用电流源构成的简易调节器

如图1所示的简易调节器使用一个开关电流源来驱动一对分路齐纳调节器。在加电状态下,穿过R_1的弱小电流提升了Q_1的栅压,使Q_1导通。L_1的电流对C_1充电,使之达到最大值15V(由D1设定)。L_1电流增大造成R_2上电压的下降。R_2上的电压通过C_2耦合到Q_1栅极,把Q_1迅速关断。随着Q_1完全关断,L_1的电流继续流动,通过D_1对C_3     

超长延时电路

图1为单结晶体管延时电路,简单可靠,能以较小的R、C位获得超长延时输出,原理介绍如下: 在图1中,R_1、C_1、BG_1组成弛张振荡器,其周期T=t_1+t_2;其中t_1=R_1C_1ln1/(1-η_1),η_1为BG_1的分压比,t_2≈R_(b1)C_1,BG_2、BG_3为脉冲整形级。R_4、D_1、R5、C_2构成积分延时电路。BG_4为C_2的电压幅度鉴别输出。当电源通过R_1向C_1充电至BG_1的峰点电压V_(p1)时,C_1立即通过R_(b1)放电,BG_3截止,使得电源通过R_4、D_1、R_5向C_2充电,随着C_1放电结束,BG_3恢复导     

红烧鸡块

原料鸡胸肉1付。调料(A)葱末1/2汤勺,姜末1/2汤勺,油3汤勺; (B)干淀粉2茶勺,香油1茶勺,酱油1汤勺,味精1/4茶勺,花椒粉1/2汤勺,盐1/2茶勺,酒1汤勺,糖1茶勺,醋1/2茶勺。制作1.鸡胸肉洗干净,切成5cm长、2cm宽的长条块,以调料(B)腌泡30分钟入味。     

二总线传送的对讲电话

<正> 本文介绍的这种对讲电话采用二总线无极性联接,传送距离远,壁挂式结构,勿须按键或拨号。甲机摘机时乙机响铃,乙机摘机后双工对讲;乙机摘机时甲机响铃,甲机摘机后双工对讲。操作简单方便、音量大、音质好、无任何噪杂音,配带交流供电电源盒,运行费用低,工作稳定可靠。广泛应用于小型企事业单位和家庭、前店后厂、前店后居、楼上楼下以及饭店吧台与灶间等场所内部的联络通话。 电源电路工作原理如图1所示,220V交流市电经T1变压、1VD1～1VD4桥式整流,1C1滤波,1VD5、1VT1射随稳压为30V左右,1R2为1VT1的分流电阻,可减轻1VT1的功耗。     

一尘不染的声音Audiovector R1 Arrete书架音箱

R1 Arrete是一款挺有意思的书架音箱,它是Audiovector R1系列里面的最高级型号,目前国内定价要5万多元一对。而整个R1系列一共有三款型号,分别是R1 Arrete、R1 Avantgarde和R1 Signature。其中,R1 Signature是三者当中最便宜的,与最贵的R1 Arrete比起来,一对R1 Arrete的价格基本上可以买到两对的R1 Signature。当然,一分钱一分货,作为R1里面最贵的R1 Arrete,它与另外两款的主要不同点在于喇叭单元的使用以及分频器的设计和调校。其实,通过一些官方参数也能看得出R1 Arrete的性能是三者当中最好的。例如低频响应能达到38Hz,承受功率为200W,这意味着它可以重播出更深沉的低音,大动态的时候也更从容。     

微波炉菜谱

★川味鱼原料鲫鱼1条(300克左右),葱2根,麻油1匙,姜2片,油2匙。调料胡椒粉1匙,蒜茸1/2匙,糖1匙。生粉1匙,料洒1匙,豆瓣酱1匙,醋2匙,红辣椒2根,盐1匙。操作1.把鱼洗净,抹干水份,用盐、料酒、胡椒粉腌     

口腔血管瘤冷冻外科治疗

1　材料和方法1 .1　临床资料40例中 ,男 2 5例 ,女 1 5例 ;年龄 7月～ 5 7岁 ,其中 5 0岁以上 3例 ,1 0岁以下 1 0例 ,其余为 1 0～ 5 0岁。病变大小 (以面积计 ) 2 .5cm2～ 2 5cm2 ,其中 1 2cm2 以上 4例 ,8～ 1 0cm2 8例 ,其余为 2 .5～ 6cm2 。类型 :海绵状血管瘤 2 1例 ,混合型血管瘤 1 0例 ,毛细血管瘤 7例 ,淋巴血管瘤 2例。分布 :唇 1 6例 ,颊 3例 ,舌 1 2例 ,牙龈 8例 ,口底 1例。所有病例都能耐受冷冻完成治疗。1 .2　治疗方法1 .2 .1　制冷设备　国产YDI -2型液氮低温治疗机为冷源 ,降温达-1 96℃。1 .2 .2　制冷准备　根据肿…     

一种超低频鉴频器

图1是一种能解调超低频信号的鉴频器,这种电路结构简单,使用在信号缓慢变化的场合,例如振动仪中。电路由电容器C_1、C_2、二极管D_1、三极管BG_1以及负载电阻R_1组成。其工作原理是,当A点加上+E值脉冲信号时,此信号经C_1、D_1、C_2充电。由于B点比C点电位高,所以BG_1,的eb结趋于反向偏置,BG_1截止。如果略去D_1的结压降,则+E脉冲电压由C_1与C_2分压,所以C点的电压是V_C=E·C_1/(C_1+C_2)。经过时间t后,输     

路灯自动电子开关

路灯的功能是夜晚接通照明,白天适时关闭。这里介绍的简易、低价电子开关路灯控制电路可以在夜晚自动开灯,早晨自动关灯,不需要人工干预。电路大致分成电源供给和灯光切换两部分。闭合开关S1,可将220V交流电源加至电路。220V交流电压经R1、D1、ZD1后降低为9郾1V直流电压,ZD1的电压用C1、C2滤除纹波。改变ZD1的稳压值,可使ZD1输出直流电压增加至18V或减低至5V。灯光切换部分由光敏电阻LDR1、晶体管T1、T2、T3和定时器IC1组成。IC1接成反相器工作模式,即②脚低时③脚高,②脚高时③脚低。它主要用来触发可控硅BT136,使街灯B1发光…     

无线局域网(WLAN)加速发展

ＷＬＡＮ的速率至今只达 1～ 2Ｍｂ /ｓ,这是因为许多应用原是根据 1 0Ｍｂ /ｓ以太网速率设计的。如此相对较低的速率 ,限制了在无线网络上运行的应用种类。不久 ,这种状况将会改变。1 999年第三季度末 ,增强型ＩＥＥＥ 80 2 .1 1标准有望获得批准。该标准可提供 1 1Ｍｂ /ｓ的数据速率 ,将从根本上改变ＷＬＡＮ设计和应用现状。1　新机遇 ,新挑战新的高速标准将使ＷＬＡＮ行业迅猛发展。新的数据速率意味着新的应用 ,新的应用又使设计面临新的挑战。1 1Ｍｂ /ｓ数据速率比两年前刚批准的ＩＥＥＥ 80 2 .1 1标准快 5倍 ,它扩大了ＷＬＡＮ的…     

Injection control of a long-pulse electron-beam pumped XeF (C→A) laser

An XeF (C→A) laser, pumped at a rate of 290 kW/cm³ with a 600-ns electron-beam pulse, has been operated as an injection-controlled oscillator. A stable cavity has been injected with radiation from a pulsed dye laser source. A significant reduction in laser turn-on time has been achieved, and the laser pulse duration has been extended to 500 ns (FWHM). As a consequence, the laser intrinsic efficiency and specific output energy have been increased by approximately 50%, to 1.8% and 3 J/L, respectively, which represent the best performance obtained thus far for any directly electrically excited XeF (C→A) laser. Also, by injecting a narrowband signal into the cavity, the XeF (C→A) laser linewidth has been reduced by more than two orders of magnitude, to less than 1.3 Å, the resolution of the spectrometer. The laser wavelength has been tuned from 478.6 to 486.8 nm, with less than a factor of two variation in output energy     

InP与In_（1－x）Ga_xAs_yP_（1－y）／InP的电解液电调制反射

研究了ＩｎＰ样品和Ｉｎ１－ｘＧａｘＡｓｙＰ１－ｙ液相外延片在３００～８００ｎｍ范围内的电调制反射光谱。利用Ａｐｓｎｅｓ三点法计算了临界点能量、增宽因子和自旋轨道分裂值。通过实验曲线与理论公式的拟合，确定了临界点能维数及相位因子。并且间接提供了被测Ｉｎ１－ｘＧａｘＡｓｙＰ１－ｙ四元合金的组份值及其它临界点能量值Ｅ０和Ｅ２。     

A study of single-phase to three-phase cycloconverters using PSPICE

A single-phase-to-three-phase cycloconverter system operating from a 50 Hz input has been simulated under various loading conditions using a PSPICE circuit simulator. The Giacolleto SCR model has been modified. Detailed waveforms of load voltage, load current, and current of various semiconductor-controlled rectifiers (SCRs) have been plotted. It has been demonstrated that for low and medium L/R loads a simple constant firing angle sequence works well, whereas the cosine wave crossing method (CWCM) seems to be optimum for high L/R loads. Theoretical results are validated with the experimental results     

高压IGBT的研制

介绍高压绝缘栅双极晶体管（ＩＧＢＴ）的终端和单元的设计与制造技术；实验验证了两种用于１０００～１２００ＶＩＧＢＴ的高压终端，研制的芯片获得了７．５Ａ，耐压１１５０Ｖ的实验结果。     

The electron irradiation effects on silicon gate dioxide used for power MOS devices

The work provides experimental results of high energy electron irradiation effects on silicon dioxide used for power MOS devices. A systematic increase of the threshold voltage has been observed in irradiated IGBT and VDMOS devices processed on Si1 0 0 and Si1 1 1, respectively. The threshold voltage shift has been interpreted as a result of the accumulated charge in the gate oxide. Single event gate rupture has been observed and attributed to the recoil ion interaction with the gate SiO₂. The result has been corroborated by reliability stress tests. After electron irradiation, an increase in breakdown voltage appeared on all devices which was attributed to a change in the surface impact ionisation coefficient. The change is most notable in devices processed on Si substrate with 1 1 1 orientation.     

Injection control of a multipass amplification of a dischargeexcited XeF (C→A) laser

The laser performance and kinetic properties of the broadband C→A transition of the XeF*-exciplex have been studied under discharge excitation. With a pulsed dye laser as the injection source, amplified output pulses with an energy of up to 4 mJ have been obtained in the wavelength range from 450 to 520 nm. Injection of a well-defined seed pulse in an unstable confocal cavity has been developed into a useful technique for identification of subtle kinetic details of the complicated lasing process in XeF*, such as the role of the competitive narrow-band B→X transition or the influence of the various buffer gases     

A chain mechanism of amplification via magnetic dipole transition

A stimulated emission at 1.25 μm has been studied under excitation of potassium vapor via a K(4S→5S ) magnetic-dipole transition. A chain mechanism of amplification, including a magnetic-dipole Raman scattering (M1-RS) and an electric-dipole four-wave parametric emission (E1-FWPE), has been introduced to model this emission     

High electron mobility in (InAs)n(GaAs)n short period superlattices grown by MOVPE for high-electron mobility transistor structure

(InAs)_n(GaAs)_n short period superlattices (SPSs) have been successfully grown by a continuous MOVPE process on InP substrates. Their structural, optical, and electrical properties have been studied. The periodic structures have been confirmed by x-ray measurements and (InAs)₁(GaAs)₁ SPSs have been clearly observed by transmission electron microscopic characterization. The optical quality of the material has been tested by 2K photoluminescence and excitonic recombinations have been observed. Mobilities as high as 10700 cm².V⁻¹.s⁻¹ and 64000 cm². V⁻¹.s⁻¹ for a sheet concentration of 3 × 10¹² cm⁻² have been obtained at 300K and 77K, respectively.     

MEMS microwave device with switchable capacitive and inductive states

A microwave microelectromechanical system (MEMS) device that can be switched between capacitive and inductive states over the frequency range of 1 to 16 GHz is reported. The device has been designed based on coplanar waveguide architecture, and realised in thickly electroplated nickel with front-side bulk micromachining of the substrate using a commercial foundry process. The capacitive-to-inductive switchover has been achieved by changing the gap of the interdigitated comb fingers using a chevron microactuator. Experimental characterisation of the device has been conducted, and capacitances ≡0.2 pF in the frequency range of 1-16 GHz have been measured in the `off` state (driving voltage of the microactuator is 0 V), whereas inductances ≡0.5 nH in the frequency range of 1 16 GHz have been measured in the `on state (driving voltage of the microactuator is ≡1 V).     

Analysis of the high resolution spectrum of the fundamental bandsv 2 andv 5 of12CH3F and their interactions

Thev ₂(A₁) andv ⁵(E) fundamental vibration-rotation bands of¹²CH₃F have been recorded under high resolution (0.015 to 0.020 cm^?1) in the spectral range of 1460 cm^?1. About 1100 transitions have been assigned. The Coriolis interaction between v₂=1 and v₅=1, and the l(2,-1) interaction in v₅=1 have been rigorously treated. Sixteen molecular constants have been determined from a least squares analysis. They reproduce the observed data with an overall standard deviation of 0.0037 cm^?1.