【正文】 四個交通燈，顯示為 4組 3個發(fā)光二極管（紅色，綠色，黃色），實際上是安裝在每個四路。這種差異帳戶使用低限流電阻與綠色發(fā)光二極管。當(dāng)領(lǐng)導(dǎo)下的測試連接到終端的測試以任何方式：如果不亮，反向測試引線。如果有疑問，二極管的極性應(yīng)確定?；A(chǔ)直徑小于四分之一英寸。這種類型的電路稱為一個施密特觸發(fā)器。 晶體管的開關(guān)速度遠(yuǎn)遠(yuǎn)超過這些光敏電阻，使光盤。因為較大的 折射率的相對空氣，內(nèi)部效率的發(fā)光二極管可以很低。 砷化鎵二極管也可以制備液相外延硅作為它的氮和磷摻雜。 圖 1 一個完整微機(jī)的組成部件 硬件驅(qū)動程序指令集，或 軟件。 89S 52： AT89S 52是一種低功耗，高性能的數(shù)字的 8位微控制器與 8字節(jié)的系統(tǒng)內(nèi)可編程快閃記憶體。 出于 這一動機(jī)的想法，這個項目的目的是設(shè)計和實施 一個根據(jù)公路的車輛密度來 運行各種 模式的交通燈控制器。S: Gallium arsenide is a directgap semiconductor with an energy gap of at room temperature. A typical GaPs LED is made by solidstate impurity diffusion with zinc as the ptype impurity diffused into an ntype substate doped with tin, tellurium or silicon. The external efficiency at room temperature is typically 5 percent. A GaAs diode can also be fabricated by liquidphase epitaxy with silicon as both its n and p dopants. If a silicon atom replaces a Ga atom, it provides one additional electron, thus the resulting GaAs in as ntype. If a silicon atom replaces arsenic atoms, an electron is missing and the resulting GaAs is a ptype. In Si doped GaAs diode, the emission peak shifts down to . Since the emission is in infrared region, GaAs light sources are suitable for application such as the optical isolator. The high switching speed, with a recovery time between 2 and 10ns, makes them ideal for data transmission. The disadvantages of the GaAs emitter are emitted wavelength and the associated attenuation an dispersion. A critical issue of using an LED for the fibre optics is the coupling of light from the semiconductor to the fibre. Because of the larger refractive index of GaAs relative to air, the internal efficiency of LED can be quite low. PHOTO SEMICONDUCTOR A Germanium or silicon diode or transistor, which has a transparent encasing, can serve as a photodiode or transistor because the light photons can initiate conduction in the pn junction region. Early devices such as the OCP 71 were Gedevices. Later, silicon types became available with lower leakage current and better light sensitivity. In a phototransistor, the base lead is not used。 but, if a resistor is connected form base to emitter it reduced the light sensitivity. Darlington connected photo transistors (two transistors together in one case) such as the 2N5777 are very sensitive with a hFE of , a dark current of 100nA and a light current of for light flux density H=2mW/cm2. The device is rated 200mW and voltage of 25V maximum. SCRs with a light window are also available, called as LASCR, which are very sensitive and can turn mains power ON and OFF, with light. The switching speed of phototransistors far exceeds those of LDRs, made of CdS. The rise is 1KHz. Photo devices are useful in optical encoding, intrusion alarms, tape readers, level control, character recognition etc. Nowadays packing containing an LED and a photodiode, called ?optocoupler? is used for switching on power or control circuits. Because the light source (LED) and photodiode are physically kept separated (with 2mm) in the package, isolation upto 2500V can be had. 555 timer The buffer circuit39。我們將用 AT89S 52單片機(jī)和紅外傳感器執(zhí)行所有的計算與控制的相關(guān)工作。該設(shè)備的生產(chǎn)使用公司的高密度非易失性存儲器技術(shù)是符合業(yè)界標(biāo)準(zhǔn)的 80C 51指令集和引腳。一旦熟悉硬件和軟件，然后用戶可以使用微控制器的問題。如果一個硅原子取代一個鎵原子，它提供了一個額外的電子，從而產(chǎn)生在 n型砷化鎵。 光電半導(dǎo)體 ： 鍺或硅二極管或晶體管，它有一個透明的裝箱，可以作為一個光電二極管或晶體管是因為光的光子可以啟動傳導(dǎo)的 p n 交界地區(qū)。上升時間為 75?2n5777和下降時間是 50?美國最大開關(guān)速度是 1 kHz。 如果高靈敏度是 必要的滯后是一個問題，但在許多電路，它是一個有用的特性。實際的直徑略有不同的是。一個簡單的板凳的方法是使用歐姆表納入 3伏歐姆表的功能細(xì)胞