Weak electron

Wednesday, January 26, 2011

Weak current College】【LCD display principle and explain more about nouns (3)】.

3. terminology Many people purchase computer products, often been descriptive information in proper names causing dizziness brain. Optional LCD monitor is the same, there are some whose contact with nouns will let everyone know .what to do. Therefore the author in the following article in the LCD-related, some of the more important technical terms for easy sorting and explained that we buy LCD monitor with a reference basis. 1. size marking and .Visual angle LCD monitor with a CRT monitor display in different ways, the biggest difference is the size of the marking method is not the same. For example, the CRT in specification Gakko 17 inches, but the actual Visual size .but absolutely not only about 17-inch, 15 inch more; but on the LCD monitor, if labeled 15.1 inch monitor, then the Visual dimension is 15.1 inch. Integrated top story: CRT monitor size marking, is based .on the diagonal length of the shell as the basis for marking; whereas in the LCD monitor, only to the Visual range of diagonal lines as shown. Sin is currently sold on the LCD monitor, the Visual angle is symmetrical .(that is, from the left or right you can see the angle of the images on the screen are the same. For example on the left to 60 degree Visual angle, the right must be the Visual angle 60 °). And up and down .the Visual angle is usually less than about Visual angle. From the user's position is, of course, the greater the Visual angle, the better. But we must understand the definition of Visual angle. When we say the Visual .angle is around 80 degrees, that stood at the beginning to monitor normal (that is, the monitor is in the middle of an imaginary line), perpendicular to the normal left or right 80 ° position, will still be able to clearly see the image .on the monitor. Because each person's eyesight is different, so we take contrast. In the maximum amount the Visual angle is to contrast the more the better. 2, brightness, contrast, TFTLCD .monitor acceptable brightness 150cd/m2 or more. The current domestic market can see TFT LCD display brightness is about 200cd/m2 (LCD monitor brightness measurement units are meters square candle "cd/m2", that is generally known as NIT). Brightness too .low will feel screen Dim light point, of course. However, if the screen is too bright, human eyes to watch the screen too long will have yaotui. Therefore, for the vast majority of users, the brightness too high is not practical. < .br> Brightness and contrast for LCD monitor image rendering, compared to CRT monitors have a greater impact. High brightness of the LCD display to the user, and feel better. But also to provide enough contrast to display brightness, to ensure that .the colour fidelity and color accuracy. TFTLCD monitor brightness range from 150Nits to 200Nits. Usually, good quality standard brightness of the LCD monitor at least 200Nits, and most of the CRT monitor maximum brightness of around only .150Nits. In case of brightness 200Nits, LCD monitor is a CRT monitor's image better. When consumers buy a monitor that you want to pay special attention to the brightness of the indicators, because there is no one definitive standard for measuring the adequacy of the bright .brightness. Also worth noting is that the LCD monitor in the central part of the screen is very bright, but close to the edge brightness decreases nearly 25%. The best and most effective method, that is, the LCD .monitor side-by-side comparison of one-to-one. Contrast index refers to the brightest white and the darkest black brightness levels between different measurements. When reaching 120: 1 contrast ratio, you can easily display vivid ., rich color. And contrast as high as 300: 1, you can support various levels of color. From there, users in the purchase of LCD monitors, also does not have an effective and fair criteria to measure the .contrast and brightness of the indicators. So the best recognition method or use your own eyes to judge. Upcoming LCD monitor to the lightest and darkest, and see how I feel. Now we can only use this method to find a more appropriate LCD monitor. . 3. response time The so-called "response time", is the LCD monitor for the input signal reaction speed, turn off the LCD by dark or light dimmer response time. Basically, "response time" indicators as small as possible. Response time is small, the user was watching mobile screen does not appear similar to blur or towing. Typically, a variety of LCD monitor reaction speed will be divided into two .parts - the "Rising" and "Falling", which represents the sum of the two. 4, display color Early color LCD monitor in color performance, can only display up to high .color (256K). Many manufacturers use so-called FRC (FrameRateControl) technology, to simulation approach to demonstrate a full color picture. Recently, due to advances in technology, the LCD monitor can display at least to the high color 16-bit color .. Resolution, to 15.1 TFTLCD monitor as an example, the Basic can support to 1024 x 768 resolution; 17-inch LCD monitor can be above the reach 1280 x 1024 resolution, color performance in full color (32 bit) mode is easy. < .br> 5, the screen refresh rate For a CRT monitor, the refresh rate to the screen refresh rate. Refresh faster, less prone to blinking screen. But if the refresh rate in more than user 75Hz .is not easy to find the screen flicker. For LCD monitors, the refresh rate and does not cause the screen to flicker. Refresh rate in 60Hz, LCD they can get a good picture. In the LCD monitor, each .pixel will continue to glow, until no light signal was sent to the controller, so LCD monitor does not have the result of continuous charging and discharging of flashing phenomenon. Some people may ask: If most of .the LCD monitor in 60Hz refresh rate under can achieve the best visual quality, why not lock the refresh rate, and to have 60Hz 60-75Hz selection? this is related to the use of flexibility and compatibility issues. Due to the LCD monitor is attempting .to replace CRT monitor market position, but nowadays most of the display card is still a CRT monitor for design objects, the greater use of flexibility and compatibility will help to cut into the market, LCD monitor and replace CRT monitor. 6. resolution Whether it be buying LCD or CRT monitors in General, the resolution is a measure of the monitor. Because the monitor must support hardware needed resolution. Traditional CRT monitor supports the .resolution of the more flexible. Whether it's higher resolution or low resolution, all to be able to display, and no loss of quality. This is because the CRT display of images by pixels (Pixels) is composed of dots and lines and, therefore, .the amount of pixels is resolution. However, LCD monitor, but it only supports the so-called "true interpretation", can be compared to ordinary CRT monitor to the highest resolution. The main difference is that the LCD .flat panel monitor only "true resolution" to the best performing video effects. Resolution is lower than the real resolution, the images can be rendered, but the displayed image is not as real as optimized resolution. LCD flat panel monitor real resolution is defined as ."fixed-point format", so we use the LCD monitor, keep in mind the resolution set to maximum, this picture of the rendered image will be clearer, it will feel better. .

Weak current College】【LED lights for the latest protection technology (1)】.

White led as has many advantages, is more and more into people's daily life, its usage now become very large. It is a new device, has its own use. White led is voltage-sensitive device. Each LED work do not exceed the current 20mA, over too many LED will easily destroyed. LED if normal use, their life is very long. But people in the actual use LED tend to bad, why? "is actually does not take into account the characteristics and the use of LED on it plus protection circuit.
First, why would you want to protect the LED

White led as has many advantages, is more and more into people's daily life, its usage now become very large. It is a new device, has its own use. White led is voltage-sensitive device. Each LED work do not exceed the current 20mA, over too many LED will easily destroyed. LED if normal use, their life is very long. But people in the actual use LED tend to bad, why? "is actually does not take into account the characteristics and the use of LED on it plus protection circuit.

LED is an optoelectronic semiconductor devices, the mounting process easily electrostatic wounded. This requires the Assembly process for static electricity protection. We found many manufacturers who do not have this concept, or simply do not understand that this is not acceptable.

LED in practice to 20mA current ceiling, but often because of various reasons current increases, if you do not take protective measures, which increase the current exceeds a certain amount of time and amplitude will damage after LED.

Second, LED the cause of the damage caused by

1, power supply voltage jumps. Let the power supply voltage jumps reason many, such as power quality issues, or the user's reason for improper use, and so on, may let power voltage jumps.
2. line a symbol or printed lines or other conductor short-circuit and formation LED power supply circuit, short circuit of the place of the voltage increase.
3, a LED for the quality of their own because damage resulting in short, it's original voltage drop is passed on to other LED.
4, lamps within the temperature is too high, the characteristics of the LED.
5. lamp inside into the water, the water is electrically conductive.
6. when the Assembly is not good anti-static work, LED by internal hurt by static electricity. Despite the imposition of the normal voltage and current values, it is extremely easy to cause damage to the LED.

These reasons will cause the led current apparent rise significantly, soon LED chips will cause overheating and burnt. In our experience, most LED after burning poles short-circuit, few are circuit breakers. Each LED about 3.2V pressure drop around, it burned down the conspiracy after if circuit breaker LED does not light up. If this voltage is transferred to the short circuit of the other LED, causing other more current LED, LED to faster burned, or even emergency power supply. Originally a small damage caused on extremely easy big accident. LED General installation in height when the installation is not easy, and even more difficult to repair. So LED protection is a real demand, but we currently do not have to be valued, and many people but there is no way to deal with challenges.
Third, how to protect LED to

Protection against LED our first thought was to use fuse, but the fuse is a one-time, and reaction speed is too slow, poor actually use both effects are also very cumbersome, the fuse is not suitable for now led lighting products, because of the LED lamp now mainly in the cities of light engineering and lighting project. In response to actual needs, we did a lot of experimental and engineering requirements summarized LED protection circuit should have a feature, which is very demanding: beyond the normal use of the current time can start immediately, have LED power supply pathway would be disconnected, so that the LED and power can be protected, in the light of normal and to be able to automatically restore the power supply, without prejudice to the work, the key LED is because it is the civil products, the circuit must not be too complex volume must not be too large, the cost is lower. These requirements are contradictory, the mutual dependence, it is difficult to implement.

First you should determine what kind of protection circuit selection and protection devices.

1, we can choose to use transient voltage suppression diode (TVS). Transient voltage suppression diode is a diode forms of high-performance protective device. When it is reverse-polarity of transient high energy impact, can be negative in 10 12 th seconds a very short time, make your own high resistance between the two poles to immediately reduce to low resistance, absorb up to several kilowatts of power, the bipolar surge of voltage clamp in an target voltage values, valid preserving electronic circuit in precision components. Transient voltage suppression diode has a faster response time, transient power, leakage current is low, votalge deviation uniformity is good, clamping voltage are easier to control, limit without damage, small size, etc.

But in the actual use of the discovery is not very satisfactory. First of all is to find enough voltage value of TVS devices is not easy. TVS devices primarily applied to Thunder and lightning and overvoltage 220V + absorption, and the LED lights on the power supply voltage of 12V or 24V General is, the voltage value of the finished product rarely TVS, the test is not good. At the same time we know: LED light Pearl of damage is mainly due to the current Ambassador chip overheat. TVS can only detect voltage cannot detect overcurrent. Overvoltage is certainly cause overcurrent, but to choose a suitable voltage protection is difficult to master, this device will not be able to produce also is very difficult to use in practice.

2, we can choose fromRecovery insurance. Since recovery insurance tube, also known as polymer PTC thermistor PTC, is a polymer and conductive particles, etc. After special processing, conductive particles in polymer chain conductive pathway components. When normal operating current through (or component is in a normal ambient temperature), PTC Resettable fuse is low resistance State; when the circuit have exceptions over current through (or ambient temperature rise), high-current (or the ambient temperature rises) the heat generated rapid expansion of the polymer, which breaking the conductive particles composed of conductive pathway, PTC Resettable fuse is a high-impedance state; when the circuit overcurrent (over-temperature condition) disappears, polymer cooling, the volume is back to normal, which constitute the conductive particles conductive path again, PTC Resettable fuse also assumes an initial low resistance State. In normal working state since recovery insurance tube heating is very small, at anomaly working state it very high resistance of fever is very large, which has limited the adoption of its current to play a protective role. Its small size, low cost, can be repeatedly used for the protection of auto-start automatic exit; it is a solid package impact resistance is not easy to be damaged; our actual tests found: because it is heat sensitive devices, the temperatures are high, due to the PTC encapsulated in lamps, light Pearl surely influence to fever is about to PTC's work performance. On the identified lamps can test to select the PTC, relatively reliable used method is to keep it away from heating dengzhu.

In the specific circuit, there are two ways available to choose from:

1. tap protection. General led lamp is divided into many threaded branch. For example, 24V voltage, we are 7 branch of threaded Pearl phase LED light plus a resistance, current General 17 ~ 19mA, as needed, we can choose an integer multiple of 7 light Pearl to combine into a whole lamp. We can be in front of each line with a PTC element individually protected. This approach has the advantage of high accuracy, the reliability of protection.

2. overall protection. In front of all light Pearl plus add a PTC component, on the whole lamp for protection. The benefits of this approach is simple, not the volume. We usually use this approach. As household products, such protection in the actual use of results or satisfactory.
PTC's selection of elegant, we are a long time before seeking out the fairly accurate corresponding values.

【 Weak current College 】 how cleaning and testing anti-static clothing 】

Anti-static overalls are applicable to the electronic, optical instruments, pharmaceuticals, microbial engineering, precision instruments and other industries have clean and antistatic properties of special overalls, the material is generally the conductive wire embedded in woven fabrics of synthetic fibers, clean uniform management of the most important aspect is the clean, although the fiber itself is very difficult to get dirty and clean fiber, but how to maintain is an important factor, that is the method used for cleaning. If using ordinary washing method, of course, on the contrary will be dirty. You must use a special method. Clean clothes, from management, cleaning time must also be in a clean room cleaning confessed little 飾 packaging. Normally clean washing of clothes at least once a week, some demanding trades or even washing every day. In a normal room cleaning, dust and bacteria attached, as well as cleaning agent of pollution. In addition, the packaging and handling process, will be attached to the risk of dust and micro-organisms. Clean working clothes cleaning is generally rely on professional cleaning company for cleaning.

First, the cleaning process should be aware of

(1) a new sewing clean washing of clothes may direct, but recovery through the discovery of oil pollution clean uniform, carefully removing the greasy dirt to washing program.
(2) washing before on chafed, damage and buckle, and other accessories for inspection of defective to repair, replace or scrap.
(3) must be used in the ratio of Workwear Cleanroom cleanliness of clean room for washing, drying and packaging.
(4) wet and dry cleaning of water filtration, solvents are distilled on the point of use after use is less than 2 μ m aperture of membrane filters, make the filter more than once.
(5) in order to remove soluble pollutants, washing with water, then uses the distillation of solvents for the last washing to remove oily pollutants.
(6) wet washes the water temperature is as follows:
Polyester cloth 60-70C (highest 70C)
Nylon 50-55C (highest 60C)
(7) in the final rinse water permeability, can be used to improve the anti-static antistatic characteristics, but selection of antistatic agent should be combined with the fiber is good, no dust particles.
(8) the uniform of a buckle, fastening State washing.
(9) in the washing dedicated clean air circulation system for drying.
After drying, cleaning in washing dedicated indoor fold, Mount clean nylon polyester bag or, on request, double packaging can also be vacuum molding, packaging materials, preferably with antistatic material with good. Due to the collapse process most prone to dust, folding processes must be in the high level of purification space, such as a class 100 clean overalls folding packing should be in the 10-level environments.

II. performance testing of clean overalls

1 purifying performance testing

On clean indoor use clean cloth and clothing for the attachment of pollution particles, with the following four methods: ASTM F-51 method (microscopy), F-51 between Buddhist ideas method (count), HELMKE drum (drum method, ASTM test method), and vibration test method (vibration).

(1) ASTM-F-51 method (microscopy)
Test probe with filter diaphragm, direct connect suction pump, by the amount of air to 28L/min. Testing the air through the test material, will air in the dust particles caught testing of filtration membrane, with 400 x microscope and statistical dust particles. Read out the filter above 0.5-5 and 5 above the number of particles. In the filter above printed 3.08mm lattice, can read out a number of particles within the lattice.

(2) amendments to the law ASTM-F-51 (counting)
The air through the test material, with particle counters for the determination of a dust particle size and number. The sample is placed in the with metal net-bench, sampler (47mm filter bracket in place), by the amount of air to 28L/min.

(3) barrel (HelmkeDrumTest)
The sample is put into a side openings of the rotating roll drums rotate, the grain of drums on dust particles sampled with particle counters for the determination of particle number cleanliness level after the decision. Rotating drum size 43cm×33cm, the inside of the barrel was 4 blades, buckets of speed to 10 RPM.

(4) vibration method
The sample is placed in a small room, through the vibration of reversing the particle production, determination of the particle counters. At the same time, the size of large particles (25 or more) trap to filter membrane, read out the number of particles. Air volume 3.5 ft/min (0.099m/mim), vibration frequency of 150 times per minute.

Currently in clean and dust-free performance test Workwear has yet to have a national standard, refer to Japan air cleaning Association specialized Committee of Japan industrial standard JIS-B-9923, and United States RP-CC-003-87-T IES standards. For dust-free performance evaluation, the industry according to international standard ISO/TC209 under clean room standards, combining their respective clean grade a distinction between use.

2 antistatic performance testing

Antistatic sex is an important clean uniform characteristics, especially in the microelectronics industry on the clothing of antistatic performance requirements more stringent. Test method can People's Republic of China national standard GB/T12703-91 textiles static testing method, because the clean working clothes is embedded in the fabric is woven polyester conductive silk filament fabric, so the standard only friction-charged voltage (B), charge density (C) and the overalls of friction-charged (E) suitable clean working clothes of antistatic performance testing. In addition can also reference People's Republic of China national standard GB/T12059-89 the electronic industrial synthetic antistatic silk performance and experimental methods.

(1) friction-charged voltage method
The method of measurement principle is a certain tension conditions, so that the sample and standard cloth mutual friction, to this point have the highest voltage and average voltage on dress and coat the evaluation of friction-charged relationship. Its approach is to use the specimen (block of 4, 2, 2-up, size 4cmX8cm) clips over drum (diameter 150 ± 1mm, width 60 ± 1mm) sample clip card, drum to 400rpm speed and standard cloth (nylon or polypropylene) friction, testing the sample live 1min voltage Max (V).

(2) charge-density method
Specimens in the provisions of the conditions in a particular way and nylon fabric friction with the standard.

Weak current College】【electronic industry in English (12)】.

N magnets Arctic symbol
Nn-micro
NAB (United States) National Association of broadcasters
NABcurveNAB curve
Name name
Nano-Micro
Narrowband narrow band
National State
Naturalfrequency natural frequency, natural frequency
Naturalmagnet natural magnets
Nc normally closed, empty legs
NC numerical control
Near near, close
Nearfield proximal field
Necklacemicrophone neck hanging microphone
Needle-pin, hands, needle
Needletalk needle vocalization
Neg negative, negative
Negativecharge negatively charged
Negativeelectricity negative
Negativefeedback negative feedback
Negativeion anion
Network of networks, circuit
Networkfilter network filters
Neutral neutral
New new
NHK Japan Broadcasting Association
NI-CAD cadmium batteries
No normally open (point)
Nobottomnotop lack off bass
Node node, node, corrugated
Noise noise and clutter
Noiseanalyzer noise Analyzer
Noisebackground noise
Nnoise-cancelingmicrophone anti-noise microphone
Noisefitter static noise filter
Noisefloor inherent noise level
Noisegate noise gate (limited)
Noisereduction noise reduction system
Noiselevel noise level and noise level
Noisesuppressor noise suppressor
Nominal nominal and rated
Nominalvalue nominal value
Nnon-, no
Nonchromaticpercussion no tonal percussion
Nondirectionalmicrophone undirected microphone, Omni-directional microphone
Nonlinear nonlinear
Nonlineardistorton nonlinear distortion
Normal standard, normal
Normallycloscd normally closed, empty legs
Music notation
Notch gap
Notchfilter notch filter
Note tone, musical notes, notes, comments
Npntransisternpn-type transistor
NTSC (United States) national television system Committee
Null useless, null, null
Number, number, number, number,
Numeric number, number of

【 Weak current College 】 on digital multimeter selection 】

Digital multimeter meters with the accuracy is high, the measure of the wide, measurement speed, small size, strong anti-interference ability, easy to use, etc and are widely used in national defense, scientific research, factories, schools, and other areas of metrology and measurement technology, but its specifications, performance indicators, use of environmental and working conditions also vary, depending on the circumstances, therefore you should choose the appropriate digital multimeter.

Select digital multimeter General from several areas to consider:

1. function

Now the digital multimeter in addition to measuring AC, DC voltage, AC, DC current, resistance, and so on five features, there are figures, keep posting, reading, error detection, read the diode IEE488 interface or RS232 interface and other functions, use the selection according to the specific requirements.

Second, the scope and range

Digital multimeter many range, but the basic range, the highest accuracy. Many digital multimeter with automatic range feature, no need to manually adjust the range, allows measurements convenient, secure and fast. There are many digital multimeter has had the ability, in measurement range values exceed the quantum but haven't reached the maximum display time can not change the range, thereby increasing the accuracy and resolution.

3. accuracy

Digital multimeter maximum error of not only its variable error, but also to see it fixed the error. Select time depends on the stability of the error and the linearity error is the number of requests, the resolution meets the requirements. General digital multimeter if 0.0005 ~ 0.002 level, at least 61 digits display; 0.005 ~ 0.01 level, at least 51 digits display; 0.02 ~ 0.05 level, at least 41 digits display; 0.1 following, at least 31 bits of the digital display.

4. input resistance and zero-current

Digital multimeter input resistance is too low and zero current too high will cause measurement error, key measurement device allows extreme is the number that you want to see the signal source resistance. Signal source impedance should choose a high input impedance, low zero current instrument, so that its impact can be ignored.

Fifth, string mode suppression ratio and common-mode rejection ratio

In the presence of various interference such as electric and magnetic fields and a variety of high-frequency noise or for distance measurement, easily into the interference signal, resulting in inaccurate readings should therefore be based on the usage environment select series and high common-mode rejection ratio, particularly for equipment for high precision measurement, you should choose the belt protection-G digital multimeter, can inhibit the common mode interference.

6. display and power supply

Digital multimeter display form is not limited to digital, you can also display the graphics, text and symbol for on-site observations, operation and management. According to it's display of dimensions can be divided into small, medium, large and very large four categories.

Digital multimeter with power General 220V, and some new digital multimeter power range is very wide, 110-240. Some small digital multimeter with battery to use, there are also some digital multimeter available AC, internal nickel-cadmium batteries or an external battery.

7. response time, measurement speed, frequency range

Response time as short as possible, but there are some tables of response time longer, take some time to stabilize after reading. Measurement of the speed shall be based on whether or not combined with the system test, such as coupling, the speed is important, but the sooner the better. Frequency range, the appropriate choice according to your needs.

VIII. the AC voltage conversion form

AC voltage measurement points average conversion, peak and RMS conversion. When the waveform distortion is large, the average conversion and peak transfer not accurate, valid values are converted to wave, brings the measured result more accurate.

9 resistor connection modes

Resistance measurement connection modes have four line, two-wire system. With low resistance and high-precision measurement, you should choose four wire connection mode of resistance measurement.

With LSI and display technologies, digital multimeter to miniaturization, low power, low-cost, digital multimeter is also clearly divided into two types of portable and desktop. Portable General 31 bits or 41 bit, small size, light weight, low power consumption, suitable for the production plant or field use; desktop up to 61 61 or, accuracy and resolution is getting higher and higher, the use of microprocessor and GPIB interface equipment, measurement, scientific research and production departments as a standard table and precise measurements.

In short, the choice is not necessarily need to have all of the above conditions, should be based on the use of specific requirements to choose the most appropriate digital multimeter.

【 Weak current College 】 capacitor testing method and replace 】

Capacitor common markup is direct marking of the common unit has a pF, μ F, very easy to recognize. But some small-capacity capacitor is digital marking method, generally have three digits, the first and second digits as a valid number, and the third digit for the multiples means that many back to 0. For example: 343 represents 34000pF, in addition, if a third digit is 9, said 10-1, instead of the 9 th of October, for example: 479 4.7pF said.

Replace the main attention should be paid when the capacitance of the capacitor voltage values generally require no less than the original capacitive voltage requirements. In the requirements more stringent circuits, its capacity is less than the original capacity of ± 20%. In less strict circuit, such as a bypass circuit, General requirements not less than the original capacitance of 1/2 and not greater than the capacitance of the 2 x ~ 6 times. 

1 fixed capacitor testing

A detection of small capacitor 10pF following due to the fixed capacitor 10pF following capacity is too small to be measured using a multimeter, only qualitative check whether there is leakage, the phenomenon of internal short-circuit or breakdown. When measuring, you can use multimeter R×10k retaining, using two tables respectively any received two pin capacitance, the resistance should be infinity. If the measured resistance value (a pointer to the right swing) is zero, then the capacitor leakage damage or internal breakdown.

B testing 10PF ~ 0.01 μ F fixed capacitor is charging phenomena, thus it is good or bad. Multimeter R×1k retaining selection. Two technologies ' > transistor of β value of 100 or more, and penetrate current to some optional 3DG6, model composed of composite pipe silicon transistors. Multimeter red and black table respectively and composite pipe of the emitter and collector c e. Due to the magnification composite transistors, the measured capacitance of charging and discharging process be amplified so that the pointer pendulum amplitude increase multimeter to facilitate observation. It should be noted: in test operations, particularly in measuring smaller capacitance, repeatedly swap measured capacitance pin contact A, B, you can clearly see the multimeter pointers.

C for 0.01 μ F above Fixed capacitors, available multimeter R×10k retaining direct testing capacitors have no charging process and there is no internal short-circuit or leakage, and may act according to the pointer to the right margin size estimation of swing out of the capacitor capacity. 

2 Electrolytic Capacitor Technology ' > Electrolytic Capacitor testing

A capacity for electrolytic capacitor is generally fixed capacitor, so the measurement should be for different size selected appropriate quantum. As a rule of thumb, in General, 1 ~ 47 μ F, available between capacitance R×1k retaining measurement, greater than the capacitance of the 47 μ F R× 100 retaining measurement available. 

B the multimeter red table amount received negative electrode, the black table amount received positive, just contact moments, multimeter pointer is to the right tilt larger skewness (for the same power, the greater the capacity, the greater the swing), then gradually turning to the left until it stops at a certain location. This resistance is Electrolytic Capacitor leakage resistance of forward, this value is slightly larger than the reverse leakage resistance. Actual experience that Electrolytic Capacitor leakage resistance should generally be in more than a few hundred k Ω, otherwise it will not work correctly. In tests, if positive, the reverse is not charging, i.e. table PIN is not moving, then disappear or internal circuit breaker capacity; if the measured resistance is too low or zero, the capacitor leakage current large or breakdown damaged, can no longer be used.

C for the positive and negative signs of electrolytic capacitors, can use the measuring leakage resistance of discrimination. Namely any leakage resistance, to have your mind its size, and then exchange table pen and then measured a resistance. Two measurement resistance value of the time it is being received, the black table by pen received is positive, then red table amount is negative.

D use electric barrier, using a multimeter to a Electrolytic Capacitor, reactive charging method, according to the pointer to the right size of oscillations, you can estimate the capacity of the electrolytic capacitors. 

3 variable capacitor testing

A swirled gently by hand, you should feel very shaft is smooth and should not be felt at times when tight even pine scuffing. Will contain the forward, rear axle, top, bottom, left, right, direction drive, the hinge should be loose.

B with one hand in a swirling hinge, another hand touch dynamic piece group of outer edge, you should not feel any loose phenomenon. The hinge and dynamic between bad variable capacitor, is no longer in use.

C place the multimeter R×10k, hand two tables sum respectively variable capacitor of tablets and tablets of terminations, the other will hinge slowly swirling several pointer back and forth, multimeter should position at infinity. In a swirling the hinge of the process, if the pointer is sometimes point to zero, the motion Tablet and fixed between the shorts point; if encountered an angle, multimeter readout is infinity, but appear a certain resistance, description of the dynamic variable capacitor tablets and tablets between leakage phenomenon.

Saturday, January 22, 2011

Weak current College】【printer terminology explained】.

Control language: by far the most common is the Post Script language. Has been designated as the International Organization for the publishing industry use the standard page description language. In the color laser printer, it's color has its precise location ., make the printer faithfully the output image, the display on your monitor's colors and scanners scanned color better achieve harmonization. It is now widely used is the Post Script Level 2 language. Color saturation: Saturation refers to the output .of the package in a point (Dot) in the fullness of color, commonly referred to as color coverage ratio. Color saturation for different types of printers and their standards are not the same. It not only with the printer's design structure and work patterns, .but also with the use of print media (paper, etc.) have a certain relationship. For color laser printer, because it is extremely fine toner fuser (or hot) on paper, so to be able to easily achieve better color saturation. As .for color inkjet printers, chose to meet the quality requirements of the paper, in order to achieve the ideal color saturation. Grayscale enhancement technology: the technology is improving the quality of laser printer output of the more commonly-used .method. It is without altering original pixel size of the printer, the output of the grey-scale level (level). This technique primarily through the printer's ASIC chip to achieve, at the same time to increase the print controller's memory capacity for aid. .As a result of various manufacturers have chosen ASICs, adopt the solutions vary, so eventually the grayscale enhancements are very different. In a commercial product in the EPSON company MGT (Micro Gray Technology) is doing better. PCL: .PCL (Printing Control Language) is the HP specifications of a page description language, it prints in a Windows environment, you have to be Windows bitmap format converted to PCL format code, so the printer receives the print interpretation and implementation of the CPU. Although .other companies also have their own print control language, but its applicability as PCL. Print interface: print interface, early using a SPP (Standard Parallel Port) of the parallel interface, through to high-end 486, this .years of consistent policy interface is EPP (Enhanced Parallel Port: enhanced parallel interface). As the EPP than SPP increased 10 times, thus increasing popularity upon adoption. EPP is not only a good solution to a printer, high-speed transmission needs, but .also with the SPP and port compatible. Today, another high-speed parallel port ECP - (Enhanced Capabilities Port: enhanced high power interface) is already in use. Because support DMA (DirectMemory Access: direct memory access) mode, and therefore has .good prospects for development. Color resolution enhancement technology: this technology is available in three color series printer performance improvement: one is to make the image's edge effect to be improved; the second is to improve the image quality grayscale; .third, increase the color series. Because of the different types of printers, color inkjet printer, color laser printing Kun machine and the thermal transfer printer, color resolution enhancement technology to implement. Coupled with the affected by paper, ink, toner, and other .factors, therefore, when the resolution is raised to a certain extent, then go to the one-sided pursuit of DPI is only half done. Especially on a color printer. Because the color output per inch on more points, and do not necessarily get .better output, and other relevant factors (such as color saturation, etc.) is a very important role. Resolution enhancement technology: get rid of the special resolution enhancement card after some major manufacturers have implemented a this kind of .technology. The core of which is dependent on the hardware and software, without increasing (or limited) hardware costs down and increase the output quality of a technology. Use of this technology can enable printing results have improved. Early resolution enhancement technology: HP company .REt, EPSON company RITech, Apple's Fine Print, Destiny company EET, etc. Other inputs to the practical and Canon company AIR, EPSON company MGT, NEC Corporation of AMB. Resolution enhancement technology to get rid of the special resolution enhancement card after some major .manufacturers have implemented a this kind of technology. The core of which is dependent on the hardware and software, without increasing (or limited) hardware costs down and increase the output quality of a technology. Use of this technology can enable printing results have improved. .Early resolution enhancement technology: HP company REt, EPSON company RITech, Apple's Fine Print, Destiny company EET, etc. Other inputs to the practical and Canon company AIR, EPSON company MGT, NEC Corporation of AMB. Resolution: .it is a printer, an important technical indicators. Because it has a significant impact on the quality of the output, so the printer usually resolution (Resolution) of the grades of measured. Unit of measure is the DPI (Dot Per Inch). It .means that every inch of points can be printed. For example, a printer resolution is 600DPI, which means that its print output per inch hit 600 points. DPI the higher the value, the effect of the printed output, the more realistic the finer, .and of course the output time is longer, the price of expensive. Color resolution enhancement technology, the technology is available in three dimensionsOn the color series printer performance improvement: one is to make the image's edge effect to be improved; the second is to improve .the image quality grayscale; third, increase the color series. Because of the different types of printers, color inkjet printer, color laser printing Kun machine and the thermal transfer printer, color resolution enhancement technology to implement. Coupled with the affected by paper, ink ., toner, and other factors, therefore, when the resolution is raised to a certain extent, then go to the one-sided pursuit of DPI is only half done. Especially on a color printer. Because the color output per inch on more points, .and do not necessarily get better output, and other relevant factors (such as color saturation, etc.) is a very important role. Resolution enhancement technology to get rid of the special resolution enhancement card after some major manufacturers have implemented a this kind of technology .. The core of which is dependent on the hardware and software, without increasing (or limited) hardware costs down and increase the output quality of a technology. Use of this technology can enable printing results have improved. Early resolution enhancement technology: HP company REt ., EPSON company RITech, Apple's Fine Print, Destiny company EET, etc. Other inputs to the practical and Canon company AIR, EPSON company MGT, NEC Corporation of AMB. Resolution enhancement technology to get rid of the special resolution enhancement card after some major manufacturers .have implemented a this kind of technology. The core of which is dependent on the hardware and software, without increasing (or limited) hardware costs down and increase the output quality of a technology. Use of this technology can enable printing results have improved. Early .resolution enhancement technology: HP company REt, EPSON company RITech, Apple's Fine Print, Destiny company EET, etc. Other inputs to the practical and Canon company AIR, EPSON company MGT, NEC Corporation of AMB. PPM (Pages .Per Minute): number of pages per minute output is color inkjet printers, laser printers (including color laser), thermal transfer printers used to measure the output speed is an important indicator. PPM value refers to the continuous average speed when printing, if you .print only one page, you also need to add Home warm-up time. Specific to a particular type of product, because the output of the object (a plain text, there is a belt of colored text and pictures with true-color, plus .coverage), combined with the manufacturer's testing standards are not harmonized, resulting in a greater difference between PPM target. In view of the PPM could only serve as a reference value. PCL PCL (Printing Control Language) is the HP specifications of a page description .language, it prints in a Windows environment, you have to be Windows bitmap format converted to PCL format code, so the printer receives the print interpretation and implementation of the CPU. Although other companies also have their own print control language, but its applicability as .PCL. Print interface printing interface, early using a SPP (Standard Parallel Port) of the parallel interface, through to high-end 486, this years of consistent policy interface is EPP (Enhanced Parallel Port: enhanced parallel interface). As the EPP than .SPP increased 10 times, thus increasing popularity upon adoption. EPP is not only a good solution to a printer, high-speed transmission needs, but also with the SPP and port compatible. Today, another high-speed parallel port ECP - (Enhanced .Capabilities Port: enhanced high power interface) is already in use. Because support DMA (DirectMemory Access: direct memory access) mode, and therefore has good prospects for development..