How Did the Amazon River Get Its Name?

A South American legend has it that when the spanish conquistadores made their expedition through the Amazon rainforest they arrived at a great river, starving and exhausted due to illnesses and weather. From the other side of the river, they spotted a number of naked human figures that looked like women and before anyone could react to them they threw a rain of arrows on their heads and dissappeared again into the foliage. Due to the conditions the men were in this couldve very well been an hallucination, hence why it is a legend.

Once the conquistadores came back and told their stories they referred to the tribe of women as amazons, adapting the name from greek mythology. Thus the river theyd discovered came to be known as the river of the Amazons or the Amazon river

· Related Questions

What did the scientist Maxwell do?

Well, you know, sat about a lot not doing much, like most scientists.

When he was bored he came up with his Dynamical Theory of the Electromagnetic Field which pretty much laid the foundation for physics as we know it today.He did other stuff too. The large structures that people like me hang over multi million dollar superstars have a lot to do with his work on rod and joint frameworks, you know, trusses like the ones that supported the floors of the WTCs.

Apart from that? Not a lot. Oh, I forgot that Maxwell-Boltzmann distribution thing, because I always hated statistics.

He was one of the most important people ever to work in the natural sciences. He would be in everybodys top five, maybe three; some might have him at number one on the scientific hit parade. If Newton stood on the shoulders of giants like Copernicus, Galileo, Kepler and others, Einstein stood on Clerk-Maxwells

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Is Mitch McConnell starting to regret covering for Trump during the impeachment trial?

The entire impeachment degraded the Congress. It was a desperate effort on the part of the Dems to get Trump removed from the office and from the ballot -they said they could not beat him unless they impeached him.McConnell Im sure has fully reassurance he did the right thing when Biden was promoted as the Dem candidate and then Biden adopted the most pro-Marxist platform of any major party in the history of the country.

As it stands, it would be miraculous - I mean fire-on-high - for Biden to secure more than 30M votes in November. I seriously doubt there are even 10M Dem voters who would approve the platform by voting for Biden.But the whole notion that the Democrats are moderate, has been tossed out the window.

Anyone voting for Biden is by definition declaring themselves hard-Left

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What if Gunther and Rachel got married?

So, Gunther and Rachel got married huh? Here are the possible scenarios that could have happened, in that seemingly impossible assumptionu2026Ross would not want to come again at the coffee shop.

He will be like.u201cyou,. you see her, u2026aahmm.

how happy she is.and then crying his hearts out.Joey: Hey!

Rachel can I now have coffee here for free? Oh wait! can I have those cookies with it too.

Chandler: Oh no! I am gonna die alone, now even Gunther is married and look at me! I am just sitting here making jokes.

Hey Rach, what's up with u201cgunchelu201d?.(Joey would not understand it)Monika: Hey, let me organise a grand reception for your marriage and oh!

I will cook lasagna. Yeah, yeahu2026everybodyu2026(Chandler says. .

meh!)Phoebe: You know what's better than getting married? Having a family.

,which by the way I never had.-Bonus.Janice: Oh!

My God. ;)

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How was Einstein influenced by Maxwell?

Einsteins creation of Special Theory of Relativity arose from the necessity to satisfy the principle of relativity which says that all laws of nature should be the same for all observers.

Maxwells Equations is one of those laws of nature which should preserve its form from one stationary observer to another moving observer.Einstein assumed that Maxwells Equations is a true description of how nature works and therefore is a valid law of nature. He then sought to find transformation equations which would retain the form of Maxwells Equations and which should also preserve the speed of light for both the stationary observer and the moving observer.

He was able to derive the transformations which we now know as the Lorentz Transformations first derived by the Dutch theoretical physicist Hendrik Antoon Lorentz and by the French mathematician Henri Poincare

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Which is worse, physical pain or emotional pain?

Neither. Emotional and Physical Pain Activate Similar Brain Regions.

When people feel emotional pain, the same areas of the brain get activated as when people feel physical pain: the anterior insula and the anterior cingulate cortex.our bodies decided to take the economy route and use a single neural system to detect and feel pain, regardless of whether it is emotional or physical. In fact, people who take Tylenol for emotional pain can feel temporary relief similar to taking Tylenol for a headache.

The study, Acetaminophen Reduces Social Pain: Behavioral and Neural Evidence, says:We used functional magnetic resonance imaging to measure participants brain activity and found that acetaminophen reduced neural responses to social rejection in brain regions previously associated with distress caused by social pain and the affective component of physical pain (dorsal anterior cingulate cortex, anterior insula). Thus, acetaminophen reduces behavioral and neural responses associated with the pain of social rejection, demonstrating substantial overlap between social and physical pain. Physical and emotional pain works the same way in our brain.

Both are equally bad

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A fact is a thing that is known and a thing to be proven. Is this true or false?

First, you are trying to evaluate a word definition (as a normative expression) as being true or false.

By true, you might mean u201creflective of common usageu201d. One way of assessing common usage is to consult dictionaries. In your case:Definitions of fact - OneLook Dictionary SearchI donu2019t see your definition reflected in any of the definitions I see there.

You might be trying to establish a new, alternative meaning that you think better reflects common usage, or has some other advantage, such as operativity. I find it hard to see how true or false might apply in this case. For what it is worth, I think fact is a proposition that you think should be useful to others, independent of you as an observer.

Unlike propositions regarding the natural world, mathematical facts can potentially be proven, which can help establish mathematical utility. There are many things that I know that are not facts.

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What is the solution to flood and drought at the same time in a country?

When it is happening, there is no real solution other than search and rescue in flood and conservation in drought. Unless the flooding is from a truly overwhelming, historic condition, the only solution is civil engineering which requires analysis, planning and construction. That is long term.

The same can be said for drought. What is the best way to conserve water for such times?In southern California, we have an example of both, in a way.

The long term system is designed to prevent damaging floods - which means in drought, water is not conserved but sent quickly out into the ocean. Changes are being made.The idea of moving water from one area of a country to another depends on the size of the country and the geography.

Certain conditions just are and there is no way to effectively get water , by example from Texas and Louisiana that are being doused to Southern California, New Mexico and Nevada. what is the solution to flood and drought at the same time in a country?

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How did Trump hijack the Republican Party?

Mostly by saying outrageous things that the media reflexively repeated across the world at no cost to the Trump campaign.He got a lot of votes from people who believe that all press is good press, or that anyone who is pissing off this many people must be doing something right, or that any change is better than leaving things the same (the biggest lie in politics?).

This is terrible but popular reasoning.There is also a long American tradition of hyperbolic condemnation. People don't just make mistakes, they're crooks.

They're communists or fascists or the anti-Christ because of small differences in policy or ideology. We exaggerate everything, which makes us expect everything we hear to be exaggerated. We learn to ignore the cries of "Wolf!

" And now the wolf is here, and no one believes the sounding alarm.(Even this answer is exaggerating! It's my habit as well, even when I recognize and resist that habit.

)Those are the main reasons Trump succeeds.

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How long does an LCD TV last?

The biggest determining factor in a televisions lifespan is its lights.

5u20137 years is probably a fair rule of thumb, but if you were to go by most manufacturer specifications, they claim the lighting last up to (and sometimes more than) 100,000 hours. Theoretically an OLED should last much longer, but they slowly lose light output over time. 5u20137 years assumes 40,000 - 60,000 hours of 24 hour use or less.

So itu2019s pretty generous. But after 5u20137 years itu2019s likely worthwhile to upgrade, anyway. As TVs have become so much more affordable, 7 years use equates to as little as $3.

60 / month for an entry-level 55u201d 4K UHD HDR television.So in the big grand scheme of things, TVs have a pretty long expectancy of life. Theyu2019re definitely built to outlive technology advances that motivate the average consumer to upgrade.

I hope the info helps. What is the life expectancy of an LCD TV?

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Can the President of the United States fire the Vice President?

No, the Vice President is different from members of the Presidents cabinet.The cabinet serves at the Pleasure of the President, which means he can fire anyone in his cabinet. To remove a sitting Vice President requires impeachment proceedings, which authority rests solely with the House and Senate, respectively.

One interesting wrinkle related to this lies in the 25th amendment; Section 4 allows the Vice President, along with a majority of the cabinet principals, to declare the sitting president unable to discharge the powers and duties of his office and convey that declaration to the house and senate.In this regard, the Vice Presidents job security can be construed to be a check to the power of the president himself, (unless of course his cabinet or the legislature back the president). This is theoretical of course; this section has never been invoked.

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What is Andrew Weill's opinion on Donald Trump releasing his personal tax returns?

He promised that he would.His promise is worthless.

Trump has the right to refuse to disclose the returns voluntarily.A good federal prosecutor knows how to get disclosure if relevant to his investigation.Robert Mueller, the Special Counsel, is as good as they come.

This answer is not a substitute for professional legal advice. This answer does not create an attorney-client relationship, nor is it a solicitation to offer legal advice. If you ignore this warning and convey confidential information in a private message or comment, there is no duty to keep that information confidential or forego representation adverse to your interests.

Seek the advice of a licensed attorney in the appropriate jurisdiction before taking any action that may affect your rights. If you believe you have a claim against someone, consult an attorney immediately, otherwise there is a risk that the time allotted to bring your claim may expire. Quora users who provide responses to legal questions are intended third party beneficiaries with certain rights under Quora's Terms of Service (http://www.

quora. com/about/tos).

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Is the Traditional Energy-saving Lamp Regulator Used for LED Circuit? Detailed Analysis of 11 Defect
Is the Traditional Energy-saving Lamp Regulator Used for LED Circuit? Detailed Analysis of 11 Defect
Can the controller of traditional energy-saving lamp act on LED circuit?There are many options for buying LED bulbs, but compatible led dimmers are difficult to choose. Many users will confidently say that it is OK to use the dimmer of traditional incandescent lamps. Now the most commonly seen on the market is thyristor dimmer, which is divided into DC and ac. it is very easy to use in incandescent lamps.After selecting the LED lamp with appropriate color temperature, lumen grade and beam angle, the dimming requirements are met. Different from the random dimming method of ordinary incandescent lamps, dimming LED bulbs with thyristors may be successful, but many problems will occur in most cases.Four conditions:The most common problem is that there is a buzzing beep or a strong stroboscopic. Ordinary incandescent lamps only need to adjust the voltage to adjust the light and shade, but it may not work for LED lamps. We have done experiments and the following four situations have occurred:1. It can't be opened at all. It doesn't light up at all!2. It can only be on at 100% illumination.3. It can work normally, but the buzzing sound is very loud.4. Stroboscopic occurs when it is adjusted to a certain brightness.Dimming principle:During the test, sometimes the LED can be used normally after it is dimmed to a certain limit. We judge that the reason why it doesn't light up is that the applied voltage of the dimmer is too small to reach the required voltage.The internal circuit of LED is much more complex than that of incandescent lamp. The real led dimmer is not only regulating voltage, but also has three principles:1. Wave width control dimming: digitize the square wave of the power supply and control the duty cycle of the square wave, so as to control the current.2. Constant current power supply regulation: the current can be easily adjusted by analog linear technology.3. Grouping control: group multiple LEDs and control them with a simple grouping device.Note the strobe:The reasons for the most stroboscopic cases are as follows: the adjustable resistor itself is not a very reliable component. Often, due to the entry of dust or the lax manufacturing process, there will be an instant jump fault when operating the adjustable resistor, and the light source will flash. Therefore, we need high-quality adjustable resistance, or use linear technology to regulate current rather than voltage.In fact, the internal driving function of LED itself can easily adjust the brightness and darkness, but most LED manufacturers remove this function to save costs. Whether the LED lamp can be dimmed is usually marked on the box. If there is no mark on the box, please use the dimming function with caution or use a special LED dimmer.Dimming will reduce life:A reminder is that dimming can easily reduce the life of the bulb. Why? Simply take a dimming method: we divide one second into 1000 parts, each part is 1 millisecond, and then make the LED light work for 7 milliseconds and turn off for 3 milliseconds through the control chip. In this way, it only works for 0.7 seconds in one second. However, due to the fast flashing interval, we can't feel its brightness flickering with our naked eyes, and we will only feel that its brightness has darkened, which is 0.7 times the original, This achieves the effect of dimming. Similarly, we can achieve 50% brightness, 32% brightness and any brightness. Blink in this way, it's strange not to break early!In order to avoid various problems, try not to use the physical dimming method for the smart bulb. Take out the mobile phone and open the app to adjust the light and shade.In fact, I still like to use the way of grouping device to control the brightness, which is simple, safe and easy to use. It can be easily done by touching the key switch or independent grouping switch. It is not necessary to fine tune the brightness from 0 to 100% perfectly in the home. It is OK to realize several levels of brightness adjustment, which can fully meet the needs.Analysis and retrieval of 11 disadvantages of LED wick:Compared with traditional incandescent lamps, led filament lamps have higher requirements for packaging. It is reported that at present, led filament lamps have very strict requirements for filament working voltage design, filament working current design, LED chip area and power, LED chip luminous angle, pin design, glass bulb sealing technology, etc. it can be seen that the manufacturing process of LED filament lamps is very complex, and there are certain requirements for the financial strength, supporting facilities and technology of manufacturers.In the production process, due to different processes, the requirements for materials are also different. In addition, in production, many equipment need to be transformed according to the performance characteristics of LED filament lamps, which also makes the manufacturers of relevant materials of LED filament lamps miserable. The defects in the bulb material also make the LED filament lamp easy to be damaged during transportation. The complex process and low yield make the LED filament lamp unable to obtain high praise from manufacturers and consumers.1. Difficult process, poor heat dissipation and easy damageAlthough led filament lamps have attracted much attention in the domestic market in the past two years, at present, the problems existing in the production of LED filament lamps can not be ignored: the manufacturing process is difficult, several different processes need to be integrated, and the yield is low; More than 8W led filament lamps are prone to heat dissipation problems; It is easy to be broken and damaged in the process of production and use.2. Structure, performance and price to be improvedDue to the relatively late entry of LED filament lamps into the market, the market-related sharp bubbles, tail bubbles and spherical bulbs are mainly "patch type". In addition, the filament lamps that entered the market in the early stage are far from consumers' expectations in terms of structure, performance and price, which makes consumers have some misunderstandings about led filament lamps. With the breakthrough of key technologies, the maturity of packaging technology and the improvement of bubble sealing technology, the luminous efficiency, finger display, service life and cost of LED filament lamps will be improved to a certain extent.At present, the LED filament lamp needs to be improved in too many places. It is like a newborn "premature baby". It is not very mature in all aspects, with high cost, complex production process and low production capacity. Therefore, we should improve the raw materials, led beads and manufacturing process in the future, so as to improve the production capacity of LED filament lamps, reduce losses and improve delivery efficiency.3. Low power and poor heat dissipation are obstaclesAffected by the production process, there are many problems in LED filament lamps, such as high cost and high damage rate during transportation due to the defects of bulb material. In addition, the heat dissipation of high wattage led filament lamps has also become an obstacle for LED filament lamps to enter ordinary people's homes.Problem 2: high priceAccording to the market survey, the average retail price of a 3W led filament lamp is about 28-30 yuan, which is much higher than that of LED bulb lamps and other lighting products with the same power, and several times higher than that of LED incandescent lamps with the same power. Therefore, many consumers are scared away by the price of LED filament lamps.At this stage, the market share of LED filament lamps is less than 10%. Nowadays, as a characteristic product, led filament lamp restores the luminous feeling of traditional tungsten filament lamp and is loved by many consumers. However, the high cost, low light efficiency and small application range of LED filament lamps are also the problems that lighting manufacturers must face and look directly at in the next stage.1. Supporting materials increase product costThe market prospect of LED filament lamp is very bright, but there are difficulties in the promotion of LED filament lamp at this stage, mainly due to its high cost and the lack of large wattage, which makes the application of LED filament lamp limited to the flower lamp market. In addition, the matching of raw materials also increases the cost, because there is no standard in the specification and shape of filament lamp, and its market volume is small, As a result, the supporting materials are basically customized, and the manufacturing cost remains high.2. The cost of LED filament is too highAmong all parts of LED filament lamp, the highest cost is led filament, mainly because of its complex production process and high cutting cost; The production efficiency is not high and the degree of automation is low, resulting in the cost. At present, the cost of 3-6w filament bulb can be controlled below 15 yuan, of which the cost of LED filament accounts for more than half.3. The packaging of LED filament lamp is exquisiteThe packaging of LED filament lamps is more exquisite. The light effects encapsulated by each enterprise are different. Led filament lamps still have certain limitations in power and heat dissipation, resulting in higher prices than ordinary LED light sources.Problem 3: small marketAt this stage, the power of the best-selling led filament lamp in the market is basically less than 10W, which shows that at this stage, the LED filament lamp is technically trapped in the problem of heat dissipation and can not achieve high power. It also shows that it can only cover a small section of the whole lighting product line and can not be widely promoted. Even if it plays the "nostalgic" brand, the LED filament lamp market is only a small market, It can't become the mainstream for the time being.1. Low consumer acceptanceWith the shrinking incandescent lamp and energy-saving lamp market, LED lighting products are slowly recognized by end consumers. However, at present, the market of LED filament lamps is still very limited. Due to the limited application and power of LED filament lamps, the acceptance of LED filament lamps by end consumers is not very high.In addition, consumers do not know enough about led filament lamps. Many people think it is just an improvement of ordinary incandescent lamps.2. The main demand comes from the projectAs LED filament lamps are mainly used in flower lamps, and their main demand comes from engineering lighting, general dealers will not mainly promote LED filament lamps. Even if a few businesses sell LED filament lamps, they won't have too much inventory.Problem 4: difficult to promoteEntering the terminal market, we can find that the LED filament lamp is not as hot as expected for two reasons:1、 Many stores do not promote filament lamps as key products, and consumers' awareness and acceptance of filament lamps are not high;2、 Compared with LED light source products such as bulb and sharp bulb, led filament lamp products have no qualitative change. On the contrary, the price is relatively high and it is difficult to go. Let alone replace the market position of LED bulb, energy-saving lamp and other products.Therefore, at present, the market advantage of LED filament lamp is not very obvious, and the market is basically waiting and trying.At present, the difficulty of pushing led filament lamps in the terminal market lies in:1、 Poor integration between traditional bubble sealing industry and LED packaging industry (concept and process integration);2、 It is not easy to reverse the concept of end consumers;3、 The acceptance of LED filament lamp products by society and government is not clear. In addition, the price of LED filament lamp is high, and consumers have not really distinguished the difference between LED filament lamp and incandescent lamp, which leads to the difficulty of LED filament lamp market promotion.1. Merchants are not active in promotionAt present, if led filament lamps want to achieve good performance in the market, they also need to strengthen publicity and innovation. The development of LED industry is increasingly fierce, and industry standards have been issued one after another, which has exacerbated the market development resistance of LED filament lamps. Especially at this stage, many consumers do not understand led filament lamps, and merchants are not active enough in promoting led filament lamps. Even most merchants are not very optimistic about their development prospects. In actual sales, customers usually see or ask, Businesses will push this product.2. High price makes promotion difficultAt present, it is difficult to promote LED filament lamps in the market. Because consumers do not know much about led filament lamps, the probability of purchase is very small. In addition, due to the impact of e-commerce, the transaction rate of LED in physical stores is lower. Some consumers pay more attention to the price when purchasing products. Therefore, there is still a long way to go for LED filament lamps to enter the families of ordinary consumers.3. Lack of new selling points of LED filament lampsAt present, led filament lamp is in the primary stage of promotion, and very few people know its advantages because of the appearance and original quality of the product
The Market Prospect of LED Transparent Screen Is Considerable
The Market Prospect of LED Transparent Screen Is Considerable
As the "Darling" of the current LED display market, led transparent screen is becoming more and more popular in the display field with the continuous maturity of industrial chain technology and the continuous decline of cost, as well as the concepts of intelligence, new retail and immersive vision. According to the data of relevant prediction institutions, the market output value of transparent display will be about 87.2 billion US dollars by 2025, so the market prospect of LED transparent screen is very promising.As we all know, led transparent display is favored by the market because of its transparent, thin, easy installation, energy conservation and environmental protection. Especially in recent years, the rectification of urban appearance has accelerated, and led transparent display is becoming more and more irreplaceable in China's urban landscape display market. With the increase of extensive market demand, led transparent screen technology and products are also developing and innovating, especially the application of interactive technology makes led transparent screen more attractive.1、 Advanced technology and continuous innovation of LED transparent screenAt present, the LED transparent screen can realize human screen interaction by carrying touch technology (sensor), infrared sensing, VR AR, face recognition, etc. at present, the field of LED floor tile screen is the most widely used technology. In addition, the combination of transparent LED display screen and Internet can be realized through screen network linkage. Use mobile phone, PC and other ports for networking operation, combined with QR code, app and other functions, to realize the joint interaction between the LED transparent screen and the audience, stimulate the growth of audience interest and enhance the audience's participation.Moreover, led transparent technology, product structure and product application are also continuously improved and innovated. For example, led curtain wall screen, led film screen, LED strip screen, led grid screen and led transparent screen of cob packaging technology all show that the current transparent LED display screen is developing in multiple technologies and directions.2、 Demand innovation and customization trend is obviousFirst of all, the current market for LED transparent screen is the medium and high-end market and professional display market. The needs of customers in these markets are more professional, personalized and demanding. In this context, the LED transparent screen market is further subdivided, and more and more customized led transparent products and solutions continue to appear, which also accelerates the professional customization development trend of LED transparent screen industry.At the same time, the customized led transparent screen has higher technical requirements and more stable product performance, which also puts forward higher requirements for the R & D, production, marketing, enterprise management and after-sales service of LED transparent screen enterprises. Screen enterprises need to constantly update and improve the whole operation system chain in order to better adapt to and serve the market.However, we must face up to the fact that compared with traditional display products, the high price of LED transparent screen will still be prohibitive, which also leads to the difficulty of starting the volume of LED transparent screen market. Manufacturers are constrained by costs and cannot research and produce many application fields; At the same time, from the perspective of industrial development, at present, there are only a few large LED transparent screen enterprises, and few enterprises can realize the customization of LED transparent screen. Facing the outbreak of the market, how to improve the stability of technology and products and the mass production strength of the industrial chain as soon as possible is the challenge faced by the whole LED transparent screen industry.
When Will the National Standard for LED Solar Street Lamps Be Improved
When Will the National Standard for LED Solar Street Lamps Be Improved
At present, the lighting electrical products that have carried out energy-saving certification include: self ballasted fluorescent lamps for general lighting, double ended fluorescent lamps for general lighting, single ended fluorescent lamps, high-pressure sodium lamps, electrodeless lamps, (gold halide lamps) metal halide lamps, ballasts for tubular fluorescent lamps, ballasts for high-pressure sodium lamps, (gold halide lamps) metal halide lamps and road lighting systems. After two years of technical research and development, China Quality Certification Center (CQC) will soon carry out energy-saving certification for semiconductor (LED) and electrodeless lighting products, mainly including electrodeless road / tunnel lighting products, led downlights and reflective self ballasting LED lamps.CQC is an energy-saving product certification organization accepted by the state, and has established a certification and identification system for high-efficiency lighting electrical products. All products in the government procurement catalogue of energy-saving products shall pass the "section" mark certification of CQC before they can be adopted by government procurement.According to the voluntary principle, enterprises can apply for energy-saving certification. If the applied products meet the requirements of product energy efficiency standards (or technical specifications) and the implementation rules of energy-saving product certification, and are reviewed and confirmed by CQC, they can obtain the China energy-saving product certification certificate issued by CQC. After signing the agreement on the use of certification certificate and mark with CQC, the enterprise can use the certification certificate and "section" mark on the advertising and publicity materials of the certified products.Solar street lamp manufacturers introduced the implementation of lighting energy-saving measures. The national investment is the smallest and the effect is the most obvious. Since July 18, 2006, China has included energy-saving certified products in the government procurement catalogue. In order to further expand the scope of government procurement of energy-saving products and strengthen the government procurement of energy-saving products, according to the notice of the general office of the State Council on establishing the system of government compulsory procurement of energy-saving products and the opinions on the implementation of government procurement of energy-saving products, the Ministry of finance In July 2010, the national development and Reform Commission readjusted and published the eighth "government procurement list of energy-saving products", which identified air conditioners, lighting products (including double ended fluorescent lamps, self ballasting fluorescent lamps, single ended fluorescent lamps, tubular fluorescent lamp ballasts), televisions, electric water heaters, computers, printers, displays, toilets Nine categories of products, such as faucets, are energy-saving products that the government compulsorily purchases.
Application Analysis of Constant Current Ic-nu510 for LED Light Box
Application Analysis of Constant Current Ic-nu510 for LED Light Box
1: IntroductionLED modules are widely used in blister words, luminous words and other advertising light sources with the characteristics of high brightness, high luminous efficiency, low cost and easy installation. The traditional LED backlight module generally adopts the scheme of DC12V / 24V power supply, 3 / 6 LED beads and a current limiting resistor. This scheme has the advantages of low cost and simple manufacture, but it also has obvious disadvantages:A: The brightness consistency of the front and rear modules is poor. Due to the voltage drop on the conductor, the front modules are relatively bright and the rear modules gradually darken. Although it can be improved by adding power at both ends, the method of adding power at both ends will cause the phenomenon of bright at both ends and dark in the middle, which increases the construction difficulty; Especially when the module current is large, the defect is more prominent.B: The number of LED modules that can be connected in series is small and the length is short. The length of traditional resistance current limiting modules is generally about 5m. If the number of modules is increased, the power interface needs to be increased; At the same time, the difficulty of installation and construction is also increased.C: The LED module is ordered to be short. The LED module generally works in a sealed environment, with difficult heat dissipation and high working environment temperature. The LED is a current driven component, and the VF of the LED decreases with the increase of temperature, resulting in the increase of voltage on the current limiting resistance. The working current of the module will increase with the increase of temperature. Therefore, the increase of temperature will accelerate the aging of the LED and reduce the service life of the LED module. With the development of technology, LED modules are developing towards higher brightness and higher current, and the market share of modules with high current and 24V power supply is increasing. However, under the condition of high current and high voltage, the above disadvantages of LED modules with resistance current limiting mode will be more significant.2 advantages of using nu510Nu510 is a low dropout linear constant current IC very suitable for LED module applications. The module developed with nu510 has the following outstanding advantages:A. The brightness is highly consistent, and the use of nu510 can ensure the current deviation between modulesB: The number of LED modules connected in series can be extended and the installation is more convenientC: It can prolong the service life of the module. The LED module with constant current IC scheme works in the constant current state. Therefore, even if the temperature increases, the working current of the LED is always constant, and there will be no problem of accelerating aging and reducing the service life. In case of abnormal overheating, the constant current IC also has overheating protection function to automatically PWM dimming the output and reduce the temperature.3 function introduction of Taiwan digital energy nu510Nu510 is a low differential pressure linear LED constant current drive chip, which provides a single channel constant output current. The current output range is 10 160mA. The current value can be set through external resistance. It has a wide power supply design of 1.6 16V. It is easy to obtain power from the power supply. It has a single output channel and can be combined in parallel.It is convenient to drive medium and low-power LEDs. A resistor can be used to control the output current value. (current output specification: 10 160mA), low channel cross voltage, improve system efficiency and reduce mass production cost. Support high-speed power PWM dimming applications. Support series connection applications to withstand higher voltage fluctuation range. Built in overheating protection function.Advantages of nu510 linear constant current IC: minimum starting voltage (0.4V); Current accuracy - 3%. Settable current / fixed current fqj
Mulin Forest Ji Liang: the Prospect of LED Filament Lamp Is Worth Looking Forward To
Mulin Forest Ji Liang: the Prospect of LED Filament Lamp Is Worth Looking Forward To
Lin Jiliang, executive general manager of mullinsen Co., Ltd., as a lighting professional with nearly 18 years of senior experience, is good at management and fine marketing, and has unique opinions on the development status and trend of lighting market at home and abroad. In his opinion, Mu Linsen's achievements today are by no means accidental, but his rationality and perseverance in achieving all this. In 2016, new challenges are coming. For this reason, mullinsen has launched its layout in an all-round way.Lin Jiliang, executive general manager of Mu LinsenOptimistic about the market potential of LED filament lampLed filament lamp, a product that can not be ignored more and more, is a product with broad market prospects.According to Lin Jiliang, executive general manager of Mu Linsen, the advantages of LED filament lamps are very obvious:1. Because the packaging device is all-round luminous type, the primary optical loss is small, so the luminous efficiency of LED filament lamp is high;2. The filament of LED filament lamp itself is full-cycle luminous, and the cost of secondary optical light distribution is reduced;3. Led filament lamp relies on gas for heat dissipation, so the hardware and plastic structure is changed to glass;4. Led filament lamp can adopt HV line structure to realize simple dimming function.These advantages make the market potential of LED filament lamp promising. In addition, the chip price is reasonable and the bulb assembly process is stable. The relevant life regulations of "Energy Star" and "EU energy efficiency" labels can be fully realized, which makes the LED filament lamp products up to standard, reasonable price and beautiful shape, and win more widespread favor in the terminal market. Therefore, mullinson will cooperate with relevant enterprises to develop a new generation of LED all-round filament bulbs.President Lin also said: "when fighting in the market, Mu Linsen never fights unprepared battles. Mu Linsen works closely with upstream and downstream partners for common development with its advantages in packaging technology and production scale."President Lin said: "at present, mullinson's LED filament lamp related products have completed the certification of the mainstream market at home and abroad, and began to distribute samples. Soon, mullinson will set off a 'led filament lamp whirlwind' all over the world."The pace of entering the world has never stoppedAfter entering the lighting industry for many years, Lin Jiliang has his own unique interpretation of the trend of the industry. In his opinion, in recent years, with the influx of capital and the improvement of technology, the lighting industry has become more and more changeable. From 2012 to 2014, the lighting industry has gone through a process of survival of the fittest, and new brands such as mulinson strive to rise and stand out; Many traditional lighting brands follow suit to achieve a gorgeous turn.President Lin said: "with the changing domestic economic situation and the changing ownership of international brands, the international brand pattern will change in 2016. Chinese lighting enterprises are bound to shoulder more responsibilities in the world lighting industry and lead the world lighting industry in a better direction.""No matter how the industry develops and changes, Mu Linsen lighting will not stop its efforts to move forward," President Lin said, "Mu Linsen lighting has made great progress in recent years. In addition to providing high-quality lighting components for the whole industry, it has also made contributions to the technical innovation and marketing model innovation of finished lighting products. Today, Mu Linsen hopes to show himself more on the world stage and inject new vitality into the global lighting industry.""Mu Linsen has built two production bases in Xinyu, Jiangxi and Ji'an, Jiangxi, in order to prepare for better and faster entry into the global market," President Lin is full of confidence: "now, Mu Linsen lighting is ready!"
Detailed Anatomy of Various Protection Circuit Examples of Switching Power Supply
Detailed Anatomy of Various Protection Circuit Examples of Switching Power Supply
1、 Input undervoltage protection circuit 11. Overview (circuit category and description of main functions): this circuit belongs to the input undervoltage circuit. When the input voltage is lower than the protection voltage, pull down the power supply VCC of the control chip to close the output.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle):When the power input voltage is higher than the undervoltage protection set point, the voltage at point a is higher than the VREF of U4, U4 is on, the voltage at point B is low, Q4 is on, and VCC power supply is normal; When the input voltage is lower than the protection voltage, the voltage at point a is lower than the VREF of U4, U4 is cut off, the voltage at point B is high level, and Q4 is cut off, so that VCC has no voltage. At this time, VREF is also low level. When the input voltage gradually increases, the voltage at point a also gradually increases. When it is higher than the VREF of U4, the module works normally. R4 can set the return difference of undervoltage protection point.4. Advantages and disadvantages of the circuit: the advantages of the circuit: simple circuit and accurate protection point; Disadvantages: high cost.5. Precautions for application: when using, pay attention to the values of R1 and R2. Sometimes two resistors need to be connected in parallel to obtain the required protection point. It is also necessary to pay attention to the temperature coefficients of R1 and R2, otherwise the undervoltage protection points will differ greatly at high and low temperatures.2、 Input undervoltage protection circuit 21. Overview (circuit category, description of main functions): input undervoltage protection circuit. When the input voltage is lower than the set undervoltage value, turn off the output; When the input voltage rises to the set recovery value, the output automatically returns to normal.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle):When the input voltage is within the normal working range, VA is greater than the regulated value of VD4, vt4 is on, VB is 0 potential, vT5 is off, and the protection circuit does not work at this time; When the input voltage is lower than the set undervoltage value, VA is less than the regulated value of VD4, vt4 is cut off, VB is high potential, vT5 is turned on, comp (pin 1 of the chip) is pulled to 0 potential, and the chip closes the output, so as to realize the undervoltage protection function. R21, VT6 and R23 constitute the return differential circuit during undervoltage shutdown and recovery. When undervoltage is turned off, VT6 is turned on and R21 and R2 are connected in parallel,; On recovery, VT6 is off,, the return difference voltage is (VIN '- VIN).4. Advantages and disadvantages of the circuit:Advantages: simple circuit form and low cost.Disadvantages: the undervoltage protection point fluctuates up and down due to the difference of voltage stabilizing value between VD4 batches of voltage stabilizing tube. Relevant parameters need to be debugged frequently during mass production.5. Precautions for application:VD4 should select a voltage stabilizing tube with good temperature coefficient, and multiple components to be debugged, such as R2, should be considered in parallel to facilitate debugging.Output overvoltage protection circuit1、 Output overvoltage protection circuit 11. Overview (circuit category, description of main functions): output overvoltage protection circuit. When an applied voltage higher than the normal output voltage range is applied to the output terminal or the output voltage is higher than the regulated value due to the fault of the circuit itself (open-loop or other), the circuit will clamp the output voltage at the set value.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle): when the output voltage is over-voltage, when the voltage applied to VD3 is greater than its regulated value, VD3 is turned on, the output voltage is clamped, and feedback to the primary side through iC4.4. Advantages and disadvantages of the circuit:Advantages: simple circuit form and low cost.Disadvantages: due to the difference of voltage stabilizing value between VD3 batches of voltage stabilizing tube, the overvoltage clamp position fluctuates up and down, and relevant parameters need to be debugged frequently during mass production.5. Precautions for application: VD3 should select a voltage stabilizing tube with good temperature coefficient, and multiple components to be debugged, such as R32, should be considered in parallel to facilitate debugging. When the overvoltage protection circuit works, the circuit is in an abnormal working state. For the circuit with the function of up and down regulation of output voltage, the overvoltage protection point shall be greater than the maximum value of up regulation of output voltage.2、 Output overvoltage protection circuit 21. Overview (circuit category, description of main functions): output overvoltage protection circuit. When an applied voltage higher than the normal output voltage range is applied to the output terminal or the output voltage is higher than the normal value due to the fault of the circuit itself (open-loop or other), the circuit will stabilize the output voltage at the set value.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle): when outputting overvoltage, VA > VREF, IC3 is on, and iC4 feeds back to the primary side, and the output voltage is stable at the set overvoltage protection value.4. Advantages and disadvantages of the circuit:Advantages: the output overvoltage protection value can be set accurately.Disadvantages: the cost is slightly higher than that of the clamping mode of the pressure stabilizing tube.5. Precautions for application: when the overvoltage protection circuit works, the circuit is in abnormal working state. For the circuit with the function of up and down regulation of output voltage, the overvoltage protection point shall be greater than the maximum value of up regulation of output voltage.Overvoltage protection self-locking control circuit1. Overview (circuit category and description of main functions realized): in the power supply system, when the feedback circuit fails, the output voltage is uncontrolled and the voltage rise exceeds the specified range. At this time, the excessive output voltage may cause damage to subsequent electrical equipment. In order to solve this problem, an overvoltage protection circuit is usually added to the power supply. There are generally three ways of overvoltage protection.A. Clamp type: when the feedback fails, clamp the output voltage at a fixed value through the overvoltage clamp circuit.B. Intermittent protection type: when the feedback fails, the output voltage is restarted back and forth through the protection circuit, and the highest point of the output voltage is the overvoltage protection point.C. Self locking type: when the output voltage reaches the overvoltage protection point, the circuit acts and turns off PWM so that the module has no output. After troubleshooting, restart the power output to supply power normally. The following circuits are self-locking control circuits.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle):The figure above shows the isolated self-locking control circuit. When the overvoltage protection signal control terminal gives a high level, the triode in U1 is turned on, and VCC is the power supply terminal of the whole circuit. VCC sends a base current to Q2 through R5, Q1 turns on and enters the saturation state, the shut end is pulled to the low level by Q2, PWM is turned off, and there is no output. Q2 simultaneously controls the conduction of Q1. When Q2 is on, the base current of Q1 reaches the ground through R2, Q1 is on, and a base current is provided to Q2 through R3 to maintain Q2 on. Q1, R1, R2 and R3 constitute the positive feedback circuit of Q2.4. Advantages and disadvantages of the circuit:Advantages: it can effectively carry out self-locking protection, and the whole circuit is equivalent to a thyristor.Disadvantages: the whole circuit needs a fixed VCC. When there is no power supply at the PWM power supply terminal, it is also necessary to ensure the existence of VCC voltage in the figure above.5. Precautions for application:1. The self-locking of this circuit is effective only when there is continuous power supply.2. This circuit should not be used in unattended power supply system.Over temperature protection circuit1. Overview (circuit category and description of main functions): the circuit belongs to over temperature protection circuit, but when the temperature is higher than the set protection point, close the module output, and automatically open the module when the temperature recovers.2. Circuit composition (schematic diagram):3. Analysis of working principle (main functions, performance indicators and implementation principle): the regulator provides 5V voltage to u103max6501. When the temperature is normal, the five pins of u103 output high level. When the temperature exceeds the protection point, the five pins of u103 output low level. When the temperature is restored, the five pins of u103 output high level.4. Advantages and disadvantages of the circuit:The circuit has the advantages of simple circuit and high accuracy.Disadvantages: high cost.5. Precautions for application:5.1 when the 3-pin and 1-pin of max6501 are connected, the return difference temperature is 10 ℃, and when the 3-pin is connected to the ground, the return difference temperature is 2 ℃.5.2 the power supply voltage of max6501 shall not exceed 7V, otherwise it will be damaged.5.3 max6501 must be placed near the hottest part.Over temperature protection circuit - Thermistor1. Overview (circuit category and description of main functions): this circuit uses thermistor to detect the substrate temperature. The thermistor resistance changes with the substrate temperature. The change of thermistor resistance leads to the change of input voltage of operational amplifier, so as to realize the turnover of operational amplifier, control the output of PWM chip, and then close the module.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle, calculation and analysis of key parameters):R99 thermistor is a thermistor with negative temperature coefficient. At room temperature, R99 = 100k, and the partial voltage of R99 and r94 is 0.45V, which is the negative input of U2 operational amplifier, which is much lower than the positive input of 2.5V (R23 and r97 partial voltage). Therefore, the output of operational amplifier is high level, has no impact on the SS terminal of lm5025, and the module works normally. As the substrate temperature increases, the R99 resistance decreases. When it decreases to a certain value, so that the negative input of the operational amplifier is greater than the positive input, the operational amplifier outputs a low level and pulls down the SS of lm5025, so as to close the module output; The temperature protection point can be adjusted accordingly by appropriately adjusting the resistance values of r94, R23 and r97.After the module turns off the output (overtemperature protection), the substrate temperature will decrease, the R99 resistance will increase, and the negative input of the operational amplifier will decrease. In order to turn the operational amplifier over normally, the resistance r98 is introduced. The principle is that after the output of the operational amplifier is low, r98 is equivalent to being connected in parallel with r97 to lower the reference of the operational amplifier and open the voltage gap between the positive and negative inputs of the operational amplifier, so as to realize the temperature difference. For example, the substrate is protected at 90 ℃ and turned on at 80 ℃.4. Calculation and analysis of key parameters:4.1 positive input voltage of operational amplifier: vr97 = VREF2 = 5 / (1 R23 / r97) = 5 / (1 10 / 10) = 2.5V4.2 negative input voltage of operational amplifier: vr94 0.007 = vr97 = 5 * r94 / (R99 r94) 0.007,4.3 obtain the resistance value of thermistor during temperature protection: R99 (T) = (VREF * R24 / (VREF * r97 / (R23 r97) - 0.007)) - r944.4 see the following table for the calculation when considering the tolerance:4.5 value of R99 during over temperature protection4.6 r99-sdnt2012x104j4250ht (f) is a thermistor with negative temperature coefficient, 100k at 25 ° C and about 10K during over temperature protection (see the table above). The calculated temperature is:Rt=R*e(B(1/T1-1/T2)) T1=1/(ln(Rt/R)/B1/T2))T2: normal temperature 25 ° C, where T2 = 273.15 25 = 298.15; B:4250±3%; R: The resistance value at 25 ° C is 100k, and the calculated T1 value is also the value after adding 273.15. Therefore, T1 = t1-273.15 in the following table is Celsius. RT: resistance value after temperature change, 10K, 9.704k, 10.304k, see the above table4.7 return differenceWhen the output of the operational amplifier is low, the resistor r98 (51K) will be connected to r97 and the reference will be pulled down. The new reference voltage vref1 = VREF * (r98 / / r97) / (R23 r98 / / r97) = 2.28v. When it reaches 2.44v, the resistance value R99 = VREF * r94 / vref1-r94 = 11.9k, and when R99 reaches 10.49k, the temperature will be calculated according to the following tableTemperature return difference = 82.6-77.3 = 5.3 ℃5. Advantages and disadvantages of the circuit:Advantages: the temperature protection point and temperature return difference can be adjusted easilyDisadvantages: low temperature accuracyThe circuit is slightly more complex than using temperature switchThe temperature protection reflects the substrate temperature near the thermistor and cannot reflect the maximum device temperature of the module. However, this can be solved in the design. For example, if the substrate temperature is protected at 90 ℃, and the maximum device temperature on the actual board has reached 130 ℃, the temperature protection point can be adjusted appropriately to play a protective role.6. Precautions for application:Try to place the thermistor near the heating device.fqj
Micro LED Display Technology Can Not Be Mass Produced, and Mass Production Remains to Be Seen
Micro LED Display Technology Can Not Be Mass Produced, and Mass Production Remains to Be Seen
Throughout 2019, as a brand-new living room entertainment center in consumers' daily life, TV products represented by OLED display technology camp and QLD display technology camp have attracted the attention of most consumers with their respective advantages.At the same time, micro LED display technology, which is widely concerned by another group of consumers, has also brought the latest "Gospel" recently.At the just concluded CES exhibition, Samsung, a large Korean manufacturer, said that it was ready to mass produce micro LED display technology TV products and would strive to make 2020 the first year of micro led.According to Samsung's external statement, micro LED display technology can have a higher contrast and better black field effect, and there will be no screen burning phenomenon of OLED TV.It can be said that micro LED TV has more obvious display effect than OLED TV.So why does micro led have such outstanding image quality performance?The author learned that micro LED display technology miniaturizes the LED panel to reach 1% of the original size, and integrates these miniaturized LEDs on the driving circuit and glass substrate to finally form a complete screen.Compared with ordinary LED screen, micro LED can show micron level pixel spacing and better imaging effect.Moreover, each pixel can be controlled independently, which is very similar to OLED. It can also reach the level of OLED panel in terms of brightness, resolution, contrast and energy consumption.Back to Samsung itself, according to Samsung's current production progress and rhythm, Samsung is likely to be the first company to bring micro LED display technology to the market.It is understood that in order to achieve mass production of micro LED display technology TV this year, Samsung is actively looking for factories and equipment that match their requirements and making investment.On the other hand, according to several media reports, Samsung is already evaluating and preparing micro LED production equipment, and plans to share micro LED production planning with partners.In this regard, some insiders said that micro LED display technology does not have a large-scale mass production level at present, which needs to be further watched.In addition, LG has been committed to the research of micro LED display technology, and also unveiled one of its micro led TVs at the IFA exhibition last September.As another major solution of display technology, the author believes that micro LED display technology has reason to become an innovator of the next generation display technology, which is worth looking forward to.
This Paper Briefly Introduces 7 Methods to Improve the Heat Dissipation Effect of LED Display Screen
This Paper Briefly Introduces 7 Methods to Improve the Heat Dissipation Effect of LED Display Screen
LED display screen will generate heat during use, especially outdoor LED display screen has high requirements for use environment. When it exceeds 4000 CDs, they generate a lot of heat. In practical use, increasing the heat dissipation of LED electronic screen can not only effectively improve the heat dissipation efficiency of LED electronic screen, but also achieve energy-saving effect, help to increase the service life of LED electronic screen and ensure the performance of LED electronic screen. Shenzhen LED display manufacturer introduces 7 heat dissipation methods of LED display screen!7 ways to improve the heat dissipation effect of LED display screen:1. Fan heat dissipation, which is a general method to enhance heat dissipation through long-life and efficient fans inside the lamp shell. This method has low cost and good effect.2. The most common cooling method using aluminum fins - aluminum fins are used as part of the shell to increase the heat dissipation area.3. The thermal conductivity ceramic with high thermal integration and the heat dissipation of the lamp shell reduce the working temperature of the LED HD display chip. The difference between the expansion coefficient of the LED chip and the thermal conductivity and thermal expansion coefficient of the metal is very large, and the LED chip cannot be directly welded to prevent the LED display chip from being damaged by high temperature and low thermal stress.4. Heat transfer tube is used for cooling. The heat transfer tube technology is used to transfer the heat in the LED display chip to the heat dissipation pin plate of the shell.5. An economical and efficient heat dissipation enhancement method for manufacturing convective air by using aerodynamics and the shape of the same sheet.6. Surface radiation heat dissipation treatment: radiation heat dissipation treatment is carried out on the surface of the lampshade, which is easier to radiate heat dissipation coating. It is a method of radiating heat outward from the surface of the lampshade.7. Heat conductive plastic shell, which is filled with heat conductive materials when injected into the plastic shell, which increases the heat dissipation of the plastic shell.fqj
Lesson 23: LED Nixie Tube Static Display Interface and Programming
Lesson 23: LED Nixie Tube Static Display Interface and Programming
In single chip microcomputer system, led nixie tube display is often used to display various numbers or symbols. Because it has the characteristics of clear display, high brightness, low voltage and long service life, it is widely used.Introduction: remember the "matchstick game" we played when we were children? Several matchsticks can be combined to form a variety of graphics. In fact, led nixie tube display is such a thing.Eight Segment LED nixie tube displayThe eight Segment LED nixie tube display is composed of eight light-emitting diodes. In the base, seven long strip-shaped light-emitting tubes are arranged in the shape of "day". Another dot shaped light-emitting tube is used to display the decimal point in the lower right corner of the nixie tube display. It can display various numbers and some English letters. Led nixie tube display has two different forms: one is that the anodes of 8 light-emitting diodes are connected together, which is called common anode led nixie tube display; The other is that the cathodes of 8 light-emitting diodes are connected together, which is called common cathode led nixie tube display. As shown in the figure belowThe name and arrangement position of each stroke segment of LED nixie tube display with common Yin and common Yang structure are the same. When the diode is turned on, the corresponding stroke segments are illuminated, and various characters are displayed by the combination of the illuminated stroke segments. Eight stroke segments hgfedcba correspond to D7 D6 D5 D4 D3 D2 D1 d0 of one byte (8 bits), so the font code of the character to be displayed can be represented by an 8-bit binary code. For example, for the common cathode led nixie tube display, when the common cathode is grounded (zero level) and the anode hgfedcba sections are 011011, the nixie tube display displays the "P" character, that is, for the common cathode led nixie tube display, the font code of the "P" character is 73h. If it is a common anode led nixie tube display, the common anode is connected to high level, and the font code of "P" character shall be 10001100 (8CH). It must be noted here that in order to facilitate wiring, many products often do not correspond to the relationship between fields and bits in a regular way. At this time, the font code must be designed according to the wiring. We will give a routine later.In the application system of single chip microcomputer, there are two common methods for nixie tube display: static display and dynamic scanning display. The so-called static display means that each nixie tube display occupies a separate I / O interface with latch function for stroke segment font code. In this way, as long as the single chip microcomputer sends the font code to be displayed to the interface circuit, it doesn't have to worry about it. Until new data is to be displayed, it will send a new font code. Therefore, using this method, the CPU overhead in the single chip microcomputer is small. There are many I / O interface circuits that can provide separate latch. Here, taking the commonly used serial parallel conversion circuit 74LS164 as an example, a commonly used static display circuit is introduced to make everyone have a certain understanding of static display.The serial port mode of MCS-51 single chip microcomputer is shift register mode, 6 pieces of 74LS164 are connected externally as the static display interface of 6-bit led nixie tube display, RXD of 8031 is used as the data output line and TXD is used as the shift clock pulse. 74LS164 is a TTL unidirectional 8-bit shift register, which can realize serial input and parallel output. Among them, a and B (pins 1 and 2) are serial data input terminals. The two pins input signals according to the logic and operation law. When one input signal is common, it can be connected in parallel. T (pin 8) is the clock input terminal, which can be connected to the TXD terminal of the serial port. When the rising edge of each clock signal is added to the t end, the shift register is moved by one bit. After 8 clock pulses, all 8-bit binary numbers are moved into 74LS164. R (pin 9) is the reset end. When r = 0, each bit of the shift register is reset to 0. Only when r = 1, the clock pulse works. The parallel output terminals of Q1... Q8 (pins 3-6 and 10-13) are respectively connected to the corresponding pins of hg--- a segments of LED nixie tube display. The 74LS164 can also be introduced as follows: the so-called clock pulse end actually requires high, low, high and low pulses. No matter how the pulse comes, for example, we use a wire, one end is connected to t, the other end is held by hand, and the high level and low level are connected respectively. That is to give the clock pulse and obtain the clock pulse at the moment of 74LS164 (to be clear, it is at the edge of the pulse) if the data input terminal (pins 1 and 2) If it is a high level, a 1 will enter the 74LS164. If the data input is a low level, a 0 will enter the 74LS164. After eight pulses are given, the first data entering the 74LS164 reaches the highest level, and then what happens to another pulse? Another pulse, the first pulse will move out of the highest level, just like the station platoon When the team buys tickets, the railing is so long. If you want to go in from the back, you must go out from the front.After understanding this point, let's look at the circuit. Six pieces of 7ls164 are connected in series, and the clock ends are connected together. In this way, when eight pulses are input, the data output from the RXD end of the single chip microcomputer enters the first piece of 74LS164. When the second eight pulses arrive, the data enters the second piece of 74LS164, and the new data enters the first piece of 74LS164. In this way, When the sixth eight pulses are completed, the data sent for the first time is sent to the leftmost 164, and other data appears in the first, second, third, fourth and fifth 74LS164 in turn. There is a problem. When the first pulse arrives, what are the other chips doing except receiving data in the first 74LS164? They are also receiving data, because their clock ends are connected together Yes, but the data has not been sent to other chips yet. What data are they receiving? In fact, the so-called data is just a statement. In fact, it is the level. When the first pulse arrives, the first chip 164 certainly receives data from the single chip microcomputer, and other chips are also connected to the Q8 of the previous chip, which is a wire, which is used in the digital circuit There are only two possible states: low or high, i.e. "0" and "1" So its next 74LS164 is also receiving data. It only receives 0 or 1. This problem is explained here. Some friends may ignore it, but some friends may still not know it. This actually involves the essence of numbers. If you don't understand it, please think carefully, find some numbers of digital circuits and understand the working principle of 164, Let's look at this problem again, or take a look at my other article "lesson 27: some basic concepts about single chip microcomputer". Be sure to understand it. If you understand this, your level will be higher than the beginning learner and can be described as a beginner.Entry: put the number to be displayed in 6 units of display buffer 60h-65h respectively, and correspond to each nixie tube led0-led5 respectively.Exit: convert the 6 numbers preset in the display buffer into corresponding display font codes, and then output them to the nixie tube display for display.The LED display program of single chip microcomputer is as follows:Disp: mov scon, #00h; initialize serial port mode 0Mov R1, #06h; display 6 digitsMov R0, #65h; 60h-65h is the display bufferMov dptr, #segtab; entry address of font tableLOOP:Mov a, @ R0; take the highest data to be displayedMOVC a, @ a dptr; look up the table to get the font codeMov SBUF, a; send serial port displayDelay: JNB Ti, delay; wait for sendingCLR Ti; clear send flagDec R0; the pointer moves down one bit, ready to take down a number to be displayedDjnz R1, loop; until all 6 data are displayed.RETSettab: font table, which was introduced earlier. We will introduce the production of font table later.DB 03H 9FH 27H 0DH 99H 49H 41H 1FH 01H 09H 0FFH; 0 1 2 3 4 5 6 7 8 9 blanking codeMain program for single chip microcomputer display testORG 0000HAJMP STARTORG 30HSTART: MOV SP,#6FHMOV 65H,#0MOV 64H,#1MOV 63H,#2MOV 62H,#3MOV 61H,#4MOV 60H,#5LCALL DISPSJMP $If the nixie tube is arranged as shown in the figure, the above main program will display 543210. Think about it. How to send data if 012345 is to be displayed?Next, let's analyze the making of font table. Let's look at the above "standard" graphics first. Write the corresponding relationship between data bits and font and make a table as follows (set it as common Yang type, that is, when the corresponding output bit is 0, the pen segment is bright)How about the font table? Just make a table like this. Write the 0 and 1 of the corresponding bits according to the requirements (0 or 1). Do an exercise and write the font code of a-f.If the order of wiring is disrupted for the convenience of wiring, how to connect the font table? It is also very simple and the same list. Take the new experimental board as an example, common Yang type. The wiring is as follows:P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0C E H D G F A BThen the font code is as follows:;0 00101000 28H;1 01111110 7EH;2 10100100 0A4H;3 01100100 64H;4 01110010 72H;5 01100001 61H;6 00100001 21H;7 01111100 7CH;8 00100000 20H;9 01100000 60HAs an exercise, write the font code of a-f.Originally, this is to explain the static interface of single-chip microcomputer nixie tube display. This should be the end, but I also want to talk about the essence of numbers mentioned above. There are some terms and nouns in single-chip microcomputer that originally help us understand things, but sometimes we will be confused by the related semantics of these terms, so that we can't further understand their essence Therefore, we are generally confused. Only by deeply understanding the working characteristics of 74LS164 can we really understand what serial data is. Interested friends can also look at my website to find relevant content
What Is the Use of the Small Circuit Board Inside the LED Lamps
What Is the Use of the Small Circuit Board Inside the LED Lamps
LED lamps have a small circuit board inside. What's the use?Nowadays, LED lamps have become the mainstream of lighting, and few families use incandescent lamps. Its main advantage is that led lamps are more energy-saving. Under the same light efficiency, the electric energy consumed by LED lamps is more than 70% less than that of incandescent lamps. The service life of LED lamps is longer than that of incandescent lamps. People who have used incandescent lamps know that the tungsten wire in them will burn out after a short period of use. According to statistics, the average service life of incandescent lamps is about 1000 hours, that is, they can only be used for about 100 days, about 3 months. The service life of LED lamps can reach 100000 hours, that is, the theoretical service life can reach 10 years. Some people will say, how can it be so long? It breaks after a few months of use. This is only a theoretical value. The actual service life is related to the driving circuit design of LED beads. In order to save cost and simplify design, many manufacturers lead to unstable current and voltage of LED lamps, which reduces the service life of LED lamps.Household lighting LED beads belong to low-voltage and small current devices. Their working voltage is generally about 3V and working current is about 20mA. Lighting LED lamp beads requires LED driving circuit, so a small circuit board in LED lamps is led lamp driving circuit board.Functions of common LED lamp driving circuit board1. Simple LED lamp driving circuit board with capacitive resistance step-down, rectification and filtering methods.The circuit board in this way has the advantages of simple structure and cost saving, but the circuit is unreliable, high failure rate and short service life of LED lamps.The following figure shows the circuit diagram of LED lamp with capacitance resistance step-down mode. 220V AC capacitance resistance step-down, and then DC voltage is obtained through rectification and filtering to directly drive LED lamp beads.2. LED constant voltage drive board.The following figure shows the LED constant voltage driving board. Its circuit principle is equivalent to a switching power supply. The constant voltage output by the switching power supply directly drives the LED bulb.The principle of switching power supply is shown in the figure below. 220V AC is transformed into about 310V high-voltage DC through rectifier bridge, and then the switching tube is turned on / off at high speed through PWM modulation to form alternating current signal, output AC voltage through high-frequency transformer, and then rectifier and output DC.3. LED constant current source driving board.The constant current source driving effect of LED is the best. The brightness of LED lamp is uniform, not easy to be damaged and has a longer service life.For example, the following figure shows the principle of constant current source driving LED lamp, which is designed by bp3122 constant current source driving chip, in which R1 is the current sampling resistance. Changing the resistance value of R1 can change the load current.Summary: Lighting LED lamp beads requires LED driving circuits. Generally, LED driving circuits include constant voltage drive, constant current drive, PWM drive, etc., which is the role of LED lamp small circuit board.
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