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Introduction Potentiometer is a common instrument that uses compensation principle and comparison method to accurately measure DC potential difference or power supply electromotive force. It has high accuracy, convenient use, and stable and reliable measurement results. But even so, when we do potentiometer experiments, we still have to deal with different error problems. The content of this article tells you how to avoid too many errors without getting too large deviations in the experimental results. Potentiometer Experiment (Compare EMF of Two Cells) Catalog Introduction Ⅰ Potentiometer Principle Analyses 1.1 Compensation Principle 1.2 Operational Principle Ⅱ UJ25 DC Potentiometer Overview Ⅲ UJ25 DC Potentiometer Application 3.1 Working Current Adjustment 3.2 Experimental Content 3.3 Laboratory Apparatus Ⅳ Discussion of Experimental Results Ⅴ FAQ Ⅰ Potentiometer Principle Analyses If you want to firmly acquire the use of the basic potentiometer, you must first understand its compensation principle and operational principle. 1.1 Compensation Principle The electromotive force (EMF) of the power supply is theoretically equal to the voltage of the two poles when there is no net current flowing inside the power supply. If you directly use a voltmeter to measure it, the result is actually the terminal voltage not the EMF. Because the power supply has internal resistance r0, if the voltmeter is directly connected in parallel to the two ends of the power supply, there must be a current I through the inside of it, and also there is inevitably a potential drop Ir0 inside. So the indicated value of the voltmeter is only the terminal voltage of the power supply (U=E-Ir0) size. Obviously, in order to be able to accurately measure the EMF of the power supply, the current I must be zero. At this time, the terminal voltage U of the power supply is equal to its electromotive force E. Figure 1. Closed Loop As shown in the figure on the right, connect the electromotive force as Es, Ex and galvanometer G to form a closed circuit. When Es<Ex, the current direction is as shown in the figure, and the pointer of the galvanometer is biased to one side. When Es>Ex, the direction of current is opposite to the direction shown in the figure, and the pointer of the galvanometer is biased to the other side. Only when Es=Ex, there is no current in the loop. At this time, i=0, and the pointer of the galvanometer is not deflected. We call these two electromotive forces in a compensation state. Conversely, if i=0, then Es=Ex, this method is called zero-show method. 1.2 Operational Principle As shown in the figure, the compensation principle shows that Ex can be determined by measuring Vab. The next step is how to accurately measure Vab. Here, the comparative measurement method is used. Connect Ex to the tap of Rab. When the tap is slid to position Rab, no current flows in G, then Ex=I*Rab, where current I is the main circuit current. Then connect a standard battery EN with known EMF in the circuit, when the tap slides to the position Rcd, G is 0 again, then EN=I*Rcd, where This method is to obtain the ratio relationship between the voltage to be measured and the EMF of the standard battery through the comparison of resistance. Because R is a precision resistance, Rab/Rcd can be read accurately, EN is a standard battery with high-accuracy EMF. Therefore, as long as the auxiliary power supply E is stable and the galvanometer G has sufficient sensitivity during the measurement process, Ex can have a very high measurement accuracy. The voltage measuring instrument made according to the above principle is called a potentiometer. Figure 2. Auxiliary Circuit It should be pointed out that the condition for the establishment of  is that the working current of the auxiliary circuit in the two compensations must be equal. In fact, in order to facilitate the reading, I=EN/Rcd should be standardized, so that the corresponding resistance value can be directly read out abV, which is Ex.Actually, there is no sliding rheostat in the instrument provided to us in the experiment, only 2 resistance boxes. This experiment requires us to use a rheostat box to replace the sliding rheostat. Therefore, we will use a resistor box R1 instead of the compensation method to measure the sliding rheostat RP, the other resistor box R2 acts as Rab. Since the resistance of them can be read directly, we can easily keep the current through the auxiliary circuit unchanged, that is, keeping R1+R2 constant.   Ⅱ UJ25 DC Potentiometer Overview UJ25 DC Potentiometer is a kind of high potential device, the upper limit of measurement is 1.911110V, the accuracy is 0.01 grade, and the working current I=0.1mA. Its principle is shown in the figure, the bottom of the right figure is its panel, and the functions of the upper 12 binding posts have been indicated on the panel. The Rab in the figure is two step resistance knobs, marked with the value of the standard battery EMF at different temperatures for correction when adjusting the working current. RP is used to adjust the working current I. Rcd is the six large knobs marked with voltage values, used to measure the unknown voltage value at the lower left corner of the function switch. When it is off, the potentiometer does not work; when it is at N, it can be connected to check and adjust the working current. When it is at X1 or X2, it can measure the unknown voltage of the first channel and obtain the second channel. The three buttons marked G0, G1, and short circuit are the control switches for rapid current detection. By being in the off state and pressing G0, the galvanometer is on in the circuit, but a large resistor R is connected in series to compensate for the principle. At the same time, protect the galvanometer; press G1 down, the galvanometer is directly connected to the circuit, so that the potentiometer is in a high-sensitivity working state. When the damping switch turns on, the galvanometer coil is short-circuited, and the coil does not swing due to the large electromagnetic damping. Figure 3. UJ25 DC Potentiometer Circuit   Ⅲ UJ25 DC Potentiometer Application 3.1 Working Current Adjustment Turn the function switch to N, turn the temperature compensation resistor Rab to the last two digits of the corrected standard battery EMF "1.018V", press the "G0" and "G1" respectively, and adjust RP to zero for the galvanometer.Measure the voltage to be measured.Switch the function switch to X1 or X2, press the "G0" and "G1" buttons respectively, and adjust Rcd to the galvanometer zero, finally the displayed value is the voltage to be measured. 3.2 Experimental Content 🔺Assemble Potentiometer(1) Design and connect the potentiometer circuit, the following is the standard battery temperature correction formula: (2) Standardize the working current, and measure the electromotive force of the dry battery.(3) Measure the sensitivity of potentiometer. 🔺UJ25 DC PotentiometerUse UJ25 box-type potentiometer to measure dry cell electromotive force. 3.3 Laboratory Apparatus ZX-21 resistance box (two), pointer galvanometer, standard battery, regulated power supply, dry battery to be tested, double pole double throw switch, UJ25 box type potentiometer.Data Processing and Error Quantitative Analysis.🔺Raw DataStandard battery electromotive force: E20=1.01186V, UJ25 measurement Ex=1.469285V, accuracy level 0.01Ambient temperature: T1=20.5℃, T2=21.5℃ EN R1=1018.6Ω R2=1983.8Ω EX R'1=1469.8Ω R'2=1532.6Ω Sensitivity Measurement/14div R''1=1484.1Ω R''2=1518.3Ω 🔺Potentiometer Measurement ResultsStandard Electricity Correction Value where ，get EN=1.01857VPosition battery EMF calculation 🔺Error and Uncertainty Analysis(1) Instrument Error get Similarly Knowing that R1, R2, R'1, R'2 are independent of each other, then the data in (1) can be obtained: (2) Sensitivity ErrorSensitivity  (3) Effects of the Temperature Change Assuming the temperature is constant, then Because of , therefore, this part of the error and its uncertainty can be ignored.(4) EN Stability Because of therefore, this part of the error and its uncertainty can be ignored.(5) Error Analysis and Synthesis of UncertaintyFrom the calculation of (3) and (4), it can be seen that the combination of uncertainty can omit the error of EN indication, and omit the error caused by the change of the auxiliary power supply and the standard battery EN during the two zero indications. Also the sensitivity error of the circuit during the two times of zero display, and because the readings of multiple measurements are almost unchanged. So only one measurement result is recorded and used, and we do not consider the impact of EN error on the measurement of Ex.Compared with the uncertainty of (2) obtained by (1), the uncertainty of (2) is about one-tenth of the uncertainty of (3), but considering that the uncertainty of (3) is of the order of 10^(-3), it can ignore the magnitude of 10^(-4). In the end , get the final result of the measurement.   Ⅳ Discussion of Experimental Results The use of UJ25 potentiometer can more accurately measure the electromotive force of the unknown power source, so as to further analyze the measurement results of the self-assembled potentiometer.Knowing that the measurement result of UJ25 potentiometer is EX=1.469258, and calculate the sensitivity error of the instrument: Because the readings of multiple measurements are consistent, it is ignored.That is, the actual measurement result of UJ25 potentiometer is .The measurement result is .That is, the relative error is .The operation of this experiment is relatively simple, but the data processing is slightly complicated, especially the calculation of uncertainty. Because of its many sources, it is impossible to analyze the errors one by one, so the smaller influencing factors are ignored to simplify the calculation. In this process, we understand that the principle of compensation to eliminate the internal resistance of the electric meter and the battery will be of great help to subsequent experiments.   Ⅴ FAQ 1. What is a potentiometer in a circuit?A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. ... Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. 2. What is the purpose of the potentiometer?A potentiometer is a type of position sensor. They are used to measure displacement in any direction. Linear potentiometers linearly measure displacement and rotary potentiometers measure rotational displacement. 3. How does a potentiometer affect a circuit?The potentiometer is a three-wire resistive device that acts as a voltage divider producing a continuously variable voltage output signal which is proportional to the physical position of the wiper along the track. 4. What happens when you turn potentiometer?It will behave like a normal resistor. When the circuit is connected to a center lead, and an outside lead, the potentiometer will behave like a variable resistor - turning the post of the potentiometer will increase (clockwise), or decrease (counter-clockwise) the resistance of the potentiometer. 5. How does a potentiometer change resistance?As you turn the knob of a potentiometer, the change in the resistance can be either linear or logarithmic. The way the resistance changes is called the taper. With a linear taper potentiometer, turning a knob a certain amount will change the resistance by a set amount, no matter the position of the knob. 6. How much voltage can a potentiometer handle?The easiest way to think about it is that there is a maximum current through the pot. If you have a 1W 100 ohm potentiometer, the max. current is 100mA (full voltage = 10V); if you are using only 27 ohms of the potentiometer then the max. 7. How does current flow in a potentiometer?Assume V to be the voltage produced by the cell in the primary circuit across the length of the potentiometer wire, and E to be that produced by the cell of the secondary circuit. 8. What is the formula for potentiometer?It is calculated as V/L, where V is the potential difference between two points and L is the distance between two points. Also K = (IρL/A)/L = Iρ/A. 9. How is potentiometer power calculated?Imax = √(P/R) where Imax is the maximum amount of current that can pass safely through any part of the pot, P is the specified power rating of the pot, and R is the specified resistance of the pot. For example, a 10,000-ohm, 1-watt potentiometer can safely pass √[1/(1 x 104)] amperes, or 10 milliamperes. 10. How do you calculate the output voltage of a potentiometer?Measure the total battery voltage, and then measure the voltage between the same two points on the potentiometer (wiper and negative side). Divide the potentiometer's measured output voltage by the measured total voltage. 11. What is the working principle of potentiometer?The principle of a potentiometer is that the potential dropped across a segment of a wire of uniform cross-section carrying a constant current is directly proportional to its length. The potentiometer is a simple device used to measure the electrical potentials (or compare the e.m.f of a cell). 12. What is potentiometer calculate the internal resistance of a cell?To calculate internal resistance, we use a potentiometer to first calculate the voltage across the battery, with no current through it. Then we attach a resistor in parallel to the battery and recalculate the voltage across it. ... Using the battery equation, we calculate the internal resistance. 13. What are the two uses of potentiometer?The applications (uses) of the potentiometer:Voltage divider: The potentiometer can be used as a voltage divider to change the output voltage of a voltage supply.Audio control: Sliding potentiometers are commonly used in modem low-power audio systems as audio control devices. 14. How do you calculate the emf of a cell using a potentiometer?Using a potentiometer, we can determine the emf of a cell by obtaining the balancing length l. Here, the fall of potential along the length l of the potentiometer wire is equal to the emf of the cell, as no current is being drawn from the cell. 15. How can potentiometer be used to calculate potential difference?A Potentiometer can be to measure e.m.f of a cell which cannot be measured by a voltmeter. When a voltmeter is connected in a circuit it draws current through the circuit and thus can measure the potential difference across the cell terminals. ... Thus it measures the e.m.f. of the cell. 16. What is the principle of potentiometer support with equation?The basic potentiometer working principle is based on the fact that the potential across any piece of the wire is directly proportional to the length of the wire, which has a uniform cross-sectional area and the constant current flowing through it. 17. What is potentiometer write its principle and construction?The potentiometer is a device used to compare the e.m.f of two cells. It works on the principle that when a constant current flows through a wire of uniform cross-sectional area, a potential difference between its two points, is directly proportional to the length of the wire between the two points.

CatalogⅠ IntroductionⅡ What is a Car Battery Tester?Ⅲ How Does a Battery Tester Work?Ⅳ Types of Battery Tester4.1 Electronic Battery Tester4.2 Domestic Battery Tester4.3 Universal Battery Tester4.4 Car Battery TesterⅤ Features of Battery Tester5.1 Battery Type5.2 Ease of Use5.3 DisplayⅥ How to Use a Battery TesterⅦ Why We Need a Car Battery TesterⅧ How to Check Your a Car’s BatteryⅨ How to Choose a Battery TesterⅩ Frequently Asked Questions About Battery Tester Ⅰ IntroductionMaking ensuring your battery is in good operating order is an often overlooked element of car maintenance. When your car's battery dies unexpectedly, it may really throw a kink in your day. A car battery tester is a low-cost way to ensure that your battery is in good working order before you hit the road. It's even better if you get into the practice of periodically inspecting your car's battery, as well as the rest of the electrical system, for signs of weakness. In this article, we will go over battery tester information in detail. Ⅱ What is a Car Battery Tester?A car battery tester is a gadget used to assess the condition of your battery. If you browse through our product list, you'll find that some testers are fairly simple, while others provide more data and information about your vehicle's electrical system. It's entirely up to you which type you buy, but it's generally advisable to have a simple tester on hand so you can replace your batteries before it's completely dead.  More complex tests will perform a more complete job, even testing your car's alternator for any problems. Ⅲ How Does a Battery Tester Work?Battery testers operate by providing a load to the battery and monitoring its voltage and current. The actual procedure is straightforward: when the tester's conductive parts make contact with both the positive and negative contacts on the battery, current is released and can be measured. Because battery testers only measure current, they produce more accurate readings on certain types of batteries than others. For example, the current in an alkaline battery often decreases at a constant rate, resulting in more reliable findings when tested. Li-ion batteries, on the other hand, face higher drops at specific charge levels. Because of their less exact charge levels, these batteries are more prone to produce false findings. Ⅳ Types of Battery TesterThere are several varieties of battery testers, each suited to a distinct battery type and size. The following are some of the most frequent types. 4.1 Electronic Battery TesterElectronic and digital battery testers are used to determine a battery's remaining capacity. Most digital models have an LCD display that displays the battery test results in a clear and easy-to-read style. Depending on the model, information is often shown in the form of bars or a graph, allowing for easy viewing and interpretation of the test findings via a user-friendly interface. 4.2 Domestic Battery TesterA domestic or household battery tester is typically used for rechargeable cylindrical batteries such as AA, AAA, and 9V PP3 batteries. Alkaline, NiCd, and Li-ion are common battery chemistries. These basic chemical types encompass the vast majority of everyday household batteries, including those mentioned above, as well as other battery kinds such as C batteries and D batteries. A standard household battery tester will be adequate for testing a combination of these battery types, if not all of them. 4.3 Universal Battery TesterUniversal battery testers are designed to work with batteries of various sizes. They are primarily used for cylindrical batteries, as are household battery testers. Some voltage meters, on the other hand, can test a wide range of battery sizes, from little button cell batteries to huge industrial and automobile batteries. 4.4 Car Battery TesterLead-acid batteries are intended for use with car battery testers. These testers attach to vehicle batteries and provide an accurate reading of the battery's health, condition, and voltage output. Battery tests for automotive use are essential. Because huge currents are drawn during start-up, it is critical to determine the health of automotive batteries. To ensure safe testing settings, you must first check that your tester is compatible with lead-acid batteries. Ⅴ Features of Battery Tester5.1 Battery TypeDifferent types of batteries are used in various sorts of automobiles. Some automobile battery testers and chargers are compatible with a wide range of batteries, including conventional, AGM, gel cell, spiral wound, and deep cycle. The more the device's versatility, the more beneficial it is. Just make sure it will work on your specific vehicle's battery before you buy it. 5.2 Ease of UseA car battery load tester is, for the most part, easy to use. If you are not mechanically inclined, select a gadget that is simple to use right out of the box and does not necessitate a complex setup. It should also deliver test results that are easy to understand. Smaller and more ergonomically shaped gadgets are ideal for transporting, and some feature a tiny design that allows them to fit in a pocket. 5.3 DisplayThe voltage of your battery is displayed on the automobile battery tester's display. Is it a classic battery tester with a single metric display or an LCD display with a plethora of functions? Choose the one that best fits your budget and requirements. Ⅵ How to Use a Battery TesterIt is usually a good idea to consult the instruction manual or manufacturer's advice for your specific model. Furthermore, before testing a battery, make sure that the tester is completely operational and compatible with the type of battery you wish to test. Using a voltage meter is a reasonably basic and uncomplicated technique. Insert the battery into the tester, making sure the positive and negative contacts on both the battery and the tester are properly aligned. Before taking the reading, make sure the battery is securely fastened in position. As with any other item or gadget, you should take precautions to safeguard and maintain your battery tester in order to extend its useful life and reduce the chance of damage. Battery testers should be kept in a cold, dry place, such as a toolbox. They are low-maintenance pieces of equipment that normally only require a simple wipe down to maintain the screen clean and clear of dust and debris. Remember not to use a moist cloth as this may cause damage to the gadget. Rather, use a clean cloth or, better yet, specialized electronics cleaning wipes. How to Take a  V oltage Meter ReadingYou should be able to take a voltage meter reading once the battery is properly positioned. Depending on the model, the outcome of the test may differ between various different results formats. If your battery tester displays a graph or chart, determining the battery's remaining capacity should be simple. As a general rule, batteries in the green or pointing towards the higher end of the scale are likely to be in good operating shape with plenty of capacity remaining. Batteries with results in the middle of the scale may still be appropriate for use in some low-power applications, but they must be closely monitored. Batteries with a low capacity indicator, such as those in the red section, should be replaced or recharged, depending on the type of battery. Ⅶ Why We Need a Car Battery TesterYou want to buy a car battery tester so that you may check the state of your car's battery on a regular basis. This way, you'll know when your car's battery is about to fail, allowing you to replace it before it entirely dies and can't hold a charge. Most testers are inexpensive, and they are a little investment to avoid the headache of being stuck unexpectedly. Ⅷ How to Check Your a Car’s BatteryAfter you've purchased a car battery tester, it's time to determine the state of your battery. Most tests will include full instructions on how to use the individual gadget, but here are some general actions to take and suggestions to keep in mind. (1) When dealing with your batteries, it's usually a good idea to put on a pair of rubber gloves and goggles before you start. Gloves and goggles will keep your hands and eyes safe from the acid. (2) Begin by making sure your vehicle's ignition is shut off and all of its lights are turned off. (3) Connect your battery tester's positive lead to the positive terminal on your battery. (4) Connect the negative lead on the battery tester to the battery's negative terminal. (5) Inspect the battery voltage in your vehicle. If it is above 12.6 volts, your battery is in excellent condition (100 percent). A voltage reading of 12.4 volts indicates that your battery is in good condition – approximately 75% charged. A value of 12.2 volts is approximately 50%, which indicates that readings of 12.2 volts or less indicate a defective battery. (6) Once you've finished verifying the battery's condition, disconnect the negative terminal first. If the clamps won't come off easily, you'll need to use a battery terminal puller to get them off. Ⅸ How to Choose a Battery TesterSeveral considerations will influence the purchase of a battery tester. Most importantly, be sure the tester you select is compatible with the type or types of batteries you will be testing. Additional elements will mostly be determined by personal desire and your specific needs. The following are some important considerations while looking for the best battery tester: Compatible battery types Price and your budget Brand loyalty Additional features offered As a result, determining what is the best battery tester will be based mostly on your particular requirements, thus it is critical to undertake thorough research and verify the tester you purchase fulfills your demands. Ⅹ Frequently Asked Questions About Battery Tester1. How do you test if a battery is good or not?Check your battery using a multimeter or voltmeter. On your reader, you should be looking at volts. If your battery is reading at or above 12.45 volts, it is still in good condition, and any troubles you are experiencing are most likely caused by some thing else. 2. What do battery testers check?A state of charge battery tester is an electric instrument used to test the life and chargeability of a battery. A state of charge tester can determine a battery's current charging state and voltage output, as well as discover any defects that may damage the battery's overall performance. 3. Do battery testers work on lithium batteries?Traditional battery testers that only measure voltage and impedance are incapable of accurately measuring lithium battery storage capacity. Even as they age, lithium-ion batteries maintain a consistent degree of internal resistance. 4. How do you know if you have a bad battery?Here are some methods for testing and determining the health of your battery at home:Broken terminal.Bulge or bump in the case.Crack or rupture of the plastic.Excessive leaking.Discoloration. 5. How accurate is a car battery tester?Measuring the open circuit voltage and measuring the internal resistance are not conclusive indicators of battery health. A dead battery is simple to detect, and most testers are completely accurate. The difficulty comes from evaluating a battery in the 80–100% performance range while it is in operation. 6. Do battery testers work on rechargeable batteries?Even if they only have half a charge left, these batteries will read as completely charged. Additionally, testers will not tell you if a rechargeable battery can be charged again. To test this, you'll need a battery conditioner or a battery tester developed specifically for rechargeable batteries. 7. What is the average lifespan of a car battery?The usual life expectancy of a car battery is three years or so, however this estimate can be influenced by a number of circumstances. Even in the best of circumstances, chemical interactions cause batteries to fail, and your vehicle will most likely require a new battery within a few years. 8. Can a car battery go dead from sitting?Typically, your car's battery will die after four to two months of not being driven. The fact that your car battery is in use even when you're not driving is why it can only sit for so long before dying. 9. Can a battery test good and still be bad?Yes, a battery can have a high voltage and still be defective. When you want to use your battery, it should display the correct 12.6 volts and switch off. This is why, after testing the voltage, you should do a load test on your battery. The load test will tell you whether or not your battery is bad. 10. What is the difference between a battery tester and a multimeter?Unlike the multimeter, the battery tester lets you choose which sort of battery is being tested and how much capacity it has from a menu. The tester performs a diagnostic test on the battery by applying a load to it to evaluate its capacity. 

Warm hints: The word in this article is about 3000 words and reading time is about 12 minutes.     This article would introduce you different kinds of power supply circuits.   Catalog   I. Circuit Arrangement of Switching Power Supply II. The Principle of the Input Circuit and the Common Circuits 2.1 Principle of AC Input Rectifier Filter Circuit 2.1.1 Lightning Protection Circuit 2.1.2 Input Filter Circuit 2.1.3 Rectifier Filter Circuit 2.2 Principle of DC Input Filter Circuit 2.2.1 Input Filter Circuit 2.2.2 The Anti-surge Circuit III. Power Conversion Circuits 3.1 The Working Principle of MOS Tube 3.2  Common Schematic Diagram 3.3 Working Principle 3.4 Push-pull Power Conversion Circuit 3.5 Power Conversion Circuit with Transformer Driver IV. Output Rectifier Filter Circuit 4.1 Forward Rectifier Circuit 4.2 Flyback Fectifier Circuit 4.3 Synchronous Rectifier Circuit V. Principles of Steady-voltage Loop 5.1 Schematic Diagram of Feedback Circuit 5.2 Working Principles VI. Short Circuit Protection Circuits 6.1 Current-limiting Circuit 6.2 Short Circuit Protection for Low-power Circuit 6.3 Short Circuit Protection for Medium-power Circuit 6.4  Common Current-limiting, Short-circuit Protection Circuit 6.5 Current Transformer Sampling Current Protection Circuit VII. Output Current Limiting Protection VIII. Output Overvoltage Protection Circuits 8.1 SCR Trigger Protection Circuit 8.2 Optocoupler Protection Circuit 8.3 Output Voltage Limiting Protection Circuit 8.4 Output Overvoltage Lockout Circuit IX. Power Factor Correction Circuit (PFC) 9.1 Schematic Diagram of PFC Circuit 9.2 The Working Principles X. Input Under-voltage and Overvoltage Protection 10.1 Schematic Diagram 10.2 The Working Principles FAQ       I. Circuit Arrangement of Switching Power Supply   The main circuit of the switch-mode power supply is composed of an input EMI filter, rectifier filter circuit, power conversion circuit, and PWM controller circuit, output rectifier filter circuit. The auxiliary circuits include the input & output Undervoltage protection circuit, the output overcurrent protection circuit, the output short circuit protection circuit, and so on.   The block diagram of switching power supply circuit arrangement is as follows:   FIG.1 Block diagram of switching power supply circuit arrangement   II. The Principle of the Input Circuit and the Common Circuits   2.1 Principle of AC Input Rectifier Filter Circuit 2.1.1    Lightning Protection Circuit When there is a lightning strike, the circuit composed of MOV1, MOV2, MOV3, F1, F2, F3, and FDG1 is used to provide protection against the resulting high voltage introduced into the power supply through the electrical grid.   When the voltage applied to the two ends of the piezoresistor exceeds its operating voltage, the resistance value will decrease, making the high voltage energy be consumed on the piezoresistor; if the current is too large, the F1, F2, and F3 will burn out to protect the following circuits. 2.1.2     Input Filter Circuit The double Pi filter network composed of C1, L1, C2 and C3 is mainly used to suppress the electromagnetic noise and clutter signal of the input power supply to prevent its interference to the power supply, and also to prevent the interference of the high-frequency clutters generated by the power supply itself to the electrical grid. The C5 will start to be charged when the power is turned on, producing a large instantaneous current, which is called surge current, but with an RT1 (thermistor) it can be effectively prevented. Because the instantaneous energy is all consumed on the RT1, after a certain time the resistance of RT1 will decrease as the temperature rises (RT1 is a negative temperature coefficient device) and the energy consumed by RT1 will be very small at this time, to make sure the following circuits work normally.     2.1.3   Rectifier Filter Circuit After the AC voltage is rectified by BRG1 and filtered by C5, a purer DC voltage can be obtained. If the C5 capacity becomes smaller, the output AC ripples increase with it.     2.2 Principle of DC Input Filter Circuit FIG.3 The schematic of rectifier circuit   2.2.1   Input Filter Circuit The double Pi filter network composed of C1, L1and C2 is mainly used to suppress the electromagnetic noise and clutter signal of the input power supply to prevent its interference to the power supply, and also to prevent the interference of the high-frequency clutters generated by the power supply itself to the electrical grid. C3 and C4 are Safety Capacitors and the L2, L3 are Differential Mode Inductors.   2.2.2   The Anti-surge Circuit This anti-surge circuit is composed of R1, R2, R3, Z1, C6, Q1, Z2,  R4, R5, Q2, RT1 and C7. At the instant of switch-on, Q2 does not conduct due to the presence of C6, and the current forms a loop through the RT1. Q2 turns on when the voltage on C6 is charged to Z1's steady voltage value. If C8 leaks or the following circuits are short-circuited, the voltage drop generated by the instantaneous current at the instant of switch-on on RT1 causes the Q1 conducted, so that Q2 does not have a gate voltage and does not conduct, making the RT1 burnt out in a very short time to protect the following circuits.   III. Power Conversion Circuits   3.1   The Working Principle of MOS Tube At present, the most widely used insulated gate FET is MOSFET, which uses the electroacoustic effect that occurs on the semiconductor surface to work, making it also known as surface field effect transistor. Because its gate is in a nonconducting state, the input resistance can be greatly increased up to 105 ohms. The MOSFET uses the gate-source voltage to change the amount of charge induced on the semiconductor surface to control the drain current.   3.2   Common Schematic Diagram FIG.4 Schematic of power conversion circuit    3.3  Working Principle The buffer composed of R4, C3, R5, R6, C4, D1, and D2 are connected in parallel with the MOS transistor switches, so that the voltage stress of the switch transistor and EMI are reduced, without secondary breakdown occurring. When the switch Q1 is turned off, the primary coil of the transformer is prone to generate peak voltages and spike currents. These components are combined to absorb the peak voltage and current well. The peak current signal measured from R3 participates in the duty cycle control of the current operating cycle and is therefore the current limit of the current operating cycle. When the voltage on R5 reaches 1V, the UC3842 stops working and switch Q1 turns off immediately.   The junction capacitances CGS and CGD in R1 and Q1 together form an RC network. The charge and discharge of the capacitor directly affects the switching speed of the switch. If R1 is too small, it will cause oscillation and electromagnetic interference will be great. If R1 is too large, the switching speed of the switching tube will be reduced. Z1 usually limits the GS voltage of the MOS transistor to less than 18V, thus protecting the MOS transistor.   The gate-controlled voltage of Q1 is a saw wave. The larger the duty cycle is, the longer the Q1 conduction time is, the more energy the transformer stores. When Q1 is turned off, the transformer releases energy through D1, D2, R5, R4, and C3 and at the same time, it also achieves the goal of resetting the magnetic field, which prepares the transformer for the next storage and transfer of energy. According to the output voltage and current, the IC adjusts the duty cycle of 6-pin sawtooth wave, thus stabilizing the output current and voltage of the complete machine.   C4 and R6 are voltage surge absorption loops.   3.4  Push-pull Power Conversion Circuit Fig.5 Schematic diagram of push-pull power conversion circuit Q1 and Q2 will be turned on in turn.   3.5  Power Conversion Circuit with Transformer Driver FIG.6 Schematic diagram of power conversion circuit with transformer driver T2 is the transformer driver, T1 is the switch-mode transformer, TR1 is the current loop .   IV. Output Rectifier Filter Circuit   4.1   Forward Rectifier Circuit FIG.7 Schematic diagram of forward rectifier circuit T1 is a switch-mode transformer, its primary and secondary sides are in a same phase. D1 is a rectifier diode, D2 is a flyback diode and R1, C1, R2 and C2 form a despiker circuit. L1 is a freewheeling inductor and C4, L2, and C5 form a π filter.   4.2  Flyback Fectifier Circuit FIG.8 Schematic diagram of flyback fectifier circuit T1 is a switch-mode transformer, and the primary and secondary sides are opposite. D1 is a rectifier diode, and R1 and C1 form a despiker circuit. L1 is a a freewheeling inductor, R2 is adummy load and C4, L2 and C5 form a π type filter.   4.3   Synchronous Rectifier Circuit FIG.9 Schematic diagram of synchronous rectifier circuit Working principle: When the upper end of the secondary winding of transformer is positive, the current through C2, R5, R6 and R7 makes Q2 turned on and form a loop. Q2 is the rectifier and the Q1 gate is turned off due tothe reverse bias. When the lower end of second wingding is positive, the current through C3, N4 and R2 makes Q1 conducted as a freewheeling diode. The Q2 gate is turned off due to the reverse bias. L2 is a freewheeling inductor, C6, L1 and C7 form a π filter and R1, C1, R9 and C4 form a despiker circuit.   V.  Principles of Steady-voltage Loop   5.1  Schematic Diagram of Feedback Circuit FIG.10 Schematic diagram of feedback circuit 5.2  Working Principles When the output U0 is increased, the voltage of pin 3 of U1 chip is increased either after dividing voltage with these sampling resistors R7, R8, R10 and VR1, until exceeding the reference voltage of pin 2 of U1 chip, it begins to output a high level, turning the Q1 and photoelectric triode on, and lighting the optocoupler OT1 and LED. Accordingly, the potential of pin 1 of UC3842 becomes lower and therefore decreases the duty cycle of pin 6 of U1 chip and U0.    On the contrary, when the output U0 is decreased, the voltage of pin 3 of U1 chip is decreased either until it exceeds the reference voltage of pin 2 of U1 chip, it begins to output a low level, Q1 and photoelectric triode are not conducting, and optocoupler OT1 and LED do not shine. Accordingly, the potential of pin 1 of UC3842 becomes higher and therefore increases the duty cycle of pin 6 of U1 chip and U0. Repeatedly, so that the output voltage remains stable. Regulating VR1 can change the output voltage.   Feedback loop is an important circuit that affects the stability of switching power supply. If the feedback resistors and capacitors are wrong, missed or false soldered, self-excited oscillations will occur, resulting in fault phenomena, such as abnormal waveforms, oscillations within empty or full load condition and unstable output voltage.   VI. Short Circuit Protection Circuits   6.1  Current-limiting Circuit In the case of short circuit at the output end, PWM control circuit can limit the output current within a safe range. There are many ways to  realize the current limiting. When the current limiting circuit does not work in short circuit, all we can do is to add additional circuits.   6.2  Short Circuit Protection for Low-power Circuit FIG.11 Schematic diagram of low-power short-circuit protection circuit When the output circuit is shorted, the output voltage disappears, the optocoupler OT1 does not turn on, the voltage of pin 1 of UC3842 rises to about 5V, and the partial voltages of R1 and R2 exceed the TL431 reference, making it conductive, the VCC potential of pin 7 of UC3842 is pulled down, and the IC stops operating. After UC3842 stopped working, the potential of pin 1 disappeared, TL431 did not conduct, and the potential of UC38427 increased, making UC3842 restart, and go round and begin again, until the short-circuit phenomenon disappears, then the circuit automatically returns to normal operation.   6.3  Short Circuit Protection for Medium-power Circuit FIG.12 Schematic diagram of medium-power short-circuit protection circuit When the output is short-circuited, the voltage of pin of UC3842 rises. When the potential of pin 3 of U1 chip is higher than that of pin 2, the comparator inverts the output high level of pin 1 to charge C1. When the voltage across C1 exceeds the pin 5 reference voltage, the pin 7 of U1 chip outputs low level. The voltage of pin 1 of UC3842 begins to be lower than 1V and UC3842 stops working, making the output voltage be zero, and go round and begin again, until the short-circuit phenomenon disappears, and the circuit begins to work normally. R2 and C1 are charge and discharge time constants respectively, and the short circuit protection will not work if the resistance is not correct.   6.4  Common Current-limiting, Short-circuit Protection Circuit FIG.13 Schematic diagram of protection circuit 1 When the output circuit is short-circuited or overcurrent, the primary current of the transformer increases, the voltage drop across R3 increases, the voltage at pin 3 increases, and the duty cycle of pin 6 of UC3842 increases. When the voltage at pin 3 exceeds 1V, the UC3842 turns off and without output.   6.5  Current Transformer Sampling Current Protection Circuit The current transformer sampling current protection circuit which has low power consumption but high cost, and the circuit is often complicated. FIG.14 Schematic diagram of protection circuit 2 The larger the output current is (the extreme case refers to short circuit), the higher the voltage sensed by the TR1 secondary coil. When the voltage of pin 3 of UC3842 exceeds 1 volt, the UC3842 stops working. Go round and begin again, until the short-circuit or overload disappears, the circuit recovers itself.   VII. Output Current Limiting Protection FIG.15 Schematic diagram of protection circuit 3 The above is a common output current limiting protection circuit, and its working principle is as follows:   When the output current is too high, the voltage across the RS (manganese copper wire) rises, the voltage of pin 3 of the U1 chip is higher than the reference voltage of pin 2. Pin 1 of the U1 chip outputs a high voltage, which makes Q1 turned on, and the optoelectronic effect occurs on the optocoupler, the voltage of pin 1 of UC3842 is reduced, together with the output voltage, to achieve the goal of overload protection or current limiting.     VIII. Output Overvoltage Protection Circuits   The role of the output overvoltage protection circuit is to limit the output voltage to a safe value when the output voltage exceeds the design value.    When an internal voltage regulator loop of a switching power supply fails or an overvoltage occurs due to a user's improper operation, an overvoltage protection circuit is used to protect against damage to downstream electrical equipment.   The most commonly used overvoltage protection circuits are as follows:   8.1  SCR Trigger Protection Circuit FIG.16 Schematic diagram of protection circuit 4 As shown above, when the output of Uo1 rises, the Zener diode (Z3) breaks down and it is pulled into conduction, letting the control terminal of the Silicon Controlled Rectifier reach the trigger voltage, so the SCR turns on and the Uo2 is shorted to ground. Then the overcurrent or short circuit protection circuit will work and stop the operation of the entire power supply circuit. When the overvoltage condition on the output terminals is eliminated, the trigger voltage of the control terminal of the thyristor is discharged to the ground through R, and the thyristor returns to the off state.   8.2  Optocoupler Protection Circuit FIG.17 Schematic diagram of protection circuit 5A FIG.18 Schematic diagram of protection circuit 5B As shown in the above figure, when an phenomenon of overvoltage occurs in the Uo, the Zener breaks down and conducts current through the optocoupler (OT2) and R6 to the ground, lightening the light-emitting diode of the photocoupler, which causes the phototransistor of the photocoupler to conduct. The base of Q1 is turned on and the voltage of pin 3 of UC3842 is reduced, turning off the IC and the entire power supply while Uo is zero, and go round and begin again.   8.3  Output Voltage Limiting Protection Circuit FIG.19 Schematic diagram of protection circuit 6 The output voltage limiting protection circuit is shown in the diagram. When the output voltage rises, zener and optocoupler are on, and the base of Q1 turns on either due to a driving voltage according. The voltage of pin 3 of UC3842 rises and the output drops. When the zener is not conducting, the voltage of pin 3 of UC3842 drops and the output voltage rises. As time goes by, the output voltage will be stable within a range (depending on the zener's value).   8.4  Output Overvoltage Lockout Circuit FIG.20 Output overvoltage lockout circuit A FIG.21 Output overvoltage lockout circuit B The working principle is shown in Figure A is that when the output voltage Uo rises, the Zener and optocoupler turn on, and then go with the base of Q2, because of which the base of Q1 is on due to the drop of voltage.   Q2 is on all the time after the voltage of Vcc is through R1, Q1, and R2, making the pin 3 of UC3842 always be conducted with high level and therefore stop working.   In Figure B, the voltage of pin 3 of the U1 chip raises due to big rises of Uo, and pin 1 outputs a high level. Because of the presences of D1 and R1, the pin 1 of U1 chip is always on and outputs a high level, so it is always low and then it stops working. Is it positive feedback?     IX. Power Factor Correction Circuit (PFC)   9.1 Schematic Diagram of PFC Circuit FIG.22 Schematic diagram of PFC circuit 9.2  The Working Principles The input voltage is rectified by an EMI filter composed of L1, L2, L3, and so on and a BRG1, one part of which is then fed into the PFC inductor and another part of which is fed into the PFC controller as the sampling of the input voltage to adjust the duty cycle of the control signal before divided by R1 and R2, that is to change them on and off time of Q1 and to stabilize the output voltage of PFC.   L4 is a PFC inductor that stores energy when Q1 is on and releases energy when Q1 is switched off. D1 is the start diode. D2 is the PFC rectifier diode, and C6, C7 are filtered. One part of the PFC voltage is sent to the downstream circuit, and another part of it is fed into the PFC controller as the sampling of the output voltage before divided by R3 and R4, to adjust the duty cycle of the control signal and to stabilize the output voltage of PFC.     X. Input Under-voltage and Overvoltage Protection   10.1  Schematic Diagram FIG.23 Schematic diagram of input undervoltage and overvoltage protection circuit   10.2  The Working Principles The input under-voltage and overvoltage protection principles of the switching power supply of AC input and DC input are almost the same. The sampling voltages of the protection circuits all come from the same input filtered voltage.   The sampling voltage is divided into two ways, one way is fed into pin 3 of the comparator after divided by R1, R2, R3, and R4. If the sampling voltage is higher than the reference voltage of pin 2, then pin 1 of the comparator will output a high level to control the main controller and make the main controller turned off, so there is no power output. The other way is fed into pin 6 of the comparator before it is divided by R7, R8, R9, and R10.   If the sampling voltage is lower than the reference voltage of pin 5, then pin 7 of the comparator will output a high level to control the main controller and make it turned off, so there is no power output.   How To Make a Switching Power Supply     FAQ   1. What are the 3 types of power supply? There are three subsets of regulated power supplies: linear, switched, and battery-based. Of the three basic regulated power supply designs, linear is the least complicated system, but switched and battery power have their advantages.   2. What is meant by switch mode power supply? A switch mode power supply is a power converter that utilises switching devices such as MOSFETs that continuously turn on and off at high frequency; and energy storage devices such as the capacitors and inductors to supply power during the non-conduction state of the switching device.   3.What are the advantages and disadvantages of switch mode power supply? Advantages & disadvantages of switch mode power supply (SMPS) a. The switch mode power supply has a smaller in size. b. The SMPS has light weight. c. It has a better power efficiency typically 60 to 70 percent. d. It has a strong anti interference. e. SMPS has wide output range. f. Low heat generation in SMPS.   4. What is a DC switching power supply? A Switching DC power supply (also known as switch mode power supply) regulates the output voltage through a process called pulse width modulation (PWM). The PWM process generates some high frequency noise, but enables the switching power supplies to be built with very high power efficiency and small form factor.   5. What is the difference between a switching power supply and a linear power supply? Linear power supplies deliver DC by passing the primary AC voltage through a transformer and then filtering it to remove the AC component. Switching power supplies feature higher efficiencies, lighter weight, longer hold up times, and the ability to handle wider input voltage ranges.   6. Do I need a switching power supply? The switching power supply implies higher efficiency due to the high switching frequency, enabling it to use a smaller, less-costly high-frequency transformer as well as lighter, less-costly filter components. Switching power supplies contain more overall components, therefore are usually more expensive.   7. Is a switching power supply regulated? A switch mode power supply regulates an output voltage with pulse width modulation (PWM). This process creates high-frequency noise but it provides a high-efficiency rating in a small form factor. ... The low DC voltage is finally converted into a steady DC output with another set of diodes, capacitors, and inductors.   8. How do I know if my power supply is regulated? You can generally stick one probe into the middle of the connector, and hold the other against the outside. With a few exceptions, the middle is positive, so use the red lead there, and use the black lead on the outside shell. Regulated supplies, without any load, should measure very close to the target voltage of 12v.   9. Can I use a switching power supply to drive a DC motor?   A simple unregulated analog power supply may be easier and be able to supply the large starting under load current more that the switching one. DC motors are not too fussy about the supply, and will usually run quite well on unfiltered DC.   10. Are switch mode power supplies any good? Switch mode power supplies, SMPS provide improved efficiency & space saving over traditional linear supplies, but care has to be taken to ensure noise on the output is low. Switch mode power supplies are widely used because of the advantages they offer in terms of size, weight, cost, efficiency and overall performance.   You May Also Like: Transformers Basics: Construction, Types, Materials and Design Modeling and Control of Full Bridge Push-Pull Bi-Directional DC/DC Converter Review and Application of Electronic skin How to Drive Thermostat by Using Solid State Relay

DB9 connectors are commonly used in serial communication. This article will focus on the definition and test method of DB9 connector port and introduce DB9 port in detail. Soldering DB9 Connectors Catalog I What is a DB9 connector? II Where are DB9 Connectors used? 2.1 Communication ports 2.2 Network port 2.3 Computer video output, game controller port III How to test the quality of the serial port cable? IV Is serial cable directly connected or crossed? FAQ I What is a DB9 connector? What is DB9 connector and what are the applications of DB9 female and male connectors? Many people do not understand what is DB9 connector. In fact, DB9 connector is a common electrical connector, is one of the common D-Sub type of connectors. DB9 is the smallest model of D-Subminiature connector, DB9 female connector has 9 pin holes, while DB9 male connector is 9 pins. In addition, DB9 connector is DE9 D-sub 9-pin connector, just incorrectly called "DB9" connector, where E is the size of the shell. For example, computer first used DB25 connector as its serial and parallel port when PC serial port started to use DE9 D-sub 9-pin connector. However, due to ignorance, it was usually labeled as DB9 instead of DE9 connector, incorrectly using B to indicate the fact of shell size. So now it is common to sell DE9 connectors as DB9 connectors, and DB9 means 9-pin connector with E size shell. II Where are DB9 Connectors used? 2.1 Communication ports The most widespread use of D-subs connectors is for RS-232 serial communications, although the standard does not mandate such connectors. RS-232 devices originally used DB25, but for many applications, the less common signals were omitted, allowing the use of DB9 female and male connectors. Many uninterruptible power supply units are equipped with DB9 connectors to send signals to a connected computer through the RS-232 interface. These typically do not send data serially to the computer, but instead use a handshake control line to indicate low battery, power failure, or other conditions. However, this use is not standardized between DB connector manufacturers and may require special cables. 2.2 Network port DE9 connectors are used for some token ring networks as well as other computer networks. DB9 connectors are usually used for CAN: DB9 female connectors are located on the bus, while DB9 male connectors are located on the device. 2.3 Computer video output, game controller port III How to test the quality of the serial port cable? 1. Use a multimeter to test whether the two ends are connected directly with a multimeter to determine whether the two ends are connected, just test 2/3/5 pins. To measure the female head, you need to put the multimeter into the pin air. Because the measuring end of the multimeter is relatively thick, it is necessary to weld two relatively thin metal pins or pins with resistance to the pins of the multimeter to facilitate the measurement of the female head. Use the multimeter to measure 2/3/5 of the serial cable. When measuring, use a straight connection, 2/3/5 corresponds to 2/3/5, and cross-wire 2 to 3, 3 to 2, 5 to 5 for measurement (that is, the 2 on one end of the cross serial port is measured at the other end of 3). 2. The situation of using the serial port assistant to send and receive is to connect RXD to TXD and TXD to RXD, use the serial port assistant to short-circuit the 2/3 pin of DB9, and use the serial port assistant to send data. If there is no problem with the serial port, self-transmit and self-receive can be realized. IV Is serial cable directly connected or crossed? 1. Serial port interface and connection method Male and female headers are divided into three types: male-to-female, male-to-male, and female-to-female. The above three types of connection lines have crossover lines and straight lines, so there are a total of 6 connection modes. 2. What is the direct connection and the crossover connection serial cable: 2 pairs 2, 3 pairs 3, 5 pairs 5. Crossover serial cable: 2 to 3, 3 to 2, 5 to 5. 3. Why are there crossover and direct serial lines? The standard DB9 definition is that pin 2 is RXD and pin 3 is TXD. When designing the circuit, some people connect pin 2 to TXD and pin 3 to RXD in order to use a direct connection. If you don’t reversely connect the transceiver and the standard pin definitions when designing the circuit, you have to use a crossover cable. Under normal circumstances: the two female ends are cross wires, and one male and one female are straight lines. Communication conditions: RXD is connected to TXD, TXD is connected to RXD, and the choice is crossover or direct connection according to the circuit design. Make a serial cable: when there is only a straight cable at hand, you can cut it off. Welding 2 to 3, 3 to 2, and 5 to 5 is a crossover cable. FAQ 1. Is DB9 and VGA the same? The VGA connector can use a classic DB9 connector or (more commonly today) a DB15 style connector. ... The VGA connector (15 pin) is still widely used and while it was originally used to carry a 640 x 480 pixel format it is used to carry a variety of geometries including HDTV formats. VGA is an analog standard. 2. What does DB in DB9 stand for? The DB moniker used on multiple Aston Martin models actually stands for David Brown, who purchased Aston Martin in 1947. 3.What is a D-sub connector used for? D-Sub ports are used for connecting external devices to a computer. They are an older method of connection, but some modern computers still contain them. These ports are gradually being replaced by more efficient connection technology, such as USB and Thunderbolt. 4. Is DB9 the same as RS232? RS-232 is a signalling standard, and DB9 is a connector standard. Most cables that are intended to carry RS-232 signals, have DB9 connectors -- but some RS-232 cables have different connectors, and some cables for other signals have DB9 connectors. 5. What devices use DB9? DB9 connectors were commonly used for serial peripheral devices like keyboards, mice, joysticks, etc. Also they are used on DB9 cable assemblies for data connectivity. Today, the DB9 has mostly been replaced by more modern interfaces such as USB, PS/2, Firewire, and others. 6. What is DB 9 connector used for? The DB9 connector is mainly used in serial ports, allowing asynchronous data transmission according to the RS-232 standard (RS-232C). Note that there are DB9-DB25 adapters that easily convert a DB9 socket to DB25 and vice versa. 7. Can you connect DB9 to VGA? Quickly and easily connect your hard-wired MultiSync® monitor from the VGA video card to a 9-pin cable input. Make the right connection! This adapter allows the MultiSync® DB9 style video output port on a desktop or laptop computer to connect to a VGA (HD15) style video input port on a monitor. 8. On what type of cable would you find a DB9 connector? Serial Cable. 6ft DB9 Female to 3.5mm Serial Cable. This is a generic serial cable for devices. It has a stereo 3.5 mm Jack to DB9-F serial port. You can use this cable when you want transfer serial data back and forth from small devices like mobile phones. 9. Which pins on the db9 connector are for communication? Serial communication devices make use of 9 or 25 pin D-type connectors for their cabled connections. They are commonly designated as DB-9 or DB-25 with the number used to differentiate between the pin counts. 10. What is the difference between DB25 and db9 serial ports?

Ⅰ IntroductionPin connectors are made up of various different types of connections. In general, one side is a set of pins soldered to a PCB, and they might be at a right angle to the PCB surface (referred to as "straight") or parallel to the board's surface (referred to as "parallel") (confusingly referred to as "right-angle" pins). These connectors are available in a range of pitches and with any number of separate rows of pins. pin connector A male connector has pins that plug into a female connector. The number of pins in a connector is occasionally used to describe it (for example, "a 25-way D-type connector"). The pinout is a description of the signal associated with each pin. CatalogⅠ IntroductionⅡ 3 pin connector2.1 Basic Information about 3 Pin Connector2.2 Frequently Asked Questions about 3 Pin ConnectorⅢ 4 pin connector3.1 Basic Information about 4 Pin Connector3.2 Frequently Asked Questions about 4 Pin ConnectorⅣ 6 Pin Connector4.1 Basic Information about 6 Pin Connector4.2 Frequently Asked Questions about 6 Pin ConnectorⅤ 7 Pin Trailer Connector5.1 Basic Information about 7 Pin Trailer Connector5.2 Frequently Asked Questions about 7 Pin Trailer ConnectorⅥ 8 Pin Connector6.1 Basic Information about 8 Pin Connector6.2 Frequently Asked Questions about 8 Pin ConnectorⅦ 9 Pin Connector7.1 Basic Information about 9 Pin Connector7.2 Frequently Asked Questions about 9 Pin ConnectorⅧ 12 Pin Connector8.1 Basic Information about 12 Pin Connector8.2 Frequently Asked Questions about 12 Pin ConnectorⅨ 24 Pin Connector9.1 Basic Information about 24 Pin Connector9.2 Frequently Asked Questions about 24 Pin ConnectorⅩ ConclusionⅡ 3 pin connector2.1 Basic Information about 3 Pin ConnectorA three-pin connector consists of three pins: power (5/12 volt), ground, and signal. The signal wire measures how rapidly the fan is moving in the absence of any fan speed controls. The fan speed is normally adjusted by increasing or reducing the voltage across the power wire with this type.  3 pin connector Power connectors for chassis and CPU fans might be 3-pin or 4-pin. 3-pin connectors are typically used for smaller chassis fans that consume less power. CPU fans with significant power consumption typically require 4-pin interfaces. Backwards compatibility exists between fans and on-board fan headers. 2.2 Frequently Asked Questions about 3 Pin Connector1.What to do with 3 pin LED strip connectors?This kit is so well-rounded that it even includes a tool for prying apart connectors without damaging your nails. These connectors are fantastic because they are so easy to use: just position them and snap them together, and you're done! 2.What is a 3 pin socket?The 3-pin plugs are designed to safely supply energy to electrical gadgets. As indicated above, each wire has its own specific color, and each pin must be correctly linked to the three wires in the electrical line. Ⅲ 4 pin connector3.1 Basic Information about 4 Pin ConnectorA four pin connector differs from a three pin connector in that it has an additional (fourth) wire for controlling and sending signals to the fan, which most likely has a chip on it that tells it to slow down or speed up (in addition to the other wires the three pin connector has). 4 pin connector The 4 pin power connector cable (12 volt cable) is intended to provide additional power to the motherboard. These two additional 12 volt cables (two yellow, two black) allow the motherboard to access more power (through these cables). They are typically used to support the CPU, although they can also be employed for other purposes. If your motherboard does not have an extra port, you will not require this additional power. If your motherboard has this port but your power supply does not, you will need to buy a new power supply or an adapter that converts the 4 pin peripheral connector into this 12 volt cable. This cable is sometimes known as the ATX12V or P4 cable, however neither is really valid. 3.2 Frequently Asked Questions about 4 Pin Connector1.What is 4 pin Molex connector?Typically refers to the 4-pin connections used to connect DC power to drives inside a PC cabinet. Molex is a large maker of electrical plugs and sockets that has been in business since the 1940s. 2.Why do you need 4 pin light connectors?They're bright, they're energy efficient, and they're quite simple to use, even when you're creating something from scratch. However, if you require a large number of lights, you will also require something to hold them all together. It's been said that a chain is only as strong as its weakest link, and that anything with LED lights is only as good as its connectors. 3.What is a 4 pin peripheral connector?Peripheral Power Cable (4 Pin) The older IDE hard drives and CD/DVD drives are connected to the power supply through a peripheral power cable. These peripheral power connectors were the original power cables of a computer and were commonly used for hard drives or CD drives. 4.What is the purpose of the 4 pin Molex connector?The 4-pin "Molex" standard connector is a power connector used in computers to power peripheral data drives. It has a 5V and a 12V power supply, as well as ground connections for both. 5.What is a 4 pin auxiliary connector?The 4 pin EPS connector is referred to as the 'tertiary' connector, whereas the 8 pin EPS connector is referred to as the 'auxiliary' connector. In the ATX specification, the 4 pin ATX connector is referred to as the 'auxiliary' connector. Ⅳ 6 Pin Connector4.1 Basic Information about 6 Pin Connector6-pin power connectors are commonly seen in cheap and mid-tier graphics cards. The 6-pin power connector has a 4.2mm pitch and can draw up to 75 watts straight from an external power supply, bypassing the motherboard completely. 6 pin connector When a graphics card requires more power than its PCIe x16 connector can supply, the 6-pin connector serves as a backup power source, allowing the GPU to draw up to 150 watts. 4.2 Frequently Asked Questions about 6 Pin Connector1.What is a 6 pin PCIe power connector?PCI Express (PCIe) 6pin power connector March 1st, 1998 This connector provides additional 12 volt power to PCI Express expansion cards. Because many video cards consume substantially more power than the 75 watts given by the motherboard slot, the 6 pin PCI Express power cable was developed. 2.Do all PSUs have 6 pin connectors?Not all power supplies include PCI-E connectors; some have none, others have one 6/8 pin connector, and some have four or more. When it comes to the PCI-E connector, the simplest rule of thumb to follow is that if the PSU lacks the connector for your card, it was not built to support it. 3.Can you plug a 4 pin into a 6 pin?Everything will be OK. It will be notched in such a way that you can only plug it in one way. 4.What is a 6 pin trailer connector?A 6-way connector provides one wire for trailer brakes and one wire for a battery connection in addition to the basic lighting capabilities of running lights, brake lights, turn signals, and a ground wire. Ⅴ 7 Pin Trailer Connector5.1 Basic Information about 7 Pin Trailer ConnectorTrailer connectors connect the vehicle's electrical systems to those of the trailer or caravan. If you use the indicators, turn on the tail lights, use the brakes, or switch on the fog lights, the trailer or caravan will display the accompanying lights. This is critical for the safety of your driving while towing. 7 pin trailer connector If others behind you are unable to perceive the indications you are providing them, this could result in serious accidents in extreme cases. It is therefore critical to ensure that you have the appropriate fittings and connectors before embarking on a journey with a trailer or a caravan in tow. Trailer connectors are classified into two types: 7 pin and 13 pin. Both are widely used throughout Europe. 5.2 Frequently Asked Questions about 7 Pin Trailer Connector1.What is a 7 pin trailer connector?The 7-Way Trailer Plug is a 2′′ diameter connector with an extra pin for supplemental 12-volt electricity or backup lighting. Towing heavy-duty cargo trailers, aluminum trailers, dump trailers, utility / landscaping trailers, equipment trailers, open car haulers, and enclosed car haulers is common. 2.What is the difference between 4 pin and 7 pin trailer plug?The only real functional difference between them is that the 4-pole trailer connector on part # 37185 is situated to the side of the 7-way, rather than under it, as it is on part # HM47180. Both adapters attach to an existing 4-pole car connector and convert the lighting signals to a 7-way arrangement. 3.Are there different 7 pin trailer connectors?There are two kinds of 7-way connectors: those with flat pins (blades) and those with circular pins. Round pin connectors are extremely rare, although flat pins are popular and frequently found on contemporary SUVs and trucks that come factory equipped with a trailer hitch. Wiring color coding: White = Ground. 4.What is a 7 pole trailer connector?This 7-pole standard RV connector ensures a safe connection between your trailer and tow vehicle. The black plastic construction resists rusting, improves look, and simplifies plug removal. Ⅵ 8 Pin Connector6.1 Basic Information about 8 Pin ConnectorHigh-end graphics cards have 8-pin power connectors. 8-pin connectors have a 4.2mm pitch and can deliver up to 150 watts, which is twice as much as a 6-pin connector. 8 pin connector If a 6-pin connector is inserted into an 8-pin slot, the GPU will attempt to pull more power than the cable is rated for, posing a fire risk. Multiple connections are routinely utilized on high-end GPUs to increase maximum power consumption; the table below illustrates the various 6-pin and 8-pin combinations. Adding more cables has proven less practicable as power needs have increased, as they begin to block air flow and interfere with components in compact places. This is the starting point for the next generation of power connectors. Graphics Card Maximum Power Consumption in WattsPCI Express x166-Pin Connector8-Pin ConnectorTotal Power75W  75W75W1×75W 150W75W 1×150W225W75W2×75W 225W75W1×75W1×150W300W75W 2×150W375W The 8-pin power connector can supply up to 150W to your graphics card. So, if the power usage of your graphics card exceeds 150W, it will almost certainly come with an 8-pin connector or two 6-pin connectors. A graphics card with one 8-pin power connector can receive up to 225W of power, 75W from the PCI Express x16 slot and 150W from the power supply's 8-pin connector. The most recent high-end graphics cards feature an 8-pin power connector, and some of the most power-hungry top-end graphics cards can have both 6-pin and 8-pin connectors, or two 8-pin connectors. A graphics card with both 6-pin and 8-pin connectors can consume up to 300 Watts (75W + 75W + 150W). 6.2 Frequently Asked Questions about 8 Pin Connector1.What is a 8 pin connector called?These are sometimes referred to as "PCI Express cables." They are also sometimes referred to as "PEG cables," where "PEG" refers for PCI Express Graphics. The cable has an 8-pin PCIe power connector. The cable has a 6+2 pin PCIe power connector. 2.What is the 8 pin ATX connector for?An ATX power supply includes a number of peripheral power connectors as well as (in modern systems) two motherboard connectors: an 8-pin (or 4+4-pin) auxiliary connector that provides additional power to the CPU and a main 24-pin power supply connector, which is an extension of the original 20-pin version. 3.Do I need both 8 pin CPU power connector?You must attach the 8 pin connector. If you intend to overclock the CPU, connect both. If you're not using an 8-pin connector. It is not required for normal operation or even a minor overclock. 4.Can you plug an 8 pin into a 4 pin?You can put an 8 pin cable into a 4 pin connector and leave 4 pins hanging over the end, just like you can with a 24 pin cable into a 20 pin motherboard connector, however you may get the same issues with items preventing it from fitting. If it fits, it will be OK. Ⅶ 9 Pin Connector7.1 Basic Information about 9 Pin ConnectorThe word "DB9" refers to a popular connector type, one of the D-Subminiature or D-Sub varieties. The DB9 connector has the smallest "footprint" of the D-Subminiature connectors, with 9 pins (for the male connector) or 9 holes (for the female connector). 9 pin connector The DB9 connector is most commonly seen in serial ports, where it allows for asynchronous data transmission in accordance with the RS-232 standard (RS-232C). It's worth noting that there are DB9-DB25 adapters that can quickly convert a DB9 socket to a DB25 socket and vice versa. 7.2 Frequently Asked Questions about 9 Pin Connector1.Is DB9 and VGA the same?The VGA connector can be a traditional DB9 or (more typically today) a DB15 type connector. While the VGA connector (15 pin) was originally meant to carry a 640 x 480 pixel format, it is now utilized to carry a number of geometries, including HDTV formats. 2.Is there a 9 pin VGA?Pin 9 was deleted from 14-pin cables because the key signal had become obsolete with current computer monitors and was no longer used in the VGA standard's default applications. However, Pin 9 has lately been resurrected as a power supply pin in certain screens to power circuitry. Ⅷ 12 Pin Connector8.1 Basic Information about 12 Pin ConnectorThe 12-pin power connector is the most recent advancement in NVIDIA component power supply. The 12-pin connector has a 3.0mm pitch, hence its overall physical width is the same as that of an 8-pin connector. The connector's architecture has been simplified, with one row for power and the other for ground. 12  pin connector 8.2 Frequently Asked Questions about 12 Pin Connector1. Is there a 12-pin connector?The 12-pin power connector is the most recent advancement in NVIDIA component power supply. The 12-pin connector has a 3.0mm pitch, hence its overall physical width is the same as that of an 8-pin connector. The connector's architecture has been simplified, with one row for power and the other for ground. 2.Does the 3070 require 12-pin?Some board partner 3070s use a six-pin and an eight-pin connector instead of two eight-pins or two eight-pins into the 12-pin adaptor, but this should only be used if your power supply has two eight-pin PCIE connectors. 3.Do I need to buy a 12 pin connector?You are not need to obtain the 12 pin. They are only used by Nvidia Founders Edition cards and come with the video card. Depending on the 3080 you buy, the other brands use two or three 8-pin PCIe cables. 4.Does the 3080 come with a 12-pin connector?You are not need to obtain the 12 pin. They are only used by Nvidia Founders Edition cards and come with the video card. Depending on the 3080 you buy, the other brands use two or three 8-pin PCIe cables. 5.Does the 3080 come with the 12-pin adapter?Yes, Nvidia designed a new proprietary 12-pin power connector to fit on the shortened special PCB inside the GeForce RTX 3080 Founders Edition. The Founders Edition, on the other hand, comes with an adaptor that transforms a pair of 8-pin power cables to the new 12-pin socket. Ⅸ 24 Pin Connector9.1 Basic Information about 24 Pin ConnectorThe ATX 24-pin 12V power supply connector can only be plugged in while the motherboard is pointing in a specified orientation. The original ATX standard included a 20-pin connector with a layout that was very similar to the 24-pin connector but excluded pins 11, 12, 23, and 24. This means that the newer 24-pin power supply is beneficial for motherboards that require more power, eliminating the need for ATX 12V power supplies to include an auxiliary power cord (although some still may). 24 pin connector The extra four pins are often detachable, allowing it to be utilized with a 20-pin motherboard connection. The extra pins simply dangle from the motherboard connector; they do not plug into another slot. Some motherboards allow the older 20-pin power supply cable to be used on a 24-pin motherboard connector. If you need to utilize a 24-pin power supply connector on a motherboard that only supports a 20-pin cable, you can buy a 24-pin to 20-pin converter from a variety of internet suppliers. 9.2 Frequently Asked Questions about 24 Pin Connector1.Can I use a 20 pin connector on a 24 pin motherboard?You can connect a 20-pin cable to a 24-pin motherboard and it will function properly. At least for the time being. They included the extra four pins for a reason. When you insert a 20-pin cable into a 24-pin connector, you are not providing the extra current carrying capacity that the motherboard may require. 2.Do all motherboards have 24 pin connectors?Almost all new power supplies on the market today include a 24-pin power connector for connecting to a computer motherboard. Some motherboards, however, still include a 20-pin ATX power connector. Fortunately, practically all 24-pin power connectors are constructed with four pins that may be disconnected or moved out of the way. 3.How do you remove a 24 pin connector?I did it by pushing the clip, wriggling the connector from side to side, and finally pulling the connector out. If the connector still won't budge, push the clip and wiggle some more. Make certain that you are pushing the clip the entire time. 4.What is the function of 20 24 pin Molex connector?On ATX motherboards, the Mini-Fit Jr. connector can be utilized as the main power connector in 20/24-pin layouts. The same connector design, in single or paired 4-, 6-, or 8-pin combinations, can be used for additional CPU and graphics card power. 5.What is the difference between a 24 pin and a 20 pin motherboard power connector?The 24 pin motherboard connector is essentially a 20 pin connector with four extra pins added to the end. The original 20 pins remained untouched. The additional four pins are not independent rails. They are simply additional lines to give more current to the same rails. Ⅹ ConclusionThere is a wide range of connector types: they can feature holding devices such as pegs, they may require selective soldering, and some are even a "hybrid" of SMT and through-hole. All of these variations can make connectors more difficult to assemble on a PCB, thus it is critical to be aware of potential manufacturing challenges when selecting a connector. When selecting a connector, keep the following points in mind:1) Avoid using through-hole connectors because they have the highest manufacturing costs. Typically, all-SMT designs are less expensive to construct. Even if through-hole components appear to be less expensive, additional production expenses often eat into any savings. 2) Steer clear of connectors that require selective soldering. A connector that requires selective soldering in an otherwise all-SMT design necessitates the assembler doing an SMT/reflow pass, followed by another pass with selective solder. Masking out the components may necessitate additional work. All of this can raise prices and potentially lower yields. 3) Select "pure" SMT connectors devoid of holding features (such as pegs). SMT connectors with retaining components are often more expensive to install. Not all of these components are compatible with all pick and place machines. If using retaining components is required, make the receiving holes as large as possible. Assemblers can and will utilize SMA (surface-mount adhesive) when employing SMT connectors since it is usually strong enough to give more than enough physical strain relief and typically incurs no extra work. 

ROM and RAM belong to the semiconductor memory. ROM is the abbreviation of read only memory, and RAM is the abbreviation of random access memory. ROM can keep data when the system powers off, and RAM is in the opposite, a typical RAM is the computer memory. But sometimes we are not clear: what is the difference between Flash Memory and ROM and RAM? How much do you really know about memory, or RAM, ROM, and flash memory specifically? Here we will tell them in different aspects, this article will act as a guide to basic memories.   Catalog     I What are types of RAM?  1.1 Static RAM (SRAM)  1.2 Dynamic RAM (DRAM) II What are types of ROM? III What is Flash Memory?  3.1 Performance Comparison  3.2 Interface Difference  3.3 Capacity and Cost  3.4 Reliability and Durability  3.5 Simple Operation  3.6 Software Support IV Conclusion FAQ     I What are types of RAM? RAM Upgrade Guide - What You Need to Know 1.1 Static RAM (SRAM) SRAM is very fast and the fastest storage device to read and write currently, but it is also very expensive, so it is only used in demanding places, such as the first and second level buffer of CPU. 1.2 Dynamic RAM (DRAM) DRAM keeps data for a short time and its operation is slower than the SRAM, but it's still faster than the ROM. In addition, it's much cheaper than SRAM. The computer memory is DRAM. DRAM is divided into many kinds, the most common ones are FPRAM / FastPage, EDORAM, SDRAM, DDR, RAM, RDRAM, SGRAM, WRAM and so on. DDR RAM, one of which is introduced here. DDR RAM (Double-Date-Rate RAM), also known as DDR SDRAM, the improved RAM and SDRAM, are essentially the same, except that they can read and write data twice in one clock, doubling the speed of data transmission. This is the most used memory in a computer today, and it has a cost advantage, which in fact defeats another Intel memory~ Rambus DRAM. Many high-end graphics cards are also equipped with high-speed DDR RAM to increase bandwidth, which can greatly improve the pixel rendering capability of 3D accelerator cards.     II What are types of ROM? PROM (programmable ROM), is programmed once that can not be modified, this is an early product, now it is gone. EPROM (erasable and programmable ROM), is a kind of universal memory which erases the original program by ultraviolet radiation. EEPROM, is electronically erased, very expensive, long writing time. For example, mobile phone software is generally placed in the EEPROM, when we call, some of the last numbers that are dialed are temporarily in the SRAM, but not immediately written in the call log (the call record is stored in the EEPROM).   Memory is used to storage data and programs that are currently in use (that is in execution), and the memory of the computer we normally used refers to dynamic memory (that is DRAM). The so-called "dynamic" in dynamic memory refers to when we write data to the DRAM, after a period of time, the data will be lost, so we need an extra circuit to refresh the memory. It works like this: whether a DRAM's memory cell stores 0 or 1 depends on whether the capacitor has a charge. 1 represents a charge, 0 represents no charge. But over time, the capacitance of 1 will discharge, and the capacitance of 0 will absorb the charge, which is why the data is lost. Taking refresh operation regularly checks the capacitor, if the charge is greater than 1/2 of the full charge, it is considered to represent 1, charging the capacitor fully; If the quantity of electricity is less than 1/2, it is considered to represent 0, and the capacitor is discharged to maintain the continuity of the data. ROM III What is Flash Memory? Flash memory combines the advantages of ROM and RAM. It not only has the electrically erasable and programmable capability (EEPROM), but also can read data quickly without power loss (the advantage of NVRAM). This memory is used in USB  and MP3. For the past 20 years, embedded systems have been using ROM (EPROM) as their storage device. However, in recent years, FLASH has completely replaced the position of ROM (EPROM) in embedded systems to store Bootloader and operating systems, or Program code or directly as the hard disk (U disk). At present, there are two kinds of NOR Flash and NAND Flash. NOR Flash reading is the same as the common SDRAM reading. Users can run the code loaded in NOR FLASH directly, which reduces the capacity of the SRAM and saves cost. NAND Flash doesn’t have memory random read technique, which reads in the form of a block at a time, usually 512 bytes at a time, thus it is cheaper. Users cannot run program code on NAND directly, so many developers using NAND have to use a small NOR Flash to startup and run code. NOR Flash, is generally used in small capacity because of its fast reading speed, and it is used to store important information such as operating system. The most common NAND FLASH used for large capacity, combines with embedded system DOC (Disk On Chip) and common "flash disk", which can be erased online. At present, the FLASH on the market mainly comes from Intel, AMD, Fujitsu and Toshiba, and the main manufacturers of NAND Flash are Samsung and Toshiba. NOR and NAND are the two main non-volatile flash memory technologies in the market. Memory IC Intel first developed NOR flash technology in 1988, which completely changed the situation in which EPROM and EEPROM dominated the world. Then, in 1989, Toshiba published its NAND flash architecture, emphasizing lower cost per bit, higher performance, and easy upgrades via interfaces like disks. But after more than a decade, a considerable number of hardware engineers still can not distinguish between NOR and NAND flash memory. Flash memory is often used interchangeably with phase NOR memory. Many in the industry are also confused about the advantages of NAND flash over NOR, because in most cases flash memory is only used to store a small amount of code, and NOR flash memory may be more appropriate, while NAND is an ideal solution for data needed high storage density. NOR is the main non-volatile flash memory technology in the market. NOR is generally used to store a small amount of code, especially in code storage media. NOR is characterized by simple application, no special interface circuit, high transmission efficiency, it belongs to the in-chip execution(XIP, eXecute In Place), so that applications can run directly in (NOR) flash memory. No longer need to read the code into the system RAM. Low write and erase speed can be very cost-effective but affect its performance for small capacity when it is 1~4MB. NOR flash comes with an SRAM interface and has enough address pins to access, it is convenient to storage and use each byte. NOR flash accounts for the majority of the 1~16MB flash market. NAND structure can provide extremely high cell density and high storage density, and fast write and erase speed. The difficulty of applying NAND lies in the management of flash and the need of special system interface. 3.1 Performance Comparison Flash memory is non-volatile memory and can be erased and reprogrammed on memory cell block. The write operation of any flash device can only be done in an empty or erased cell, so in most cases, the erasure must be performed before the writing. In general, the NAND devices perform the erasure operation easily. But NOR requires that all bits in the target block be written as 1 before erasing. Since the NOR device is erased as a block of 64~128KB, the time to perform a write / erase operation is 5s. In contrast, the erasure NAND device is performed as a block of 8~32KB, and the same operation only needs 4 ms at most. The performance gap between NOR and NADN is further widened by the difference of block size in the execution of erasure. It is shown that for a given set of write operations (especially when updating small files), more erasure operations must be performed in NOR based cells. Therefore, when choosing a storage solution, the designer must weigh the following factors: The read speed of NOR is a little faster than NAND, but the writing speed is on the opposite. The 4ms erasure speed of NAND is much faster than that of NOR. Most writing operation need running erasure. The NAND erasure unit is smaller and the corresponding erasure circuit is less. Flash memory 3.2 Interface Difference NOR flash has a SRAM interface, and enough address pins to address, and easy storage and program to every byte inside. NAND devices use complex I/O ports to serially access data, which may vary from product to product or from manufacturer to manufacturer. Eight pins are used to transmit and control address and data information. NAND read and write operations use 512-byte blocks, which is similar to the hard disk management. Naturally, NAND based memory can replace hard drives or other block devices. 3.3 Capacity and Cost The cell size of NAND flash is almost half that of NOR devices. Because of the simpler manufacturing process, the NAND structure can provide higher capacity within a given die size, thus lowering the price accordingly. NOR flash accounts for most of the 1~16MB flash market, while NAND flash is only used in 8~128MB products, which means that NOR is mainly used in code storage, and NAND is suitable for data storage, mainly used in CompactFlash, Secure Digital, PC Cards and MMC memory cards. 3.4 Reliability and Durability One of the key issues needed to consider is reliability when using flahs media. For systems that need to extend MTBF, Flash is a very suitable storage solution. So the reliability of NOR and NAND can be compared between bit switching, lifetime (durability) and bad block processing. - Service Life The maximum number of erasures per block in NAND flash memory is one million times, while that of NOR is 100,000 times. In addition, NAND memory has the advantage of 10: 1 erasure speed, 8 times smaller than that of the NOR device, and each NAND memory block has fewer deletions at a given time. - Bit Switching All flash devices are plagued by bit switching. In some cases (rarely, NAND occurs more often than NOR), a bit reverses or its reversion is reported. One changing bit may not be obvious, but if it happens on a critical file, this minor failure could cause the system to shut down. If existing wrong report, it may be solved by reading it a few more times. Of course, if the bit really changes, the error detection / error correction (EDC/ECC) algorithm must be used. The problem of bit inversion is more common in NAND flash memory, therefore, it is  recommended that using NAND flash memory and EDC/ECC algorithm at the same time. But this problem is not fatal when storing multimedia information in NAND. Of course, if you use a local storage device to store an operating system, configuration file, or other sensitive information, you must use the EDC/ECC system to ensure reliability. - Bad Block Processing The bad blocks in NAND devices are randomly distributed. There have been previous efforts to eliminate bad blocks, but they found that the yield is too low and the cost is too high. The NAND device needs to initialize the medium to detect the bad block and mark it. In the fabricated devices, the failure rate will be high if this treatment cannot be carried out by a reliable method. 3.5 Simple Operation NOR-based flash memory can be used very directly, can be connected as other memory, and can run code directly on it. NAND is much more complex because of the need for an I / O interface. Access methods for various NAND devices vary from manufacturer to manufacturer. When using NAND devices, you must write to the driver before doing anything else. Writing information to NAND devices requires that designers don’t write to bad blocks, which means virtual mapping is necessary all the time on NAND devices. 3.6 Software Support When discussing software support, a distinction should be made between basic read / write / erasing operations and higher-level software for disk emulation and algorithms of flash management, also including the performance optimization. Running code on a NOR device doesn't require any software support. But using a NAND device, you usually need a driver, that is MTD(Memory Technology Driver). Both NAND and NOR devices need MTD when writing and erasing operations. NOR devices requires less MTD, because many vendors offer more advanced software for NOR devices, including M-System 's TrueFFS driver, which is used by manufacturers such as Wind River System, Microsoft, QNX Software System, Symbian and Intel. It also used to simulate DiskOnChip products and manage the NAND flash memory, including error correction, bad block handling, and loss balancing. The main manufacturers of NOR FLASH is INTEL and MICRO, used to be the mainstream of FLASH products, but its market share now squeezed by NAND FLASH. Its advantage is that it can run programs directly from FLASH, but the process is complex, thus it is expensive. NAND FLASH's main suppliers are SAMSUNG and Toshiba, and it widely used in USB drives, memory cards, and MP3 players. With different processes, it has larger storage capacity and is cheaper than the NOR FLASH. But also has the drawback, is unable to address runs the program directly, only used to store the data. In addition, NAND FLASH is very prone to bad blocks, so it is necessary to detect it by the related algorithm.  NAND FLASH is used to store data and programs in laptops, but it must be started with NOR FLASH. In addition to SAMSUNG processors, other mainstream processors for laptops do not support NAND FLASH startup directly. Therefore, you must start the machine with a small piece of NOR FLASH, and run OS and other software through the NAND FLASH load into SDRAM. IV Conclusion The DRAM uses the charge on the gate capacitor of the MOS transistor to store the information. Once the power is down, all the information will be lost. Because the grid will leak, it needs refresh operation to replenish the charge on these gate capacitors regularly. And every time the data is read out, it requires running the same work. This is called dynamic refresh, so it is called dynamic RAM. Because it uses only one MOS to store information, it can be highly integrated and can do a lot of work. SRAM uses registers to store information, so once the power is down, the data will be lost. But when the power supply, its data will always exist without the need for dynamic refresh, thus it is called static RAM. The above is mainly used in the system with large capacity, do not need to recover data through refresh operation. Flash ROM uses the capacitor on the floating gate to store the charge to store the information, because the floating gate does not leak, so the information can still be saved after the power is off. Also because of its simple mechanism, it can be integrated highly, and the capacity can be very large. Flash rom needs to be erased by electricity before writing, but in different approach of erasure, EEPROM can be erased in bytes, and flash rom can only be done in sector. However, it can be written in byte units, mainly used for bios, U disk and Mp3 devices that require large capacity and data storage when power is down.   FAQ   1.What is ROM and its function? Read-only memory (ROM) is a type of storage medium that permanently stores data on personal computers (PCs) and other electronic devices. It contains the programming needed to start a PC, which is essential for boot-up; it performs major input/output tasks and holds programs or software instructions.   2. What are the four types of ROM? MROM (Masked ROM) ... PROM (Programmable Read Only Memory) ... EPROM (Erasable and Programmable Read Only Memory) ... EEPROM (Electrically Erasable and Programmable Read Only Memory) ...   3. What is a RAM in a computer? RAM stands for random-access memory, but what does that mean? Your computer RAM is essentially short term memory where data is stored as the processor needs it. This isn't to be confused with long-term data that's stored on your hard drive, which stays there even when your computer is turned off.   4. What is flash memory used for? Flash memory is a long-life and non-volatile storage chip that is widely used in embedded systems. It can keep stored data and information even when the power is off. It can be electrically erased and reprogrammed. Flash memory was developed from EEPROM (electronically erasable programmable read-only memory).   5. Is Flash memory a RAM or ROM? RAM is Read Only Memory. Unlike RAM, ROM is the persistent storage. ... Flash Memory is one category of ROM i.e Electrically Erasable Read Only Memory (EEPROM).   6. What is flash memory and its types? Flash memory is a type of erasable read-only memory (EEPROM) that clears and rewrites data in chunks for fast, energy-efficient access and rewriting. Flash memory, or flash storage, is non-volatile, which means it remains viable even without an active power source.   7. What is RAM and ROM? RAM, which stands for random access memory, and ROM, which stands for read-only memory, are both present in your computer. RAM is volatile memory that temporarily stores the files you are working on. ROM is non-volatile memory that permanently stores instructions for your computer.   8. Which is better RAM or ROM? RAM is random access memory and cannot hold the data without the power, whereas ROM is a read-only memory and can hold the data even without the power. ... With RAM, writing data is a much faster and lightening process, whereas ROM, writing data speed is much slower as compared to RAM.   9. What are the disadvantages of ROM? The disadvantages of Erasable Programmable ROM (EPROM) are: The static power consumption is high as the transistors used have higher resistance. It is not possible for a particular byte to be erased, instead the entire content is erased. UV based EPROM takes time to erase the content.   10.What are the disadvantages of RAM? If CPU wants to read data only from the RAM, then the data access from the cache and the registers is slow in comparison to ROM. RAM is volatile, which means it is difficult to store data for a lengthy period of time. Unplanned circumstances like a power outage can result in data loss.   11. What is the work of ROM? Read only memory (ROM) provides permanent storage for instructions needed during bootstrapping, or the process of turning on the computer. It does so by storing the BIOS and other firmware for the computer hardware. This firmware is very hardware-specific and rarely needs updating.   12. Why is more RAM better? Generally, the faster the RAM, the faster the processing speed. With faster RAM, you increase the speed at which memory transfers information to other components. Meaning, your fast processor now has an equally fast way of talking to the other components, making your computer much more efficient.   13. Is RAM is a volatile memory? Volatile memory is computer memory that requires power to maintain the stored information. Most modern semiconductor volatile memory is either Static RAM (see SRAM) or dynamic RAM (see DRAM).   14. Why is ROM so important? ROM provides the necessary instructions for communication between various hardware components. As mentioned before, it is essential for the storage and operation of the BIOS, but it can also be used for basic data management, to hold software for basic processes of utilities and to read and write to peripheral devices.   15. What is stored in ROM? ROM is memory that cannot be changed by a program or user. ROM retains its memory even after the computer is turned off. For example, ROM stores the instructions for the computer to start up when it is turned on again.