard for Automotive Electrical Connectors Ⅶ FAQ Ⅰ Automotive Connectors There are nearly 100 types of connectors used in general automobiles, and there are hundreds of connectors used in a single model. As people have higher and higher requirements for safety, environmental protection, comfort, and intelligence in automobiles, the application of automotive electronic products is increasing, which make the number of automotive connector applications increase. Figure 1. Automotive Connector Type Ⅱ Basic Structure The four basic structural components of automotive connectors, it is these four basic structural components that enable automotive connectors to act as a bridge to make cars run stably.First, the contact piece is the core part of the automobile connector to complete the electrical connection function. Generally, a contact pair is composed of a male contact piece and a female contact piece, because the electrical connection is completed by the insertion of two parts.The male contact is a rigid part, and its shape is cylindrical (round pin), square column (square pin) or flat (insert). The male contacts are generally made of brass and phosphor bronze. The female contact piece is the jack, which is the key part of the contact pair. It relies on the elastic structure to elastically deform when it is inserted into the pin to generate elastic force to form close contact with the male contact piece to complete the connection. There are many types of jack structures, including cylindrical type (split slot, necking), tuning fork type, cantilever beam type (longitudinal slotting), folding type (longitudinal slotting), box type (square jack) and hyperboloid wire spring jacks, etc.Second, the shell, is the outer cover of the automotive connector. It provides mechanical protection for the built-in insulating mounting plate and pins, and provides alignment when the plug and socket are inserted, thereby fixing the connector to the device.Third, insulators, are also often referred to as automobile connector bases or inserts. Its function is to arrange the contacts according to the required position and spacing, and to ensure the insulation performance with the shell. Good insulation resistance, withstand voltage performance and ease of processing are the basic requirements for selecting insulating materials to be processed into insulators.Fourth, accessories, are divided into the structural part and the installation part. Structural accessories such as retaining rings, positioning keys, positioning pins, guide pins, coupling rings, cable clamps, sealing rings, gaskets, etc. Mounting accessories such as screws, nuts, spring rings, etc. Most of the accessories have standard parts and general parts.   Ⅲ Design Criteria With the rapid development of the automobile industry, various functional parts and various components on the automobile are constantly developing in the direction of intelligence, refinement and reliability. The structural design, appearance design and material of automobile connectors are also proposed. higher requirement. Automotive connectors must meet the USCAR-20 standard, which is the performance standard of automotive electrical connector systems. It is necessary to stipulate that the electrical connector contact surface of automotive connectors should always be reliable throughout the service cycle, including the following factors:1) The material of the connector contacts is stable and reliable.2) Positive force stability.3) The voltage and current of the circuit are stable.4) The temperature requirements are within the specified range, including the surrounding temperature and its own temperature rise.5) Better robustness.6) It must be the same as the connector used for high-speed and long-distance communication computers, and the automotive connector must be able to work reliably under harsh conditions.7) Connector insertion force: below 20.5kg8) Connector retention force: 2.5kg or more9) Heat resistance: -40~120℃ Figure 2. Automotive Connectors Ⅳ Automotive Connector Development Trends The "Miniaturization", "High Speed" and "Intelligence" of connector products are the trends of future development. The future technological innovation of the industry is mainly concentrated in the following directions:1) Miniaturization DevelopmentThis technology is mainly developed for the miniaturization trend of connectors, and can be applied to micro-miniature connectors below 0.3mm, which belongs to the new varieties of MINI USB series products. It can be used for multi-contact expansion card slot connectors, which can meet and exceed the strict requirements of multi-contact surface mount technology butt joint coplanarity, with high accuracy and low cost.2) Wireless TransmissionThe high-frequency and high-speed wireless transmission of connector technology is mainly aimed at a variety of wireless device communication applications and has a wide range of applications.3) Simulation Application TechnologyIt is based on a variety of disciplines and theories, using computer and its corresponding software such as AutoCAD, Pro/E program stress analysis software as tools, through the establishment of product models and corresponding boundary conditions, to its mechanical, electrical, high-frequency simulation analysis and confirmation of other performances, thereby reducing the cost of product development failure caused by factors such as material selection and unreasonable structure, improving the development success rate, and helping to provide support for the realization of complex system applications for products.4) Connector Intelligence TechnologyThis technology is currently mainly used in DC series power connector products. Intelligent signal detection can be performed before power transmission to ensure that the positive and negative poles are turned on and the power is turned on after the plug is inserted in place. In the future, enterprises will need to develop similar intelligent technologies for other products because of the adverse consequences of arc damage and burn-in caused by conductive contact.5) Precision connector technologyPrecision connectors involve many aspects such as product design, process technology and quality control technology. The main technologies include the following aspects:a. Precision mold processing technology: Adopt CAD, CAM and other technologies, introduce high-precision processing equipment in the industry, and use personnel production experience and advanced equipment and technical means to achieve high-precision high-quality mold products.b. Precision stamping and injection molding technology: realize precise, efficient and stable all-round control and perfect surface quality of various stamping parts and injection molding parts to ensure product quality.c. Automated assembly technology: Through the application of precision control technology, semi-automatic testing machine technology, etc., the problem of manual operation of precision products is overcome and the core competitiveness is improved.6) Manufacturing Process ResearchThe competitiveness of products depends to a certain extent on the level of manufacturing technology. Continuously developing new manufacturing processes and improving existing production and processing technologies can greatly improve the manufacturing efficiency and quality assurance capabilities of products.a. Fine manufacturing process: This process is mainly aimed at technologies such as small spacing and thin thickness. Some companies have carried out research on the process of connectors with a spacing of less than 0.4mm. This type of technology can ensure that the company reaches the advanced level of the international industry in the field of ultra-fine manufacturing.b. Integrate development technology of light source signal and electromechanical structure. It can be applied to audio connectors placed in electronic components. By adding IC, LED and other electronic components to the audio connectors, which can also transmit analog signals and the function of digital signal. It breaks through the current design of audio connector conduction transmission in the form of mechanical contact.c. Low temperature and low pressure molding process technology. The sealing and physical and chemical properties of the hot-melt material are used to achieve the functions of insulation and temperature resistance. After packaging, the wire protects the welding point from being pulled by external forces, and the packaging of the DC connector body and the wire has a insulation, temperature resistance, impact resistance and other functions ensure product quality and reliability, and will continue to be developed and applied in different products in the future. Figure 3. Automotive Connectors Ⅴ Connector Selection 1) Electrical FactorCurrent requirements: high current, low current, signal level; Steady state, cyclic, transient.They determine the type of terminal/size of contact segment/plating (0.64mm to 8.0mm pin and male terminal).Wire diameter/insulation requirements: voltage drop and/or corrosion resistance, which determine the center distance of the connector.2) Location/EnvironmentTemperature: Engine compartment – sealed, ambient temperature >105℃; vibration, fluid compatibility, passenger compartment – unsealed, ambient temperature <85℃.Sealing: Potential for high pressure jet/splash, potential for immersion, humidity; fluid type, sealed or not for device connectors.3) StandardStandards: Customer StandardsInstitutional StandardsDomestic StandardsInternational StandardsConnector performance test requirements are included in system-level specifications. For GM, Ford and Chrysler are usually USCAR specifications, that is, engine-related applications have relatively high vibration requirements. Other OEMs generally have their own standards (similar to USCAR). What’s more, equipment-side suppliers are responsible for the performance of mating-side connectors.4) Customer PreferencePreferred product strategy: Reduce cost of connector systems with different methods:Ford: Design competition for door connectors.Ford: Prefer terminal design/supplier (focus on contact interface).General: Prefer the terminal design (focus on the hole position of the connector).Chrysler: Strategies for favoring terminal/plastic Part suppliers.5) Regional preferenceNorth America: USCAR Drawing/Performance/Design Criteria —Tangless Terminals, TPA, CPA regulations. In many instances the harness supplier has a significant influence.Europe: Design influence of contact contacts/development with major OEMs; preference for two-piece contacts, even if cost pressures and North American porting operations force OEMs to consider U.S technology, that is, accepting Tangled contacts. Long-term relationships between OEMs and suppliers.Asia: Traditionally influenced by Toyota. Focus on assembly ability (ergonomics) that affects quality assurance; North America influences China to change the status, like low-cost solutions.6) Physical factorsSize, number of circuits, mating position, wire harness docking or equipment connection, mechanical main features: levers, bolts; manual docking capability; multiple types of connectors for high input/output applications.7) AssemblyWire Harness: Insertion force of connectorVisual, audible and tactile operational feedback for users. Figure 4. Terminals & Connectors Ⅵ Performance Standard for Automotive Electrical Connectors For a connector, the specification parameters such as the ambient temperature, current carrying capacity, protection level, anti-vibration level, etc. will be defined in its specifications at the beginning of research and development, because when the connector is selected according to different requirements. The following are three most widely used standards USCAR-2-6, QC/T1067-2017 and GMW3191-2012.🔺QC/T-1067 Temperature Classification Class Ambient Operating Temperature Typical Installation Position A -40~85℃ Passenger compartment (Not recommended) B -40~100℃ Passenger compartment C -40~125℃ On engine D -40~150℃ On engine (hot locations) E -40~175℃ and above Negotiate   🔺QC/T-1067 Vibration Classification Class Typical Installation Position V1 On elastic parts of the body but not to the engine V2 On engine but not to heavily vibrating parts V3 Components subject to serve vibration V4 Components subject to extreme vibration V5 On Wheel   🔺QC/T-1067 Sealing Classification Class Description Typical Installation Position S1 Unsealed Passenger compartment or trunk S2 Sealed Exposed areas S3 Sealed (with high pressure spray) Exposed areas (with high pressure spray)   🔶GMW-3191 Temperature Class Class Ambient Operating Temperature Typical Installation Position 1 -40~85℃ Passenger compartment or trunk 2 -40~100℃ Underhood, chassis 3 -40~125℃ On engine, transmission 4 -40~150℃ On engine (hot locations) 5 Per connector CTS Per CTS GTS=Component Technical Specification   🔶GMW-3191 Vibration Class Class Typical Installation Position 1 On body or chassis 2 On engine 3 On wheel, Unsprung Mass 4 Severe applications (e.g., ECU, Throttle Body, EGR) 5 Transmission (internal and external) ECU=Engine Control Unit, EGR=Exhaust Gas Recirculation   🔶GMW-3191 Sealing Class Class Description Typical Installation Position 1 Unsealed Unsealed Passenger Compartment or trunk 2 Submersion Sealed Underhood or exposed areas, including door 3 High Pressure Spray Protected Exposed areas where high pressure spray is expected   🔻USCAR-2 Temperature Classification Class Ambient Operating Temperature Typical Application T1 -40~85℃ T1 is not recommended for new applications T2 -40~100℃ Typical suitable for use in passenger component T3 -40~125℃ Typical suitable for use in engine component T4 -40~150℃ Needed for some on-engine applications near hot components T5 -40~175℃ For use as needed   🔻USCAR-2 Vibration Classification Class Common Name Typical Application Other Requirements Met V1 Chassis Profile Components on sprung portions of vehiele not coupled to Engine None V2 Engine Profile Components coupled to Engine with no severe vibration possible Pass on V2 - pass also for V1 V3 Severe On-Engine Components subject to serve vibration Pass on V3 - pass also for V1 and V2 V4 Extreme Vibration Used as needed to correlate to extreme vibration areas Pass on V4 - pass also for V1 and V2 and V3 V5 Unsprung Component Wheel-mounted components None   🔻USCAR-2 Sealing Classification Seal Class Common Name Typical Application S1 Unsealed S1 is suitable for use in passenger components or other dry areas on a vehicle such as the trunk S2 Sealed S2 (meets requirements of 5.9.7) is for exposed locations S3 Sealed (with high pressure spray) S3 is for exposed locations. It meets Sections 5.9.7 plus 5.6.7; S3 is applications when robustness to direct splash is needed Regarding the vibration test, the main purpose is to check whether the performance of the connector system under the simulated actual vehicle vibration conditions meets the requirements. In the case of vibration or in shock, it will cause the coating wear of the terminal contact surface, the positive pressure attenuation, the failure of the mechanical system performance of the supporting plastic material, etc. Therefore, it is necessary to continuously monitor the contact resistance in the vibration experiment and ensure that it does not exceed 7Ω (or 1Ω) in the line for more than 1 microsecond. According to the definition and analysis of the connector using environment through the above different standards, it is necessary to understand that the use position, the temperature level, vibration level, and protection level should be considered to make the best choice.   Ⅶ FAQ 1. What are connectors in cars?Connectors used in automotive applications enable everything from stereo systems to drivetrains. As these systems become more connected, more automated, and more energy-efficient, they require connectors that can deliver high-speed connectivity in rugged, lightweight, and easy-to-install designs. 2. How do I choose a car connector?There are several criteria to consider when selecting electrical interconnect components, including:Current rating (current density)Connector size (circuit density)Engagement forceWire sizeConfiguration and circuit sizeOperating voltageAgency approvalsPrice per circuit 3. What are the different types of automotive electrical connectors?Automotive TerminalsContactsCrimp Wire Pins, Tabs & FerrulesFoil TerminalsInterconnect DevicesKnife DisconnectsMagnet Wire TerminalsPCB Terminals 4. How many connectors does a car have?Today, there are an average of 274 connectors in a vehicle. 5. Are all car stereo connectors the same?All aftermarket car stereos can use the same car stereo wiring harness, but it all depends on what the owner of the vehicle wants to do for one main reason. 6. What is uscar standard?SAE USCAR-2. May 1, 2004. PERFORMANCE STANDARD FOR AUTOMOTIVE ELECTRICAL CONNECTOR SYSTEMS. Procedures included within this specification are intended to cover performance testing at all phases of development, production, and field analysis of electrical terminals, connectors, and so on.

Introduction In this lesson, we'll look at what a servo motor is and how it works. First, let's define what a servo motor is and look at some of the unique characteristics of the different types of servo motors and their applications. You will also learn how to control Servo Motors with an Arduino and a Raspberry Pi in this blog. Introduction Ⅰ What is a Servo Motor? Ⅱ Servo Motor Related Video: Ⅲ Types of Servo Motors 3.1 AC or DC 3.2 Brushed or Brushless 3.3 Synchronous or Asynchronous Ⅳ Servo Motor Working Principle Ⅴ Applications of Servo Motors Ⅵ Difference Between Stepper Motor and Servo Motor  Ⅶ Servo Motors Control with an Arduino  7.1 Experiment 1 Ⅷ Control with  Raspberry Pi 8.1 PWM (Pulse Width Modulation) 8.2 Components Required 8.3 Circuit Diagram 8.4 Working and Programming Explanation 8.5 Code Ⅸ FAQ   Ⅰ What is a Servo Motor? A servo motor is a self-contained electrical device that rotates machine parts with high efficiency and precision. This motor's output shaft can be moved to a specific angle, position, and velocity that a standard motor cannot. The Servo Motor  combines a standard motor with a sensor to provide positional feedback. The most important component of the Servo Motor  designed and used specifically for this purpose is the controller  . Figure1:Servo Motor      Ⅱ Servo Motor Related Video:   How servo motor works   Servo Motor Video Description: This movie gives an overview of how RC servo motor works and how it's made.   Ⅲ Types of Servo Motors Servo motors are classified into two types based on their application: AC servo motors  and  DC  servo motors. There are three major factors to consider when evaluating servo motors. The first type of consideration is the current type –  AC  or  DC – and the second type of consideration is the type of commutation used, whether the motor uses brushes. The third type of consideration is the motor's rotating field, the rotor, and whether the rotation is synchronous or asynchronous.   3.1 AC or DC Let's start with the first servo consideration. The most fundamental classification of a motor is based on the type of current it will use. When it comes to performance, the primary distinction between  AC and DC motor  s is their inherent ability to control speed. Figure2:DC or AC Servo Motor  With a constant load, the speed of a DC motor  is directly proportional to the supply voltage. The frequency of the applied voltage and the number of magnetic poles determine the speed of an alternating current motor.   Figure3:DC or AC Servo Motor  While both AC and DC motor  s are used in servo systems, AC motors  can handle more current and are more commonly used in servo applications such as robots, in-line manufacturing, and other industrial applications requiring high repetitions and precision.   3.2 Brushed or Brushless The next step is to decide whether to use a brushed or brushless finish. A DC Servo Motor  can be commutated mechanically with brushes, electronically without brushes, or mechanically with a commutator. Brushed motors are less expensive and easier to operate in general, whereas brushless designs are more reliable, have higher efficiency, and are quieter.   Figure4:brushed or brushless Servo Motor  A commutator is a rotary electrical switch that reverses the current direction between the rotor and the drive circuit on a regular basis. It is made up of a cylinder made up of multiple metal contact segments on the rotor. Two or more electrical contacts known as "brushes" made of a soft conductive material such as carbon press against the commutator, making sliding contact with commutator segments as it rotates. Figure5:brushed or brushless Servo Motor  While the majority of servo motors are AC brushless designs, brushed permanent magnet motors are occasionally used as servo motors due to their simplicity and low cost. The permanent magnet DC motor  is the most common type of brushed DC motor  used in servo applications. Figure6:brushed or brushless Servo Motor  Brushless DC motors replace the physical brushes and commutator with an electronic commutation method, typically using Hall effect sensors or an encoder. Figure7:brushed or brushless Servo Motor  AC motors are generally brushless, though some designs do have brushes and are mechanically commutated, such as the universal motor, which can run on either AC or DC power. Figure8:brushed or brushless Servo Motor      3.3 Synchronous or Asynchronous While DC motor  s are generally classified as brushed or brushless, AC motors  are often distinguished by the rotational speed of their synchronous or asynchronous field. If we recall from the AC-DC discussion, the frequency of the supply voltage and the number of magnetic poles determine the speed of an AC motor. This speed is known as the synchronous speed. As a result, in a synchronous motor, the rotor rotates at the same rate as the rotating magnetic field of the stator. Figure9:synchronous or asynchronous Servo Motor  In an asynchronous motor, also known as an induction motor, the rotor rotates at a slower rate than the stator's rotating magnetic field. However, the speed of an asynchronous motor can be varied using a variety of control methods, including changing the number of poles and changing the frequency, to name a few. Figure10:synchronous or asynchronous Servo Motor      Ⅳ Servo Motor Working Principle A servo is made up of a motor (either DC or AC), a potentiometer, a gear assembly, and a control circuit. First and foremost, we use gear assembly to reduce RPM and increase motor torque. Assume that at the initial position of the servo motor shaft, the position of the potentiometer knob is such that no electrical signal is generated at the potentiometer's output port. An electrical signal is now applied to the error detector amplifier's other input terminal. The difference between these two signals, one from the potentiometer and one from other sources, will now be processed in a feedback mechanism and output will be provided in the form of an error signal. This error signal serves as the motor's input, and the motor begins to rotate. The motor shaft is now connected to the potentiometer, and as the motor rotates, so does the potentiometer, generating a signal. As a result, as the potentiometer's angular position changes, so does its output feedback signal. After a while, the position of the potentiometer reaches a point where the output of the potentiometer is the same as the external signal provided. There will be no output signal from the amplifier to the motor input because there is no difference between the externally applied signal and the signal generated at the potentiometer in this condition, and the motor will stop rotating. Figure11:synchronous or asynchronous Servo Motor    Ⅴ Applications of Servo Motors Servo Motors are used in a variety of applications, some of which are listed below:In robotics, the servo motor is used to activate movements, giving the arm its precise angle.The servo motor is used to start, move, and stop conveyor belts that transport the product through multiple stages. As an example, consider product labeling, bottling, and packaging.The servo motor is built into the camera to correct a lens and improve out-of-focus images.In a robotic vehicle, the servo motor is used to control the robot wheels, producing enough torque to move, start, and stop the vehicle as well as control its speed.In a solar tracking system, the servo motor is used to correct the angle of the panel so that each solar panel faces the sun.The servo motor is used in metal forming and cutting machines to provide milling machines with precise motion control.Textiles use servo motors to control spinning and weaving machines, knitting machines, and looms.The Servo motor is used in automatic door openers in public places such as supermarkets, hospitals, and theaters to control the door.   Ⅵ Difference Between Stepper Motor and Servo Motor  Comparison Chart Basis for ComparisonStepper MotorServo MotorBasicStepper motor operates in steps.It is continuous operating machine.System configurationOpen loopClosed loopPower requirementMoreComparatively lessDesignSimpleComplexAbility to responseHighComparatively lowCostInexpensiveExpensiveReliabilityMoreLessNoise and vibrationHighComparatively lessOperating speedSlowFastFeedback mechanismNot existExistHeat generationMoreComparatively lessNumber of polesGenerally 50 to 150Around 4 to 12Life spanMoreLessDamage due to overloadLess prone to get damaged.Comparatively more prone to get damaged.Torque producedHighLowEfficiencyLessMoreTolerance towards moment of inertiaHighLowApplicationsIn gaming, textile, welding machineries, medical and 3D printing equipments, etc.In robotics, antenna positioning systems, automatic doors, cameras, remote controlled equipments, etc. Ⅶ Servo Motors Control with an Arduino  You can connect small servo motors directly to an Arduino  to control the shaft position very precisely. Most servo motors have the following three connections: Black/Brown ground wire.Red power wire (around 5V).Yellow or White PWM wire. In this experiment, the power and ground pins will be connected directly to the Arduino  5V and GND pins. The PWM input will be connected to a digital output pin on the Arduino,  7.1 Experiment 1 Hardware Required1 x TowerPro SG90 servo motor1 x Arduino  Mega25603 x jumper wires   Wiring Diagram The best thing about servo motors is that they can be directly connected to an  Arduino ,  Connect the motor to the Arduino  in the manner shown in the table below: Servo red wire – 5V pin Arduino          Servo brown wire – Ground pin Arduino          Servo yellow wire – PWM(9) pin Arduino  Caution: Do not try to rotate the servo motor by hand, as you may damage the motor.     Figure12: Wiring Diagram Code When the program starts, the servo motor will slowly rotate from 0 to 180 degrees, one degree at a time. When the motor has rotated 180 degrees, it will start rotating in the opposite direction until it reaches the home position. #include //Servo library Servo servo_test; //initialize a servo object for the connected servo int angle = 0; void setup() { servo_test.attach(9); // attach the signal pin of servo to pin9 of arduino} void loop() { for(angle = 0; angle < 180; angle += 1) // command to move from 0 degrees to 180 degrees { servo_test.write(angle); //command to rotate the servo to the specified angle delay(15); } delay(1000); for(angle = 180; angle>=1; angle-=5) // command to move from 180 degrees to 0 degrees { servo_test.write(angle); //command to rotate the servo to the specified angle delay(5); } delay(1000);} Ⅷ Control with  Raspberry Pi In this tutorial, we will use the Raspberry Pi  to control a servo motor. Before we get to the servo, let's talk about PWM because it's the basis for controlling a servo motor.   8.1 PWM (Pulse Width Modulation) PWM is an abbreviation for 'Pulse Width Modulation.' PWM is a technique for obtaining variable voltage from a steady power supply. Consider the circuit below to better understand PWM.   Figure13:PWM   In the figure above, if the switch is closed continuously for a period of time, the LED will be 'ON' during that time. If the switch is closed for half a second and then opened for the next half a second, the LED will be turned on only for the first half a second. The percentage of time the LED is on over the total time is known as the  Duty Cycle , and it can be calculated as follows:   Duty Cycle =Turn ON time/ (Turn ON time + Turn OFF time) Duty Cycle = (0.5/ (0.5+0.5)) = 50% As a result, the average output voltage will be 50% of the battery voltage. When we increase the ON and OFF speed to a certain level, the LED will dim instead of being ON and OFF. This is because our eyes cannot clearly detect frequencies higher than 25Hz. Consider a 100ms cycle with an LED that is off for 30msec and on for 70msec. We will have 70% stable voltage at the output, so the LED will glow continuously at 70% intensity. The Duty Ratio ranges from 0 to 100. '0' denotes complete inactivity, while '100' denotes complete activation. This Duty Ratio is critical for Servo Motor,  This Duty Ratio determines the position of the Servo Motor,    8.2 Components Required We're running Raspbian Jessie on a Raspberry Pi  2 Model B. All of the basic hardware and software requirements have already been discussed, and you can find them in the Raspberry Pi  Introduction; however, we will need: Connecting pins 1000uF capacitor SG90  Servo Motor  Breadboard   8.3 Circuit Diagram Figure14:Circuit Diagram If A1000F is not connected across the +5V power rail, the  PI  may shut down unexpectedly while controlling the servo.   8.4 Working and Programming Explanation Once everything is connected according to the circuit diagram, we can power on the  PI and begin writing the program in PYHTON. We will go over a few commands that we will use in the PYHTON program. We will import a GPIO file from the library, and the function below will allow us to program the GPIO pins on the PI. We're also renaming "GPIO" to "IO," so in the program, whenever we refer to GPIO pins, we'll say "IO." import RPi.GPIO  as IO When the GPIO pins that we are attempting to use are performing other functions. In that case, we'll get warnings while running the program. The following command instructs the PI to disregard the warnings and continue with the program. IO.setwarnings(False) We can refer to the GPIO pins of the PI by either their pin number on the board or their function number. On the board, for example, 'PIN 29' is 'GPIO5'. So we specify whether we want to represent the pin here by '29' or '5'. IO.setmode (IO.BCM) PIN39 or GPIO19 is selected as the output pin. This pin will provide PWM output. IO.setup(19,IO.OUT) After we have set the output pin, we must configure it as a PWM output pin. p equals IO. Power-Wave Modulation (PWM) (output channel, frequency of PWM signal) The above command is for configuring the channel as well as the frequency of the channel." 'p' is a variable that could be anything. We'll use GPIO19 as the PWM "Output channel," and the "Frequency of PWM signal" will be 50, because the SG90's working frequency is 50Hz. The command below is used to initiate PWM signal generation. 'DUTY CYCLE' is used to specify the 'Turn On' ratio, as previously explained. p.start(DUTYCYCLE) The following command is used to create a forever loop, which means that the statements inside the loop will be executed indefinitely.   8.5 Code import RPi.GPIO  as IO        # calling for header file for GPIO’s of PI import time                           # calling for time to provide delays in program IO.setwarnings(False)          # do not show any warnings IO.setmode (IO.BCM)            # programming the GPIO by BCM pin numbers. (like PIN29 as‘GPIO5’) IO.setup(19,IO.OUT)             # initialize GPIO19 as an output p = IO.PWM  (19,50)              # GPIO19 as PWM output, with 50Hz frequency p.start(7.5)                             # generate PWM signal with 7.5% duty cycle while 1:                                                       # execute loop forever                                             p.ChangeDutyCycle(7.5)                   # change duty cycle for getting the servo position to 90º         time.sleep(1)                                      # sleep for 1 second         p.ChangeDutyCycle(12.5)                  # change duty cycle for getting the servo position to 180º         time.sleep(1)                                     # sleep for 1 second         p.ChangeDutyCycle(2.5)                  # change duty cycle for getting the servo position to 0º         time.sleep(1)                                     # sleep for 1 second   Ⅸ FAQ 1. Are servo motors AC or DC? AC servo motors depend on an AC power source whereas DC Servo motors depend on DC power source (like Batteries). AC servo motors performance is dependent upon voltage as well as frequency whereas DC servo motors performance mainly relies upon voltage alone. 2. Can servo motors rotate 360? The position of the servo motor is set by the length of a pulse. ... The end points of the servo can vary and many servos only turn through about 170 degrees. You can also buy 'continuous' servos that can rotate through the full 360 degrees. 3. Which motor is used in servo motor? While the majority of motors used in servo systems are AC brushless designs, brushed permanent magnet motors are sometimes employed as servo motors for their simplicity and low cost. The most common type of brushed DC motor used in servo applications is the permanent magnet DC motor.

Introduction In the FOC(Field Oriented Control) algorithm, the sampling current is the basis of the algorithm implementation and a very important part. So accurate current sampling can bring better result to the algorithm. In other words, if the current sampling is accurate, it will be very helpful for the subsequent coordinate transformation to obtain required results. From this we can see the role of current sampling in the entire FOC algorithm. Understanding Field-Oriented Control Catalog Introduction Ⅰ Current Sampling Method Ⅱ Three Sampling Methods and Precautions 2.1 Single-resistor Sampling 2.2 Dual-resistor Sampling 2.3 Triple-resistor Sampling Ⅲ The Key to Sampling Ⅳ Delay Source Ⅴ Delay Type and Typical Time Ⅵ Analysis in Details 6.1 PWM Dead Time Insertion 6.2 Optocoupler Delay and Pre-Driver Delay 6.3 Transistor Switching Delay 6.4 Other Delays Ⅶ FAQ Ⅰ Current Sampling Method In motor control, the current sampling method is generally to use PWM to trigger ADC to convert. Taking SoC(System-on-a-Chip) as an example, the ADC module will be configured to automatically sample and trigger conversion. When the trigger point set by the PWM module matches, the signal will be given to the ADC module. At this time, the sampling switch in circuit will be disconnected, and then the ADC module will start to convert, and the voltage of the corresponding sampling current can be obtained after the conversion is completed. The AD value of the signal, you can use this value in the program to write and verify the algorithm. Figure 1. Current Sampling Time Ⅱ Three Sampling Methods and Precautions Current sampling is the basis of FOC, including current sensor sampling and resistor sampling. Resistor sampling is widely used for its simple and low-cost characteristics. The method includes single-resistor sampling, dual-resistor sampling, and triple-resistor sampling. 2.1 Single-resistor Sampling The biggest difference between the single-resistor and the other two methods is that it cannot obtain two current signals at the same time. Even if two current signals are obtained, there is an error in estimating the third current signal. The formula Iu+Iv+Iw=0 is conditional, that is, the three currents must be recorded at the same time. When the inductance of the motor is larger, the two currents obtained are closer to the real situation. When the inductance is small, the deviation may be relatively large. So if the inductance of the current is large, single-resistor sampling can be selected.This method requires two samplings in one PWM cycle. In this case, it is necessary to analyze the switch state in the algorithm to clarify which phase current the reconstructed current corresponds to at the time of sampling. 2.2 Dual-resistor Sampling In the case of dual-resistor sampling, the sampled two-phase current must be used directly. Even if there is a deviation, it needs to be used. This method cannot be used to calculate the third-phase current based on the other two-phase sampling like the triple-resistor sampling. That is to say, this method needs to consider the problem of the sampling window. If the sampling current is to be guaranteed to be accurate, the sampling window must be large enough. To make the sampling window large enough, the PWM waveform needs to be deformed. But this will increase the execution time of the algorithm. The advantage of this approach is to reduce a current-sense resistor and an op amp.As shown in the figure below, the front of the red circle is the oscillating area. If the sampling window is small, only the oscillating area will not be able to obtain an accurate current. To process the sampling window, you can refer to the following figure, so that the obtained current will be more accurate. Figure 2. Current Sampling Zone 2.3 Triple-resistor Sampling This method is the simpler among the three methods. It directly uses three current-sensing resistors to sample the three-phase phase current of the motor, and the result obtained in this way is relatively straightforward. Using the formula Iu+Iv+Iw=0, recalculate the phase current of one phase with a small sampling window. So that the accuracy of the result obtained is the highest, and the implementation of the following related algorithms is easier. It is the advantage of this method. However, three current-sense resistors and three op amps are used, the hardware cost will be higher than the other two.   Ⅲ The Key to Sampling The current sampling includes peak current and average current sampling. Generally, the most common is the average current sampling and its control, so there are actually two ways to sample the average current. One is that the current-sense resistor is placed on the upper bridge of the inverter bridge. The other is that the current-sense resistor of the inverter bridge is connected to the lower end of the lower bridge.The general method is the latter. The current detection circuit corresponding to this method is relatively simple, and the corresponding power consumption will also be reduced. In this case, the freewheeling current is collected at the lower end, and then we can sample at the midpoint of the lower bridge opening. At this time, the corresponding current reflects the average current, so the corresponding current control is the average.Then, if we use the three-resistor sampling method, the selected ADC module must have at least the function of simultaneous sampling of three channels. So as to ensure that the three-phase currents obtained by sampling are the currents at the same time, and at this time, to meet the condition, Iu+ Iv+Iw=0.In the case of dual-resistor sampling, there are only two sampling resistors, and the obtained current cannot use the formula Iu+Iv+Iw=0. Therefore, even if the sampling window is small, if the algorithm is not processed, the double-resistor scheme has limitations. In order to get a better adaptation to the scene, algorithm compensation must be performed on the dual-resistor method, which is also the key point of it.Similarly, for the single-resistor sampling way, the corresponding current needs to be obtained according to different switch combinations, and it needs to be sampled twice in a PWM cycle. This method cannot satisfy Iu+Iv+Iw=0, and can only be determined by an algorithm. Compensation and correction are performed, so the single-resistor method is more difficult to take. However, if the difficulty can be solved, this method is the best and cheapest one.   Ⅳ Delay Source During the development of the motor-driven FOC control, have you encountered the situation that the motor is too noisy, inefficient or even unable to operate? All of this may be due to sampling anomalies of the phase currents, resulting in the inability to reconstruct the correct three-phase currents in the FOC algorithm. Here is an analysis of a factor that affects current sampling: the delay source.In the motor drive FOC control of double-resistor sampling, the sampling point is set as the middle moment when the lower tube of the drive bridge is turned on. Note that this is the middle moment when the lower tube of the drive bridge is turned on, not the middle moment of the PWM cycle output by the MCU. There are as many as seven delay sources in this typical drive topology because the PWM is calculated from the MCU to the ADC module where the current signal is sent to the MCU. Figure 3. MCU Output Ⅴ Delay Type and Typical Time The table below details the seven sources of delay that exist in motor drive system topologies and their typical timings. These delays will be superimposed together, and the effect is that the actual output PWM waveform lags behind the PWM waveform that the MCU calculates the expected output. According to this calculation, the phase current sampling point needs to lag the middle moment of the MCU calculating the expected output PWM waveform. Delay Type Typical Time PWM Dead Time Insertion 100ns-2μs Optocoupler Isolation to Pre-driver 40ns-300ns Pre-driver Switch Delay About 50ns MOSFET Switching Time 100ns-1μs Amplifier Delay <1μs Low-pass Filter Delay 1-2μs ADC Delay 50ns-200ns   Ⅵ Analysis in Details 6.1 PWM Dead Time Insertion In the three-phase brushless motor drive system, three bridge arms are required to control the current flow of the phase line, and there are two power devices on each bridge arm, such as MOSFET and IGBT. The pair of power devices cannot be turned on at the same time, otherwise a short circuit will occur. Here MOSFET is used as a power device to illustrate. In the control, dead time must be inserted to ensure that the upper and lower MOSFETs are not turned on at the same time. Typical values of dead time may be between 100ns and 2μs, depending on various factors in the system, such as MOSFET drive voltage and type.After the required PWM waveform is inserted into the dead time, what you get is that both the PWM midpoint and the rising edge are shifted to the right. When using the FOC control algorithm calculates the proper PWM, we start seeing the first delay, recording the dead time. Figure 4. Dead Time Insertion 6.2 Optocoupler Delay and Pre-Driver Delay The signal response of the various optocouplers and pre-drivers causes additional delays between the moment the MCU controls the FTM module to output the PWM waveform and the moment the MOSFET gate is controlled. The output of the pre-driver is delayed by a period of time (Delay1) compared to the waveform output from the MCU pins. Figure 5. Delay 1 6.3 Transistor Switching Delay Through the pre-driver, the PWM waveform reaches the MOSFET transistors, but due to their inherent characteristics, all transistors take a certain amount of time to turn on and off. This delay time varies depending on the transistor type and the voltage level required to switch between on/off. Delay 2 is the total delay between the theoretical switching point (CMP2) of the phase line voltage and the instant of the actual switching point. Figure 6. Delay 2 Finally, the gate voltage reaches the level that can make the transistor turn on, the current passes through the phase line and the sampling resistor, and a voltage difference is generated across the sampling resistor. The red waveform is the phase current waveform in an ideal state. At this time, there is a total delay time between the midpoint of the PWM cycle calculated and generated by the MCU, and the "phase current midpoint shift" is shown in the figure. Figure 7. Phase Current Midpoint Shift 6.4 Other Delays As shown in the figure below, the final delay chain that affects the current sampling is formed by the amplifier slew rate, the low-pass filter on the MCU pins, and the ADC slew rate. The time marked by the red circle in the figure is the correct current sampling time. It can be seen that the phase current sampling point is greatly delayed compared with the PWM midpoint output by the FTM. Figure 8. Other Delay In all and electrical and electronic circuits, there will be signal delay problems. And it is impossible to completely eliminate them, but the impact can be reduced by selecting low-delay devices. In the motor drive, in addition to selecting the appropriate device, it is also necessary to perform software compensation for the signal delay. The precise delay time of these delay sources mentioned in the article can be obtained by oscilloscope and calculation, and the correct current sampling time can be obtained by compensating for these delays in software. In this way, the data collected at the correct moment can be used as the data source for reconstructing the three-phase current of the motor in the FOC control.   Ⅶ FAQ 1. What is FOC algorithm?Field-oriented control (FOC), or vector control, is a technique for variable frequency control of the stator in a three phase AC induction motor. 2. What is FOC drive?Vector control, also called field-oriented control (FOC), is a variable-frequency drive (VFD) control method in which the stator currents of a three-phase AC or brushless DC electric motor are identified as two orthogonal components that can be visualized with a vector. 3. What is FOC brushless motor?FOC implementation allows the BLDC motor to run more efficiently (high power factor and better light load efficiency), more smoothly (lower torque ripples) with quick dynamic response (better dynamic performance to load and speed changes). 4. What is FOC in BLDC motor?Field oriented control (FOC) is an important control approach for Brushless DC motors. It resembles sinusoidal commutation but adds a major mathematical twist. Figure 3a shows control schemes for both sinusoidal commutation and field oriented control. 5. How is Bldc phase current measured?With a BLDC motor use an ac voltmeter to measure the voltage between any 2 wires of the 3 motor wires and then convert the line-to-line voltage to the phase voltage value by dividing the line-to-line voltage by 3 =1.73. 6. Do BLDC motors have inrush current?Handle Peak Inrush Current of a BLDC Motor to protect the Power Supply. Summary: BLDC motors have a Peak current on startup which is 3x or more the rated current. The motor has a rated current of 7.3A. 7. What causes motor inrush current?When an electrical device, such as an AC induction motor, is switched on, it experiences a very high, momentary surge of current, referred to as inrush current. ...The interaction of these two magnetic fields produces torque and causes the motor to turn.

IntroductionⅠ What is a Wireless Transmitter?Ⅱ How to Make a Transmitter and Receiver Ⅲ Wireless Transmitter vs Wireless Receiver    3.1 Wireless Transmitter    3.2 Wireless Receiver    3.3 What are Optical Transmitters and Receivers?    3.4 How do You Use a Wireless Transmitter? Ⅳ Transmitter Specifications Ⅴ The Types of Transmitter Based on Modulation Scheme and Conversion Technique Employed    5.1 AM Transmitter    5.2 FM Transmitter    5.3 SSB Transmitter    5.4 Direct Conversion Transmitter    5.5 Super Heterodyne TransmitterⅥ Smart Wireless Transmitters    6.1 What are Smart Transmitters?    6.2 What are the Main Features of Smart Transmitters?Ⅶ 5 Tips to Optimize Your Sennheiser Wireless System    7.1 Don’t Cover the Antenna    7.2 Fresh Batteries are Essential    7.3 Frequency Selection is Important When Using Multiple Systems    7.4 Maintain Line of Sight between Components    7.5 Keep Transmitters and Receivers as Close as PossibleⅧ Answers to 6 Questions about the Wireless TransmitterIntroduction A wireless transmitter is a telecommunications device that generates radio waves in order to broadcast or transfer data via an antenna.This article on the transmitter specs, usage, and other parts of a full introduction will allow you to have a more detailed grasp of the wireless transmitter.Ⅰ What is a Wireless Transmitter?A wireless transmitter and associated receiver are required for devices that communicate data without the use of cables. The transmitter converts the audio signal to a radio signal and broadcasts it via an antenna as a radio wave. The antenna may protrude from the transmitter's bottom or be hidden within the transmitter. Government rules regulate the strength of radio transmission. Depending on the conditions and signal quality, the signal can successfully go up to 1,000 feet. There are two types of transmitters available. A "body-pack" or "belt-pack" transmitter, for example, is a compact box the size of a deck of cards (or smaller in some cases). The transmitter is worn on the body or clipped to the user's belt. A body-pack transmitter is commonly hooked to a guitar strap or attached directly to an instrument such as a trumpet or saxophone for instrument applications. The transmitter is incorporated into the handle of a portable wireless microphone, resulting in a wireless microphone that is just slightly larger than a normal wired microphone. For handheld wireless microphones, a range of microphone elements or "heads" are usually offered. A battery (typically a 9-volt alkaline type) is required to run all wireless transmitters.Figure-1 A wireless routerA router with an integrated wireless transmitter and receiver is included in the home or office wireless local area network (WLAN). Most routers also include a modem, allowing a single, high-speed Internet account to be shared by all connected computers. Instead of using Ethernet cables to connect the computers, each has a wireless network card (or wireless adapter) that has its own transmitter and receiver on board. Now, for instance, an individual computer can send a data request to the router, and the router can receive the request, forward it to the appropriate party, and then send the return response.Ⅱ How to Make a Transmitter and ReceiverThe Video Shows: How to make a transmitter and receiveMake your very own transmitter and receiver! Ⅲ Wireless Transmitter vs Wireless Receiver3.1 Wireless TransmitterThe radio's transmitter is powered by an alternating current flowing through a conductor (in this case an antenna). The alternating current changes direction very quickly, frequently millions or billions of times per second. The energy contained in such a fastly alternating current can be converted into Electromagnetic (EM) radiation. Electrons flowing as current produce electromagnetic radiation in the form of photons (energy packets).The resulting waves are sinusoidal, but their amplitude and frequency can be altered through modulation.3.2 Wireless ReceiverReceivers operate in the inverse of how transmitters do.The incident radio waves generate a tiny alternating current in the receiver's antenna (the photons impart their energy onto the electrons in the wire, resulting in the current). An alternating current is generated because EM waves oscillate). This alternating current signal is routed to the receiver's input.It's vital to recognize that when you tune a radio, you're selecting a frequency to listen to. To get the clearest signal, set your radio to the circuit's resonant frequency.' This is determined by the components used.3.3 What are Optical Transmitters and Receivers?The optical fiber communication system consists primarily of a transmitter and receiver, with the transmitter located on one end of a fiber cable and the receiver located on the other end of the cable. The majority of systems make use of a transceiver, which is a module that includes both a transmitter and a receiver. The transmitter receives an electrical signal and converts it to an optical signal using an LED or laser diode.Figure-2 Fiber-optic-data-linkA connector connects the light signal from the transmitter end to the fiber cable, which is then broadcasted through the cable. The light signal from the fiber end can be connected to a receiver, and wherever a detector converts the light signal to an electrical signal, it is conditioned appropriately for use by the receiving equipment.3.4 How do You Use a Wireless Transmitter?An electromagnetic disturbance is a radio wave. It spreads out in the same way that ripples in water do.First, the current flows through a wire. The wire is then surrounded by an electromagnetic field.This can be used by transmitters. They can send a pulse of electricity through a copper antenna.Furthermore, one end of the antenna will be grounded. This will restrict the signal to a single pulse.Metal effectively traps any radio waves that come into contact with it because it is a conductor of both electricity and magnetism. As a result, large metal objects in the home, such as a refrigerator, will interfere with the Wi-Fi signal. The radio waves will then emit in a regular pattern, much like ripples. The frequency of the emission will be measured in hertz (Hz).Transmitters create a carrier frequency, which is then mixed with the data signal and broadcast. This signal will be received by the receiver, which will then divide the two frequencies into their individual portions.Ⅳ Transmitter Specifications1DC coupled LEDs are used.2A serial port is Max232 IC Driver. 3The wavelength of the source is 660nm. 4The data rate is 1 Mbps.5The highest input voltage is +5V.6The maximum supply current is 100 mA. 7The maximum input voltage is +5V.8The supply voltage is +15V DC.9The LED driver is on board IC Driver.10The interface connectors are 2mm sockets. 11The type of input signal is digital data.  Ⅴ The Types of Transmitter Based on Modulation Scheme and Conversion Technique Employed The following are the different types of transmitters based on the modulation scheme and conversion technique used.5.1 AM TransmitterFigure-3 Typical block diagram of AM transmitter systemThe frequency range of an AM radio system is 540 to 1700kHz, with an IF of around 455 kHz. The frequencies are separated by 10 kHz.To convert audio information into an AM modulated signal, an AM transmitter employs amplitude modulation. AM modulation employs audio as the modulating signal and a high-frequency signal as the carrier. To achieve AM modulated output, the amplitude of the carrier signal is varied by the amplitude of the modulating audio signal.5.2 FM Transmitter          Figure-4    FM transmitter system block diagramFM radio systems operate in the frequency range of 88 to 108 MHz, with an IF of approximately 10.7 MHz. To convert audio information into an FM modulated signal, an FM transmitter employs frequency modulation. FM modulation makes use of audio as the modulating signal (Fm) and a high-frequency signal as the carrier. To achieve FM modulated output, the frequency of the carrier signal (Fc) is varied in accordance with the amplitude of the modulating audio signal.5.3 SSB Transmitter Figure-5 SSB transmitter block diagramThe upper and lower sidebands are transmitted by the AM transmitter. The upper band represents the sum of Fc and Fm, while the lower band represents the difference between Fc and Fm. A single-sideband (either upper or lower) is transmitted by an SSB transmitter, not both. In comparison to an AM transmitter, an SSB transmitter saves bandwidth and power.5.4 Direct Conversion TransmitterLet's take a look at how a direct conversion transmitter works. The signal constellation produced by this transmitter type is known as QPSK, which stands for Quadrature Phase Shift Keying.The first bit of digital data to be transmitted is divided into I and Q signals.The I and Q signals are processed by DACs.Low pass filtering is used to feed the output of DACs to mixers.The architecture employs LO (local oscillator). Before the mixing process, the LO signal is phase-shifted by 90 degrees to one of the mixers.The mixed I and Q components are added together to produce a QPSK modulated signal.Before transmission into the air, the QPSK modulated signal is amplified using a PA (Power Amplifier).Figure-6 Direct conversion transmitter5.5 Super Heterodyne TransmitterFigure-7 Superheterodyne-transmitterAfter obtaining a modulated signal via direct conversion transmitter, this architecture employs one more mixing component. The signal is bandpass filtered both before and after mixing. This necessitates the inclusion of one more LO (Local Oscillator) in the design. This type, like other transmitter systems, employs PA (Power Amplification) prior to transmission. With the help of gain control, AGC is used to vary the amplitude of the output signal. AGC stands for Automatic Gain Control.Ⅵ Smart Wireless Transmitters6.1 What are Smart Transmitters?Smart transmitters are controlled by a microprocessor. They also include an in-built sensor. The sensor enables a transmitter to filter the surrounding atmosphere. Furthermore, the transmitters can store data in memory. You can program transmitters to retain a default setting using memory storage.6.2 What are the Main Features of Smart Wireless Transmitters?The following are the key features of OMNI's smart wireless transmitters:Multiple sensors can be added for varying measurement changes.The transmitter is then adjusted to produce linear results.The transmitters are self-calibration capable.The transmitters can self-diagnose. They are capable of detecting faults and maintenance alerts.Ⅶ 5 Tips to Optimize Your Sennheiser Wireless SystemFor years, Sweetwater has configured and used large-scale Sennheiser wireless microphone systems. There are some simple steps you can take to get the most out of your Sennheiser wireless system in terms of channel count, range, and sound quality.7.1 Don’t Cover the AntennaThe antenna on a transmitter should never be covered for optimal performance. When using a handheld microphone, take care not to cover the antenna with your hand. If you don't see an antenna on your microphone, it's most likely hidden inside the last few inches of its body. Hold the microphone closer to its head/capsule to avoid covering it with your hand as you pick it up.Figure-8 Don't cover the antennaWhen wearing a belt pack with an external antenna, make sure the antenna isn't wadded up or bent. This is not only bad for the antenna (bending a wire enough times will cause it to break), but it also severely reduces its transmission. With a wadded-up antenna, you'll get limited range and more dropouts.7.2 Fresh Batteries are EssentialFigure-9 BatterySignal strength and operational range decrease when the transmitter's battery expires, so even if the battery isn't fully dead, it's better to change it at the start of every performance, event, or service.7.3 Frequency Selection is Important When Using Multiple SystemsFigure-10 Frequency SelectionTo avoid interfering with each other, the frequencies of numerous wireless systems must be properly synchronized. It's not always enough to have distinct frequencies. Using wireless systems from the same manufacturer and series is usually the best way to do this — Sennheiser's wireless systems automatically use frequencies that are already pre-coordinated to avoid interference. Consult an expert if you're integrating systems from various manufacturers or series.7.4 Maintain Line of Sight between ComponentsImproper antenna installation is the most prevalent cause of signal losses. Between the antennas and the transmitters, there should always be a clear line of sight. If this isn't possible in your rack, the antennas should be put distant from the receivers, perhaps on a wall, on a balcony rail, from the ceiling, or somewhere else where line-of-sight placement is possible.Figure-11 Maintain line of sight between componentsKeep in mind that the human body is a great RF energy absorber. Your wireless transmitter is unlikely to have enough "oomph" to carry an entire audience of people on their feet. If your antennae are in the rear of the room, the pastor's back, which requires the signal to pass through his body on its way to the receiver, may not be the best place for the belt pack transmitter.7.5 Keep Transmitters and Receivers as Close as PossibleIf you're having trouble getting clear reception, consider placing the receivers closer to the stage to shorten the distance between the transmitters and receivers. If that isn't possible, consider moving the antennae closer together by mounting them remotely. If you need to run long antenna cables, don't skimp on quality to save money — obtain the lowest-loss cable you can find. It is suggested that you use RG-8. If the cable line is longer than 25 feet, an antenna booster may be required, and it's time to contact a professional.Ⅷ Answers to 6 Questions about the Wireless Transmitter1. What is a transmitter in a wireless system?A wireless system consists of two main components: a transmitter, and a receiver. The transmitter handles the conversion of the audio signal into a radio signal and broadcasts it as a radio wave via an antenna. The antenna may stick out from the bottom of the transmitter or it may be concealed inside.2. How do I connect Bluetooth kit to FM transmitter?Simply turn on the Bluetooth on your cellphone. Or whichever device you plan on using. And search for the t-ten. And just connect the t10 and and just like that is paired.3. Can any transmitter work with any receiver?You can use a transmitter with any receiver. BUT you have to have a way of changing the antenna when you transmit. There are antenna relays for this purpose that will automatically make the change for you. The power of the transmitter would quickly destroy your receiver.4. What are the main features of transmitter?What are the main features of a transmitter? Explanation: Some of the main features which make the transmitter complex are higher clock speed, higher transmit power, directional antennas and need for a linear amplifier.5. Is transmitter is same as sender?What's the difference between sender and transmitter here. Many times both terms are used for the same thing. Could it be here "Sender und Sendegeraet"? The HFN values in the sender and the transmitter are different,i.e. the HFN synchronization between the sender and receiver is lost.6. What is perfect transmitter?The important feature of the transmitter is extremely fast current, turn-off time, less than 1 μs for the shallowest depth, while the current after the ramp time is practically absent. douwdek0 and 6 more users found this answer helpful. 

Ⅰ Introduction In this project, we will use hardware ultrasonic sensor and  Raspberry Pi 3, Software Python code. Not everyone is familiar with ultrasonic sensor and Raspberry Pi3. Therefore, in the front part ,we will introduce some basic knowledge about ultrasonic sensor and Raspberry Pi3. This is conducive to understanding the project better. And then, we will have a look at the project of wiring Ultrasonic Sensor  (HC-SR04) with Raspberry Pi3 Catalog Ⅰ Introduction Ⅱ Ultrasonic Sensor Related Video Ⅲ Basic Guide to Ultrasonic Sensor  3.1 What is an ultrasonic sensor? 3.2 How Ultrasonic Sensors Work？ 3.3 Using Multiple Sensors & Avoiding Disruption 3.4 How are Ultrasonic Sensors Used? Ⅳ Basic Guide to Raspberry Pi3 4.1 What is  Raspberry Pi3? 4.2 What Is the Raspberry Pi3 Capable of？ 4.3 How do I Get Started With the Raspberry Pi 3? 4.4 How Is the Raspberry Pi 3 Different From Its Predecessors? Ⅴ Ultrasonic Sensor (HC-SR04) + Raspberry Pi3 5.1 Hardware 5.2 Wire Setup 5.3  Breadboard  5.4 Software Ⅵ FAQ     Ⅱ Ultrasonic Sensor Related Video   Ultrasonic Sensor Video Description: Connecting the Ultrasonic Sensor( HC-SR04) to the Raspberry Pi to measure distance. Equipment you need One 1 kilo-Ohm resistor One 2 kilo-Ohm resistor 8 Female-Male Jumper Wire   Ⅲ Basic Guide to Ultrasonic Sensor  3.1 What is an ultrasonic sensor? An ultrasonic sensor is a device that uses ultrasonic sound waves  to determine the distance between two objects. An ultrasonic sensor employs a transducer to send and receive ultrasonic pulses that relay information about the proximity of an object. High-frequency sound waves  reflect off boundaries, resulting in distinct echo patterns. Fihure1: Ultrasonic Sensor   3.2 How Ultrasonic Sensors Work？ Ultrasonic sensors  operate by emitting a sound wave at a frequency  that is above the range of human hearing. To receive and transmit an ultrasonic sound, the sensor's transducer functions as a microphone. Like many others, our ultrasonic sensors  use a single transducer to send a pulse and receive the echo. The sensor calculates the distance to a target by measuring the time elapsed between sending and receiving the ultrasonic pulse. Figure2:How Ultrasonic Sensors Work This module's operation is straightforward. It emits a 40kHz ultrasonic pulse that travels through the air and, if it encounters an obstacle or object, bounces back to the sensor. The distance can be calculated by multiplying the travel time by the speed of sound. Ultrasonic sensors  are an excellent solution for detecting clear objects. Because of target translucence, applications that use infrared sensors.  for example, struggle with this particular use case for liquid level measurement. Ultrasonic sensors  detect objects regardless of color, surface, or material for presence detection (unless the material is very soft like wool, as it would absorb sound.) Ultrasonic sensors  are a reliable choice for detecting transparent and other items where optical technologies may fail.   3.3 Using Multiple Sensors & Avoiding Disruption When putting multiple sensors  into an application, it's critical to connect them in a way that prevents crosstalk and other interference. To prevent the ultrasonic signals from your sensor from being disrupted, keep the face of the ultrasonic transducer clear of any obstructions. Common obstructions include: DirtSnowIceOther Condensation We recommend our Self Cleaning sensors  for this application. Our self-cleaning function is designed to run continuously for the self-cleaning feature to be active. They are intended specifically for applications requiring condensation resistance in high moisture environments. Please keep in mind that the Self Cleaning function is not intended to remove dirt from the transducer's surface. Its purpose is to clear the transducer's face of moisture so that it can operate normally.   3.4 How are Ultrasonic Sensors Used? Our ultrasonic distance, level, and proximity sensors  are frequently used in conjunction with microcontroller platforms such as Raspberry Pi,  ARM , PIC,  Arduino , Beagle Board, and others. Ultrasonic sensors send sound waves  toward a target and measure the time it takes for the reflected waves to return to the receiver to determine their distance. This sensor is an electronic device that transmits ultrasonic sound waves  to measure the distance to a target and then converts the reflected sound into an electrical signal. Our sensors are frequently used as proximity detectors. Ultrasonic sensors are also used in obstacle detection systems and in manufacturing. Our ShortRange sensors provide the option for closer range detection in situations where a sensor that ranges objects as close to 2cm is required. These are also designed with very low power requirements in mind, as well as environments requiring noise rejection.   Ⅳ Basic Guide to Raspberry Pi3 4.1 What is  Raspberry Pi3? The  Raspberry Pi 3 Model B is the most recent model of the $35 Raspberry Pi computer. The Pi isn't your typical machine; in its most basic form, it lacks a case and is simply a credit-card-sized electronic board, similar to those found inside a PC or laptop but much smaller.   4.2 What Is the Raspberry Pi3 Capable of？ Surprisingly large. For starters, the Pi 3 can be used as a low-cost desktop, media center, retro gaming console, or router, as shown below. That, however, is only the tip of the iceberg. There are hundreds of projects where people have used the Raspberry Pi to build tablets, laptops, phones, robots, smart mirrors, take pictures on the edge of space, and run experiments on the International Space Station.   Figure3:The Raspberry Pi 3.   4.3 How do I Get Started With the Raspberry Pi 3? One thing to keep in mind is that the Pi is merely a bare board. You'll also need a power supply, a monitor or TV,  HDMI  cables to connect to the monitor, and a mouse and keyboard. After connecting all of the cables, the simplest way for new users to get up and running on the Pi is to download the NOOBS (New Out-Of-Box Software) installer. Once the download is complete, follow the instructions to learn how to install an operating system on the Raspberry Pi. The installer makes it simple to install various operating systems, though the official OS Raspbian is a good choice for first-time users—other operating systems are listed below. Raspbian's appearance and feel should be familiar to any desktop computer user. The operating system, which is constantly being updated, recently received a graphical makeover and now includes an optimized web browser, an office suite, programming tools, educational games, and other software.   4.4 How Is the Raspberry Pi 3 Different From Its Predecessors? The Raspberry Pi 3 quad-core processor is both faster and more capable than its predecessor, the Raspberry Pi 2. For those interested in benchmarks, the Pi 3's CPU—the board's main processor—outperforms the Pi 2 by roughly 50-60% in 32-bit mode, and is 10x faster than the original single-core Raspberry Pi (based on a multi-threaded CPU benchmark in SysBench). Real-world applications will see performance increases ranging from 2.5x for single-threaded applications to more than 20x when video playback is accelerated by the chip's NEON engine when compared to the original Pi. Unlike its predecessor, the new board can play 1080p MP4 video at 60 frames per second (with a bitrate of around 5400Kbps), further enhancing the Pi's media center credentials. That's not to say that all videos will playback this smoothly; performance will vary depending on the source video, the player used, and the bitrate. With built-in Wi-Fi and Bluetooth, the Pi 3 also supports wireless internet right out of the box. The most recent board can also boot directly from a USB-attached hard drive or a pen drive, as well as from a network-attached file system via PXE, which is useful for remotely updating a Pi and sharing an operating system image between multiple machines.   Ⅴ Ultrasonic Sensor (HC-SR04) + Raspberry Pi3 A distance measurement is required or advantageous for many (outdoor) projects. These small modules, which start at 1-2 dollars and can measure distances of up to 4-5 meters using ultrasound, are surprisingly accurate. The connection and control are demonstrated in this tutorial. 5.1 Hardware Raspberry pi 3Ultrasonic Sensor(s) - HC-SR04A set of resistors for each sensor you are connecting330Ω and 470ΩJumper wires to connect the sensor(s) to the piBreadboard to connect the sensor(s) to the pi   5.2 Wire Setup Pins The sensor has four (labeled) pins that must be connected to the Raspberry Pi's pins. Pin 2 to VCC (5v - power)Pin 6 to GND (ground)Pin 12 receives a TRIG signal (GPIO18) The ECHO resistor 330 - Attach it to Pin 18 at one end (GPIO24) - Connect it to Pin6 as well, using a 470 resistor (ground). - This is done because GPIO pins can only withstand a maximum voltage of 3.3V.   5.3  Breadboard  As shown in the circuit diagram, connect the sensor to the pi using a breadboard. By replicating this exact setup on the other half of the breadboard, an additional sensor can be connected to the pi. Connect the VCC and GND pins together (2 and 6) For the TRIG and ECHO connections, use any two GPIO pins. Just make sure to include the correct GPIO pins in your code. Figure4: Connecting resistors and jumper wires between sensors and pi       5.4 Software Python Create a new script Figure5:Creating a new script in Python 3 Choose Menu → Programming → Click on Python 3 to create a new scriptWhen you run the code, the script below will print the distance of the object in front of the sensor.Because this code is easily manipulated to add another sensor, all variables have a "1" after them.Simply copy and paste each section of code, renaming variables with a "2."Make sure to connect a TRIG2 and an ECHO2 to the pi's two new GPIO Pins and to mirror the circuit diagram on the other half of the breadboard. import  RPi.GPIO  as GPIO import time GPIO.setmode(GPIO.BCM) TRIG1 = 18 ECHO1 = 24 #print ("Distance Measurement In Process") GPIO.setup(TRIG1, GPIO.OUT) GPIO.output(TRIG1, False) GPIO.setup(ECHO1, GPIO.IN) #print ("Waiting For Sensor1 To Settle") time.sleep(.1) GPIO.output(TRIG1, True) time.sleep(0.00001) GPIO.output(TRIG1, False) while GPIO.input(ECHO1) == 0:     pass     pulse_start1 = time.time() while GPIO.input(ECHO1) == 1:     pass     pulse_end1 = time.time() pulse_duration1 = pulse_end1 - pulse_start1 distance1 = pulse_duration1 * 17150 distance1= round(distance1, 2) print ("Distance1:",distance1, "cm") time.sleep(10) GPIO.cleanup()   Make a copy of your script and save it as ultrasonic distance.py. Go to File and click on Save as In the Save in field, navigate to the C: drive and then select a folder to save in. In the File name field, enter ultrasonic distance.py. Select All Files in the Save as type field. Click the Save button. To run the script, use the terminal. Clicking on the monitor icon at the top of the screen will launch the terminal. Enter cd "folder name" to change directory to your pythonpractice folder, then enter ultrasonic distance.py to run your program. Ⅵ FAQ 1. Does HC-SR04 need resistor? If you are using the ultrasonic transmitter from a HC-SR04 , I think you will find it needs between 5 and 12V to drive it. So you don't need a resistor you actually need a transistor circuit to provide the greater voltage under the control of the gpio. 2. What is the range of HC SR04? 2 cm to 400 cm The HC-SR04 ultrasonic sensor uses SONAR to determine the distance of an object just like the bats do. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package from 2 cm to 400 cm or 1” to 13 feet. 3. Is ultrasonic sensor digital or analog? The output of the Ultrasonic Sensor is digital. Two of the four pins are forsupplying power to it, one is for sending an echo signature to it, and the other is for getting output from it. 4. What is ultrasonic sensor HC-SR04? The HC-SR04 Ultrasonic Distance Sensor is a sensor used for detecting the distance to an object using sonar. ... The HC-SR04 uses non-contact ultrasound sonar to measure the distance to an object, and consists of two ultrasonic transmitters (basically speakers), a receiver, and a control circuit. 5. What are the types of ultrasonic sensor? All together there are four types of ultrasonic sensors, classified by frequency and shape: the drip-proof type, high-frequency type, and open structure type (lead type and SMD type). 6. Is HC SR04 analog or digital? One of them is digital and the other is analog. We choose to use two sensors that measure: The UltraSonic Sensor (HC-SR04): Digital Sensor.