Executive Summary: 2026 Relay Testing GuideTo properly test a relay in 2026, you primarily need a digital multimeter to measure coil resistance (typically 50–120 Ω) and contact continuity. This guide covers the complete diagnostic workflow for both electromechanical and solid-state relays (SSRs), ensuring you can safely troubleshoot automotive and industrial electronics without replacing functioning parts. What is a Relay and How Does It Work?A relay is an electrically operated switch that uses a low-voltage signal to control a high-power circuit. In its simplest electromechanical form, it consists of a coil, an armature, and contact points. When a low voltage (such as 12V in a car) energizes the coil, it creates a magnetic field that pulls the armature, switching the connection from one contact to another. This isolation protects sensitive control electronics from high-current loads.Understanding the terminal designations is critical for 2026 diagnostics:COM (Common): The moving armature connection.NC (Normally Closed): The circuit is connected when the relay is off.NO (Normally Open): The circuit connects only when the relay is energized.This mechanism allows a small dashboard switch to control high-amperage devices like headlights or fuel pumps without melting the wiring.Internal schematic of a standard electromechanical relay Video Tutorial: How to Test a Relay with a MultimeterVisual Guide: The following video demonstrates the 2026 industry-standard method for bench-testing an automotive relay using a digital multimeter. This "out-of-circuit" method is safer and more accurate than guessing based on symptoms alone.What Tools Are Required for Relay Diagnostics?The primary tool required is a Digital Multimeter (DMM) capable of measuring resistance (Ohms), DC Voltage, and Continuity. While older analog VOMs (Volt-Ohm-Milliammeters) exist, modern DMMs are preferred in 2026 for their auto-ranging capabilities and precision.Essential capabilities for testing include:Ohmmeter Mode: To check the health of the internal coil winding.Continuity Mode: To verify if the contacts are opening and closing correctly (often indicated by a beep).Diode Test Mode: Essential for relays with built-in flyback diodes used to suppress voltage spikes. Why are Relays Critical in Modern Electronics?Relays serve as the bridge between logic components (like ECUs) and power components. They are ubiquitous in 2026, found in everything from EV charging stations to smart home systems.Key applications include:High Amperage Control: Switching 30A+ circuits (like cooling fans) using milliamp-level signals.Cable Protection: Preventing high current from traveling through the dashboard, reducing the risk of electrical fires.Logic Operations: Performing simple logic functions, such as ensuring a radio turns off when a door opens. Safety Precautions Before TestingElectrical safety is paramount; incorrect testing can damage the vehicle's computer (ECU) or cause injury. Before handling relays, adhere to these 2026 safety standards:Consult the Service Manual: Modern vehicles have complex wiring. The owner's manual is insufficient; use a technical service manual or a reputable online database.Environment Safety: Never test relays near flammable vapors (gasoline fumes/hydrogen from batteries) as relays can arc (spark) during operation.Physical Handling: Do not drop relays. The internal mechanical armature is sensitive to shock. If a relay is dropped on concrete, consider it compromised.Avoid "Parts Cannon" Swapping: Do not swap a suspected bad relay with a critical relay (like the fuel pump or airbag relay) unless specifications match exactly. A short circuit could damage the good relay or the circuit it protects. Step-by-Step Guide: How To Test a Relay?Testing a relay involves verifying two distinct circuits: the control circuit (coil) and the load circuit (switch). Relays are mechanical devices with a finite lifespan (often rated for 100,000+ cycles), but they eventually fail due to carbon buildup on contacts or coil burnout.Below is the comprehensive workflow for validating a relay's function using a multimeter. Phase 1: Visual & Bench Inspection Step 1: Perform a Visual AssessmentExamine the relay casing. Look for signs of heat stress, such as melted plastic or charred pins. If the relay has a transparent case (common in industrial "ice cube" relays), look for black soot on the contacts. Some modern industrial relays feature a built-in LED status indicator; if the LED is lit but the load isn't running, the contact points are likely failed.Visual inspection reveals internal contact wear Step 2: Isolate the Power SourceAlways remove the relay from the circuit before testing to avoid false readings from other components. Ensure the vehicle or machine is powered down. Be aware of capacitors in related circuits that may retain charge.Always disconnect power before removing the relay Step 3: Identify the Pinout ConfigurationMost automotive relays follow the standard DIN numbering system printed on the side:85 & 86: Control Coil (Input)30: Common Feed (High Power)87: Normally Open (NO) Output87a: Normally Closed (NC) OutputConsult the datasheet if the relay is specialized or lacks markings.Standard DIN relay pinout schematic Phase 2: Testing Solid-State Relays (SSRs) Step 1: Check Output Terminals for ShortsUnlike mechanical relays, SSRs do not click. They typically fail in the "shorted" (closed) position. With no control power applied, use an ohmmeter across the AC output terminals. It should read OL (Open Loop) or infinite resistance. If it reads near zero ohms while disconnected, the internal TRIAC or MOSFET has shorted, and the relay must be replaced.Testing SSR output for internal shorts Step 2: Input Testing (Diode Mode)Use the Diode Test mode on your multimeter to check the control input (A1/A2). Since the input is effectively an LED (optocoupler), testing it like a diode can sometimes verify functionality. In one direction, you may see a voltage drop (e.g., 1.0V - 1.4V for stacked diodes), and OL in reverse. Note that some advanced 2026 SSRs have internal conditioning circuits that make this test difficult; bench testing with a voltage source is preferred.Verifying the input circuit using diode test mode Step 3: Thermal Management CheckHeat is the #1 killer of SSRs. If an SSR has failed, check the thermal paste and heatsink seating. Unlike mechanical relays, SSRs generate significant heat during operation (approx 1W per Amp). Ensure the replacement is properly mounted with thermal compound. Phase 3: Testing Mechanical (Coil) Relays Step 1: Identify Coil SpecsBefore applying power, verify the coil voltage (usually 12VDC for cars, 24VDC for trucks, or 120VAC for industrial). Applying 120V to a 12V coil will instantly destroy it. Step 2: Check for Suppression DiodesMany modern relays include a "flyback" diode across pins 85 and 86 to protect the ECU. Polarity matters here. If you reverse the test leads on a diode-protected relay, you may damage the diode or your test equipment power supply. Look for the diode symbol on the relay case.Flyback diode symbol indicating polarity sensitivity Step 3: Measure Coil Resistance (The Most Important Test)Set your multimeter to Ohms (Ω). Measure across the coil pins (usually 85 and 86). Pass Criteria: A healthy 12V automotive relay coil typically reads between 50Ω and 120Ω. Fail Criteria:0Ω - 5Ω: Shorted coil (will blow fuses).OL (Infinite): Broken coil wire (relay will not activate).Identifying Coil (85/86) vs Load (30/87) Terminals Step 4: Verify Resting State (Continuity)With no power applied:Pin 30 to 87a (NC): Should have Continuity (near 0Ω).Pin 30 to 87 (NO): Should be Open (OL).Testing the de-energized state (Pins 30 to 87 should be Open) Step 5: Energize the RelayConnect jumper wires from a 12V battery (or bench power supply) to pins 85 and 86. You should hear a distinct, sharp "click". Note: A click does not guarantee the relay is good; the contacts could still be burnt. Proceed to Step 6.Energizing the coil to listen for the mechanical "click" Step 6: Voltage Drop/Contact TestWhile the coil is energized (clicking):Measure resistance between Pin 30 and Pin 87.Result: It should read 0.5Ω or less. If it reads higher (e.g., 5Ω+), the contacts are pitted/carbonized and the relay is bad, even if it clicks. Alternative Method: Testing with a DC Power SupplyFor a more controlled test, use a variable DC power supply. Increase voltage slowly to the coil. A 12V relay should pull in (click) at around 8V (Pick-Up Voltage) and drop out (release) at around 1V-5V. If the relay requires full 12V or more to click, it is "lazy" and aging. This method is excellent for diagnosing intermittent failures in 2026 electronics. Diagnosing a Bad Relay Without Removal (Socket Testing)If you cannot remove the relay, or want to test the circuit wiring:Verify Control Power (Pin 86): With the switch ON, Multimeter (DC Volts) should read battery voltage at slot 86.Verify Ground (Pin 85): Multimeter (Continuity) should beep between slot 85 and chassis ground.Verify Load Power (Pin 30): Slot 30 should always have battery voltage (check fuse if missing).The "Bypass" Test: Use a fused jumper wire to jump slot 30 directly to slot 87. If the component (e.g., horn, fan) turns on, the component and wiring are good, pointing to a bad relay or control signal.Socket diagnostics logic flow How to Test a 5-Pin Changeover Relay5-pin relays are common in headlight and window motor circuits. They switch power between two different outputs (87 and 87a).Standard 5-pin configurationResting Test: Measure resistance between Pin 30 and 87a. It must be near 0Ω. Measure Pin 30 to 87; it must be OL (Open Loop).Active Test: Energize the coil (85/86). Now measure Pin 30 to 87. It must be near 0Ω. Pin 30 to 87a should switch to OL.Common Failure: Often the "Normally Open" side works, but the "Normally Closed" (87a) side fails due to oxidation from lack of use. Automotive Relay Diagnostics: A 2026 Field Guide Step 1: Gather Diagnostic ToolsPrepare a Digital Multimeter (DMM), fused jumper wires, and alligator clips. While test lights are traditional, DMMs are safer for modern computer-controlled vehicles to avoid drawing excessive current. Step 2: Locate the Relay BoxCheck the "Power Distribution Center" under the hood or the interior fuse panel. Refer to the diagram often printed on the underside of the fuse box cover.Typical relay block location Step 3: The "Swap Logic" MethodThe quickest field test: Find an identical relay in the box (e.g., swap the Horn relay with the AC Compressor relay if part numbers match). If the problem moves to the horn, the original relay was bad. Warning: Ensure the amperage ratings match exactly to avoid damaging the circuit. Step 4: Bench Test the ResistanceWith the relay removed, measure the control pins (85-86). Expect 50-120 Ohms. If you see "OL" or extreme heat discoloration, replace the unit immediately.Multimeter readout showing resistance check Frequently Asked Questions (2026 Update)Can I test a relay without a multimeter?Not reliably. You can swap the relay with a known good one (as described in the "Swap Logic" step), which is the only reliable method without tools. The "shake test" (listening for a rattle) works only if the internal armature is physically broken, which is rare compared to burnt contacts. Why can't I find the relay in my 2026 vehicle?Modern vehicles increasingly use PCB-mounted relays inside Smart Junction Boxes (SJBs) or Body Control Modules (BCMs). These are soldered directly to the board and are not user-serviceable. In these cases, the entire module often requires replacement or professional board-level repair. How much does a replacement relay cost?In 2026, a standard 4-pin or 5-pin automotive relay typically costs between $8 and $25. Specialized high-amp relays or solid-state versions can range from $50 to over $100. A basic digital multimeter for testing can be purchased for under $30. What is the difference between a relay and a switch?A switch is manually operated (by a human finger), while a relay is a switch operated by an electrical signal. A relay allows a small manual switch (like a headlight dial) to control a massive power flow safely and remotely. What is the correct resistance reading for a DC relay?For a standard 12V automotive relay, the coil resistance should be between 50Ω and 120Ω. Values significantly lower (e.g., 20Ω) indicate a short that may blow fuses, while infinite resistance (OL) indicates a broken internal wire.{ "@context": "https://schema.org", "@type": "Article", "headline": "How to Test a Relay with a Multimeter: The 2026 Diagnostic Guide", "datePublished": "2022-12-10", "dateModified": "2026-01-24", "description": "Learn the industry-standard methods for testing mechanical and solid-state relays using a multimeter. Updated for 2026 automotive and electronics standards.", "author": { "@type": "Organization", "name": "ApogeeWeb Electronics" }, "image": "https://www.apogeeweb.net/upload/pdf/20221210/Relay.png", "mainEntity": [ { "@type": "HowTo", "name": "How to Test a Relay with a Multimeter", "step": [ { "@type": "HowToStep", "name": "Visual Inspection", "text": "Check the relay casing for signs of melting, charring, or corrosion." }, { "@type": "HowToStep", "name": "Identify Pins", "text": "Locate pins 85/86 (Coil) and 30/87 (Switch) using the relay schematic or datasheet." }, { "@type": "HowToStep", "name": "Measure Coil Resistance", "text": "Set multimeter to Ohms. Measure between pins 85 and 86. Value should be 50-120 Ohms." }, { "@type": "HowToStep", "name": "Test Continuity", "text": "Energize pins 85 and 86 with a 12V power source (listen for a click). While energized, check for continuity (0 Ohms) between pins 30 and 87." } ], "tool": [ { "@type": "HowToTool", "name": "Digital Multimeter" }, { "@type": "HowToTool", "name": "Jumper Wires" }, { "@type": "HowToTool", "name": "12V Power Source" } ] }, { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "Can I test a relay without a multimeter?", "acceptedAnswer": { "@type": "Answer", "text": "Not accurately. The only reliable tool-free method is swapping the suspect relay with a known good relay of the exact same part number." } }, { "@type": "Question", "name": "What should a relay coil read in Ohms?", "acceptedAnswer": { "@type": "Answer", "text": "A standard 12V automotive relay coil should read between 50 and 120 Ohms. Readings outside this range usually indicate a failure." } }, { "@type": "Question", "name": "How do I know if a solid state relay is bad?", "acceptedAnswer": { "@type": "Answer", "text": "Solid State Relays (SSRs) typically fail shorted (closed). 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Executive Summary: Proximity Sensors in 2026What is a proximity sensor? A non-contact device that detects the presence or distance of an object using electromagnetic fields, light, or sound waves. Essential for Industry 4.0 automation, robotics, and consumer electronics.Key Types: Inductive (Metals), Capacitive (Non-metals/Liquids), Ultrasonic (Distance/Clear objects), Photoelectric (Long-range), and IR (Short-range).2026 Trends: Integration with IO-Link for predictive maintenance, miniaturized MEMS technology, and AI-driven signal processing for higher accuracy in harsh environments.Ⅰ What is a Proximity Sensor? (2026 Overview)A proximity sensor is a non-contact electronic instrument that detects the presence, proximity, or exact distance of an object without physical contact. In the 2026 landscape of industrial automation, these sensors serve as the "eyes" of machines, ensuring precise control in manufacturing, robotics, and smart devices.While there are many types of proximity sensors, they share a common operational principle: they transmit an electromagnetic field, electrostatic field, or beam of light, and analyze the reflection or field disruption to confirm if an object (the target) is approaching, leaving, or present. The maximum detection limit is defined as the "rated range." Modern smart sensors allow this range to be dynamically adjusted via software protocols like IO-Link. Proximity sensors are renowned for high reliability and zero mechanical wear, as the lack of physical contact prevents component fatigue, giving them a functional lifespan often exceeding 100,000 hours in industrial settings. The five primary categories utilized in 2026 include:Inductive: For ferrous and non-ferrous metals.Capacitive: For liquids, plastics, and powders through barriers.Ultrasonic: For sound-based distance measurement.Photoelectric: For long-range light detection.Hall Effect: For magnetic field detection. Ⅱ How Does a Proximity Sensor Function?Proximity sensors work by emitting a specific field or signal (electromagnetic, electrostatic, or acoustic) and measuring changes in the return signal caused by a target object.2.1 Inductive Sensor PrincipleInductive sensors generate an electromagnetic field via an internal oscillator. When a conductive metal object enters this field, eddy currents are induced in the target, causing a dampening of the oscillation amplitude. The sensor detects this energy loss to trigger a switch.2.2 Capacitive Sensor PrincipleCapacitive sensors function as an open capacitor. They generate an electrostatic field between the sensing electrode and the ground. When any object (metal, water, plastic) enters this field, the capacitance increases, changing the oscillation frequency. Once this frequency crosses a DC voltage threshold, the sensor activates. Ⅲ Detailed Types of Proximity SensorsChoosing the right sensor depends on the target material and environment. Below is the breakdown of the industry standards for 2026.3.1 Inductive Proximity Sensor (Metal Detection)Best for: Harsh industrial environments, detecting machine parts, gears, and cams. Inductive sensors remain the backbone of heavy industry. They utilize a coil-wound oscillator to create a high-frequency magnetic field. They are robust, impervious to oil, dirt, and water (often rated IP67/IP69K), and rely on the principle of induction (Faraday's Law).  Key Characteristics:Target: Metals only (Iron, Steel, Aluminum, Copper).Range: Short (typically 1mm to 60mm).Speed: High switching frequency (up to 5 kHz), ideal for counting rotating gears.Ferrous vs. Non-Ferrous: Detection distance is greatest for ferrous metals (iron) and reduced for non-magnetic metals (aluminum) unless "Factor 1" sensors are used. 3.2 Capacitive Proximity Sensor (Versatile Detection)Best for: Level detection through container walls, detecting plastics, liquids, and granulars. Unlike inductive sensors, capacitive units detect changes in dielectric constant, allowing them to sense virtually any material. They contain two charging plates (internal and external/sensing face). When a target approaches, it alters the dielectric capacity, triggering the switch. Pros & Cons:See-Through Ability: Can detect water inside a plastic tank or powder inside a glass tube.Speed: Slower than inductive (10 to 50 Hz).Sensitivity: Can be adjusted to ignore thin container walls while detecting the contents. 3.3 Ultrasonic Proximity Sensor (Sound Waves)  Best for: Transparent objects (glass, clear plastic), long distances, and difficult lighting conditions. Ultrasonic sensors utilize echolocation—similar to bats or dolphins. A piezoelectric transducer emits a high-frequency sound pulse (chirp) and measures the "Time of Flight" (ToF) for the echo to return. Advantages in 2026:Color Immunity: Unlike optical sensors, color or transparency does not affect accuracy.Distance: Capable of detecting objects several meters away.Blind Spots: While effective, they have a "dead zone" immediately in front of the sensor face.  Limitations: Performance can be impacted by air turbulence, foam on liquids, or extreme temperature fluctuations (which alter the speed of sound), though modern units include temperature compensation. 3.4 IR Proximity Sensor (Infrared) Best for: Short-range detection, security systems, and mobile devices. IR sensors emit a beam of infrared light. If an object is present, the light reflects back to a photodetector at a specific angle (triangulation). These are cost-effective but can be confused by ambient sunlight or dark surfaces that absorb light rather than reflect it. 3.5 Photoelectric Sensor (Optical)Best for: Long-range detection, packaging lines, and logistics.  Photoelectric sensors use a light transmitter (LED or Laser) and a receiver. They are modulated to specific frequencies to avoid interference from ambient light.  Three Key Configurations:Through-Beam: Emitter and receiver are separate. Detects when the beam is broken. Longest range (up to 50m+).Retroreflective: Emitter and receiver in one unit; requires a reflector. Medium range.Diffuse: Light reflects off the object itself. Short range, but easy to install. Ⅳ Key Applications in Industry 4.0  By 2026, proximity sensors are integral to the Industrial Internet of Things (IIoT):Automotive & EV Manufacturing: Inductive sensors detect chassis positioning and gear rotation speeds with extreme precision.Food & Beverage: Capacitive sensors monitor liquid levels in bottles and grain levels in silos through sight glass.Logistics & Warehousing: Photoelectric sensors trigger conveyor belts and size parcels for automated sorting.Smart Electronics: Mobile phones use proximity sensors (often IR or Time-of-Flight/LiDAR) to disable touchscreens during calls or for facial recognition.Vibration Monitoring: Analog proximity sensors measure shaft runout and vibration in large turbines to predict maintenance needs.  Ⅴ Buyer's Guide: How to Choose a Proximity SensorSelecting the correct sensor requires analyzing the target material, environmental constraints, and required range. Use this 2026 decision matrix: Selection CriteriaKey ConsiderationsRecommended Sensor TechnologyTarget Material• Is the object Metal?• Is it Non-Metal (Plastic, Liquid, Wood)?• Is it Transparent (Glass, Clear Film)?• Metal: Inductive (Best reliability)• Non-Metal/Liquids: Capacitive• Transparent: UltrasonicEnvironment• Is it dirty, oily, or dusty?• Are there extreme temperatures?• Is washdown required (IP69K)?• Dirty/Oily: Inductive or Capacitive (Excellent immunity)• Clean/Dry: Photoelectric or IR• Avoid in Dust/Smoke: Optical sensorsSensing Range• Very Close (<50mm)• Medium Range (50mm - 2m)• Long Range (>2m)• Close: Inductive / Capacitive• Medium: Diffuse Photoelectric / Ultrasonic• Long: Through-beam Photoelectric / LiDAR  Ⅵ Frequently Asked Questions (FAQ)1. What does a proximity sensor do in simple terms?It detects if an object is nearby without touching it. This triggers an action, like stopping a machine for safety, counting items on a conveyor, or turning off your phone screen when you hold it to your ear. 2. Which sensor detects plastic or water?Capacitive proximity sensors are the industry standard for detecting non-metallic objects like plastic, glass, wood, and liquids (water, oil, chemicals). 3. Can inductive sensors detect aluminum?Yes, but with reduced range compared to ferrous metals like iron or steel. However, modern "Factor 1" inductive sensors can detect aluminum and steel at the same distance. 4. What is the typical range of a proximity sensor?Inductive and Capacitive sensors typically work between 1mm and 60mm. Ultrasonic sensors can measure up to several meters, and Photoelectric sensors can reach 50+ meters in through-beam configurations. 5. Are ultrasonic sensors affected by color?No. Since they use sound waves, ultrasonic sensors are color-blind. They are ideal for detecting clear glass, black plastic, or highly reflective surfaces that confuse optical sensors. 6. What is the difference between NPN and PNP sensors?This refers to the output transistor type. PNP sensors switch the positive voltage to the output (common in Europe/USA), while NPN switches the negative/ground (common in Asia). 7. How accurate are modern proximity sensors?High-end inductive sensors in 2026 offer repeatability down to 0.001mm (1 micron), making them suitable for precision CNC machining and quality control.{ "@context": "https://schema.org", "@type": "Article", "headline": "Proximity Sensors Explained: Types, Principles, and Applications (2026 Guide)", "datePublished": "2021-04-14", "dateModified": "2026-01-07", "description": "A comprehensive guide to proximity sensors in 2026. Learn about Inductive, Capacitive, Ultrasonic, and Photoelectric sensors, their working principles, and how to choose the right one for industrial automation.", "articleBody": "What is a Proximity Sensor? A proximity sensor is a non-contact electronic instrument that detects the presence, proximity, or exact distance of an object without physical contact...", "mainEntity": { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What does a proximity sensor do?", "acceptedAnswer": { "@type": "Answer", "text": "A proximity sensor detects the presence or absence of an object without physical contact. It emits an electromagnetic field, light, or sound and measures the reflection or disruption to trigger a signal. Common uses include industrial automation, safety systems, and mobile phone screen control." } }, { "@type": "Question", "name": "How do I choose between inductive and capacitive sensors?", "acceptedAnswer": { "@type": "Answer", "text": "Choose an **Inductive Sensor** if you need to detect **metal** targets in dirty environments (oil/dust). Choose a **Capacitive Sensor** if you need to detect **non-metallic** objects like plastic, wood, or liquids, or if you need to see through a non-metallic container wall." } }, { "@type": "Question", "name": "What are the limitations of ultrasonic sensors?", "acceptedAnswer": { "@type": "Answer", "text": "Ultrasonic sensors can be affected by extreme air temperature changes (affecting the speed of sound), air turbulence, and soft sound-absorbing materials (like foam or cloth). 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2026 Executive Summary: Resistors remain the fundamental components of modern circuitry, from consumer electronics to electric vehicle (EV) power management. This guide classifies resistors by material (Film, Composition, Alloy) and application (Precision, High-Power, Sensitive), providing engineers and hobbyists with critical selection criteria for voltage, power rating, and tolerance in 2026.I. Introduction: The Role of Resistors in 2026Resistors are passive electrical components that restrict current flow to adjust signal levels and voltage. In the 2026 electronics landscape, the variety of resistors continues to expand with the rise of IoT devices and high-voltage EV architectures. Resistors are generally divided into two primary categories: fixed resistors and variable resistors. Fixed resistors are categorized by material into wire-wound and non-wire-wound types. Non-wire-wound resistors split further into film and composite types. Structurally, they appear as tubular, disc, or planar (SMD) components. Depending on protection needs, they can be painted, plastic-pressed, or vacuum-sealed. This guide details the classification, characteristics, and pros/cons of resistor types, updated for 2026 standards. It serves as an essential resource for selecting the right component for modern circuit design.Video: Understanding Types of ResistorsII. How are Resistors Classified by Material?Material composition determines a resistor's noise, tolerance, and stability. In 2026, film-based resistors dominate consumer electronics, while wire-wound types are preferred for high-power applications.2.1 Film Resistors(1) Carbon Film ResistorsCarbon film resistors consist of a ceramic core coated with a crystalline carbon layer, thermally decomposed in a high-temperature vacuum. The resistance is precisely calibrated by cutting a helical groove into the carbon film. These resistors offer a balance of cost and performance. They feature good stability, a low negative temperature coefficient, and stable pulse load handling. Due to their low production cost, they remain widely used in general-purpose consumer electronics where ultra-high precision is not critical.Figure 1. The Appearance and Structure of Carbon Film Resistor(2) Metal Film ResistorsMetal film resistors are manufactured by vacuum-depositing a nickel-chromium (NiCr) or similar alloy onto a ceramic substrate. This technology allows for tighter tolerances than carbon types.Known for superior stability, heat resistance, and low noise electromotive force, metal film resistors are the standard for 2026 precision circuits, including audio equipment and measuring instruments.Figure 2. Metal Film Resistor(3) Metal Oxide Film ResistorsThese are created by spraying metal salt solutions (like tin tetrachloride) onto a heated ceramic skeleton at approximately 550°C. The resulting conductive film is fused firmly to the substrate. Metal oxide variants excel in harsh environments, offering stronger oxidation, acid, and salt resistance than standard metal films. While their resistance range is narrower (typically 1Ω ~ 200 kΩ), they handle power ratings from 1/8 W up to 50 kW in industrial applications.Figure 3. Metal Oxide Film Resistor2.2 Composition ResistorsComposition resistors mix conductive granules with a binder. While less common in modern high-precision tech, they are prized for their high surge energy handling. The distinct advantage of solid core resistors is reliability—often 5 to 10 times higher than film types in pulse-heavy applications. Despite drawbacks like higher noise and poor linearity, they are utilized in aerospace and submarine cabling where component failure is not an option. Solid Core Resistor (Model S): Common model RS11. Range: 4.7Ω – 22MΩ. Accuracy: ±5% to ±20%.High Voltage Composite Film: Models like RHY-10 (10kV) and RHY-35 (35kV) handle extreme voltages with resistance up to 1000MΩ.Carbon Film Composition: High resistance range (up to 106 MΩ) and 35kV working voltage. Used in vacuum megohm resistors for micro-current testing, despite poor moisture resistance.Organic Solid Composition: Pressed mixtures of graphite and organic binder. Compact and robust against overload, but with poor temperature stability. Common in older automotive instrument clusters.Glass Glaze Resistor: A sintered mix of metal oxides (ruthenium) and glass glaze. Features high-temperature resistance and high voltage handling (up to 15kV). Power ratings can reach 500W in specialized units.Figure 4. Different Types of Resistors2.3 Alloy Resistors(1) Precision Wire Wound Resistors (Model RX)Used in measurement instruments requiring stability. Tolerances can be as fine as ±0.005%. However, due to the coil structure, they act as inductors, making them unsuitable for high-frequency circuits.Figure 5. Precision Wire Wound Resistor(2) Power Type Wire Wound ResistorsDesigned for dissipation, these handle 2W to 200W+. They are often ceramic-encased and used in power supplies. Adjustable versions allow for manual resistance tuning during machine calibration. (3) Precision Alloy Foil ResistorsThe gold standard for stability in 2026. These resistors automatically compensate for temperature coefficients, maintaining accuracy across wide temperature ranges. Accuracy reaches ±0.001%, with stability around ±5 × 10-5%/year, making them vital for high-speed response circuits.III. What are the Main Classifications Based on Purpose?Beyond material, resistors are categorized by their specific function in a circuit topology.General Type: Standard components for consumer tech. Power: 1/20W ~ 2W. Tolerance: ±5% ~ ±20%.Precision Type: High stability for medical and audio devices. Tolerance: 2% down to 0.001%.High Frequency Type: Non-inductive designs (often film or solid) essential for RF and 5G communication circuits. Can handle up to 100W.High Voltage Type: Engineered for 1kV ~ 100kV applications, such as X-ray power supplies.High Resistance Type: Specialized for detecting weak currents, with values exceeding 10 MΩ (up to 1014Ω).Integrated Resistance (Resistor Networks): Multiple matched resistors on a single substrate (SIP/DIP packages). Critical for saving space in computer interfaces.Insurance (Fusible) Type: A dual-function safety component. Acts as a resistor under normal load but fuses open like a circuit breaker within seconds (7s to 120s) during overloads (12x-30x rated power).Figure 6. Different ResistorsIV. What are Sensitive Resistors (Sensors)?Sensitive resistors change their resistance in response to environmental stimuli, acting as the "senses" of modern IoT devices.(1) ThermistorTemperature-dependent resistors used for measurement and protection.NTC (Negative Temperature Coefficient): Resistance drops as heat rises. Used in temperature sensors.PTC (Positive Temperature Coefficient): Resistance spikes with heat. Used as self-resetting fuses.Figure 7. Thermistor(2) Photoresistor (LDR)Made from semiconductors like Cadmium Sulfide (CdS). High resistance in dark (>1.5MΩ) drops drastically (<1kΩ) when illuminated. Used in automatic streetlights and photoelectric controls.Figure 8. Photoresistor(3) Varistor (MOV)Voltage-dependent resistors, typically Zinc Oxide. They act as open circuits normally but short-circuit dangerous voltage spikes to ground. Essential for surge protection in power strips and automotive electronics.Figure 9. Metal Oxide Varistor(4) Magneto-resistorUtilizes the magnetoresistive effect (e.g., Indium Antimonide). Resistance rises with magnetic flux. Used in speed sensors, magnetic card readers, and brushless motor control.Figure 10. Magneto Resistor(5) Force Sensitive Resistor (FSR)Converts physical pressure/stress into electrical signals. Found in electronic drums, robotics touch sensors, and industrial scales.Figure 11. Force Sensitive Resistor(6) Gas-sensitive ResistorUtilizes metal oxides (like Tin Dioxide) that change resistance when gas molecules adsorb onto the surface. Standard in 2026 smart home air quality monitors and breathalyzers.Figure 12. Gas-sensitive Resistor(7) Humidity ResistorDetects relative humidity changes. Critical for HVAC systems and weather stations.Figure 13. Humidity ResistorV. Types of Potentiometers (Variable Resistors)5.1 What is a Potentiometer?A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. It is the manual interface for many electronic devices (volume knobs, dimmer switches) and a calibration tool for circuits (trimpots).5.2 How are Potentiometers Classified?By Material: Carbon Film (standard), Cermet (Ceramic/Metal mix for long life), Wirewound (high power).By Structure: Single-turn (general use), Multi-turn (high precision), Slide/Linear faders (audio mixers).By Resistance Scale:Linear (Type B): Resistance changes evenly. Used in brightness controls.Logarithmic (Type A): Resistance changes exponentially. Used in audio volume controls to match human hearing.Figure 14. PotentiometerVI. Comparison: Advantages and DisadvantagesChoosing the right resistor in 2026 requires balancing precision, power, and cost.6.1 Mind Map of Resistor ClassificationFigure 15. Mind Map of Types of Resistor6.2 Resistor Comparison TableResistor TypeKey CharacteristicsPrimary ApplicationsAdvantagesDisadvantagesCarbon Film (RT)Hydrocarbon deposit on ceramic. Tolerance ±5% to ±20%.General consumer electronics, toys, basic logic.Low cost, widely available.Poor thermal stability, higher noise.Metal Film (RJ)Vacuum evaporated alloy. Tolerance ±0.1% to ±1%.Audio equipment, precision instruments.Low noise, excellent stability, compact.Higher cost than carbon.Metal Oxide (RY)Tin/Antimony salt spray.Industrial power supplies, high temp zones.Resists oxidation, acids, and heat.Limited resistance range.Wire Wound (RX)Resistive wire wrapped around core.Power supplies, load testing, shunts.High power handling, thermal stability.Inductive (unsuitable for HF), bulky.Organic Solid (RS)Granular conductive mix, hot pressed.High-surge audio outputs.Robust overload capacity, reliable.Low precision, unstable with temp.Cement ResistorWire-wound encased in ceramic fireproof shell.Power adapters, current limiting.Explosion-proof, heat resistant.Large physical size, runs hot.0-ohm Resistor"Jumper" resistor (~0Ω).PCB bridges, configuration toggles.Simplifies PCB routing.N/A6.3 Comparison MatrixA quick reference guide for selecting resistors based on application (vertical) and material (horizontal).Classify by Use Classify by MaterialWire WoundFilm TypeCompositeCarbon FilmMetal FilmMetal OxideGlass GlazeComp. CarbonMetal FoilOrganic SolidInorganic SolidGeneral●●●●●  ●●Precision●●●   ●  High-Resistance  ● ●●   Power●●●      High-Voltage    ●●   High-Frequency   ●     VII. Quick Quiz: Resistor ClassificationQuestionWhat are the two primary macro-classifications of resistors?Answer1. Fixed Resistors (Value remains constant)2. Variable Resistors (Value is adjustable, e.g., potentiometers)VIII. Common Resistor Questions1. What is the main function of a resistor?A resistor opposes current flow to prevent short circuits and manage signal levels. It acts as a gatekeeper, ensuring downstream components receive the correct voltage and current.2. How does a resistor work?Resistors work by restricting the flow of electrons, similar to kinking a garden hose to reduce water flow. They dissipate the excess energy as heat.3. Why are resistors important for Arduino/IoT?They are essential for voltage division (converting 5V logic to 3.3V) and current limiting for LEDs to prevent burnout.4. What is a 0-ohm resistor used for?It acts as a bridge or jumper on a printed circuit board (PCB), allowing designers to route traces over other tracks without using a multi-layer board.5. What is the difference between resistance and a resistor?Resistance is a physical property (measured in Ohms). A resistor is the physical component manufactured to provide a specific amount of that resistance.Frequently Asked Questions (2026 Update)What is the difference between thin-film and thick-film resistors?Thin-film resistors (sputtered metal) offer high precision (0.1% tolerance) and low noise for audio/medical tech. Thick-film resistors (printed paste) are cheaper and handle higher power surges but have lower precision (5% tolerance), suitable for general electronics.Why are shunt resistors critical for EV battery management?Shunt resistors with ultra-low resistance measure high currents in Electric Vehicles (EVs) with extreme accuracy. They enable the Battery Management System (BMS) to calculate state-of-charge and prevent over-current scenarios efficiently.How do I choose the right resistor power rating for PCB design?Calculate the power dissipation ($P = I^2 \times R$) and choose a resistor with a rated power at least 50% higher than your calculation (derating). For enclosed 2026 IoT devices, a 2x safety margin is recommended to minimize heat.{ "@context": "https://schema.org", "@type": "Article", "headline": "Resistor Types and Classifications: The 2026 Engineering Guide", "datePublished": "2020-04-18", "dateModified": "2026-01-20", "author": { "@type": "Organization", "name": "ApogeeWeb" }, "mainEntity": { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What is the difference between thin-film and thick-film resistors?", "acceptedAnswer": { "@type": "Answer", "text": "Thin-film resistors (sputtered metal) offer high precision (0.1% tolerance) and low noise for audio/medical tech. Thick-film resistors (printed paste) are cheaper and handle higher power surges but have lower precision (5% tolerance)." } }, { "@type": "Question", "name": "Why are shunt resistors critical for EV battery management?", "acceptedAnswer": { "@type": "Answer", "text": "Shunt resistors with ultra-low resistance measure high currents in Electric Vehicles (EVs) with extreme accuracy. They enable the Battery Management System (BMS) to calculate state-of-charge and prevent over-current scenarios." } }, { "@type": "Question", "name": "How do I choose the right resistor power rating for PCB design?", "acceptedAnswer": { "@type": "Answer", "text": "Calculate the power dissipation (P = I^2 * R) and choose a resistor with a rated power at least 50% higher than your calculation (derating). For enclosed IoT devices, a 2x safety margin is recommended." } }, { "@type": "Question", "name": "What is the main function of a resistor?", "acceptedAnswer": { "@type": "Answer", "text": "A resistor opposes current flow to prevent short circuits and manage signal levels. It acts as a gatekeeper, ensuring downstream components receive the correct voltage and current." } } ] }}

IntroductionWith the rapid development of the current mobile storage technology and the rapid expansion of the mobile storage market, the amount of FLASH memory is growing rapidly. FLASH chips are very suitable for mobile products due to their advantages of portability, reliability and low cost. The market demand has spawned a large number of FLASH chip research and development, production and application companies. In order to ensure the long-term reliable operation of the chip, these companies need to test the FLASH memory at high speed and meticulously before the product to the market. Therefore, it is very necessary to have the high-efficiency FLASH memory test.What Is Flash Memory?CatalogIntroductionⅠ FLASH Memory TestⅡ FLASH Structural FeaturesⅢ FLASH Test Method3.1 System Connection3.2 Test Implementation Method3.3 Comprehensive Use of Test Methods and Flow Test3.4 Experimental ResultⅣ ConclusionⅤ FAQⅠ FLASH Memory TestNo matter what type of electronic memory is tested, it is not easy. It cannot be concluded by testing each storage unit in the memory in turn, because the change of each storage unit may affect other units in the memory. This correlation creates a huge testing work. In addition, FLASH memory has its own characteristics. It can only write the data in the storage unit from "1" to "0", but not from "0" to "1". If you want to achieve "0" -> " 1" , only the data of the entire sector or the entire memory can be erased, and which takes a lot of time. FLASH memory has other characteristics, such as slow read and write speed, write status word before writing data, many FLASH are only suitable for sequential read and write but not suitable for jump operations, etc. Here these characteristics restrict the test of FLASH memory.In order to solve these problems in FLASH testing, people have proposed using built-in self-testing or using embedded software and other testing methods to test related performance, which have achieved good results, but most of these methods are not suitable for product testing. However, most of the algorithms that are very effective for general-purpose memory testing are difficult to directly apply to FLASH testing due to the limitations of the FLASH device itself (for example, it cannot be directly written from "0" to "1").After a brief introduction to the structure and characteristics of the FLASH chip, the principle of the FLASH memory test program is explained. On this basis, several common memory testing methods are analyzed and improved, so that they can be effectively used in FLASH testing. These methods are simple and efficient, have high fault incidence, and can be quickly pre-generated. Compared with some other test algorithms, they are more suitable for engineering testing in testers. This paper analyzes the main characteristics of these methods, and on this basis, introduces the flow applied in the actual FLASH memory test.Ⅱ FLASH Structural FeaturesThere are various types of FLASH memories, and the most commonly used ones are NOR type and NAND type FLASH. Usually, the NOR type is more suitable for storing program codes. Its random read and write speed is fast, but the capacity is generally small (for example, less than 32 MB), and the price is high; while the NAND-type has a capacity of more than 1GB, and the price is relatively cheap, suitable for storage, but generally can only read and write data in a whole block, and the RAM capability is poor. They do not use linear address mapping to access data, but serially take register operations.Generally speaking, no matter what type of FLASH, there is an ID register to read the memory information, and the specific type can be judged according to the chip data provided by the supplier. In addition, the erasing process of the FLASH memory is relatively time-consuming, and the erasing process is relatively complicated. Figure shows the general flow of FLASH chip erasing.FLASH Chip Erase FlowIt can be seen that the operation of erasing data limits the working speed of the FLASH chip. In addition, some other features, such as slow reading and writing speed, writing the status word before writing data, many FLASHs are equipped with redundant units, etc., which restrict the improvement of the test speed. Therefore, it is very necessary to design a reasonable method, or to test several pieces of FLASH together, and to apply the test algorithm to reduce the test time. Ⅲ FLASH Test Method3.1 System ConnectionThe chips selected in this article are AMD's NOR type FLASH - AM29LV400B and Samsung's NAND type FLASH K9F5608UOB, which can be directly connected to the digital channel of the digital circuit tester through a 44 PIN special adapter. The hardware experiment platform we use is the BC3192 digital-analog hybrid test system. This system can provide fast working speed and flexible algorithm graphics generation method, which is very suitable for testing needs.3.2 Test Implementation MethodAssuming that the number of memory cells that can be addressed by the memory is N, since the memory chip can only access one memory cell at a time, and each cell has only two states of "0" or "1", there are 2N possible states in total. Since the selected addresses are random, when the number of test steps is M, there may be as many combinations of address selection sequences, even with all "0" or all "1" pattern testing, which is a huge number.In order to effectively test the memory chip, the structure of the semiconductor memory must be analyzed, and several patterns that can effectively test the memory function must be determined and selected, so as to achieve the detection purpose and limit the test amount within the allowable range. However, in practical applications, because each test pattern has its limitations, and the characteristics of various manufacturers and various types of memories are not completely consistent, there is no optimal unified test method yet.According to the characteristics of FLASH chips, we mainly improve and use the following methods:🔺 Parity Pattern CheckParity pattern check method is a more suitable method for memory testing. In the parity pattern check method, the data pattern written to the memory cell matrix is determined according to the parity of the memory cell address code. If there are an even number of 1s in the row address code and column address code of a memory cell, and its parity is 0, write "0" (or "1") in the memory cell; if there are an odd number of 1s, its parity is 0, or it is 1, then write "1" (or "0") in the memory cell. In short, the signal data stored in the memory cell matrix will be the exclusive OR relationship between the row address code and the column address code.The process of FLASH parity graphics function detection is: first write the background graphics according to the algorithm, then read out bit by bit and check the correctness of the results, then erase the chip data, and repeat the above test process with the inverted graphics. The total number of test steps is M=4N.Since the parity pattern is asymmetric, the failure of any one-bit address decoder will cause repeated addressing of one of the two memory cells that should have written inverse data to each other, and the second addressing changes the first address. The content written during the secondary addressing, while the other memory location is not accessed. Therefore, the address parity pattern can well detect the failure of the address decoder.In addtion, the parity pattern writes the entire memory cell every time and then reads it out as a whole. There is no repeated erasing process (the whole process only needs to be erased twice), which is very suitable for FLASH chip testing.🔺 Step-by-Step MethodThe step-by-step method is a method in which each cell of the memory is checked in turn. First, starting from the first storage unit, each unit is inverted and checked one by one, and one scan is not completed until the end of the last unit detection. Then, in the case of reverse code, starting from the first storage unit, each unit is inverted and checked one by one, until the end of the last unit detection. The whole process is as if all the units are walking forward together, hence the name "step-by-step method". According to the characteristics of the FLASH chip, we change the process of walking under the background of the reverse code, and transform it as follows to form a suitable synchronizing algorithm.Before testing, each memory cell has information "1". First, write the background pattern in the storage matrix (the initial state is all "1"), then start from address A0 to read "1", write "0", read "0", and check the readout result. Then, repeat the operation (read "1", write "0", read "0") to the next address selection unit in turn, until all storage units (A=N-1) are repeated. Then in the read operation mode, perform a forward scan and read out on all the memory cells to check whether there is a problem of multiple writing in the forward and reverse directions. The memory input is then erased so that all cells are all "1"s. Then start the reverse scan: starting from the highest address AN-1, read "1", write "0", read "0", and perform the above operation process bit by bit until the final address is AN-1, and finally all memory cells having a read "0" scan is performed to verify the correctness of the readout.Testing the memory chips with this test algorithm allows each memory cell to be accessed. It can not only ensure that each memory cell can store "1" and "0" data, but also ensure that each memory cell is subject to reading "1", reading "0" and writing "1" and writing "0" from other surrounding cells of the interruption. The total number of test steps for this method is:In formula (3), W represents a write operation, R represents a read operation, Q represents "1", and represents "0". Bij represents the memory cell in the i-th row and j column of the memory. For example, WBij(Q) represents the time taken to write a "1" operation to the memory cell of the i-th row and j column. It can be seen from formula (3) that the total number of test steps is 9N, and the whole process only needs two erasing operations, which shows that it is a fast and effective method.🔺 Mobile Reverse MethodIt is a method of inverting the data of each address storage unit in sequence. It needs to read the data of each storage unit before and after the inversion, and it must also generate address jumps by means of the forward and backward address addressing sequence, and the address changes in increments of 20, 21..., 2n-1 power ( n is the number of address bits). After the address jump is performed according to the above rules, three operations are performed on each address: read-write-read is a cycle.The purpose of the above operation is mainly to generate effective mutual interference between addresses, but obviously, if the above operation is performed with the entire chip as a unit, data needs to be erased multiple times, so the FLASH test chip should be improved in this way: the operation is completed in units of sectors. Assuming that the FLASH chip has N sectors, the function test of the mobile inversion method must first write all memory cells with "1" as the background pattern. First, in the first sector, read and verify that the A0 storage unit is "1", then rewrite the storage unit to "0", and finally read the information of the storage unit to prove the newly written "0" still exists in this storage unit. The test address of the first sector is incremented by the order of 20 valid bits, and the above operation process of reading "1", writing "0" and reading "0" must be repeated for each storage unit, and the test step size is 3n (n is the number of storage units in the sector) can make all storage units become "0". The address sequence of this test is incremented by 1, that is, from the lowest address bit A0 to the highest bit A (n-1), read "1", write "0" and read " 0" to verify.For the second sector, the next address level 21 is used as the change amount of the address increment, and different address bits are used as the lowest bit each time (the 0th bit and the 1st bit respectively), so that the address changes by this increment. through all possible addresses. Therefore, in a test program, all memory cells of addresses are tested once. Then, take 22, 24...2N as the address increment in turn, repeat the above process, and generate a new cyclic carry every time a cycle is completed.Because the size of each sector is different, the step size of the test pattern of the mobile reverse method is 3n (n is the maximum number of storage units in the sector). The sector-based test is actually a random test of the chip function, because it does not repeatedly disturb the access data of each unit to verify the influence of signal changes between its address lines, but this in the method, the adjacent address lines are tested one by one in each sector. Since the structure of each sector is basically the same, this sampling test is very representative, and the test time is reduced by an order of magnitude.The method test pattern is a good compromise test scheme. Because it has almost the best characteristics of various test patterns, it can test the disturbance interaction between as many memory cells as possible with fewer test steps. In the specific procedure, the "1" field is reversed to the "0" field, which is generated by selecting addresses in sequence and writing these addresses, and there is a write operation between the two reads. The mobile inversion test includes functional test and dynamic test. The former test ensures that the memory cell under test is not affected by reading and writing other memory cells, while the latter test predicts the fetch time under the worst and best conditions, and predicts the impact to the address transition on these times.This test method is easy to implement. It is based on the skipping algorithm and reduces the complexity of the algorithm by changing the length of the skipping step. The mobile inverse method test is a test pattern with good functional test and dynamic test characteristics, and it requires a short test time and has good results in many cases. This method is especially effective for testing larger-capacity memories.The method can also be further expanded, that is, the data is processed by mobile inversion. Taking the chip as a 32-bit bus as an example, first write 0xAAAAAAAA to each unit of the memory, verify and erase, then write 0xCCCCCCCC to the memory, verify and erase, and then write 0xF0F0F0F0, 0x0F0F0F0F, 0xFF00FF00, 0x00FF00FF, 0xFFFF0000, 0x0000FFFF, 0xFFFFFFFF, and 0x0 in sequence, finally erase the data after verifying the correctness of the writing. The principle is the same as that of address movement inversion, which is not repeated here.3.3 Comprehensive Use of Test Methods and Flow TestIn the above, the testability of the FLASH chip is improved from the point of view of the algorithm. Although the NOR and NAND FLASH structures are different, the above algorithms can be used to test the above two types of devices because the above algorithms can be calculated to generate test patterns in sequence.The above three methods have their own advantages and can be used together in practical applications. The address parity pattern test is the most convenient and efficient, because only one address line is changed each time in the process of writing the pattern, and the opposite data is written, so if any address line is short-circuited, it will be checked immediately. This method is most suitable for checking the failure of the address decoder. The step-by-step method is suitable for checking the failure of multiple address selections and decoders, and can detect the influence of noise on the characteristics of memory chips during writing. It can ensure correct address decoding and the storage of "1" and "0" in each memory cell. In most production tests, the combination of these two methods can identify the vast majority of FLASH failures.Of course, the chips produced by various manufacturers have certain differences in structure and process, so the probability of various errors is also different, and the method can be adjusted according to the actual situation. Due to design problems, some chips may have other less common errors, which require more detailed testing. In this case, it is more appropriate to use the mobile reverse test method. This method can well test the dynamic error of the chip, and can expand the test in detail or simplify the test according to specific needs, which is very effective for product performance analysis.In the specific program design, in order to simplify the execution of the algorithm, the statement of reading the product model and calling the read and write commands can be stored in the tester as a subroutine, which can be seamlessly called every time it is needed.In the testing process, the most time-consuming operation is the program erasing operation, which often takes several seconds at a time. The solution is to deal with the erasing process separately. In a practical application, two testers can be used, where several chips run in parallel while erasing. In this way, one device is used for reading, writing, and testing, and the other device is used for erasing data, which can effectively form a pipeline operation and greatly save test time. In addition, combining several methods can also help improve fault coverage.3.4 Experimental ResultAccording to the above thought, on the test system platform of BC3192, both AMD's NOR-type FLASH AM29LV400B and Samsung's NAND-type FLASH 9F5608UOB have been tested. Experiments show that, compared with the traditional checkerboard-based test pattern, the parity method, the step-by-step method and the reverse method generate higher fault coverage of the test pattern. These algorithms have only two chip erase operations at most. Therefore, the test time can fully meet the needs of engineering testing. Among them, the mobile reverse method has no erase operation, so the test speed is the fastest. In the experiment, we use any one of the above three methods to test according to the method of running water. Under the same fault coverage, the test efficiency can be improved by more than 40%. Ⅳ ConclusionThis paper is an attempt to test FLASH on the basis of traditional memory test theory. This method retains the advantages of traditional methods and better solves the difficulty of FLASH memory test. The method is convenient and quick, the process is simple, and all test patterns can be generated in advance, so that they can be directly loaded into the tester, which is beneficial to be directly applied to the tester for production testing. Ⅴ FAQ1. Does flash memory have a large capacity?We should also point out that flash drives rarely actually have the full amount of space available. This is because each flash drive requires some storage capacity to run the device's firmware. For a smaller 1 gigabyte flash drive, you can expect the firmware to take up around 72 megabytes of space.2. Is flash memory RAM or ROM?Is Flash memory a RAM or ROM? RAM is Read-Only Memory. Unlike RAM, ROM is persistent storage. ... Flash Memory is one category of ROM i.e Electrically Erasable Read Only Memory (EEPROM).3. What is flash based storage?Flash storage is a data storage technology based on high-speed, electrically programmable memory. The speed of flash storage is how got its name: It writes data and performs random I/O operations in a flash. Flash storage uses a type of nonvolatile memory called flash memory.4. What NAND means?What does NAND stand for? Surprisingly, NAND is not an acronym. Instead, the term is short for "NOT AND," a boolean operator and logic gate. The NAND operator produces a FALSE value only if both values of its two inputs are TRUE.5. What is flash memory examples?Portable devices such as digital cameras, smartphones, and MP3 players normally use flash memory. USB drives (also called thumb drives and flash drives) and memory cards use flash memory to store data.6. How many types of flash are there?There are two main types of flash memory – NAND and NOR. NAND flash memory is usually used for general-purpose data storage and transfer, whereas NOR flash memory is typically used for storing digital configuration data. NAND is the most common type and is found in devices such as USB drives and SD cards.7. Can a flash drive be erased and reused?Erasing the USB drive deletes both partitions and data. After data wiping, there is only unallocated space on your USB drive. To reuse the USB flash drive, format and create a new volume again with EaseUS partition management software easily.8. Why does flash memory wear out?NAND flash memory is susceptible to wear due to repeated program and erase cycles that are commonly done in data storage applications and systems using Flash Translation Layer (FTL). Constantly programming and erasing to the same memory location eventually wears that portion of memory out and makes it invalid.9. Are flash drives good for long term storage?Memory cards and USB drives are NOT designed for long term storage. You should always backup your data on to another device. The data will normally stay valid for a period of up to 10 years if stored under normal conditions. The data cells inside carry a charge which can dissipate over time.10. Why is flash memory used?Flash memory is a long-life and non-volatile storage chip that is widely used in embedded systems. It can keep stored data and information even when the power is off. It can be electrically erased and reprogrammed. Flash memory was developed from EEPROM (electronically erasable programmable read-only memory).11. What is flash storage device?Flash storage definedFlash storage is a solid-state technology that uses flash memory chips for writing and storing data. Solutions range from USB drives to enterprise-level arrays. Flash storage can achieve very fast response times (microsecond latency), compared to hard drives with moving components.12. What are the advantages and problems with using flash memory?Flash memory posses high transferring speeds. Compared to a traditional hard disk drive, flash memory does read/write function at a fast rate. However the factors latency and IOPs are considered, Solid State Drives still tops in terms of performance. Flash memory does not contain any moving parts.13. How long will flash drives last?eHow says flash drives can last up to ten years, but as mentioned on NYTimes.com, flash memory doesn't usually degrade because of its age, but rather because of the number of write cycles, which means the more you delete and write new information, the more quickly the memory in the device will start to degrade.14. Can you erase and reuse a flash drive?Erasing the USB drive deletes both partitions and data. After data wiping, there is only unallocated space on your USB drive. To reuse the USB flash drive, format and create a new volume again with EaseUS partition management software easily.15. How do I check the health of my flash drive?In Command Prompt window, you can type the command chkdsk *: /f, and hit Enter key on the keyboard. Replace “*” with the actual drive letter of the target drive. The CHKDSK tool will start checking the hard drive or USB health, namely, it will scan and fix detected errors in the external hard drive or USB.16. What happens when you delete a file from a USB flash drive?Where do deleted files from USB go? Since the USB flash drive or pen drive is an external device, files deleted on the USB flash drive are deleted permanently instead of going to the recycle bin, so you cannot perform recycle bin recovery to recover files from USB.

Introduction FPGA is a product of further development on the basis of programmable devices such as PAL, GAL, and CPLD. It appears as a semi-custom circuit in the field of application specific integrated circuits (ASIC), which not only solves the shortcomings of the custom circuit, but also overcomes the limited number of gate circuits of the original programmable device. FPGA is often used in communication, network and other fields to process a large number of network data packets. It is also widely used in aerospace, military defense and other fields. As a hardware test platform before other chips are taped out, it plays an important role in cloud computing, artificial intelligence (AI) and other fields. FPGA Applications, Features and Selection Catalog Introduction Ⅰ FPGA Basic Architecture Ⅱ FPGA Basic Features Ⅲ FPGA Applications 3.1 Circuit Design 3.2 Product Design 3.3 System Application Ⅳ Vacuum Cleaner Based on FPGA 4.1 A Short Brief 4.2 The Composition of the Platform 4.3 Main Hardware Design 4.4 Program Design Points Ⅴ FAQ Ⅰ FPGA Basic Architecture FPGA consists of 6 parts, namely programmable input/output (I/O) unit, basic programmable logic unit, embedded RAM, abundant wiring resources, bottom embedded functional unit and embedded dedicated hard core. Figure 1. FPGA Basic Architecture Each unit is described as follows:🔺Programmable I/O UnitAt present, most FPGA I/O units are designed in programmable mode, that is, through the flexible configuration of software, they can adapt to different electrical standards and I/O physical characteristics; the matching impedance characteristics, the pull-up and pull-down resistors can be adjusted; the output drive current can be adjusted, etc.🔺Basic Programmable Logic UnitThe basic programmable logic unit of FPGA is composed of a look-up table (LUT) and a register. The look-up table completes the pure combinational logic function. FPGA internal registers can be configured as flip-flops with synchronous/asynchronous reset and set, clock enabled, or as latches. FPGA generally relies on registers to complete synchronous sequential logic design. Generally speaking, the configuration of a classic basic programmable unit is a register plus a LUT. However, the internal structures of registers and look-up tables of different manufacturers are different, so the combination modes are also different.An important aspect of learning the LUT and Register ratios of the underlying hive is device selection and sizing. In addition to the basic programmable logic units inside the FPGA, there are embedded RAM, PLL or DLL, dedicated Hard IP Core, etc. These modules can also be equivalent to a certain scale of system gates, so the simple and scientific method is use the number of Registers or LUTs of the device to measure.🔺Embedded RAMNow most FPGAs have embedded RAM, which can be configured as single-port RAM, dual-port RAM, pseudo-dual-port RAM, CAM, FIFO and other storage structures.CAM is the content address memory. The data written to the CAM is compared with every data stored in it and returns the addresses of all internal data that are the same as the port data. Simply put, RAM is a storage unit for writing addresses and reading data, while CAM is just the opposite of RAM. In addition to block RAM, Xilinx and Lattice FPGAs can flexibly configure LUTs into storage structures such as RAM, ROM, and FIFO.🔺Rich Wiring ResourcesThe routing resources connect all the units in the FPGA, and the length and process of the connection determine the driving ability and transmission speed of the signal on the connection. Here the division of wiring resources:1) Full dedicated routing resources: Complete the routing of the global clock and global reset/set within the device.2) Long-term resources: Used to complete the wiring of some high-speed signals and some second global clock signals between device banks.3) Short-circuit resources: Used to complete the logic interconnection and wiring between basic logic units.4) Others: There are various wiring resources and control signal lines such as dedicated clock and reset in the logic unit.In the design process, the place and router often automatically selects the available routing resources to connect the underlying unit modules used according to the topology and constraints of the input logic netlist, so routing resources are often ignored. In fact, the optimization of routing resources is directly related to the use and implementation results.🔺The bottom layer is embedded with functional units, and the resources embedded by different manufacturers will be different.🔺Embedded dedicated hard coreDifferent from the "low-level embedded unit", the hard cores here are mainly those with relatively weak generality, and not all FPGA devices contain hard cores.   Ⅱ FPGA Basic Features 1) Using FPGA to design ASIC circuit (application-specific integrated circuit), users can get suitable chips without film production.2) FPGA can be used as a mid-scale sample for other full-custom or semi-custom ASIC circuits.3) There are abundant triggers and I/O pins inside the FPGA.4) FPGA is one of the devices with the shortest design cycle, the lowest development cost and the lowest risk in the ASIC circuit.5) FPGA adopts high-speed CMOS technology with low power consumption and is compatible with CMOS and TTL levels. Figure  2. FPGA Chip Ⅲ FPGA Applications 3.1 Circuit Design Connection logic and control logic are the areas where FPGA played a relatively important role in the early days and are also the cornerstone of FPGA applications. In fact, it is still quite difficult to apply FPGA in circuit design, which requires developers to have corresponding hardware knowledge (circuit knowledge) and software application capabilities (development tools). So talents in this area are always in short supply, and they are often engaged in new technologies. The successful product development of new products will become the mainstream basic products in the market for designers to apply. In the near future, the design of general-purpose and special-purpose IP will become popular. 3.2 Product Design Apply relatively mature technology to some specific fields such as communication, video, information processing, etc. to develop products that meet the needs of the industry and can be accepted by industry customers. This aspect is mainly a combination of FPGA and professional technology. In addition, there are product design for interface issues with professional customers also includes professional tool products and civilian products. The former focuses on performance, while the latter focuses on price-sensitive product design to achieve product functions as the main purpose.FPGA is a means of realization. In this field, it has the characteristics of interface, control, functional IP, embedded CPU, etc. to realize a system product design with simple structure, high degree of curing, and comprehensive functions for FPGA market. 3.3 System Application The system-level application is the combination of FPGA and traditional computer technology to realize an FPGA version of the computer system. For example, Xilinx V-4, V-5 series FPGA is used to realize the embedded POWER PC CPU, and then cooperate with various peripheral functions. To achieve a basic environment, running LINUX and other systems on this platform also supports various standard peripherals and functional interfaces, which is very helpful for quickly forming large-scale FPGA systems.In system-level applications, if the developers do not have the ability to expand the system, it is meaningless to just engage in programming. Of course, the development of device drivers is another case. The system-level application seems to have a high starting point, but it does not have deep development ability, it is likely to become a hobbyist, just like many people can make web pages but cannot be called programming.   Ⅳ Vacuum Cleaner Based on FPGA 4.1 A Short Brief Design of indoor intelligent vacuuming platform based on FPGA.Intelligent environmental cleaners have increasingly become the focus of research because they can replace people in environmental cleaning. Although they achieve intelligence, most of them have complex structures and high integration, which are not conducive to developers to expand their functions. On the basis of researching and summarizing the relatively mature products on the market, this paper designs and implements an indoor intelligent vacuuming platform based on a highly programmable FPGA. The platform has self-navigation, can clean most of the space, and is compact in shape, stable in operation and low in noise. More importantly, it has a simple structure and a user-friendly interface, which is convenient for further development of operation and functions. Figure  3. Body Frame 4.2 The Composition of the Platform The overall frame design of the platform proposed in this paper is shown in Figure 3, and a car with four wheels is used as the carrier of the entire platform. The FPGA controller is used as the main controller of the entire platform, and is connected to the photoelectric sensors jk1, jk2, jk3, jk4 and the collision switch jk5 through I/O to realize the detection of platform obstacles. Then output PWM waveform through I/O to drive speakers and high-low, and the change of the level drives the on and off of the LED to form an acousto-optic circuit. Finally the stepper motor dj1, dj2 and the DC dust collection motor dj3 are driven by controlling the signal control line of the motor driver to realize the movement and dust collection of the platform. 4.3 Main Hardware Design The system is mainly composed of FPGA main control chip, photoelectric sensor, collision switch, wireless remote control transmitter module controlled by two STC89C52 microcontrollers, two mode selection chips, acousto-optic circuit, drive motor, vacuum cleaner motor and the power supply circuit of the whole system, such as as shown in the Figure 4. Figure  4. Main Control System 🔺FPGA Chip SelectionAccording to the overall design of the platform, the basic requirements for the chip can be drawn:(1) At least 6 PWM waveform outputs are required.(2) One serial communication interface is required.(3) A real-time chip that requires a higher 12 V to be converted to 3.3 V.(4) Higher processing speed.(5) There are more I/O interfaces.Taking these conditions into consideration, the EP2C35F672C6 model in the CycloneII series FPGA produced by Altera can basically meet the requirements. It has excellent operation speed, low cost and DSP module, large internal memory, multi-channel PWM output, flexible design and comprehensive use of multiple languages, and the cost performance is relatively high.🔺Configuration Circuit Design Points(1) Power supply circuit: The power supply system uses 12V power supply as the input power supply, uses L7805CV to step down it to 5V, and then converts 5V to 3.3V and 1.2V by TPS37HD301. The power supply point of the I/O port of the FPGA is 3.3V, the core supply voltage is 1.2V. Because the motor drive system uses the 5V signal of the controller, and the port voltage of the FPGA is 3.3V, the I/O voltage must be boosted to 5V, and the 74HCT245 boost chip is used here.(2) Clock and reset circuit: ZPB-26-16 M is an active crystal oscillator in the clock circuit, and the frequency is 16MHz, which makes the serial port baud rate more accurate. At the same time, it can support the PPL function and ISP download function inside the chip. The reset circuit takes hardware reset and software reset.(3) Debug JTAG and download circuit: Because the soft core ISP and JTAG can be built directly inside the FPGA, the hardware circuit is connected to a JTAG interface of IDC-10.(4) Configuration storage circuit: EPCS16 is selected as the ROM of the FPGA, which can be repeatedly programmed by the download cable or other equipment, and can also be programmed online through the AS interface. Use the 4MHz On-Chip memory inside the FPGA chip as the RAM of the FPGA.(5) Sensor and collision switch: E3F-DS5C4.P1R photoelectric switch, used to detect obstacles and stairs, which is a cylindrical diffusion type with a maximum distance of 5cm, or an adjustable NPN type normally open photoelectric switch. The collision switch mainly cooperates with the front sensor to protect the front of the platform. When the platform hits the obstacle ahead, trigger the switch to make the platform avoid the obstacle.(6) Wireless sending and receiving module: XL02-232AP1 wireless module is a half-duplex wireless transmission module with UART interface, which can work in the 433MHz public frequency band and meet the wireless regulatory requirements.(7) Drive and vacuum motor: The platform adopts the front wheel dual drive, the motor selects the two-phase hybrid stepping type, and the vacuum cleaner motor adopts the DC motor. The main electrical parameters of the stepping motor are: ① Step angle: 1.8°② Phase current: 0.87 A③ Holding torque: 0.24 nm④ Phase resistance: 3.3 Ω⑤ Phase inductance: 5.0 mH⑥ Weight: 0.2 kg(8) Sound and light circuit and automatic cleaning time input display circuit: The sound and light circuit is mainly composed of light-emitting diodes and buzzers, which are directly connected to the FPGA to remind the working state of the platform. Use 4 buttons (OK, Initial, Up, Down) to input the cleaning time, and then three digital tubes display the set time. The cleaning time is counted by the timer inside the FPGA. When the timer is completed, the platform stops working. 4.4 Program Design Points Divide the program into two parts: hardware programming and software programming. For hardware programming, timing simulation of hardware circuits is required to determine the effect of debugging.🔺Hardware Programming and SimulationThe platform mainly generates input signals through sensors and collision switches, and processes the signals through FPGA. Finally, the FPGA transmits the processed signals to the motor, and the motor completes a series of actions, as shown in Table 1. So its logic design is the key to realize intelligence. After the hardware selection is completed, use Quartus II to build the hardware schematic diagram. After compiling, perform timing simulation on jk1, jk2, jk3, and jk4, analyze the timing relationship, estimate the performance of the design, and check and eliminate competition risks.Table 1: Relationship between Motor Status and Platform Working Status. dj1 dj2 dj3 Cleaner Status Turn Forward Turn Forward ON Vacuuming Forward Turn Back Turn Forward ON Vacuuming Left Turn Forward Turn Back ON Vacuuming Right Turn Back Turn Back ON Vacuuming Back The realization of platform work in automatic cleaning mode depends on the cooperative work of sensors (jk1, jk2, jk3, jk4) and motors (dj1, dj2, dj3), and the logical relationship is designed according to their functions.Table 2: Relationship between Sensor Status and Platform Working Status. jk1 jk2 jk3 jk4 Cleaner Status 1 1 1 1 Vacuuming Forward 1 1 0 1 Vacuuming Left 1 0 1 1 Vacuuming Right 1 0 0 1 Vacuuming Forward 0 1 0 1 Vacuuming Forward (Turn 90° Left)  0 0 1 1 Vacuuming Forward (Turn 90° Right)  0 0 0 1 Vacuuming Back When the hardware selection is completed, use Quartus II to build the hardware schematic diagram. After compiling, perform timing simulation on jk1, jk2, jk3, and jk4 to analyze the timing relationship.🔺Software ProgrammingAfter the hardware design and debugging is completed, the software system design is also carried out. Write a C program in a C language file to program the SoPC. The overall algorithm flow of the platform work is shown in Figure 5. When the platform is powered on, firstly enter the automatic cleaning and manual remote cleaning mode. After the automatic cleaning mode is selected, input the working time of the platform's automatic cleaning through the keyboard, and use the sensor to judge whether it encounters obstacles or stairs during the cleaning process. Through the interrupt, check whether the set time is reached at all times. If not, the program will return to running. However, if the set time is up, the program will end and the platform will stop working. When remote cleaning is selected, platform movement is controlled by the operator. Figure 5. Algorithm Flowchart Through hardware selection, construction and debugging, and software language writing and debugging, a simple platform has been successfully made, and various predetermined functions have been realized. Compared with similar products on the market, its structure is simpler, the cost is lower, the flexibility and scalability are stronger, and it provides a hardware-supported platform for researchers to develop more functions, which has practical value. As microprocessors continue to advance and sensing technology evolves, their performance can continue to improve and costs can continue to decline. However, in the process of simulation and implementation, it is found that its specific process algorithm is not rigorous enough, and it is necessary to continue to improve it in the future.   Ⅴ FAQ 1. What is FPGA architecture?The field-programmable gate array (FPGA) is an integrated circuit that consists of internal hardware blocks with user-programmable interconnects to customize operation for a specific application. 2. What are the parts of an FPGA?Structure of an FPGAConfigurable Logic Block (CLB)Digital Signal Processing (DSP) Slice.Transceivers.Block Random Access Memory (BRAM)Input/Output (IO) Blocks. 3. What is a basic unit of an FPGA?The configurable logic blocks (CLBs) are the basic logic unit of an FPGA. Sometimes referred to as slices or logic cells, CLBs are made up of two basic components: flip-flops and lookup tables (LUTs). 4. What is FPGA and its types?FPGA stands for Field Programmable Gate Array which is an IC that can be programmed to perform a customized operation for a specific application. They have thousands of gates. In the field of VLSI FPGAs have been very popular. 5. What is the function of FPGA?FPGAs are mainly used to design application-specific integrated circuits (ASICs). First, you design the architecture of such a circuit. Then, you use an FPGA to build and check its prototype. Errors can be corrected. 6. What is FPGA and its application?The FPGA is Field Programmable Gate Array. It is a type of device that is widely used in electronic circuits. FPGAs are semiconductor devices which contain programmable logic blocks and interconnection circuits. It can be programmed or reprogrammed to the required functionality after manufacturing. 7. What are the advantages of FPGA?FPGA advantagesLong-term availability.Updating and adaptation at the customer.Very short time-to-market.Fast and efficient systems.Acceleration of software.Real-time applications.Massively parallel data processing. 8. What is inside CLB in FPGA?A configurable logic block (CLB) is the basic repeating logic resource on an FPGA. When linked together by routing resources, the components in CLBs execute complex logic functions, implement memory functions, and synchronize code on the FPGA. 9. What are the main applications of FPGAs?Main FPGA applications are: Medical, video & image processing, telecom & datacom, server & cloud and defense and space. FPGA chips are used in both wired and wireless communications. 10. What are the industrial applications of FPGA boards?Such applications include multiple sensor dome cameras, HD (High Definition) cameras, night-vision cameras, etc. FPGAs provide the differentiation factor and the processing power to implement such complex solutions. 11. What are the applications of CPLDs and FPGAs?Applications of CPLDCPLDs can be used as bootloaders for FPGAs and other programmable systems. CPLDs are often used as address decoders and custom state machines in digital systems. Due to their small size and low power consumption, CPLDs are ideal for use in portable and handheld digital devices. 12. What programmable technology is used in a FPGA devices?FPGA emerged from relatively simpler technologies such as programmable read-only memory (PROM) and programmable logic devices (PLDs) like PAL, PLA, or Complex PLD (CPLD). It consists of three main parts: Configurable Logic Blocks — which implement logic functions. Programmable Interconnects — which implement routing. 13. What are the features of FPGA?The basic features of FPGA are: 1) FPGA design ASIC circuit, the user does not need to chip production, you can get a combination of chips. - 2) FPGA can do all other custom or semi-custom ASIC circuit of the sample sample. 3) FPGA has a rich internal trigger and I / O pin. 14. Is a FPGA a computer?An FPGA is a chip consisting of a series of logic blocks which can be modified and configured by the user. ... FPGA are programmable chips and their functionality can be updated multiple times. FPGAs come in array of size and prices and are most likely used in low-mid size volume products.

Introduction Capacitors are the most common passive components used in circuit design. Its function is to block the AC current while pass the DC current, and it also has the function of power storage, and has a good filtering effect, which can output the pulsating signal in a smooth way. The application of capacitors in electronics is very common. Let's talk about the common types of capacitor in circuits and their uses. Basic Introduction to Capacitors Catalog Introduction Ⅰ Types of Capacitors in Use with Models 1.1 Ceramic Capacitors (CC) 1.2 Polyester Capacitor (CL) 1.3 Polystyrene Capacitors (CB) 1.4 Polypropylene Capacitors (CBB) 1.5 Monolithic Ceramic Capacitor (MLCC) 1.6 Mica Capacitors 1.7 Paper Capacitors (CZ) 1.8 Metallized Paper Capacitors (CJ) 1.9 Aluminum Electrolytic Capacitors (CD) 1.10 Tantalum Electrolytic Capacitors (CA) 1.11 Mica Trimmer Capacitors (CY) 1.12 Ceramic Trimmer Capacitors (CC) 1.13 Film Trimmer Capacitors 1.14 Air Variable Capacitor (CB) 1.15 Film Variable Capacitors Ⅱ FAQ Ⅰ Types of Capacitors in Use with Models Virtually all types of capacitor are available as following: 1.1 Ceramic Capacitors (CC) 🔺Material: Use ceramic material as medium, coat a layer of metal (silver) film on its surface, and then sinter at high temperature as an electrode. Ceramic capacitors are divided into Class 1 dielectrics (NPO, CCG); Class 2 dielectrics (X7R, 2X1) and Class 3 dielectrics (Y5V, 2F4).🔺Types: Ceramic capacitors are divided into two types: high-frequency ceramics and low-frequency ceramics. Capacitors with a small positive temperature coefficient of capacitance are used in highly stable oscillation circuits as loop capacitors and pad capacitors. Low-frequency ceramic capacitors are limited to bypassing or blocking DC in circuits with lower operating frequencies, or occasions (including high frequencies) that do not require high stability and loss. Such capacitors should not be used in pulsed circuits because they are prone to breakdown by pulsed voltages.🔺Features: Class 1 have the advantages of small temperature coefficient, high stability, low loss and high withstand voltage. The maximum capacity does not exceed 1000pF, commonly used are CC1, CC2, CC18A, CC11, CCG and other series. Mainly used in high frequency circuits.Class 2 and Class 3 are characterized by high dielectric coefficient, large capacity (up to 0.47μF), small volume, and poor loss and insulation compared to Class 1. 🔺Application Models: Widely used in medium and low frequency circuits for DC blocking, coupling, bypassing and filtering capacitors, and commonly used are CT1, CT2, CT3 and other three series. 1.2 Polyester Capacitor (CL) 🔺Material: A non-polar capacitor with a positive temperature coefficient (that is, when the temperature increases, the capacitance becomes larger) made of polar polyester film as the medium.🔺Advantages: High temperature resistance, high pressure resistance, moisture resistance and cheap price, suitable for bypass capacitors.🔺Application Models: Generally used in medium and low frequency circuits, and commonly used models are CL11, CL21 and other series.🔺Value Identification: Internationally, the withstand voltage value of capacitors is usually represented by letters. The common correspondence between codes and bases is:A: 1.0; B: 1.25; C: 1.6; D: 2.0; E: 2.5; F: 3.15; G4.0;H: 5.0; J: 6.3; K: 8.0; Z: 9.0;The number in front of the letter represents the power of 10, for example, 2A is 102*1.0=100V, 2C is 102*1.6=160V and so on.The letters behind the withstand voltage value represent the capacitance in pF.For example, 823 means the capacity is 82*10^3=82000Pf, 224 means 22*104=220000pf=0.22μF. The last letter means the precision, such as J means the capacity tolerance is ±5% and so on.Typical capacitor identification example: 2A823J is 82000Pf±5%, withstanding voltage 100V. 1.3 Polystyrene Capacitors (CB) 🔺Material: There are two types of foil type and metallized type.🔺Advantages: Foil type has large insulation resistance, low dielectric loss, stable capacity and high precision, but large volume and poor heat resistance; metallized type has good moisture resistance and stability, and can recover after breakdown, also it has advantages of the low insulation resistance and poor high frequency characteristics.🔺Application Models: Generally used in medium and high frequency circuits, and commonly used models are CB10, CB11 (non-sealed foil type), CB14~16 (precision type), CB24, CB25 (non-sealed metallization), CB80 (high pressure type), CB40 (sealed metallization) and other series. In short, they used in various precision measuring instruments, car radios, industrial proximity switches and high-precision digital-to-analog converter circuits. 1.4 Polypropylene Capacitors (CBB) 🔺Material: It is a negative temperature coefficient non-polar capacitor that made of non-polar polypropylene film as the medium. There are two types of unsealed (commonly encapsulated with colored resin paint) and sealed (encapsulated with metal or plastic housing).🔺Advantages: Small loss, stable performance, good insulation and large capacity.🔺Application Models: Generally used in medium and high frequency circuits or as starting capacitors for motors, and commonly used foil polypropylene capacitors include CBB10, CBB11, CBB60, CBB61, etc.; metallized polypropylene capacitors include CBB20, CBB21, and CBB401 series.CBB capacitor series are used in high frequency and high power circuits such as filtering, cross-line, resonance, etc. 1.5 Monolithic Ceramic Capacitor (MLCC) 🔺Material: Multi-layer laminated ultra-miniature capacitors sintered with barium titanate-based ceramic materials.🔺Advantages: It has the advantages of reliable performance, high temperature resistance, moisture resistance, large capacity (range 1pF~1μF), and small leakage current.🔺Disadvantages: Low working voltage (withstand voltage lower than 100V).🔺Application Models: Widely used in resonance, bypass, coupling, filtering, etc, and commonly used are CT4 (low frequency), CT42 (low frequency), CC4 (high frequency), CC42 (high frequency) and other series.🔺ClassificationClass 1It is a temperature-compensated NPO dielectric. The electrical performance of this capacitor is the most stable and basically does not change with temperature, voltage and time. In short, it is an ultra-stable, low-loss capacitor material type and is suitable for high stability and reliability requirements. frequency, UHF and VHF circuits.Class 2It is a high dielectric constant X7R series, so it can make capacitors with larger capacity than NPO dielectrics. This kind of capacitor has relatively stable performance. With the change of temperature, voltage and time, its unique performance does not change significantly. It is a type of stable capacitor material. It is used in DC blocking, coupling, bypass, filter circuit and frequency circuit with high reliability requirements.Class 3It uses Y5V dielectric. This capacitor has a high dielectric constant and is often used in the production of large-capacity capacitors with larger specific capacitance and higher nominal capacity. However, its capacity stability is worse than that of X7R, and its capacity and loss are more sensitive to test conditions such as temperature and voltage. It is mainly used in oscillation, coupling, filtering and bypass circuits in electronic complete machines.Monolithic ceramic capacitors are larger than ordinary ceramic capacitors (10pF~10μF), and have the advantages of large capacitance, small size, high reliability, stable capacitance, high temperature resistance, good insulation, and low cost, so they are widely used. They can not only replace mica capacitors and paper capacitors, but also replace some tantalum capacitors, and are widely used in small and ultra-small electronic devices (such as liquid crystal watches and micro instruments). 1.6 Mica Capacitors 🔺Material: Mica is used as the medium, and a layer of metal film (silver) is sprayed on the surface as the electrode, which is laminated according to the required capacity and then dipped and compressed in the bakelite shell (or ceramic or plastic shell).🔺Advantages: Good stability, small distributed inductance, high precision, low loss, large insulation resistance, good temperature characteristics, that is, good frequency characteristics, high operating voltage (50V~7kV) and so on.🔺Application: It is generally used for signal coupling, bypassing, tuning, etc. in high-frequency circuits. For example, they are common in occasions that require high stability and reliability of capacitors, such as instruments and meters of electronic, power and communication equipment, and are also used in aerospace, aviation, navigation, rockets, satellites, military electronics, and oil exploration equipment. Commonly used ones are CY, CYZ, CYRX and other series. 1.7 Paper Capacitors (CZ) 🔺Material: The thin capacitor special paper is used as the medium, and the aluminum foil or lead foil is used as the electrode.🔺Advantages: The capacitance (100pF~100μF) has a wide working voltage range, and the maximum withstand voltage value can reach 6.3kV.🔺Disadvantages: Large size, low capacity accuracy, large loss, and poor stability.🔺Classification: Paper capacitors are divided into inductive type and non-inductive type according to winding methods. The inductive core is actually a ribbon coil with many turns, so the inductance is large. The non-inductive type is to stagger the electrode foils to both sides of the paper, so that the sides of the foil strips extend out of the paper strips, and then the leads are welded after winding into a cylindrical core. In this way, the coils of the electrode foil are short-circuited with each other, so the inductance is very small. This capacitor can be used at higher frequencies.🔺Application Models: Common ones are CZ11, CZ30, CZ31, CZ32, CZ40, CZ80 and other series. 1.8 Metallized Paper Capacitors (CJ) 🔺Material: Using vacuum evaporation technology, a layer of metal film is evaporated on the paper coated with paint film as an electrode.🔺Advantages: Compared with ordinary paper capacitors, it is small in size, large in capacity, and has strong recovery ability after breakdown, which is an unique characteristic. For common situation, when the paper-dielectric capacitor is broken down, the paper medium is scorched, and the two layers of metal foil are melted together at the breakdown place to form a short circuit. But for metallized paper capacitors, the metal film at the breakdown place evaporates at high temperature, leaving only insulating holes and no short circuit.🔺Application Models: Common ones are CJ10, CJ11 and other series. 1.9 Aluminum Electrolytic Capacitors (CD) 🔺Material: The polar one is made by winding the aluminum foil (positive electrode) with an oxide film and the backing paper impregnated with the electrolyte solution together with the cathode foil lamination. Appearance package has tube type and vertical type. And there is a blue or black plastic cover outside the aluminum shell.🔺Advantages: The capacity range is large, generally 1~10000μF, and the rated working voltage range is 6.3V~450V.Disadvantages: Medium loss, large capacity error (maximum allowable deviation is +100%, -20%), poor high temperature resistance, long storage time and unstable working state.🔺Application: Usually used in DC power circuits or medium and low frequency circuits for filtering, decoupling, signal coupling, time constant setting, and DC blocking. Note that the polarity cannot be reversed when used as a filter capacitor in a DC power supply.Selection: The capacity and withstand voltage marked on the body of the aluminum electrolytic capacitor are very important and are the most basic content for selecting capacitors. In the actual selection of capacitors, a capacitor with a larger capacity should be used for places where the current changes rapidly, but it’s not always good. First, the larger the capacity, the higher the cost and volume. In addition, the larger the capacitor, the higher the charging current. The bigger it is, the longer the charging time will be. These are all to be considered in practical application selection. 1.10 Tantalum Electrolytic Capacitors (CA) 🔺Material: There are two forms:1) The foil type tantalum electrolytic capacitor adopts a winding core inside, the negative electrode is liquid electrolyte, and the medium is oxidized tantalum. Common models are CA30, CA31, CA35, CAk35 series.2) The tantalum powder sintered positive electrode is sintered with very fine tantalum powder blocks. Packaging comes in many forms. Widely used models include CA41, CA42, CA42H, CA49, CA70 (non-polar) and other series.🔺Advantages:1) Small SizeSince capacitors use tantalum powder with very fine particles, and the dielectric constant ε of the tantalum oxide film is 17 higher than that of the aluminum oxide film, the capacitance per unit volume of the tantalum capacitor is large.2) Wide Operating Temperature RangeGenerally, tantalum electrolytic capacitors can work normally under the temperature of -50℃~100℃. Although aluminum electrolytic capacitors can also work in this range, their electrical performance is far inferior to that of them.3) Long Life, High Insulation Resistance and Small Leakage CurrentThe tantalum oxide film dielectric in tantalum electrolytic capacitors is not only resistant to corrosion, but also maintains good performance for a long time.4) Good Impedance Frequency CharacteristicsFor capacitors with poor frequency characteristics, when the operating frequency is high, the capacitance drops significantly, and the loss (tgδ) also rises sharply. But solid electrolytic capacitors can work above 50kHz. As the frequency increases, the capacity of capacitors also decreases, but the decrease is small. Some data show that the capacity decreases by less than 20% when working at 10kHz, while the capacity of aluminum electrolytic capacitors decreases by 40%.5) High ReliabilityThe chemical properties of the tantalum oxide film are stable, and because the tantalum anode substrate Ta2O5 is resistant to strong acids and alkalis, it can use solid or acid-containing liquid electrolytes with low resistivity, which makes the loss of tantalum electrolysis smaller than that of aluminum electrolytic capacitors, and the temperature stability is good.🔺Disadvantages: High production cost and low pressure resistance.🔺Application: Widely used in various medium and low frequency circuits and time constant setting circuits in communications, aerospace, military and household appliances.With the properties of storing electricity, charging and discharging, etc, they are mainly used in filtering, energy storage and conversion, mark bypass, coupling and decoupling, and time constant components. Pay attention to its performance characteristics in application, and correct use will help to give full play to its functions, such as considering the working environment of the product and its heating temperature, and taking measures such as derating, if it is used improperly, it will affect the service life of the product.   A variable capacitor is a capacitor whose capacitance can be adjusted within a certain range. When the relative effective area between the pole pieces or the distance between the pieces changes, its capacitance changes accordingly. Usually used as a tuning capacitor in a radio receiving circuit. Here are several types as following: 1.11 Mica Trimmer Capacitors (CY) 🔺Material: It consists of a fixed piece and a moving piece. The fixed piece is a metal piece, and a layer of mica flakes is the most medium on its surface. The moving piece is an elastic copper or aluminum piece. Adjust the moving piece and the fixed piece by adjusting the screws on the moving piece, then the distance between the slices changes the capacitance. There are single trimmers and double trimmers.🔺Advantages: The capacitance can be adjusted repeatedly.🔺Application: Used in transistor radios, electronic instruments, and electronic equipment. 1.12 Ceramic Trimmer Capacitors (CC) 🔺Material: Ceramic is used as the medium, and the semicircular silver layer is plated on both the moving plate and the stator. By rotating the moving plate to change the relative position between the two silver plates, the size of the capacitance can be changed.🔺Advantages: Small size, can be adjusted repeatedly, easy to use.🔺Application: Used in transistor radios, electronic instruments, and electronic equipment. 1.13 Film Trimmer Capacitors 🔺Material: Use organic plastic film as a medium, that is, add it between the moving piece and the fixed piece. Adjust the screw on the moving piece, and make the moving piece rotate to change the capacity. Film trimmer capacitors are generally divided into double trimmers and quadruple trimmers. Some sealed double-connected or four-connected variable capacitors have their own thin-film trimmer capacitors, which are installed on the top of the casing, making it easier to use and adjust.🔺Advantages: With small size, light weight, it can be adjusted repeatedly and is easy to use.🔺Application: Used in transistor radios, electronic instruments, and electronic equipment. 1.14 Air Variable Capacitor (CB) 🔺Material: The electrode consists of two sets of metal sheets. One set is the fixed piece, the other is the moving piece, and the air is used as the medium between them. When the rotor is rotated to make it all screw into the stator, its capacitance is the largest, on the contrary, when the rotor is fully screwed out of the stator, the capacitance is the smallest. Air variable capacitors are divided into single-connection and double-connection.🔺Advantages: It is easy to adjust, with stable performance, and not easy to wear.🔺Disadvantage: Bulky.🔺Application: Used in radios, electronic instruments, high-frequency signal generators, and communication electronic equipment. 1.15 Film Variable Capacitors 🔺Material: A plastic film is added between the moving piece and the stator as a medium, and the shell is encapsulated by transparent or translucent plastic, so it is also called a sealed double-connected and four-connected variable capacitor.🔺Advantages: Small size and light weight.🔺Disadvantages: It is easy to wear.🔺Application: Single connection is mainly used in simple radios or electronic instruments; double connection is used in transistor radios and electronic instruments and electronic equipment; quadruple connection is commonly used in AF/FM multi-band radios.   Ⅱ FAQ 1. What are different types of capacitors?Types of CapacitorsCeramic Capacitors.Film Capacitors.Power Film Capacitors.Electrolytic Capacitors.Ceramic capacitors.Film capacitors.Paper capacitors.Electrolytic capacitors. 2. What are the 2 types of capacitor?Capacitors are divided into two mechanical groups: Fixed capacitors with fixed capacitance values and variable capacitors with variable (trimmer) or adjustable (tunable) capacitance values. The most important group is the fixed capacitors. Many got their names from the dielectric. 3. What is the difference between different types of capacitors?The primary difference between the two is that one uses paper while the other uses plastic. Plastic film capacitors hold an advantage over impregnated-paper types in that they have smaller tolerances, high reliability, a long service life, and can continue operating sufficiently while in high temperatures. 4. What devices use capacitor?Capacitors are essential components in a wide range of electronic systems including smart phones, household electric appliances, electric vehicles, and medical devices to name a few. 5. What are capacitors used for?Capacitor, device for storing electrical energy, consisting of two conductors in close proximity and insulated from each other. 6. What is capacitor and its applications?Capacitor is a basic storage device to store electrical charges and release it as it is required by the circuit. Capacitors are widely used in electronic circuits to perform variety of tasks, such as smoothing, filtering, bypassing etc…. One type of capacitor may not be suitable for all applications. 7. Where are capacitors used and why?Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies. 8. How is capacitor used in real life?The most common use for capacitors is energy storage. Additional uses include power conditioning, signal coupling or decoupling, electronic noise filtering, and remote sensing. Because of its varied applications, capacitors are used in a wide range of industries and have become a vital part of everyday life. 9. What are capacitors used for list 5 applications?Applications of capacitors1) Energy storage.2) Pulsed power and weapons.3) Power conditioning.4) Power factor correction.5) Suppression and coupling. 5.1 Signal coupling. 5.2 Decoupling.6) Motor starters. 6.1 Signal processing. 6.2 Tuned circuits.7) Sensing. 7.1 Changing the dielectric.8) Oscillators. 10. What are the advantages of capacitors?Advantages of capacitors include a very high cycle life and charge rates that nearly match discharge rates. Also, supercapacitors can be “floated” for long lengths of time. This means that they will hold their charge (potential energy) for a long period without a large residual decay. 11. Which capacitor is used for high frequency?Mica capacitors have low resistive and inductive components associated with it. Hence, they have high Q factor and because of high Q factor their characteristics are mostly frequency independent, which allows this capacitor to work at high frequency. 12. Where are capacitors used examples?They are used to store energy and then release it when needed.Case 1: Camera flash. A camera flash requires a lot of energy in a short space of time in order to produce a bright enough flash. ...Case 2: Computer emergency shutdown. If a computer loses power it will not be able to shutdown safely. ...Case 3: AC to DC conversion.