查询词典 telephone amplifier

S1 is then changed to position 1. The voltage stored on C1 is inserted between the output and inverting input of the amplifier and the output of the amplifier changes by VIN to maintain the amplifier input at the input offset voltage. The output then changes from (VOS + IbiasR2) to (VIN + IbiasR2) as S1 is changed from position 2 to position 1. Amplifier bias current is supplied through R2 from the output of the amplifier or from C2 when S1 is in position 2 and position 1 respectively. R3 serves to reduce the offset at the amplifier output if the amplifier must have maximum linear range or if it is desired to DC couple the amplifier.

接着 S1 拨到位置 1，使 C1 的电压加在放大器的输出端和反相输入端之间，(由于电容端电压不能突变，所以)输出端的电压将产生大小等于 VIN 的变化，使放大器输入端维持输入失调电压，即当开关 S1 从位置 2 拨到位置 1 时，输出端电压将从(VOS + IbiasR2)变为(VIN + IbiasR2)。S1 处于位置 2 时，放大器的偏置电流是由输出端经电阻 R2 提供的，当 S1 转向位置 1 时则由 C2 提供。R3 的作用是降低输出失调电压，如果要求放大器具有最大的线性范围，或者采用直流耦合，就应该使用该电容。

The invention discloses a DC/DC circuit, comprising a PWM controller, a current amplifier, a peak current comparator, an error amplifier, a main switch, a synchronous switch and also an operational amplifier. The non inverting input end of the operational amplifier is used for coupling with input voltage or voltage reference, or used for coupling with the input voltage and the voltage reference; the inverting input end of the operational amplifier is used for coupling with the voltage reference or ground, and the output end thereof is connected with the non inverting input end of the error amplifier.

本发明公开了一种DC/DC电路，包括PWM控制器、电流放大器、峰值电流比较器、误差放大器、主开关和同步开关；还增设运算放大器，其同相输入端用于与输入电压或基准电压耦合，或用于同时与输入电压和基准电压耦合；其反相输入端用于与基准电压或地耦合，其输出端与所述误差放大器的同相输入端连接。

This kind of technology can flex the application of optical amplifier so that a same adaptive amplifier can be used as a pre-amplifier, a boost amplifier as well as a line amplifier.

在光标记交换系统中，可满足由于路由切换导致的光功率损耗大范围动态变化的应用需求。

The connection converting apparatus includes: a hook detector for detecting a hooked state of the telephone; a relay for connecting the telephone to either the Internet or the PSTN according to a commmand; a duplex circuit for suppressing voice leakage and side tone by converting and reconverting from a two-line signal of the telephone to a four-line signal for transmission and reception; a tone decoder for decoding a DTMF tone of the telephone; and a microprocessor for exchanging control data for the user's computer, controlling the relay to cause the telephone to be connected to the Internet when the hook detector detects an off-the-hook state of the telephone, and providing number data to the user's computer when the microprocessor receives number data from the tone decoder.

所述连接转换装置包括：用于检测所述电话的摘机状态的摘机检测器；用于根据命令将所述电话连接到互联网或PSTN的转接器；用于通过从所述电话的双路信号到用来传送和接收的四路信号之间的转换及复原来抑制声音泄漏和侧音的双工电路；用于对所述电话的DTMF音进行解码的音频解码器；以及微处理器，其用于交换来自所述用户的计算机的控制数据、控制所述转接器以使所述电话在所述摘机检测器检测到所述电话的摘机状态时连接到互联网、以及在所述微处理器接收到来自所述音频解码器的号码数据时向所述用户的计算机提供号码数据。

Later, it makes some comparison with four kinds of modulation technique, and finally, it implements the three-level PWM switching power amplifier with the PWM technique. The power of the amplifier is 2kVA, and the frequency bandwidth is 10～3kHz. In the thesis, the author designs and makes the hardwares of the switching power amplifier. The hardwares contain power inverter rank circuit, control system circuit based on DSP, drive and isolation circuit, and protective circuit. The thesis also analyses the potential safety problems and put forward some solutions for the problems. Furthermore, the thesis accomplishes the software design of the control system, and successfully debugs it. The methods of designing higher power ampilfier are also discussed in the thesis. It analyses the feasibility of the methods, outlines the way of how to design higher power switching power amplifier, and does some experiments with the method of switches-parallelling.

根据电动振动试验系统对开关功放的要求，提出了以电感电流瞬时值控制技术为基础的三电平脉宽调制开关功放的设计方案，并通过系统仿真进行了原理性论证；然后设计并制作了开关功放的硬件，包括功率转换电路，基于DSP的控制电路，驱动、隔离电路以及保护电路；针对开关功放数学模型不易得出的特点，细致分析了模糊自适应PID控制方法，在此基础上编写了控制程序；研制出一台功率为2kVA，通频带为10～3kHz的三电平脉宽调制开关功放；论文中还探讨了实现大功率开关功放的方法，分析了各种方法的可行性，给出了实现大功率开关功放的思路，并进行了并联开关管实现大功率开关功放的实验。

For weak nonlinear distortion, the expressions of total harmonic distortion, the second order intermodulation distortion(IM2 ), the third order intermodulation distortion(IM 3) and intercept point(IP 3) are deduced. With the aid of software Multisim, we simulate transistor common emitter amplifier, transistor common emitter amplifier with resistor in emitter, differential amplifier and differential amplifier with resistor between emitters. The simulational results and theoretical analyses are almost the same.

针对弱非线性失真，推导了总谐波人、二阶互调失真( IM2 )、三阶互调失真( IM3)和截点( IP3)的表达式，借助于 Multisim软件，对晶体管共发放大器、发射极带反馈电阻的失发放大器、差分放大器和发射极间带反馈电阻的差分放大器进行了仿真，并与理论结果作了比较，结果令人满意。

Voltage Source and Current Source, Thevenin Theory, Trouble Shooting, Characteristic Curve of Diode, Diode Models, Rectifier Circuits, Input Filtering Capacitor, Voltage Multiplier Circuits, Limiter and Clipper Circuits, DC Clampers and Peak-to-peak Detectors, Zener Diode, Zener Diode Rectifier, Photoelectric Devices, Collector-Emitter Junction, Transistor Characteristics of common-emitter, Base Bias, LED Dirver, Establishing a Stable Q-point, PNP Transistor Biasing, Transistor Biasing, Coupling and By-Pass Capacitors, AC Emitter Resistance, Common-Emitter Amplifier, Other Common-Emitter Amplifiers, Cascaded Common-Emitter Amplifiers, AC Load Line, Emitter Follower, Class B Push-pull Amplifiers, JFET Characteristic Curve, JFET Biasing, JFET Amplifier, VMOS Circuit, Differential Amplifier, Operational Amplifier, Non-inverting Feedback, Negative Feedback.

电子学实验( S0704)(1，1)/应用电子学实验( S0472)(1，1)电压源和电流源、戴维宁定理、故障排除、二极体特性曲线、二极体近似模型、整流电路、电容-输入型滤波器、倍压电路、限制器电路和峰值检测电路、直流定位器与峰对峰检测器、齐纳二极体、齐纳二极体整流器、光电元件、集射极接面、集极特性曲线、基极偏压、LED驱动器、建立一个稳定的工作点 Q 、 PNP 电晶体偏压、电晶体偏压、耦合及旁路电容、交流射极电阻、共射极放大器、其他 CE 放大器、串接共射极放大器、交流负载线、射极随耦器、 B 类推挽式放大器、 JFET 特性曲线、 JFET 偏压、 JFET 放大器、 VMOS 电路、差动放大器、运算放大器、非反向电压回授、负回授。

LED safety lamp power telephone: telephone line desk lamp to use is that we ordinary telephone lines, voltage-driven LED light-emitting highlight, we also know that phone lines generally only 50V, the total power of only 0.3 watts, which means the lamp less electricity than the telephone, at the same time the use of 10,000 telephone lines per hour lamp consumes only 3 degrees.

LED电话台灯的安全省电：电话线台灯使用的是我们普通的电话线，电压驱动高亮LED发光，我们也知道电话线一般只有50V，总功率只有0.3瓦，也就是说该台灯的用电量比电话机还少，同时使用10000只电话线台灯每小时仅耗电3度。

Given that V2 is applied to the amplifier input lead, the high input resistance of the operational amplifier is the only load on V2, and the only current drawn from the source is the very low input offset current of the operational amplifier.

若V2加到放大器的输入端，运算放大器的高输入电阻成为V2的唯一负载，而且唯一从源吸取的电流是运算放大器非常低的输入偏置电流。

In the electronic system, a power amplifier which provides magnetic coil with exciting current to produce electromagnetic force is one of the main components. General commercialization of power amplifiers can not meet the application requirements, but should be designed.Power amplifiers are divided into linear amplifier and switching amplifier.

磁悬浮轴承是典型的机电一体化系统，在其电控系统(传感器、控制器和功率放大器)中，功率放大器具有重要的作用，它向电磁铁线圈提供相应的控制电流以产生所需要的电磁力。

Green function defined inphase space differs from one in coordinate space by its struc-ture which exhibits nonlocatity in coordinates and oscillatorybehavior with respect to momenta.

在相空间中定义的Green函数不同于通常坐标空间的Green函数，在结构上显示出对坐标的高度非局域性，而对动量则显示出振荡行为。

The upper front part of a saddle;a saddlebow.

前鞍桥马鞍前面的上部分；前鞍桥