A light-emitting diode (LED) is a semiconductor device that emits narrow-spectrum incoherent light when forward-biased.The color of the emitted light depends on the chemical composition of the semiconductor material used, and can benear-ultraviolet, visible or infrared. LEDs are more prevalent today than ever before, replacing traditional incandescent andfluorescent bulbs in many lighting applications. Incandescents use a heated filament, are subject to breakage and burnoutand operate at a luminous efficiency of 2% to 4%. Fluorescents are more efficient, at 7% to 12%, but require highdrive voltage and contain mercury, a toxic substance that may be eventually banned in certain countries. LEDs, however,produce light directly through electroluminescence, operate at low voltage and can deliver over 20% luminous efficiency.
上傳時間： 2013-11-07
上傳用戶：xiaoyuer
Abstract: We don't expect manufacturers to produce clothes that in one size that fits everyone. In thesame way, one ESD component can't solve all issues—each application has different ESD requirements.Knowing that "one size fits all" cannot apply to power design, the power designer, or the engineering"super hero," must consider all the potential disruptions to a steady flow of power and thenvarious waysto mitigate them. This tutorial describes voltage- and current-limiting devices and risetime reducers tomanage the power. It also points to free and low-cost software tools to help design lowpass filters, checkcapacitor self-resonance, and simulate circuits.
上傳時間： 2013-11-18
上傳用戶：zhouxuepeng1
Automotive batteries, industrial power supplies, distributedsupplies and wall transformers are all sources ofwide-ranging high voltage inputs. The easiest way to stepdown these sources is with a high voltage monolithicstep-down regulator that can directly accept a wide inputrange and produce a well-regulated output. The LT®3493accepts inputs from 3.6V to 36V and LT3481 acceptsinputs from 3.6V to 34V. Both provide excellent lineand load regulation and dynamic response. The LT3481offers a high effi ciency solution over a wide load range andkeeps the output ripple low during Burst Mode® operationwhile the LT3493 provides a tiny solution with minimalexternal components. The LT3493 operates at 750kHzand the LT3481 has adjustable frequency from 300kHzto 2.8MHz. High frequency operation enables the use ofsmall, low cost inductors and ceramic capacitors.
上傳時間： 2014-12-24
上傳用戶：Pzj
Many system designers need an easy way to producea negative 3.3V power supply. In systems that alreadyhave a transformer, one option is to swap out the existingtransformer with one that has an additional secondarywinding. The problem with this solution is that manysystems now use transformers that are standard, offthe-shelf components, and most designers want toavoid replacing a standard, qualifi ed transformer with acustom version. An easier alternative is to produce thelow negative voltage rail by stepping down an existingnegative rail. For example, if the system already employsan off-the-shelf transformer with two secondary windingsto produce ±12V, and a –3.3V rail is needed, a negativebuck converter can produce the –3.3V output from the–12V rail.
上傳時間： 2013-10-09
上傳用戶：Jerry_Chow
為滿足礦井安全生產要求，介紹了一種以AT89C51單片機為主控器，對環境空氣的溫度、有毒易燃氣體的濃度等進行檢測的監控系統。該系統配合外圍電路能實現對上述環境指標的控制并存儲相關數據與上位PC機通信。它采用硬件抗干擾和軟件抗干擾技術，以確保整個系統工作的準確性。 Abstract: In order to meet the needs of mine produce safety，a kind of intellignet mine ambient monotoring and control system based on AT89C51 is introduced.This system can detect the temperature of ambient of mine，the density of poisonous inflammable gas,combined external circuit.With its function part， this system can change above-mentioned elements.
上傳時間： 2013-11-10
上傳用戶：wendy15
1.The C Programming Language is a powerful, flexible andpotentially portable high-level programming language. 2.The C language may be used successfully to create a programfor an 8-bit MCU, but to produce the most efficient machinecode, the programmer must carefully construct the C Languageprogram.3.The programmer must not only create an efficient high leveldesign, but also pay attention to the detailed implementation.
上傳時間： 2013-12-27
上傳用戶：huanglang
* This function positions the cursor at the specified * x,y coordinate. It uses the ANSI standard ESCAPE * * sequence to produce the desired effect. Its not the * * fastest way to position the cursor, but perhaps the * * most portable. *
標簽： the coordinate positions specified
上傳時間： 2015-02-24
上傳用戶：chenjjer
prolog 找路例子程序： === === === === === === Part 1-Adding connections Part 2-Simple Path example | ?- path1(a,b,P,T). will produce the response: T = 15 P = [a,b] ? Part 3 - Non-repeating path As an example, the query: ?- path2(a,h,P,T). will succeed and may produce the bindings: P = [a,depot,b,d,e,f,h] T = 155 Part 4 - Generating a path below a cost threshold As an example, the query: ?- path_below_cost(a,[a,b,c,d,e,f,g,h],RS,300). returns: RS = [a,b,depot,c,d,e,g,f,h] ? RS = [a,c,depot,b,d,e,g,f,h] ? no ==================================
標簽： Part connections example prolog
上傳時間： 2015-04-24
上傳用戶：ljt101007
zemax源碼： This DLL models a standard ZEMAX surface type, either plane, sphere, or conic The surface also demonstrates a user-defined apodization filter The filter is defined as part of the real ray trace, case 5 The filter can be used at the stop to produce x-y Gaussian apodization similar to the Gaussian pupil apodization in ZEMAX but separate in x and y. The amplitude apodization is of the form EXP[-(Gx(x/R)^2 + Gy(y/R)^2)] The transmission is of the form EXP[-2(Gx(x/R)^2 + Gy(y/R)^2)] where x^2 + y^2 = r^2 R = semi-diameter The tranmitted intensity is maximum in the center. T is set to 0 if semi-diameter < 1e-10 to avoid division by zero.
標簽： standard surface models either
上傳時間： 2013-12-05
上傳用戶：003030
8點基二fft Fast Fourier Transform (FFT). Using 8 points, takes about 1.2 ms to execute one FFT. Sets up General Purpose Timer 1 to generate events at 10 kHz. Will produce 10 kHz output on T1PWM and T1PWM pins.
標簽： FFT Transform Fourier execute
上傳時間： 2013-12-18
上傳用戶：Yukiseop
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