The Kynix Blog

Introduction Everyone is familiar with Cameras. Owning a mobile phone is equivalent to owning a smart camera device that is very portable. So what does the camera use to image? And how do you get a clear picture of the object? Here we take you to understand the secrets hidden in the camera. Figure 1. Camera Image Processing Catalog Introduction Ⅰ Photomultiplier Tube (PMT) Ⅱ Charge-coupled Device (CCD) 2.1 CCD Terminology 2.2 CCD Chips 2.3 CCD Types Ⅲ Complementary Metal Oxide Semiconductor (CMOS) 3.1 CMOS Invention 3.2 CCD vs CMOS Ⅳ Imaging System 4.1 Key Elements 4.2 Calculation of Image/Video Data Volume 4.3 Storage Space Calculation 4.4 Camera Composition and Principle 4.5 Intelligent Camera Image Processing Hardware Ⅴ Smart Camera Interfaces and Communication Protocols Ⅵ Image Signal Processor (ISP) Ⅶ FAQ Ⅰ Photomultiplier Tube (PMT) PMT is the earliest image sensor, which is very mature, and it is the sensor with the best performance at present. A photomultiplier tube, useful for light detection of very weak signals, is a photoemissive device in which the absorption of a photon results in the emission of an electron. Because it has multiple electrodes built-in to convert incoming light signals into electrical signals, and even very weak light can be accurately captured. Its highest dynamic range can reach 4.2, compared with other types of sensors that can only reach 3.2~3.6. And it can operate for more than 100,000 hours. However, due to its high cost, it can only be used in professional printing, publishing industry scanners and engineering analysis. Figure 2. Photomultiplier Tube (PMT) Ⅱ Charge-coupled Device (CCD) 2.1 CCD Terminology CCD was invented by Bell Labs in the United States in 1969. It is similar to computer chip CMOS  and can also be used for computer memory and logic operation chips. CCD is a special semiconductor material composed of a large number of independent photodiodes, which are generally arranged in a matrix form (except Fuji's Super CCD). The photosensitive ability of CCD is lower than that of PMT, but in recent years, CCD technology has made great progress, and because of its small size and low cost, it is widely used in scanners, digital cameras and digital video cameras. The image sensors used in most digital cameras today are CCDs.Early CCDs were interlaced (Interline Transfer), which increased the shutter speed, but the image accuracy was greatly reduced. New CCDs are generally progressive scan (FullFrame Transfer). Figure 3. Charge-coupled Device Semiconductor 2.2 CCD Chips It integrates a light-sensitive device on a single piece of semiconductor: a photodiode and some circuits. Each unit is arranged in a neat matrix, CCD pixel = number of rows multiplied by the number of columns. About 30% of each pixel cell is used to make photodiodes, and in the remaining available area, a transfer register is placed. After receiving a command, the light intensity sensed by the photodiode is placed in this transfer register and temporarily stored here, which is an analog signal. The next step is to convert the light intensity value in each pixel into a digital signal, which is then combined into a digital image by the processor in the camera.Since in each pixel unit, only about 30% of the area is actually used for light-sensing, its light-sensing efficiency is relatively low. So in the real finished product, a small optical lens will be placed on top of each pixel unit, which we call "microlens". In terms of structure, it is directly placed above the photodiode, and its area is relatively large, so that more incident light can be concentrated on the photodiode. Therefore, the equivalent photosensitive area reaches about 70% of the pixel area. 2.3 CCD Types Primary color CCD and complementary color CCD: In fact, the CCD itself cannot distinguish colors. Therefore, color filters are required in practical applications. Generally, the filter layer of the CCD device is coated with different colors. The different color blocks on the filter are arranged like a mosaic in the order of G-R-G-B (green-red-green-blue), so that the pixels under each mosaic can sense different colors. Figure 4. Color Filter Array Sensor For example, a 1.3-megapixel CCD has 325,000 pixels sense red, 325,000 pixels sense blue, and 650,000 pixels sense green. In a digital camera with a resolution of 1280x1024 using this CCD, there are 640x512 red pixels, 640x512 blue pixels and 640x1024 green pixels, having more green pixels due to the human eye's sensitivity to green and other color is not the same. Finally, when the image is recorded, the true color of each pixel is the average of its blending with the surrounding pixel image. At present, most digital cameras use this kind of CCD.Linear CCD, different from matrix CCD, may be arranged in a linear arrangement of photosensitive elements, so it is a strip, like barcode scanners.   Ⅲ Complementary Metal Oxide Semiconductor (CMOS) 3.1 CMOS Invention CMOS was not used to make image sensors until 1998. The advantage of CMOS is that the structure is simpler than that of CCD, the power consumption is only about 1/3 of that of ordinary CCD, and the manufacturing cost is lower than that of CCD. Since Canon adopted CMOS in the professional digital SLR camera EOS D30, more and more digital SLR cameras have used it, and almost half of the digital SLR cameras now use CMOS as the image sensor. Figure 5. Complementary Metal Oxide Semiconductor (CMOS) 3.2 CCD vs CMOS CCD and CMOS sensors are different in "internal structure" and "external structure". The imaging points of the CCD device are arranged in an XY vertical and horizontal matrix, and each imaging point consists of a photodiode and a charge storage area controlled by it. Where the CCD can only output analog electrical signals, which need to be decoded by subsequent addresses. Further more, it also needs to provide three-phase power supply and synchronous clock control circuit with different voltages.CMOS devices have high integration, small size and light weight. Its biggest advantage is that it has a high degree of system integration. Because of the digital-analog signal mixed design, in theory, all functions required by image sensors, such as vertical displacement, horizontal displacement register, sensor array drive and control system (CDS), analog-to-digital converter (ADC) interface circuit, etc. can be fully integrated to achieve single-chip imaging, avoid the use of external chips and equipment, and greatly reduce the size and weight of the device.The charge information stored by the CCD needs to be read after being transferred bit by bit under the control of the synchronization signal. The charge information transfer and read output need to be coordinated by a clock control circuit and three sets of different power supplies. slower. The CMOS photoelectric sensor directly generates a voltage signal after photoelectric conversion, the signal reading is very simple, and it can also process the image information of each unit at the same time, which is much faster than CCD.From the perspective of power consumption and compatibility, CCD requires external control signals and clock signals to obtain satisfactory charge transfer efficiency, and also requires multiple power supplies and voltage regulators, so the power consumption is large. While CMOS-APS uses a single operating voltage, with low power consumption (only equivalent to 1/10-1/100 of CCD) and good compatibility, can also be compatible with other circuits.CCD sensors require special processes, use special production processes, and have high costs; while CMOS sensors use 90% of the same basic technologies and processes as semiconductor devices, and have high yield and low manufacturing costs. Currently, 500,000-pixel CMOS sensors are used for cameras.CCDs use charge shift registers, and when the register overflows, it leaks charge into adjacent pixels, causing the bright light to spread out and create unwanted streaks in the image. In CMOS-APS, the photodetector and the output amplifier are both part of each pixel. The integrated charge is converted into a voltage signal in the pixel and output through the XY output line. This row-column addressing method makes the window operation possible. You can also perform on-film translation, rotation and zooming, without smear, halo and other false signals, to get high image quality.High speed is an inherent characteristic of CMOS circuits. CMOS image sensors can drive the column bus of the imaging array extremely fast, and the ADC operates at an extremely fast rate on-chip, and has low sensitivity to output signals and external interface interference, which is beneficial to next level processor connection. CMOS image sensors are highly flexible and can perform random access to local pixel images, increasing flexibility. Camera Image Sensors as Fast As Possible   Ⅳ Imaging System 4.1 Key Elements 1) Field of View: The portion of an object that can be seen on a display.2) Depth of Field: The difference between the nearest and farthest distances at which an imaging system can remain in focus.3) Working Distance: When observing an object, the distance from the vertex of the last lens to the observed object.4) Distortion: The optical error caused by the lens makes the magnification of each point on the image surface different.5) Parallax: It is caused by the traditional lens, the change of each point on the object outside the best focus point, the telecentric lens can solve this problem.6) Image Sensor Size: The effective working area of the image sensor (usually CCD or CMOS), generally refers to the horizontal size. This parameter is important in determining the pre-magnification factor (PMAG) for the desired field of view. Most image sensors have a length to width ratio of 4:3.7) Pre-magnification: It refers to the ratio of the field of view to the size of the image sensor, which is done by the lens.8) System Magnification: It refers to the ratio of the image on the display to the actual size of the object, that is, the magnification of the entire system. It can also be written as the product of pre-magnification and electronic magnification, which is the ratio of display size to image sensor size.9) Resolution: The distance between two points on an object that can be minimally distinguished, indicating the ability to distinguish details. 4.2 Calculation of Image/Video Data Volume Definition of picture resolution in different camera pixels (number of photosensitive elements of CCD/CMOS sensor):FCIF (Full Common Intermediate Format) Resolution: 352*288=100,000 pixels DCIF Resolution: 512*384=200,000 pixelsD1(4CIF) Resolution: 704*576=400,000 pixels720P Resolution: 1280*720=1 million pixels1080P Resolution: 1920*1080=2 million pixels Figure 6. Camera Pixel Art The computer's true color pixels are stored according to the RGB three-color principle, and each color of red, green and blue is 256 (2 to the 8th power, one byte length), so a pixel needs 3 bytes and 24 bits. Now that the calculation capacity is large, a 256 grayscale is added on the basis of RGB storage, so 4 bytes are needed, that is, 32 bits. In addition, such pixels are now also called true color.Bit rate refers to the number of bits transmitted per second. The unit is bps (bit Per second). The higher the bit rate, the larger the data transmitted. The bit rate indicates how many bits per second the encoded (compressed) audio and video data needs to be represented, and a bit is the smallest unit in binary, either 0 or The relationship between bit rate and audio and video compression is simply that the higher the bit rate, the better the quality of audio and video, but the larger the encoded file. If the bit rate is lower, the situation is just the opposite.DataRate refers to the data flow used by video files in unit time, also called bit rate, which is the most important part of picture quality control in video coding. Under the same resolution, the larger the code stream of the video file, the smaller the compression ratio and the higher the image quality.1) 720P single image data volume = 1280 × 720 × 24/8/1024 = 2700 KByte.2) The amount of data of the moving image3) H.264 compressed payload data volumeThe biggest advantage of H.264 is that it has a high data compression ratio. Under the same image quality, the compression ratio of H.264 is more than 2 times that of MPEG-2, and 1.5 to 2 times that of MPEG-4. For example, the original file is 88GB, 3.5GB after MPEG-2 compression, the compression ratio is 25:1, and the H.264 compression is 1.1GB, from 88GB to 1.1GB, the compression ratio of H.264 reaches 80:1. For example, in the video conference, the original code stream is encoded and compressed by adopting H.264.4) The amount of transmitted data compressed by H.264Adding network overhead, the amount of data transmitted = the amount of payload data * 1.3At 20%, the amount of data transmitted after compression = 1.6 * 1.3 = 2.08 Mbit/s5) Home monitoring storage capacityBandwidth Calculation:The required bandwidth of the CIF video format: 512Kbps (the bit rate of the video format) × 50 (the total number of cameras at the monitoring point)=25Mbps (downlink bandwidth). That is: the network downlink bandwidth required by the monitoring center using CIF video format is at least 25Mbps.The required bandwidth of the D1 video format: 1.5Mbps (bit rate of the video format) × 50 (the total number of cameras in the monitoring point) = 75Mbps (downlink bandwidth). That is: the network downlink required by the monitoring center using D1 video format bandwidth is at least 75Mbps.The required bandwidth of 720P (1 million pixels) video format: 2Mbps (bit rate of video format) × 50 (the sum of the total number of cameras at the monitoring point) = 100Mbps (downlink bandwidth). That is: adopting 720P video format monitoring, the network downlink bandwidth required by the center is at least 100Mbps.The required bandwidth of the 1080P (2 million pixel) video format: 4Mbps (bit rate of the video format) × 50 (the total number of cameras at the monitoring point) = 200Mbps (downlink bandwidth) That is: adopting 1080P video format monitoring, the network downlink bandwidth required by the center is at least 200Mbps. 4.3 Storage Space Calculation Stream size (unit: KB/s; namely: bit rate ÷ 8) × 3600 (unit: second; seconds in 1 hour) × 24 (unit: hour; length of one day) × 30 (days saved) × 50 (the total number of camera recordings to be saved at the monitoring point) ÷ 0.9 (10% space loss from disk formatting) = the size of the required storage space (Note: unit conversion 1TB=1024GB, 1GB=1024MB, 1MB=1024KB)The required storage space for 50 channels to store 30 days of CIF video format video information is: 64 × 3600 × 24 × 30 × 50 ÷ 0.9=8789.1GB ≈ 9TBThe required storage space for 50 channels to store 30 days of D1 video format video information is: 192 × 3600 × 24 × 30 × 50 ÷ 0.9=26367.2GB ≈ 26TBThe required storage space for 50 channels of 720P (1 million pixels) video format recording information for 30 days is: 256 × 3600 × 24 × 30 × 50 ÷ 0.9=34.33GB ≈ 35TBThe required storage space for 50 channels of 1080P (2 million pixels) video format video recording information that can be stored for 30 days is: 512 × 3600 × 24 × 30 × 50 ÷ 0.9=68.66GB ≈ 69TB 4.4 Camera Composition and Principle The working principle of the camera is to project the optical signal obtained by the optical component onto the image sensor, complete the conversion from the optical signal to the electrical signal, and then convert it into a digital image signal, and finally perform the algorithm processing of the signal. The main components of the camera are optical components lens, CMOS sensor, DSP, module assembly and other components. 4.5 Intelligent Camera Image Processing Hardware Image processing capability: FPGA<DSP<High-end CPUASICs are ideal for performance and power consumption. Develop a dedicated SoC (system on chip) for a given application, implement a custom architecture to accommodate data flow, and optimize power consumption. However, the development cost is high and it is suitable for consumer products (i.e. production volumes of thousands of units). ASIC devices have very little or zero flexibility and programmability due to their specificity.FPGAs are the best choice for low- or medium-volume high-performance applications. They are very flexible and can meet the requirements of almost any application. Due to the ever-increasing number of available logic elements per device in FPGAs, increasing clock frequencies, and the possibility to exploit massive parallelism, it is possible to achieve processing performance close to ASICs, with the advantage of being fully reconfigurable. However, the power consumption of FPGAs is relatively high, and even if design methodologies and development environments exist, FPGA-based solutions require more development time and expertise than CPU-based solutions (DSP, microcontroller, etc.).DSP devices and media processors share many characteristics with embedded general-purpose RISC processors (PowerPC, ARM, etc.) and microcontrollers. All these devices are CPU based, i.e. based on processor cores. Therefore, they all have excellent programmability, using programming tools such as C/C++ and dedicated development environments. NRE (non-recurring engineering) is very low cost and has good flexibility, so it is suitable for most applications.The main difference between CPU-based devices comes at the performance level. A microcontroller can be seen as an enhanced RISC processor by adding CPU core memory (RAM, ROM, Flash), peripherals and I/O interfaces (ADC, DAC, etc.). In addition, the DSP core provides a dedicated architecture and some specific hardware structures to optimize the execution of arithmetic operations, such as MAC (multiply-accumulate) and SIMD units. Finally, media processors are a class of DSP devices dedicated to audio and video processing, suitable for processing data streams. DSPs and media processors may have a VLIW (Very Long Instruction Word) architecture, such as NXP TriMedia processors. Figure 7. Camera Color Coding Ⅴ Smart Camera Interfaces and Communication Protocols Wired Interface and Wireless Interface Table 1. Most Common Wired Communication Protocols Protocol Theoretical Bandwidth in bits per second (bit/s) RS-232 serial link USB 1.x Full-speed USB 2.0 Hi-speed FireWire or IEEE 1394a/b Camera Link Ethernet, Fast Ethernet GigE Vision (Gigabit Ethernet) 19,200 bit/s 12 Mbit/s 480 Mbit/s 400/800 Mbit/s 2.04, 4.08, or 5.44 Gbits 10/100 Mbit/s 1 Gbit/s   Table 2. Most Common Wireless Protocols Protocol Theoretical Bandwidth (bit/s) Wireless Range (m) WiFi IEEE 802.11a WiFi IEEE 802.11b WiFi IEEE 802.11g Bluetooth ZigBee (IEEE 802.15.4) 54 Mbit/s 11 Mbit/s 54 Mbit/s 1 Mbit/s 250 Kbit/s Up to 10m ~50m indoor, ~200m outdoor ~27m indoor, ~75m outdoor ~10-100m ~10-100m indoor, up to 150m outdoor For example, if the camera is equipped with the MT9M413 image sensor from Aptina Imaging (formerly Micron Imaging), capable of delivering images up to 660M pixels/s, a camera interface is required to take full advantage of the sensor (5.44 Gbit/s (680 M Bytes/s in full configuration) ). However, if there are other constraints, the rules of keeping data rates compatible between sensors and communication interfaces may be broken. For example, with a battery-operated smart camera, even real-time video transmission with a bandwidth of 250 Kbit/s makes no sense. There are two workarounds:1) Wireless ZigBee protocol, because its power consumption is very low.2) Another solution to reduce bandwidth requirements is an image compression algorithm. However, compressing and decompressing images places additional processing burden on the camera and host, and can result in loss of picture quality, depending on the desired compression ratio.And bandwidth isn't the only deciding factor. For example, GigE Vision systems are inexpensive to implement, but the end result can hinder application responsiveness and development time. GigE Vision is still in its infancy, while Camera Link and IEEE 1394 have proven. The integrity of the standard must also be considered. GigE Vision and IEEE 1394 cameras are compatible between vendors and are easier to configure than Camera Link.   Ⅵ Image Signal Processor (ISP) It is widely used in mobile phone cameras and car cameras and other fields, and is the core chip of image signal processor.ISP pipeline process: The light passes through the lens, after lens correction and color correction, is projected onto the sensor, photoelectrically converted into an analog electrical signal, and then converted into a digital signal by A/D, and then handed over to the ISP chip for processing. Then, the obtained image of the bayer pattern goes through BLC (black level compensation), lens shading (lens shading correction), BPC (bad pixel correction), CIP (demosaic), DNS (denoise), AWB (automatic white balance), color correction gamma correction, color space conversion (RGB conversion YUV), and then output data in YUV (or RGB) format, and finally transmitted to the CPU for processing through the I/O interface.The functions of each module are briefly described as follows:1) Bayer PatternThe filters that cover the surface of the image sensor are usually called Color Filter Arrays (CFA). At present, the most commonly used filter array is in checkerboard format, and the primary color Bayer Pattern CFA RGB represents the filter array unit of red, green and blue. Since human vision is most sensitive to green, the G component in Bayer CFA is twice that of R and B, and only one color component information can be obtained on each pixel, and then an interpolation algorithm is passed according to the color component information, finally get a full color image.2) Black Level Correction (BLC)Physical devices cannot be ideal. Due to impurities, heat and other reasons, even if no light is irradiated to the pixel, the pixel unit will generate charges, and these charges generate dark current. Moreover, dark current is difficult to distinguish from the charge generated by light. Black Level is used to define the signal level corresponding to 0 for image data. An effective way to reduce the influence of dark current on the image signal is to subtract the reference dark current signal from the obtained image signal. Generally, in the sensor, the first few lines of the pixel area are used as the non-photosensitive area. This part of the area is also used for RGB color filter. The average value is used as the correction value for automatic black level correction, and then the pixels in the following area are subtracted from this. Pay attention to, the brightness of the picture is reduced after black level correction.3) Lens Shading Correction (LSC)Due to the physical properties of the lens itself, the brightness around the image gradually decreases relative to the center brightness. When the image light shines on the pixel through the lens, the focus angle at the corners is greater than the center focus angle, resulting in loss of light at the corners. In order to compensate for the surrounding brightness, Lens Shading correction is necessary. The method is to calculate the brightness correction value corresponding to each pixel according to the algorithm, so as to compensate the brightness of the surrounding attenuation.4) Bad Pixel Correction (BPC)Under normal circumstances, the RGB signal should have a linear response relationship with the brightness of the scene. However, due to the bad pixels of senor, the output signal is abnormal, and there are dead spots: white spots in the output image in a dark environment, and black spots in the output image in a bright environment. There are usually two methods of repairing dead pixels: one is to automatically detect and repair the dead pixels, and the other is to establish a linked list of dead pixels to repair bad pixels at fixed positions. This method is the OTP method. 5) DNSUsing CMOS sensor to acquire images, light level and sensor issues are the main factors that generate a lot of noise in the image. At the same time, when the signal passes through the ADC, some other noise is introduced. These noises will blur the image as a whole and lose a lot of details, so the image needs to be denoised. The traditional methods of spatial denoising include mean filtering, Gaussian filtering and so on. However, the general Gaussian filter mainly considers the spatial distance relationship between pixels when sampling, and does not consider the similarity between pixel values, so the blurring result obtained in this way is usually a blur of the entire picture. Therefore, a nonlinear denoising algorithm, such as bilateral filter, is generally used, which not only considers the relationship between pixels in spatial distance, but also considers the similarity between pixels, so that the general segmentation of the original image can be maintained to keep the edge. In practical applications, wavelet denoising is more suitable, and each segment in the entire pipeline will be more or less applied to DNS, which is particularly important in the entire process of ISP, and exists in almost every part of it.6) Color InterpolationWhen the light passes through the Bayer-type CFA array, the light hits the sensor, and the BGR data is obtained respectively. Here, the data sampling ratio of BGR is 1:2:1, because the human eye is more sensitive to green light (550nm). Among them, G is also called luminance information, and BR is chrominance information. It can be seen that in the above Bayer diagram, each pixel has only one of the BGR data, so it is necessary to use CIP interpolation to supplement the color information of the other two channels to form a normal full-color image.7) Automatic White Balance (AWB) The basic principle of automatic white balance is to restore white objects to white objects in any environment, that is, by finding white blocks in the image, and then adjusting the ratio of R/G/B.The AWB algorithm usually steps as follows:Color temperature statistics, according to the image statistics color temperature.Calculate channel gain: Calculate the gain of R and B channels.Correction of color cast: Calculate the correction of color cast according to the given gain. Grayscale world method and perfect reflection method are more commonly used and effective.8) Gamma CorrectionThe sensitivity value of the human eye to the external light source is not linearly related to the input light intensity, but is exponentially related. Under low illumination, it is easier for the human eye to distinguish the change of brightness. With the increase of illumination, it is difficult for the human eye to distinguish the change of brightness. However, there is a linear relationship between the light sensitivity of the camera and the input light intensity. In order to help the human eye to recognize the image, the image collected by the camera needs to have Gamma correction. It is a nonlinear operation on the gray value of the input image, so that the gray value of the output image has an exponential relationship with the gray value of the input image.9) Color CorrectionDue to the difference between the spectral responsivity of the visible light of the human eye and the spectral responsivity of the semiconductor sensor, as well as the influence of lenses, etc., the color of the obtained RGB value will be biased, so the color must be corrected. The usual method is to pass a 3x3 Color change matrix for color correction.10) RGB Conversion YUV Color Space ConversionYUV is a basic color space, and the human eye is much more sensitive to changes in brightness than changes in color. Therefore, for the human eye, the brightness component Y is much more important than the chrominance components U and V. Therefore, some U and V components can be appropriately discarded to achieve the purpose of compressing data.Laplacian operator: YCbCr is actually a scaled and offset modified version of YUV, Y represents the brightness, Cr and Cb represent the color difference, which are the red and blue components respectively. In the YUV family, YCbCr is the most widely used member in computer systems, and its application fields are very wide. For example, JPEG and MPEG both use this format. Generally speaking, YUV mostly refers to YCbCr.The color space conversion module converts RGB to YUV444, and then performs subsequent color noise removal, edge enhancement, etc. on the YUV color space, which also provides convenience for subsequent output conversion to JPEG images.   Ⅶ FAQ 1. Does photomultiplier tube PMT scan images?Photomultiplier tubes (PMTs), also known as photomultipliers, are remarkable devices. While a PMT was the first device to detect light at the single-photon level, invented more than 80 years ago, they are widely used to this day, particularly in biological and medical applications. 2. Why are photomultiplier tubes so sensitive?Photomultipliers (sometimes called photon multipliers) are a type of photoemissive detectors which have a very high sensitivity due to an avalanche multiplication process, and also exhibit a high detection bandwidth. 3. What does CCD stand for in cameras?CCD stands for "charge coupled device", a semiconductor image sensor used in digital cameras to convert light into electrical signals. In place of the film used in conventional film cameras, digital cameras incorporate an electronic component known as an image sensor. 4. What are CCD sensors used for?CCDs are used in optical microscopes because they can possess over 10 million pixels, which enables many samples to be seen clearly, as well as a low noise ratio, ability to image in color, high sensitivity and a high spatial resolution which all contribute to the high-quality images that are necessary for modern-day. 5. What is good camera pixels?A decent 6-megapixel camera is good enough for most normal camera usage. Go for higher megapixels only if you wish to use your images for canvas-sized prints or large hoardings. If your interest is in night sky photography, then too a higher megapixel camera can be important. 6. What is resolution in camera settings?A picture's resolution describes how many pixels, or dots, are in the image. The more dots, the better the image looks and prints. Megapixel is a measurement of the amount of information stored in an image. 7. What is a good camera resolution?A Camera Resolution Reference Chart Resolution Avg. Quality Best Quality 0.5 megapixels 2x3 in. NA 3 megapixels 5x7 in. 4x6 in. 5 megapixels 6x8 in. 5x7 in. 8 megapixels 8x10 in. 6x8 in. 8. What is H264 format?H. 264 is a well-known video compression standard for high-definition digital video. Also known as MPEG-4 Part 10 or Advanced Video Coding (MPEG-4 AVC), H. 264 is defined as a block-oriented, compensation-based video compression standard that defines multiple profiles (tools) and levels (max bitrates and resolutions). 9. Which is better H 264 or H 265?265 codec compresses information more efficiently than H. 264, resulting in files of comparable video quality that are about half the size. The benefits of this are twofold: H. 265 video files don't take up as much storage space, and they require less bandwidth to stream. 10. What is a camera chip?Able to leap photographic obstacles with a single computer chip. It's a camera. It's a chip. It's a camera-on-a-chip. ... Most of today's digital cameras use charge-coupled device (CCD) sensors rather than the far less expensive complementary metal-oxide semiconductor (CMOS) chips used in most computing technologies. 11. Is CCD better than CMOS?For many years, the charge-coupled device (CCD) has been the best imaging sensor scientists could choose for their microscopes. ... CMOS sensors are faster than their CCD counterparts, which allows for higher video frame rates. CMOS imagers provide higher dynamic range and require less current and voltage to operate. 12. What is camera image sensor?The image sensor of the camera is responsible for converting the light and color spectrum into electrical signals for the camera to convert into zeroes and ones. All commercially available digital cameras (still, movie, or security) use one of two possible technologies for the camera's image sensor: CCD or CMOS. 13. How do photomultiplier tubes detect light?The reflection mode photocathode is mainly used for the side-on photomultiplier tubes which receive light through the side of the glass bulb, while the transmission mode photocathode is used for the head-on photomultiplier tubes which detect the input light through the end of a cylindrical bulb. 14. Which interface is used for camera?The most common USB 3.1 connector used in the machine vision camera industry is the USB 3.1 Micro B connector. Gradually being introduced to the market is USB-C (USB Type C), the connection type designed for the future. 15. Which of the serial communication standard is used in digital camera?Camera LinkCamera Link is a serial communication protocol standard designed for camera interface applications based on the National Semiconductor interface Channel-link. It was designed for the purpose of standardizing scientific and industrial video products including cameras, cables and frame grabbers. 16. What does image signal processor do?As the name implies, the Image Signal Processor (ISP) is used for processing images in embedded vision camera systems. The ISP also performs other operations on the captured image such as demosaicing, denoising, and auto functions that help deliver an enhanced image. 17. What is image and signal processing?The field of signal and image processing encompasses the theory and practice of algorithms and hardware that convert signals produced by artificial or natural means into a form useful for a specific purpose. ... Image processing work is in restoration, compression, quality evaluation, computer vision, and medical imaging. 18. Where are DSP processors used?DSP is used primarily in areas of the audio signal, speech processing, RADAR, seismology, audio, SONAR, voice recognition, and some financial signals. For example, Digital Signal Processing is used for speech compression for mobile phones, as well as speech transmission for mobile phones. 19. What is RGB conversion?RGB to hex conversionConvert the red, green and blue color values from decimal to hex. Concatenate the 3 hex values of the red, green and blue togather: RRGGBB. 20. What is AWB setting?One of the white balance settings, "Auto White Balance" (AWB) automatically adjusts to correct the changes in color under different light sources. The function adjusting the color tone so that white objects look white in the picture is called white balance (WB).

Introduction RF power amplifier is an important part of various wireless transmitters. In the front-end circuit of the transmitter, the power of the RF signal generated by the modulation oscillator circuit is very small, and it needs to go through a series of amplification-buffer stage, intermediate amplification stage, and final power amplification stage to obtain enough RF power before feeding. In order to obtain a sufficiently large RF output power, a RF power amplifier must be used. RF Power Amplifier Design: The Basics Catalog Introduction Ⅰ Requirements of RF Power Amplifier Ⅱ Types of Power Amplifier in Use Ⅲ Parameters of RF Power Amplifier Design Ⅳ Key Feature: Non-Linearity 4.1 Nonlinear Characteristics 4.2 Influence of Nonlinear Characteristics Ⅴ FAQ Ⅰ Requirements of RF Power Amplifier With the vigorous development of modern digital mobile communication technology, users have more requirements on the performance of wireless communication equipment. To achieve stable and high-speed data transmission in various environments is one of the main goals of future mobile communication system researchers. The RF power amplifier is the last stage of the transmitter. It amplifies the modulated frequency band signal to the required power, ensuring that the receiver in the coverage area can receive a satisfactory signal level, but it cannot interfere too much with the communication of adjacent channels, and meanwhile try to keep the amplified high-power signal without distortion. The requirements of these different aspects make the users of power amplifiers have to consider many factors in all aspects. So you should get a full knowledge of RF power amplifiers. Figure 1. Classic RF Power Amplifier Circuit Ⅱ Types of Power Amplifier in Use What are the main types of RF amplifiers for such an important device?1) According to the operating frequency bandsAccording to the working frequency band, it can be divided into narrowband RF power amplifier and broadband RF power amplifier. The former generally uses frequency selective networks as load circuits, such as LC resonant circuits. The latter does not use the frequency selection network as the load loop, but employs the transmission line with a wide frequency response as the load.2) According to the network propertiesAccording to the nature of the matching network, power amplifiers can be divided into non-resonant power amplifiers and resonant power amplifiers. The matching network of the non-resonant power amplifier is a non-resonant system, such as high-frequency transformers, transmission line transformers and other non-resonant systems, and its load properties are purely resistive, where this is also called reactance properties.3) According to current conduction angleBased on it, RF power amplifiers can be divided into class A, AB, B, C, D, E and so on. The differences between these categories can be seen in the following table: Classification Conduction Angle Efficiency Linearity Application Class A Θ=360° ≤30% Very good Small Signal Low Power Amplification Class B Θ=180° ≤60% Lower than class A For High Power Class C Θ<180° About 60% Nonlinear amplifier For High Power Class AB 180°<Θ<360° 30%~60% Better than class B Small signal works in class A, large signal works in class B Class D Work in switch mode 80% Very good, only good for low frequencies Switch mode amplifier Class E Work in switch mode 90% Completely nonlinear amp Switch mode amplifier In the classification of amplifiers, we often talk about amplifiers of class A to E according to the conduction angle. Class A power amplifier is a linear amplifier, its response to the sine-wave  input is a sine-wave output, generally without distortion amplification, and the output frequency is the same as the input frequency. Since class A amplifiers do not require additional filtering circuitry, their packages can be small and cost less. The output of a class B amplifier is a half sine wave of the input, resulting in half-wave distortion, which produces many harmonics. The output power and efficiency of the class C working state are the highest among these working states, and most of the amplifiers used for radio frequency work in the class C. Figure 2. Class A Amplifier Load Curve   Ⅲ Parameters of RF Power Amplifier Design RF power amplifiers are electronic circuits that comprehensively consider issues such as output power, excitation level, power consumption, distortion, efficiency, size and weight. In the transmitting system, the output power of the RF power amplifier can be as small as mW and as large as several kW, but this refers to the output power of the final power amplifier. In order to achieve high power output, the last stage must have a sufficiently high excitation power level. At the same time, it has other important indicators, as follows:1) Operating FrequencyGenerally speaking, it refers to the linear operating frequency range of the amplifier. If the frequency starts at DC, the amplifier is considered to be a DC amplifier.2) GainThe working gain is the main indicator to measure the amplification ability of the amplifier. Here it is defined as the ratio of the power delivered to the load by the amplifier output port to the power actually delivered by the signal source to the amplifier input port.Gain flatness refers to the variation range of amplifier gain in the entire operating frequency band under a certain temperature, and is also a main indicator of the amplifier. Figure 3. Output Power and 1dB Compression Point (P1dB) Referring to the Figure 3, when the input power exceeds a certain amount, the gain of the transistor begins to decrease, and the end result is that the output power saturates. When the gain of the amplifier deviates from a constant or is 1dB lower than other small signal gains, this point is the famous 1dB compression point (P1dB). Generally speaking, the power capacity of an amplifier is expressed by the 1dB compression point.3) EfficientSince the power amplifier is a power component, it needs to consume the supply current. Therefore, the efficiency of the power amplifier is extremely important to the efficiency of the whole system. Power efficiency is the ratio of the RF output power of the amplifier to the DC power supplied to the transistors.ηp=RF Output Power/DC Input Power4) Intermodulation Distortion (IMD)Intermodulation distortion refers to the mixed components of two or more input signals with different frequencies passing through a power amplifier. This is due to the nonlinear nature of the amplifier. Among them, because the third-order intermodulation product is very close to the fundamental signal, it has the greatest influence, so the third-order intermodulation is the most important consideration for the related products. The lower the third-order intermodulation product, the better.5) Third-order Intermodulation Cut-off Point (IP3)The intersection point of the extension line of the fundamental wave signal output power and the extension line of the third-order intermodulation in Fig is called the third-order intermodulation cut-off point, which is represented by the symbol IP3. It is also an important indicator of nonlinearity. When the output power is constant, the greater the output power of the third-order intermodulation cut-off point, the better the linearity of the power amplifier.6) Dynamic RangeThe dynamic range of a power amplifier generally refers to the difference between the minimum detectable signal and the maximum input power in the linear operating region. Naturally, this value must be as large as possible.7) Harmonic DistortionWhen the input signal increases to a certain level, the power amplifier will generate a series of harmonics due to its work in the nonlinear region. For high-power amplifier systems, filters are generally required to reduce harmonics below 60dBc.8) Input/Output VSWR (Voltage Standing Wave Ratio)This is also a very important indicator of how well the amplifier matches the overall system. The deterioration of the input-output ratio will lead to the deterioration of the gain fluctuation and group delay of the system. However, it is difficult to design a power amplifier with a high VSWR. In general systems, the input VSWR of the power amplifier is required to be lower than 2:1.The main technical indicators of RF power amplifiers are output power and efficiency. Therefore how to improve them is the core of the design goals of RF power amplifiers. Usually in the RF power amplifier, the fundamental frequency or a certain harmonic can be selected by the LC resonant circuit to achieve distortion-free amplification. In addition to this, the harmonic components in the output should be as small as possible to avoid interference with other channels. Figure 4. Increase the Power of the RF Input Signal Ⅳ Key Feature: Non-Linearity In an ideal amplifier, the output signal should faithfully reflect the input signal, that is, the waveform should be the same. But in fact, for many reasons, the input signal cannot be exactly the same waveform as the input signal, which is called amplifier distortion.Amplifier distortion mainly includes frequency distortion (linear distortion) and waveform distortion (non-linear distortion). The former mainly refers to the difference in gain and delay of the amplifier for different frequency components; the latter refers to the same frequency, the output signal and the input signal are not linear. Frequency distortion is represented by spectral changes in the frequency domain, while nonlinear distortion is represented by changes in the time-domain waveform. Non-linear distortion is different from frequency distortion mainly because a large number of new frequency components are generated. The nonlinear distortion of the power amplifier is mainly discussed here. 4.1 Nonlinear Characteristics From the small-signal model and input characteristic curve of an ideal transistor, it can be seen that the transistor amplifier itself is not an ideal linear device, and at the same time, due to the influence of parasitic parameters, the linearity is further reduced. But within a certain power range, the transistor can be regarded as linear amplification. For power amplifier designers, how to obtain higher output power and improve linearity is the key.For a transistor amplifier, its volt-ampere characteristics can be described as follows: A power series expansion can be used to describe the volt-ampere characteristics of the device: In the formula, an(n=0,1,2,3,…) is a coefficient related to the circuit characteristics. Usually, the larger the n, the smaller the value of the coefficient an. When the nonlinear device in the circuit is represented by a power series, the number of series terms taken depends entirely on the magnitude of the signal amplitude and the required precision. 4.2 Influence of Nonlinear Characteristics The influence of the nonlinear characteristics of the device on the amplifier can be discussed in two cases. One is when there is only one signal at the input end, and the other is when the input end has one to two other signals in addition to the useful signal.🔺Only one signal at the inputLet the signal at the input end be , and substitute it into formula 2, at this time there is When the amplitude of the input signal is large and the effect of the cubic term must be considered, the fundamental frequency signal obtained from formula 2 is: Figure 5. 1dB Compression Point (PA) A3 in formula 3 is usually a negative value, that is, y1(t) decreases as the input signal amplitude increases, a phenomenon called gain compression.The "1dB compression point" is often used in engineering to measure the linear performance of the device. The 1dB compression point is defined as the input signal power P1dB that reduces the gain by 1dB from the linear gain. As shown in Figure 5. According to the definition of 1dB compression point and formula 3, we can get 🔺Two signals at the input.The signal amplified at the input end of the amplifier is generally not a single tone signal, but a spectral signal composed of a certain bandwidth. Due to the nonlinearity of the device, a large number of combined interference frequency components other than the useful signal will be generated at the output end. In addition, the combined frequency components of two or more interfering signals may also cause interference to the useful signal. Have an assumption: Substitute into formula 1, where It can be seen from the above formula that the fundamental frequency components of ω1 and ω2 are generated by the first and third power terms: A total of multiple frequency components are generated: ω1 , ω2 , ω1 ± ω2, 2ω1 - ω2, 2ω2 - ω1 , 3ω1 - 2ω2, 3ω2 - 2ω1.The difference frequency 2ω1 - ω2, 2ω2 - ω1 in the combined frequency is generated by the cubic term. The combination of these two signal frequencies is just within the sideband range of the signal frequency, which may cause interference to adjacent channels, and is one of the main indicators of transmission signal. Figure 6. Intermodulation Signal Interference This interference is caused by the mutual modulation of the two signals, so it is called intermodulation interference. At the same time, it is generated by a cubic term, so it is also called third-order intermodulation interference in engineering.When the third-order intermodulation interference is an important indicator of the communication machine, it is often measured by the intermodulation distortion ratio IMR and the third-order intermodulation blocking point IP3 in engineering. IMR is defined as the ratio of the amplitude of the third-order intermodulation product to the amplitude of the fundamental signal at a certain input amplitude. Definition of IP3: When the third-order intermodulation component increases to be equal to the fundamental frequency component, the receiver cannot receive normally, so there is a . Figure 7. Third-order Intermodulation Blocking Point 🔺Sideband Signals Figure 8. Sideband Signals and the Spectrum In fact, most of the sideband signals are generated outside the bandwidth after the useful signals of different frequencies within the bandwidth are modulated with each other. That is, the sideband signal rises faster than the in-band signal, and the spectral mask in the above figure becomes more and more flat. The increase of sideband signals will cause interference to adjacent channels, so the IEEE 802.11 protocol has strict requirements on the spectrum template, as shown in the Figure 9. Figure 9. DSSS Signal Modulation Spectral Mask Figure 10. OFDM 20MHz Bandwidth Signal Spectral Mask For the power amplifier, its nonlinear characteristics will increase the sideband of the modulated signal, and the sideband amplitude is not easily suppressed by other networks such as filters, and it is easy to cause design difficulties. Therefore, when choosing a PA, not only should pay attention to the maximum linear output that it can achieve, but also whether it can meet the sideband spectrum requirements at this output power.🔺Other Effects of NonlinearityIn addition to the previously mentioned gain drop, which generates a large number of harmonic components, as well as third-order intermodulation and sidebands, nonlinearity can also cause signal and EVM to deteriorate, etc.   Ⅴ FAQ 1. What is RF power amplifier?A radio frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency signal into a higher power signal. 2. How does RF power amplifier work?An RF amplifier is actually a tuned amplifier that enables the input signal of broadcast or transmitted information to control an output signal. The RF amplifier uses frequency-determining networks to convert the input signal into an output signal that will provide the required response at a given frequency. 3. What is the most efficient class of RF power amplifier?Class C AmplifierThe Class C Amplifier design has the greatest efficiency but the poorest linearity of the classes of amplifiers mentioned here. The previous classes, A, B and AB are considered linear amplifiers, as the output signals amplitude and phase are linearly related to the input signals amplitude and phase. 4. How do I choose an RF power amplifier?Considerations When Choosing An RF Power Amplifier:Gain.Operating Frequency.Output Power Level.Efficiency.Linearity.Mismatch Tolerance.Noise Level. 5. What are the advantages of RF amplifier?Following are the RF Amplifier advantages:The RF amplifier offers greater gain i.e. better sensitivity. It offers better selectivity and hence it has ability to select wanted signals from multiple input signals at the RF receiver. 6. What are the different types of RF amplifiers?Amplifier TypesBroadband AmplifiersGain Block AmplifiersLog AmplifiersVariable Gain AmplifiersLow Noise AmplifiersCoaxial and Waveguide Power AmplifiersLinear AmplifiersBi-Directional Amplifiers 7. What is RF amplifier circuit?A radio frequency power amplifier (RF power amplifier) is a type of electronic circuit that converts a low-power radio-frequency signal into a higher power signal. 8. Is Class D amplifier better than a class AB?The most common audio power amplifier operates in the Class-AB mode. It provides the greatest amount of output power with the least amount of distortion. ... Class-D amplifiers are switches that are more efficient and produce less heat than their Class-AB equivalents. 9. What are RF amplifiers used for?Whenever people need to magnify a radio frequency signal into a higher power signal, the RF amplifier plays a pivotal role. They are used in commercial and defense avionics, space and deep space, electronic warfare, naval applications, mobile internet, satellite communication, and wireless communications. 10. Which amplifier is used in RF amplifier?RF power amplifiers using LDMOS (laterally diffused MOSFET) are the most widely used power semiconductor devices in wireless telecommunication networks, particularly mobile networks. LDMOS-based RF power amplifiers are widely used in digital mobile networks such as 2G, 3G, and 4G.

SummaryUnderstanding the 5-pin relay is essential for modern automotive electrical work, from restoring classics to upgrading 2026 electric vehicle accessories. This guide covers the fundamentals of SPDT relays, detailed wiring instructions for positive and negative triggers, differentiation between relay types, and comprehensive troubleshooting using a digital multimeter.IntroductionManufactured in Europe to exacting original equipment standards under ISO9001 supervision, modern 5-pin relays are designed for resilience. These components feature silver contacts for long-lasting performance and typically include a removable metal mounting tab for versatile installation.As of 2026, high-quality automotive relays maintain a 500,000+ cycle rating and often include a braided power strap for increased reliability under thermal stress. They are available in various amp ratings (commonly 30A, 40A, or high-current 60A) in 12V, 24V, and occasionally 48V configurations for mild-hybrid systems. Most now include resistor or diode-style circuit protection to prevent voltage spikes from damaging sensitive onboard computers (ECUs).Figure 1: Standard automotive 5-pin relayⅠ What are 5 Pin Relays Used for?A relay with five pins typically utilizes two pins to operate the electromagnetic coil and three pins to function as an SPDT (Single Pole Double Throw) switch. This configuration includes:Common Contact (30): The main power source.Normally Open (NO) Contact (87): Connected only when energized.Normally Closed (NC) Contact (87a): Connected when unenergized.This setup is technically referred to as a Form C contact.While SPST NO (Single Pole Single Throw, Normally Open) relays are common for simple on/off tasks, the SPDT 5-pin relay allows for complex switching. It can toggle power between two circuits (e.g., switching between Daytime Running Lights and High Beams) or create a disabling circuit (e.g., a starter kill switch).In 2026, complex multi-pole relays like 2PDT and 4PDT are still used in industrial applications, but the 5-pin SPDT remains the workhorse of the automotive aftermarket.1.1 Why Do You Need a Relay?Relays are crucial in the automotive industry to separate high-amperage circuits from low-amperage controls. They allow you to use a delicate, low-current switch (or a signal from a Body Control Module) inside the cockpit to control a high-power device like a fuel pump, cooling fan, or light bar located elsewhere.Key Benefits:Voltage Drop Reduction: By keeping high-current wires short (battery to relay to component), you minimize voltage loss.Safety: If a 30A circuit were wired directly through a dashboard switch, the heat generated could melt the switch or cause a fire. A relay allows a tiny 5 amp signal to safely control that 30 amp load.The device depicted above is an electromagnetic attraction type relay. When the coil is energized, it generates a magnetic field that attracts a movable armature, physically closing or opening the contacts.Ⅱ How to Wire a 5 Pin RelayThe standard Bosch-style 5-pin relay uses an SPDT configuration. Here is the universal pinout logic:Pins 85 and 86: The Control Circuit (Coil). Sending power and ground to these creates the magnetic field.Pin 30: Common Power (Input). Usually connected to the battery via a fuse.Pin 87a: Normally Closed (Output). Has power when the relay is OFF.Pin 87: Normally Open (Output). Has power when the relay is ON.Typical Horn Circuit Example:Pin 30 connects to the battery (+) via a fuse. Pin 87 connects to the horn (Load). Pin 86 connects to 12V (+), and Pin 85 connects to the horn button (which grounds the circuit when pressed). When you press the horn, the coil activates, bridging Pin 30 to Pin 87, and the horn sounds.Note: In modern automotive design, it is standard practice to place the switch on the "ground" side (Pin 85) rather than the 12V side to reduce the risk of short circuits in the dashboard.2.1 5 Pin Relay DiagramThis diagram is versatile and applies to various 2026 applications, including:Reverse Camera Triggers: Activating a camera screen only when the reverse lights engage.Amplifier Turn-Ons: Using a remote output wire to power high-wattage audio equipment.High-Draw Accessories: Powering LED light bars, air compressors, or electric water pumps.2.2 How to Wire a 5 Pin Relay with a Positive TriggerIn a positive trigger system, the switch sends 12V (+) to the relay to activate it.Pin 30: High current 12V (+) input from battery (Fused).Pin 86: Signal wire from your dash switch (sends 12V when ON).Pin 85: Connected to Chassis Ground (-).Pin 87: Output to accessory (Lights/Fan/Horn).Pin 87A: Unused (Insulate this terminal).2.3 How to Wire a 5 Pin Relay with a Negative TriggerIn a negative trigger system (common in Japanese vehicles and modern alarms), the relay has constant 12V, and the switch provides the Ground (-).Pin 30: High current 12V (+) input from battery (Fused).Pin 86: Jumper wire from Pin 30 (or an ignition-switched 12V source).Pin 85: Connects to your switch (Switch then connects to Ground).Pin 87: Output to accessory.Pin 87A: Unused (Insulate this terminal).Note: With negative switching, you cannot easily use a standard lighted switch, as the switch lacks a direct 12V feed.Ⅲ Are all 5 Pin Relays the Same?No. While they may look identical externally, internal specifications vary significantly.The only guarantee is that they have 5 pins. Variations include:Coil Voltage: 12V is standard for cars, but 24V is used in heavy trucks, and 48V is emerging in hybrids. Plugging a 12V relay into a 24V system will instantly burn out the coil.Amperage Rating: Ranging from 20A to 80A. Using a 20A relay for a 40A fuel pump will fuse the contacts.Pin-out Configuration: While "Bosch Type" is standard, some manufacturers swap Pins 30 and 86. Always check the diagram printed on the relay case.Protection: Some relays contain internal flyback diodes or resistors to protect vehicle electronics. These are polarity-sensitive; wiring pins 85/86 backward on a diode-protected relay will cause a short circuit.Ⅳ How to Test a 5-pin Relay Using a Digital MultimeterBefore replacing components, it is vital to test the relay. A faulty relay is a common cause of electrical failure in aging vehicles. Here is the 2026 standard procedure for testing:4.1 Testing the Relay’s Coil (Pins 85 & 86)The coil should have specific resistance. Consult the manufacturer's datasheet (typically between 50Ω and 120Ω for 12V relays).Set your multimeter to the Ohms (Ω) setting (typically the 200Ω scale).Connect the probes to pins 85 and 86. Polarity does not matter for resistance testing.Result: If the meter reads within range (e.g., 75Ω), the coil is intact. If it reads "OL" (Open Loop) or infinite resistance, the coil wire is broken inside, and the relay must be replaced. If it reads 0Ω, the coil is shorted.4.2 Testing the Relay’s Terminals (Contacts)We must verify that the switching mechanism actually connects and disconnects as intended.4.3 Testing Normally Open Terminal (Pin 87)Set the multimeter to Ohms or Continuity mode.Connect probes to Pin 30 (Common) and Pin 87 (NO).Result: You should see "OL" or high resistance. This is correct because the relay is at rest (OFF). If you find continuity (near 0Ω) while the relay is on the bench, the contacts have welded together, and the relay is trash.4.4 Testing the Normally Closed Terminals (Pin 87a)Keep multimeter in Ohms/Continuity mode.Connect probes to Pin 30 and Pin 87a.Result: You should hear a beep or see near 0Ω resistance. This indicates the circuit is closed by default. If it reads "OL", the internal contact is damaged or corroded.4.5 Testing the Energized StateThis is the final verification.Use a 12V battery or bench power supply.Connect Positive to Pin 86 and Negative to Pin 85. You should hear a distinct "Click".While energized, measure resistance between Pin 30 and Pin 87.Result: It should now read 0Ω (Continuity). If it clicks but shows high resistance, the contacts are burnt (carbon buildup) and cannot carry high current.Pro Tip: Relays are generally non-serviceable. If any test fails, replace the unit. In an emergency, if Pin 87 is burnt but 87a works, you cannot swap them; you must replace the relay.Ⅴ FAQ1. What can perform the function of an SPST NC relay when actuated?An SPDT 5-pin relay can perform this function. By wiring your circuit to Pin 87a (Normally Closed), the device will turn OFF when you activate the switch, effectively acting as an NC relay.2. What is the blue wire on a 5 pin trailer plug?In trailer wiring, the blue wire in a 5-way flat connector usually controls the hydraulic lockout solenoid for surge brakes. When you put the vehicle in reverse, this wire energizes to disengage the trailer brakes, allowing you to back up without the brakes locking up. It can also power reverse lights on the trailer.3. Why does my trailer have 5 wires?A 5-wire harness connects the standard lighting (Left Turn, Right Turn, Running Lights, Ground) plus a fifth line, typically for reverse lights or disabling surge brakes. This is an upgrade over the standard 4-pin setup commonly found on boat trailers.4. What is the difference between a 4-pin and 5 pin trailer plug?The 4-pin plug handles basic legal lighting (Brake/Turn/Tail). The 5-pin plug adds a fifth wire (usually blue) specifically for reverse operations (backup lights or brake lockout). Ensure your tow vehicle is wired to support this fifth pin if your trailer requires it.5. Can a 5 pin relay be used in place of a 4 pin?Yes. A 5-pin SPDT relay fits into a 4-pin SPST socket perfectly in most Bosch-style applications. The extra pin (87a) will simply slide into the empty slot in the socket (or hang in the air) and remain unused. The relay will function exactly like a 4-pin relay.{ "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What can perform the function of an SPST NC relay when actuated?", "acceptedAnswer": { "@type": "Answer", "text": "An SPDT 5-pin relay can perform this function. By wiring your circuit to Pin 87a (Normally Closed), the device will turn OFF when you activate the switch, effectively acting as an NC relay." } }, { "@type": "Question", "name": "What is the blue wire on a 5 pin trailer plug?", "acceptedAnswer": { "@type": "Answer", "text": "In trailer wiring, the blue wire in a 5-way flat connector usually controls the hydraulic lockout solenoid for surge brakes. When you put the vehicle in reverse, this wire energizes to disengage the trailer brakes, allowing you to back up without the brakes locking up. It can also power reverse lights on the trailer." } }, { "@type": "Question", "name": "Why does my trailer have 5 wires?", "acceptedAnswer": { "@type": "Answer", "text": "A 5-wire harness connects the standard lighting (Left Turn, Right Turn, Running Lights, Ground) plus a fifth line, typically for reverse lights or disabling surge brakes. This is an upgrade over the standard 4-pin setup commonly found on boat trailers." } }, { "@type": "Question", "name": "What is the difference between a 4-pin and 5 pin trailer plug?", "acceptedAnswer": { "@type": "Answer", "text": "The 4-pin plug handles basic legal lighting (Brake/Turn/Tail). The 5-pin plug adds a fifth wire (usually blue) specifically for reverse operations (backup lights or brake lockout). Ensure your tow vehicle is wired to support this fifth pin if your trailer requires it." } }, { "@type": "Question", "name": "Can a 5 pin relay be used in place of a 4 pin?", "acceptedAnswer": { "@type": "Answer", "text": "Yes. A 5-pin SPDT relay fits into a 4-pin SPST socket perfectly in most Bosch-style applications. The extra pin (87a) will simply slide into the empty slot in the socket (or hang in the air) and remain unused. The relay will function exactly like a 4-pin relay." } } ]}

CatalogIntroductionⅠ What is a Starter Relay?1.1 Definition of the Starter Relay1.2 Starter Relay Wiring DiagramⅡ What is a Starter Solenoid?2.1 Definition of the Starter Solenoid2.2 Starter Solenoid Wiring Diagram2.3 What Wires Go to the Starter SolenoidⅢ Starter Relay Vs. Starter Solenoid3.1 Is the Starter Relay the Same as starter solenoid?3.2 Starter Relay Vs. Starter Solenoid3.3 3 Differences Between Starter Solenoid Switch & Starter RelayⅣ FAQsIntroductionThe starter solenoid is sometimes referred to as the starter relay, but in many vehicles, that term refers to a separate relay that supplies power to the starter solenoid. They share some characteristics, such as the use of coil winding and electromagnetism in their operation. However, there are numerous differences between a starter solenoid switch and a starter relay.How to Test a Starter Relay on a Motorcycle, ATV, or UTV | How to Test a Starter SolenoidⅠ What is a Starter Relay?1.1 Definition of the Starter RelayA relay is a switch that is powered by electricity. It has a set of input terminals for single or multiple control signals, as well as a set of operating contact terminals. The switch may have an unlimited number of contacts in various contact forms, such as make contacts, break contacts or combinations of the two.1.2 Starter Relay Wiring DiagramStarter Relay Wiring Diagram Starter relays can vary in appearance depending on brand and vehicle type. They do, however, operate in the same manner and serve the same purpose. When you look inside these components, you will notice that they have the same parts. A starter relay is made up of housing, coil windings, a magnetic core, and an armature or plunger. When starting a vehicle, the internal construction forms an electromagnetic switch that a driver operates remotely.Ⅱ What is a Starter Solenoid?2.1 Definition of the Starter SolenoidA starter solenoid is an electromagnet that is actuated to engage an internal combustion engine's starter motor. It is typically connected directly to the starter motor that it controls. Its primary function is to act as the actuating coil of a contactor (a relay designed for high currents) that connects the battery to the starter motor itself. The starter solenoid is also used in all modern cars to engage the starter pinion with the engine's ring gear.2.2 Starter Solenoid Wiring DiagramA starter solenoid has three terminals, one small pin-type and two thicker bolt-type.The "S" terminal is a small pin-type terminal. The "S" terminal is connected to the ignition switch circuit. This is known as the starter solenoid control wire, and it connects the ignition wire to the starter solenoid. The current is routed from the ignition switch to the starter solenoid via the fuse, the neutral safety switch, the starter relay, and finally the starter solenoid.The input terminal on the starter solenoid allows positive power from the battery to enter the solenoid, and the output terminal connects to the starter motor assembly.When you turn the ignition switch key, current flows from the ignition switch to the starter fuse, then to the neutral safety or clutch pedal safety switch, then to the fusebox starter relay, and finally to the starter solenoid "S" terminal. The camshaft sensor sends information to the ECM or PCM. The ECM or PCM decides to activate the starter relay by sending a signal to it.When the starter relay is turned on, the current is sent to the solenoid pin-type "S" terminal. When the current reaches the "S" terminal, it pulls the plunger inside the solenoid, connecting the two thicker terminals, and the current begins to flow directly from the battery to the starter motor assembly.2.3 What Wires Go to the Starter SolenoidThe wiring diagram for the starter solenoid is no longer a mystery. It is extremely simple. If you're not sure which wires connect to the starter solenoid. Here is a quick example.The "S" terminal of the Pin-types is connected to the Ignition Switch.The Bolt-type Feed Terminal connects to the positive power source of the battery.The starter motor assembly is connected to the Bolt-type Output Terminal.Ⅲ Starter Relay Vs. Starter Solenoid3.1 Is the Starter Relay the Same as starter solenoid?The starter relay is frequently mixed up with the starter solenoid. This could be because both serve as relays. However, contrary to popular belief, the two names do not refer to the same vehicle component. One is just a switch, while the other is both a switch and an actuator. Here are some of the differences between these two auto parts.3.2 Starter Relay Vs. Starter SolenoidA starter relay is smaller in size than a heavy-duty starter solenoid. It consists essentially of a magnetic core surrounded by a wire. An armature or plunger at one end of the core closes contacts to operate a switch. It is spring-loaded, which aids in pushing it away from the contacts when the core loses magnetism. A starter solenoid is typically larger than a starter relay. The internal construction of the solenoid consists of two wire coils and a magnetic core at one end. With a return spring on one end, the core is free to move in and out. The other end contains the various connectors and is where the current enters the solenoid.The starter relay and starter solenoid function nearly identically. An electromagnetic field is created when a current flows through the coil winding. Magnetism moves an armature or plunger in a starter relay to close a circuit.The magnetic force created by current flowing through the coil in a starter solenoid causes the core to move out. The moving plunger accomplishes two tasks. It closes the contacts that activate the starter motor. It also shifts the pinion gear, which engages the flywheel.As we can see, a starter relay is nothing more than a switch. The starter solenoid, on the other hand, acts as an actuator by closing a circuit and moving gear. The starter relay is typically located a long distance away from the starter motor, whereas the majority of starter solenoids are attached to the motor housing.3.3 3 Differences Between Starter Solenoid Switch & Starter Relaya starter solenoid switch and a starter relay, which are vastly different in terms of construction, operation, and functionality.They share some characteristics, such as the use of coil winding and electromagnetism in their operation. However, there are numerous differences between a starter solenoid switch and a starter relay.Difference In ConstructionRelayStarter relay structureA starter relay is made up of a wire coil wound around a ferrous core and an armature attached to one end of the coil. The amateur is linked to a switch with two contacts made of the highly conducting material. A spring is located on the side. The spring regulates the armature and, as a result, the switch's closing and opening.Solenoid SwitchSolenoid Switch A starter solenoid, on the other hand, is a coil enclosing a movable plunger. Unlike the starter relay, which has an immovable coil core, the core of the starter solenoid is an iron or steel plunger that can move in and out of the coil. At one end, the steel plunger is connected to a spring. The coil, spring, and a portion of the plunger are all enclosed. The plunger's other end emerges from the casing to provide movement to an external connection. Difference In OperationRelayWhen the ignition circuit is activated, a small current flows from it, causing a much larger current to flow through the relay's coil. The electromagnetic force generated by the current in the coil magnetizes the core, causing it to pull the armature. When the armature is pulled, the contacts close, completing the intended circuit. As a result, the starter relay only serves as a switch.Solenoid SwitchAn electromagnetic force is created when current flows through the solenoid's coil winding. The force propels the movable steel core outward. This motion engages the pinion gear, which in turn engages the relevant gears on the flywheel.Difference In Function RelayThe starter relay acts as a switch. It relays the small current from the ignition circuit to cause a much larger current from the battery to operate the starter solenoid and motor. In this manner, the relay functions as a remote switch or as a link between the ignition key in the driver's seat and the starter system.Solenoid SwitchThe starter solenoid is responsible for connecting the starter motor to the flywheel. It accomplishes this by thrusting out the pinion and making contact with the flywheel, thereby starting the engine.As can be seen, a starter relay does not cause any mechanical movements. The only moving parts are the switch contacts as they close. It could be described as merely a switch in the overall ignition process.A starter solenoid generates mechanical movements that activate the starter motor and flywheel. It makes no difference. It only serves to connect the motor's moving parts and the engine flywheel.Ⅳ FAQs1. What can a Starter Relay have in various contact forms?Unlimited number of contacts.2. Can you use a starter solenoid as a relay?To operate the starting system in some automotive applications, the starter relay collaborates with the starter solenoid. In others, the ignition switch directly controls the starter solenoid circuit.3. Will a bad starter solenoid still click?You should hear a clicking sound when the starter motor solenoid engages. If you hear a clicking sound but the starter motor is not turning on, the solenoid may be engaged but not receive enough battery power. If there is no sound, the starter solenoid is most likely faulty, or you may have a dead car battery.4. What is the function of starter relay?A starter relay acts as an electrical circuit completer or circuit breaker between the vehicle's battery and the starter motor. It aids in increasing the current of the battery so that less current is required during ignition.5. Can a relay click and still be bad?If you hear or feel the relay click, the problem isn't with the relay or its wiring. If it doesn't click, the problem could be with the relay or the wiring. Unless the relay contains a diode, switching the polarity has no effect; the electromagnet will be energized regardless.6. How do I know if my starter fuse is blown?Your starter motor is on all the time. An illuminated ABS Light is one of the first signs of a blown fuse or relay. When you turn your car, a faulty relay frequently produces an audible clicking sound. A car that suddenly stalls while driving is one of the most common symptoms of a failed ignition relay.7. How to Bypass the Starter Solenoid？If you try to start your vehicle and all you hear is a clicking sound, the problem could be with the starter motor or solenoid. The clicking noise is caused by the starter solenoid attempting to force the starter gear to engage the engine. However, the solenoid may be too weak to force the gear into engagement, or the bearings within the starter motor may be frozen. You can bypass the starter solenoid to determine which component is faulty.8. How to tell if starter relay is bad？The vehicle is deadStarter making clicking soundsOccasional failures in starting the vehicleStarter does not get Switched off.

Introduction 18650 is a lithium-ion battery, where 18 means a diameter of 18mm, 65 means a length of 65mm, and 0 means a cylindrical battery, that is, they get their name from their size. As for scale, it is larger than an AA battery. 18650 battery is a rechargeable battery, has voltage of 3.7V and has capacity between 1800mAh and 3500mAh. You may also know 26650 battery and 21700 battery, what are they? and what is the difference between them? Intro To 18650 Li-ion Cells Catalog Introduction Ⅰ 18650 Battery Basic 1.1 Characteristic 1.2 Protective Function 1.3 Basic Parameters 1.4 Merits and Drawbacks Ⅱ 26650 Battery 2.1 Intro Info 2.2 Basic Parameters 2.3 18650 Battery vs 26650 Battery Ⅲ 21700 Battery 3.1 Info about 21700 3.2 Basic Parameters 3.3 21700 Battery Advantages 3.4 18650 Battery vs 21700 Battery Ⅳ Technical Specifications Comparison Ⅴ FAQ Ⅰ 18650 Battery Basic 1.1 Characteristic ① Large capacity: The capacity of a lithium battery is at least 1200mah or more, or even 3600mah, while the average battery cell is only about 500mah.② High energy storage efficiency and good stability: It can still maintain full performance output under 70°, and there is generally a protection circuit inside to prevent the battery from burning out.③ No memory effect: It is not necessary to discharge all the remaining power before charging, and it can be charged and discharged at any time, which is convenient to use.④ High charge and discharge cycle life: The number of cycles of lithium batteries is tens of thousands and the high temperature resistance is very good.⑤ Environmental protection, no toxic substances: Non-toxic, harmless, non-polluting, certified by RoHS quality. Figure 1. 18650 Battery 2200mAh 3.7V 1.2 Protective Function ① Overcharge protection: When the lithium battery is overcharged, the internal temperature rise of the battery will continue to rise, and a detection system for the battery voltage is added. When the battery overcharge voltage reaches a certain value or time period, the overcharge function will work and stop automatically to protect the battery.② Over-discharge protection: It means that the battery is always in an overloaded output state. Generally, there is discharge protection. At this time, the battery will be in a standby mode.③ Overcurrent protection: The overcurrent protection value can be adjusted, some are a few amperes, and the setting is selected according to the actual situation.④ Short-circuit protection: When the battery is short-circuited, the overcurrent protects the battery from burning.In addition to these four protection functions, some also have functions such as temperature and balance. Generally, the battery has a built-in PCM protection system with multiple protection functions. 1.3 Basic Parameters Number Item Parameter 1 Standard Voltage 7.4V 2 Rated Capacity 2200mAh 3 Continuous Working Current 1-3A 4 Overcurrent Protection Value 2-5A(adjustable) 5 Affordable Equipment Power ≤22V 6 Overcharge Protection Voltage 4.25±0.025V/Cell 7 Discharge Protection Voltage 2.50±0.05V/Cell 8 Charging Mode Constant-current and Constant-voltage 9 Maximum Charging Voltage 8.45V-8.55V 10 Recharging Current 0.2℃-0.5℃ 11 Charging Temperature 0~45℃, 45~85%RH 12 Discharge Temperature -20~55℃, 46~85%RH 13 Storage Temperature and Humidity Range Short term: more than one month -20℃~+55℃, 45~85%RH Medium term: more than three months -20℃~+45℃, 45~85%RH Long term: within one year -5℃~+20℃, 45~85%RH 14 Dimensions Brightness Reference Sample Length Reference Sample Thickness Reference Sample 15 Weight <120g   1.4 Merits and Drawbacks ✅Merits1) Large capacityThe capacity of 18650 battery is generally between 1200mah ~3600mah, and the general battery capacity is only about 800mah. If combined into a 18650 battery pack, it can easily break through 5000mah.2) Long LifeThe 18650 battery has a long service life, and the cycle life can reach more than 500 times during normal use, which is more than twice that of ordinary batteries.3) High Safety PerformanceThe 18650 battery has high safety performance. In order to prevent the short circuit of the battery, the positive and negative electrodes of the 18650 batteries are separated. Therefore, the possibility of short-circuiting has been reduced to the extreme. A protection board can be added to avoid overcharging and overdischarging of the battery, which can also prolong the service life of the battery.4) High VoltageThe voltage of 18650 lithium battery is generally 3.6V, 3.8V and 4.2V, which is much higher than the 1.2V voltage of nickel-cadmium and nickel-metal hydride batteries.5) No Memory EffectIt is not necessary to empty the remaining power before charging, which is convenient to use.6) Small Internal ResistanceThe internal resistance of the polymer battery is smaller than that of the general liquid battery, and the internal resistance of the domestic polymer battery can even be below 35mΩ, which greatly reduces the self-consumption of the battery and prolongs the standby time of the mobile phone. This polymer lithium battery that supports large discharge current is an ideal choice for remote control models, and has become the most promising product to replace nickel-metal hydride batteries.7) It can be combined in series or in parallel to form a 18650 lithium battery pack.8) Wide Range of Use18650 batteries can be employed in Notebook computers, walkie-talkies, portable DVDs, instrumentation, audio equipment, model aircraft, toys, video cameras, digital cameras and other electronic equipment.❎Drawbacks1) The biggest disadvantage of the 18650 battery is that its size has been fixed, and it is not very well positioned when it is installed in some notebooks or some products. Of course, this can also be said to be an advantage, which is compared to other polymer lithium batteries, etc. This is a disadvantage in terms of the customizable and changeable size of lithium batteries. Compared with some products with specified battery specifications, it has become an advantage.2) The production of 18650 batteries requires a protection circuit to prevent the battery from being overcharged and causing discharge. Of course, this is necessary for lithium batteries, which is also a common drawback of lithium batteries, because the materials used in lithium batteries are basically lithium cobalt oxide materials, and lithium batteries made of lithium cobalt oxide materials cannot be discharged at large currents, and their safety is poor.3) The production conditions of 18650 batteries are high, compared with general battery production, they have high requirements for production conditions, which undoubtedly increases the production cost.   Ⅱ 26650 Battery 2.1 Intro Info The 26650 battery is a cylindrical lithium battery with a diameter of 26mm and a length of 65mm. It is used in power tools, lighting, wind and solar energy storage, electric vehicles, toys, instrumentation, ups backup power supply, communication equipment, medical equipment and military lights. Figure 2. 26650 Battery Size 2.2 Basic Parameters Cycle performance: 2000 times (1C charge/1C discharge, capacity retention rate ≥80%, 100% DOD)Maximum continuous discharge current: 9.6APulse discharge current: 15A, 5sOperating temperature: Charge: 0°C ~ 55°C, discharge: -20°C ~ 60°CStorage temperature: -20°C ~ 45°CBattery weight: 86g (approx.)Nickel-cobalt-manganese ternary lithium-ion 26650 single-cell nominal voltage is generally: 3.6VNominal capacity: 4500mAh (capacity range 4500-4650mAh)AC internal resistance: ≤30mΩ (plus PTC type)Charging conditions: Cut-off voltage 4.2±0.05V, cut-off current 0.01C. (Note: Charge with 0.5C constant current to 4.2V, and charge with constant voltage until the current drops to 0.01C and cut off)Discharge cut-off voltage: 2.75VCycle performance: 500 times (1C charge/1C discharge, capacity retention rate ≥70%, 100% DOD)Maximum continuous discharge current: 13APulse discharge current: 15A, 5sOperating temperature: Charge: 0°C ~ 55°C, discharge: -20°C ~ 60°CStorage temperature: -20°C ~ 45°CBattery weight: 92g (approx.) 2.3 18650 Battery vs 26650 Battery 1) Different Rated CapacityThe rated capacity of IFR26650 is 3000mAh, and the rated capacity of IFR18650 is 1100~1400mAh.2) Different DiametersThe diameter of the IFR26650 is 26mm, and the diameter of the IFR18650 is 18mm. 3) Different Reference QualityThe production test quality of IFR26650 is 94 grams, and the IFR18650 is 45 grams.18650 lithium batteries are used in lighting, industrial supporting lithium battery packs, power tool batteries, electric bicycle batteries, power lithium battery packs, etc., while 26650 batteries are used in integrated solar street light lithium battery packs, energy storage stations, solar energy storage batteries and so on.The 26650 battery will gradually replace the 18650 battery in the application of power batteries. And with the large-scale use of lithium batteries, it will inevitably be a trend that larger-capacity 26650 batteries replace the trendy 18650 lithium batteries in the 3C era.   Ⅲ 21700 Battery 3.1 Info about 21700 The 21700 battery is a cylindrical battery with a diameter of 21mm and a height of 70.0mm. Its charge density is currently the highest energy density and lowest cost battery in the world, and it is cost-effective. Figure 3. 21700 Battery 4000mAh 3.7V   3.2 Basic Parameters The positive electrode is converted to nickel, the performance is not affected, the consistency is good, and it can be directly used as a battery pack.*Rechargeable Li-ion Cell*Size: Diameter 21mm, Length 70mm*Weight: about 65g*Rated voltage: 3.6V*Standard capacity: 4800mAh*Internal resistance: about 13 milliohms*Charging voltage: 4.2V*Discharge cut-off voltage: 2.5V*Discharge current: 10A (15-20A can be discharged instantaneously).*Applications: flashlights, scooters, LED lights, miner's lamps, lighting products, power banks, mobile power supplies, backup power supplies, computers, mobile devices, cars, bicycles, communications, medical, energy storage, solar energy, etc. 3.3 21700 Battery Advantages 1) The energy density of the 21700 type battery is higher than that of the well-known 18650 type battery. The number of single cells in use can be greatly reduced, and the cost will be reduced after grouping. The capacity of a 18650 battery is about 2600-3600 mAh, while a 21700 battery supports more than 4000 mAh, even 5000mAh has appeared on the market. And the larger capacity is increasingly beneficial to extend the battery life of modern devices.2) The single volume of the rechargeable battery is increased by 35%. Taking the Tesla 21700 rechargeable battery as an example, the energy of a single battery can be increased by 34.8ah, an increase of 35%.3) The net weight of the system software is estimated to be reduced by 10%. The total capacity is more than 21,700. With the increase of single volume and the increase of single energy ratio, the total number of batteries required under the same kinetic energy can be reduced by about 1/3, and the total number of metal components and electrical components selected for the battery pack can reduce the difficulty of managing information systems coefficient. After converting SDI (Samsung Digital Interface) to the new 21700 rechargeable battery, it was found that the system software reduced the net weight by 10% over the existing battery. 3.4 18650 Battery vs 21700 Battery The 18650 rechargeable battery has high reliability and stability, and the performance index of the 21700 battery is much higher than that of the 18650 battery. In addition, compared with other battery models, the raw materials, processing technology and technical steps of the 21700 rechargeable battery are more advanced than the 18650 rechargeable battery level. Therefore, the 18650 and 21700 production lines are the best match.   Ⅳ Technical Specifications Comparison 18650 Battery 26650 Battery 21700 Battery Nominal Voltage: 3.6V Voltage: 3.2V Voltage: 3.7V Nominal Capacity: 2,850 mAh Technologie: Lithium Iron Phosphate Capacity: 3500- 5600mAh Minimum Discharge Voltage: 3V Dimension: 26.2 (Ø) x 65.6 (H) mm Operating voltage: 2.5- 4.2V Maximum Discharge current: 1C Weight: 80g Cutoff voltage: 2 - 2.5V Charging Voltage: 4.2V (maximum) Standard capacity: 2300mAh - 0.5C (current value of 2300mA at 1C°) Weight: 55gms to 75gms Charging current: 0.5C Max. charge voltage: 3.65 ± 0.05 V Charge density (Energy per cell): 10.5- 13.7Wh Charging Time: 3 hours (approx) Inner resistance: ≤15mΩ Charge discharge cycle: 500 to 2000 Charging Method: CC and CV Max. discharge voltage: 2.0V Continuous discharge current: 20- 35 amps Cell Weight: 48g (approx) Cycle characteristic: 1500 (C/5) - 300 (10C) Optimum /Minimum charging time: 2.5 hrs to 3.5 hrs Cell Dimension: 18.4mm (dia) and 65mm (height) Working temperature: 0 ~ 55°C Discharge: -20°C ~ 60°C Charging voltage: 4.2V- 5V   Ⅴ FAQ 1. Are 18650 batteries banned?Consumers should not buy or use individual, loose 18650 lithium-ion battery cells without protection circuits due to possible fire risk, according to a warning just issued by the Consumer Product Safety Commission (CPSC). ... Samsung and Sony also warn consumers against using the cells. 2. What battery replaces the 18650?21700 battery18650 batteries are generally 3.6/3.7 volts and have capacity ratings from 2,300 to 3,600 mAh. 21700 – were designed to be a larger and higher capacity replacement for 18650 batteries. Like the 18650, the 21700 has a nominal voltage of 3.6/3.7V. The 21700 was designed to replace the 18650 in EV battery packs. 3. Are AA batteries the same as 18650?No, they are slightly larger and have completely different formula. The 18650 battery is a lithium-ion cell classified by its 18mm x 65mm size, which is slightly larger than a AA battery. They're often used in flashlights, laptops, and high-drain devices due to their superior capacity and discharge rates. 4. What makes 18650 batteries explode?The safety problem of 18650 lithium-ion battery is burning or even exploding. The root cause of these problems lies in the thermal runaway inside the battery. In addition, some external factors such as overcharge, fire source, extrusion, puncture, short circuit, etc. Will cause the battery to explode. 5. How many hours does a 18650 battery last?A standard lithium ion 18650 battery is rated to last between 300 to 500 cycles before noticing a large performance drop. That is a pretty wide range and we'll discuss some things you can do to extend your batteries life to 500 or even more cycles. 6. How can I charge my 18650 without a charger?You need a regulator to apply a minimal charge, and fortunately, small incandescent lamps in light bulbs and decorative lamps are the perfect regulators for this task. You must connect a cable to the lamp you are using and the other end of the cable will be connected to a hot battery, such as the car's battery. 7. Why are 18650 batteries so popular?The 18650 battery has a voltage of 3.6v and has between 2600mAh and 3500mAh (mili-amp-hours). These batteries are used in flashlights, laptops, electronics and even some electric cars because of their reliability, long run-times, and ability to be recharged hundreds of times over. 8. Are 21700 batteries better than 18650?The stronger heating and lower resistance of 21700 cells than the 18650 results in higher polarization in the 18650 and deviations between the voltage curves for the two formats at higher C rates. The 21700 has about 50% greater capacity and energy density than the 18650 for discharge rates up to about 3.75C. 9. Does Tesla use 21700 batteries?Tesla and Panasonic's 21700 cell was huge news when it was announced in 2017. Tesla doesn't currently use 18650 cells, though; it now uses the 21700 standard with cells measuring 21mm by 70mm. ... The new Tesla battery has gone up in size again, this time far more significantly to 4680 or 46mm x 80mm. 10. Does Tesla use 18650 batteries?Currently, Tesla mainly uses the Panasonic 18650 lithium-cobalt-acid battery, the entire battery contains thousands of independent cells, the battery costs about 135 $ / kWh, to provide 233 W / kg of energy. The future of Tesla plans to launch a new 20,700 lithium battery pack. 11. Are 18650 and 26650 batteries interchangeable?Based on their voltage and current outputs, yes, the 18650 and 26650 batteries are interchangeable. However, the two battery types are very different in size. The 26650 has a much greater diameter, so it will not fit in items designed for the slimmer 18650 battery. 12. What battery can I use instead of 26650?Well, 18650s rechargeable lithium-ion batteries can be used alone or with other batteries too including 26650 batteries in order to build battery packs and power banks or devices used for recharging a device. So, depending on the purpose, both 26650 and 18650 battery can be used together. 13. How long does it take to charge a 26650 battery?around 20 hoursIt may take around 20 hours to charge the 26650 battery fully. 14. Are 18650 batteries the same as AAA?AAA Batteries vs 18650 BatteriesAt first, AAA and 18650 batteries don't have much in common - AAA batteries are cylindrical batteries 10.5 mm (0.41 inch) in diameter and 44.5 mm (1.75 inches) in length, while 18650 batteries are cylindrical batteries 18.6 mm (0.73 inches) in diameter and 65.2 mm (2.56 inch) in length. 15. Can I use regular batteries instead of 18650?Technically yes, you can even buy an adapter that takes 3 AA's to replace an 18650, I use them in my tactical torch if the 18650 dies. However AA batteries are generally much lower capacity than an 18650 so they don't tend to last anywhere near as long. 16. Is 26650 battery same as C battery?They may appear the same and or the same size, but the C battery has a 1.5V nominal voltage while the 26650 lithium battery has a 3.6V or 3.7V nominal voltage. 17. What is the best 26650 battery for Vaping?The Hohm Grown 2 is our top pick for 26650s. It is an accurately rated 30A battery and its large capacity will have it running for much longer than your typical 18650 cell. The 26650 battery has been used for vaping for quite some time now. 18. How many 21700 batteries are in a Tesla?Currently, 4,416 (2170) cells are placed inside Tesla Model 3/Y Long-Range battery packs. In contrast, there will only be 960 cells required to fill the same space. 19.What does 18650 mean on a battery?lithium-ion batteryAn 18650 battery is a lithium-ion battery. The name derives from the battery's specific measurements: 18mm x 65mm. For scale, that's larger than an AA battery. The 18650 battery has a voltage of 3.6v and has between 2600mAh and 3500mAh (mili-amp-hours).

CatalogIntroductionⅠ How to Wire a Relay?Ⅱ Why Use a Relay?Ⅲ Relay Wiring DiagramⅣ 4 Pin Relay Wiring Diagram vs 5 Pin Relay Wiring Diagram4.1 The Main Difference between 4 or 5 Pin Relays4.2 4 Pin Relay Wiring Diagram4.3 Sample Wiring Diagrams for a 4 Pin Normally Open Relay4.4 Why to Use a 4 Pin Relay for Driving Lights4.5 5 Pin Relay Wiring Diagram4.6 How To Use 5 Pin Relay4.7 5 Pin Relay Wiring Diagram for lightsⅤ FAQIntroductionIn layman's terms, a relay is an electromagnetic switch that is typically used to switch the power supply either automatically or manually. In this post, I'll go over the fundamentals of 4 and 5 pin relay wiring diagrams. The relay comes in a variety of shapes and sizes. It can be based on the pins or contacts, ampers, or voltage ratting (AC or DC). These contacts are pins 4, 5, 8, 11, 14, and so on. However, we have two coil pins on each pin. Where we supply the necessary ratting current. As an example, suppose we have a 12-volt DCV relay. As a result, we will supply 12 volts of DC (Direct current) to the relay coil. And if we have the 220 ACV, we can supply the relay coil with 220 volts AC (alternating current).The remaining pins and contacts are known as main contacts or switching contacts. The relay switching pins include the following: common, NC (normally open), and NO (normally close).Ⅰ How to Wire a Relay?How To Wire A Relay - Quick TipStill confused? See the full video here. Ⅱ Why Use a Relay?There are several reasons why you might need or want to use a relay:Using a lower current circuit to replace a high current circuit.This is the most common reason, and it is useful when an in-line switch or existing circuit cannot handle the required current. For example, if you wanted to install some high-powered work lights that activate with the headlights, there's a chance they'd exceed the capacity of the existing loom.Cost SavingBecause high current capacity wiring and switches are more expensive than lower current capacity versions, using relays reduces the need for more expensive components.Activating more than one circuit from a Single InputA single input signal from one part of an electrical system (e.g., central locking output, manual switch, etc.) can be used to activate one or more relays, which then complete one or more other circuits, allowing you to carry out multiple functions from a single input signal.Carrying Out Logic FunctionsWhen linked together, electromagnetic relays can be used to perform logical operations based on specific inputs (for example, latching a +12V output on and off from a momentary input, flashing alternative left and right lights, and so on). Although electronic modules have largely replaced these logical functions in OEM designs, it can still be useful, fun, and often more cost-effective to use relays to perform them in some after-market projects (particularly where you have a bespoke application).Ⅲ Relay Wiring DiagramA simple wiring diagram of a relay is shown here to help you understand how it works in a circuit.Relay wiring diagramLet's talk about this relay wiring diagram now.It is the relay that is powered by the DC supply. Pin 1 is the magnetic coil's positive pin. Pin 2 is the coil's negative pin. As a result, we used an SPST switch to connect a DC power source across terminals 1 and 2. We can use this switch to turn on or off the power supply to the relay coil whenever we want.Terminal 3 is shared by NO and NC contacts. Terminal 5 is designated as NO, while Terminal 4 is designated as NC. This means that under normal circumstances, terminal 3 is connected to terminal 4. When we apply power to the coil, terminal 3 is connected to terminal 5.As you can see, we connected two LEDs here. The NO terminal is connected to the red LED, and the NC terminal is connected to the green LED. So, under normal circumstances, the green LED will glow, but when we apply power to the relay by turning on the switch, the red LED will glow.Ⅳ 4 Pin Relay Wiring Diagram vs 5 Pin Relay Wiring Diagram4.1 The Main Difference between 4 or 5 Pin RelaysA 4 pin relay controls a single circuit, whereas a 5 pin relay switches power between two circuits.4 Pin Relay2 pins (85 & 86) control the coil and 2 pins (30 & 87) switch power on a single circuit in a 4 pin relay. Four-pin relays are available in two configurations: normally open and normally closed. When the coil is activated, a normally open relay turns on the power to a circuit. When the coil is activated, a normally closed relay turns off the power to the circuit.5 Pin Relay5 pin relays have two pins (85 & 86) for controlling the coil and three pins (30, 87 & 87A) for switching power between two circuits. They have connection pins that are both normally open and normally closed. Power is switched from the normally closed pin to the normally open pin when the coil is activated.4.2 4 Pin Relay Wiring Diagram The diagram of a four-pin relay is depicted in the image below. This circuit diagram will be used later to wire a relay for driving lights.4 Pin Relay Wiring DiagramYou'll need to use a fuse to connect the relay's Pin 30 to the 12V battery for driving lights. We're not directly connecting pin 30 to the battery here; instead, we're using a fuse. This is because the fuse protects us from overcurrents.If there is a fault in the driving light circuit, the fuse protects the burning of lights and other circuits from current overshoots.Pin 85 of the relay is grounded, while Pins 87 and 86 are switching pins. You can turn on the main beams of the driving light using this 4 pin relay by switching the battery connections to either circuit connected with pin 86 or 87 of the relay.4.3 Sample Wiring Diagrams for a 4 Pin Normally Open Relay Sample Wiring Diagrams for a Normally Open RelayExample 1. 4 pin (normally open) relay with the switch on the control circuit's positive side.  Example 2. 4 pin (normally open) relay with the switch on the control circuit's negative side.   Note: These circuits have been simplified to demonstrate the function of a relay and thus do not include the fuse protection that would be required. Relay coil terminals have no polarity unless the relay coil is protected by a diode (inside the relay), in which case the coil terminal wired to the diode's anode must be connected to negative.4.4 Why to Use a 4 Pin Relay for Driving LightsThe main reason for installing this relay system is to keep dangerous voltages outside of your cabin or driving area.The high voltage required by your headlight, which is supplied by the battery, is kept inside the engine compartment by a relay.Simply put, a relay is a switch that is controlled by another switch. The switch installed in the vehicle's sitting cabin, on the front side of the driver, operates on very low voltage. As you can see, this voltage is not high enough to harm the driver or other electronic components. This switch provides power to the relay, which is essentially an electromagnet. It will also control the high current circuit that is directly connected to the headlights.This is how a low current circuit controls a high current circuit, keeping both the driver and the car electronics safe, and why we need a relay in our headlights!4.5 5 Pin Relay Wiring Diagram A pin relay is SPDT relay, which means that the contacts of relay single pole double throw. In single pole double throw relay, we have one pin is common, 2nd are normally close and 3rd are normally open. Two pins for the coil. This relay can be used for different types of controlling or switching. Such as for lights, fan, fuel pump, etc. Here I showed the 5 pin relay wiring diagram. 5 pin relay wiring diagramIn the diagram above, I've depicted a single pole double throw relay (5 pin relay). Not that his relay can be 5 volts DCV, 12 volts DCV, 24 volts DCV, and so on, depending on the coil's ratting voltage. In the above 5 pin relay diagram, pins 1 and 2 are for the coil, pin 3 is the common pin, pin 4 is normally closed, and pin 5 is normally open.4.6 How to Use 5 Pin RelayA relay can be used for a variety of switching purposes. If you want to control electrical devices automatically, a relay is the best option. When we talk about relays, as I previously stated, there are various types of relays for various applications. This post, however, is about the 5 pin relay. As illustrated by the 5 pin relay diagram. This has three main pins. As opposed to a single pole double throw.So when we say single pole double throw, we mean that it has a common point as well as two other points (NC and NO).To switch something from a single pole double throw relay, you must use the common and other points. For example, if you require that the light bulb be turned off when the relay operates. Then you must use a common, normally closed pin. If you want to turn on the light bulb, you must use the common and normally open pins. I've shown how to wire a 5 pin relay for lights in this article.4.7 5 Pin Relay Wiring Diagram for lightsIn the 5 pin relay wiring diagram below, I show how to turn on lights when the relay is activated and how to turn them off when the relay is deactivated.Similarly, if you want to control or wire a fan with a relay, you can use the same method. It is important to note that the ratted voltage must be applied to the relay coil. If your relay is powered by 12 volts DCV. Then you must supply the 12-volt DCV.Ⅴ FAQ1. What costs more than lower current capacity versions?High current capacity wiring and switches.2. What can you use to activate one or more relays?A single input from one part of an electrical system.3. How can you use a single input from one part of an electrical system?To activate one or more relays that then complete one or more other circuits and so carry out multiple functions from one input signal.4. What will switch power on for a circuit when the coil is activated?A normally open relay.5. What is the main purpose of installing a 4 Pin Relay for Driving Lights?To keep dangerous voltages outside of your cabin or driving place.