Telecommunication, satellite links and set-top boxes allrequire tuning a high frequency oscillator. The actualtuning element is a varactor diode, a 2-terminal device thatchanges capacitance as a function of reverse bias voltage.1 The oscillator is part of a frequency synthesizingloop, as detailed in Figure 1. A phase locked loop (PLL)compares a divided down representation of the oscillatorwith a frequency reference. The PLL’s output is levelshifted to provide the high voltage necessary to bias thevaractor, which closes a feedback loop by voltage tuningthe oscillator. This loop forces the voltage controlledoscillator (VCO) to operate at a frequency determined bythe frequency reference and the divider’s division ratio.
標(biāo)簽： 開關(guān)穩(wěn)壓器 低噪聲 上傳時間： 2013-12-20
上傳用戶：ABCDE
在大功率弧焊電源設(shè)計中，IGBT 已成為主流的可控功率開關(guān)器件。IGBT 驅(qū)動電路作為功率電路和控制電路之間的接口，應(yīng)具備驅(qū)動延遲小、安全隔離、IGBT 過電流／過電壓保護(hù)準(zhǔn)確等功能。針對新型高壓大功率IGBT 驅(qū)動模塊2ED300C17－S 的過電流檢測及保護(hù)功能進(jìn)行了研究，提出了與過電流保護(hù)功能相關(guān)的參數(shù)選擇原則，并進(jìn)行了實驗驗證。
上傳時間： 2013-11-05
上傳用戶：kaje
介紹一種以Atmel公司的Attiny13為處理器的投影儀防盜器設(shè)計方案。該防盜器具有功耗低，功能完整，防盜效果良好等特點，除具有報警功能外，防盜器還具有以無線方式向主機(jī)發(fā)送報警信號的功能。采用315MHz發(fā)射模塊實現(xiàn)無線信號發(fā)送。該投影儀防盜器可適應(yīng)眾多廠家生產(chǎn)的防盜器主機(jī)。 Abstract: This paper introduces the design scheme of overhead projector's anti-theft device which users ATMEL company’s Attiny13as processor.This anti-theft device features low powerloss，functional integrity，good effect of anti-theft.In addition to its own with alarm functions，the anti-theft device also has alarm function which can send alarm signal to the host through wireless way.It sends wireless signal using315MHz transmitting module，so this overhead projector’s anti-theft device is adapted to anti-theft device host produced by many manufacturers.
上傳時間： 2013-11-02
上傳用戶：ysystc699
介紹了當(dāng)前普通標(biāo)記機(jī)控制系統(tǒng)現(xiàn)狀及其存在缺點，給出氣動標(biāo)記機(jī)及相頻修正PWM模式的工作原理。采用ATmega16單片機(jī)和USB轉(zhuǎn)換RS232接口器件CH341T實現(xiàn)驅(qū)動控制系統(tǒng)與PC的實時通訊，標(biāo)記控制系統(tǒng)可升級到USB接口。采用基于ATmega16的相頻修正PWM替換555振蕩電路產(chǎn)生的PWM，可直接通過軟件調(diào)整PWM信號。使用達(dá)林頓三極管TIP122替代直流繼電器驅(qū)動高頻電磁閥，使得電磁閥驅(qū)動電路簡單，成本低廉。該控制系統(tǒng)已成功應(yīng)用于氣動標(biāo)記機(jī)。 Abstract: In this paper,the actuality and demerit of the common gas marking machine control systems are described.The operation principle of the gas marking machine and the phase and frequency correct PWM of ATmega16is introduced.The real-time communication between the driving control system and PC by CH341T which its function is translated USB to RS232is realized,the control systems is updated grade to USB interface.The PWM signal can be adjustable by software for the555surge circuit was substituted by the phase and frequency.The high frequency electromagnetic value’s driving circuit by DC relay is replaced by TIP122,therefore,the circuit is become simple and the cost cheap.The control systems has been widely used in gas marking machine.
標(biāo)簽： ATmega 16 標(biāo)記 控制系統(tǒng)
上傳時間： 2013-10-18
上傳用戶：1427796291
針對目前燃?xì)庠钍袌龅臓顩r，提出一種基于PIC16C711單片機(jī)的燃?xì)庠蠲}沖點火控制器設(shè)計,具體包括有系統(tǒng)的組成和功能介紹、硬件電路設(shè)計及軟件功能實現(xiàn)。 Abstract: Aiming at today’s gas cooker market, a pulse ignition controler design based on PIC16C711 is presented.The specific descriptions of system components and functions,hardware circuit design and software function are given.
上傳時間： 2013-10-31
上傳用戶：zhqzal1014
提出了一種基于C8051F320的列車安全巡檢儀的設(shè)計方案，詳細(xì)闡述了巡檢儀的各個模塊的硬、軟件設(shè)計。巡檢儀集信息采集、軸溫檢測、照明和記錄存儲等功能于一體，實現(xiàn)了對列車安全巡檢工作有效的監(jiān)督和科學(xué)管理。系統(tǒng)軟件采用C51編寫，對單片機(jī)進(jìn)行有效的電源管理，保證了巡檢儀的穩(wěn)定性、可靠性和低功耗性。 Abstract: This paper puts forward a design of train safety inspection based on C8051F320,describes all modules hardware and software design of inspection instrument.The inspection instrument has the function of information collection, axle’s temperature detection, lighting and records storage.It can supervise and administer train safety inspection work effectively.The system software using C51 can manage the power of single chip microcomputer, and guarantee the stability, reliability and low power consumption of the inspection instrument.
標(biāo)簽： C8051F320 列車 儀的設(shè)計 巡檢
上傳時間： 2013-12-22
上傳用戶：落花無痕
介紹了電力操作電源與智能電池巡檢系統(tǒng)的特點，給出了一種基于超低功耗單片機(jī)MSP430 F149針對中小型變電站自動化運行的專用設(shè)備的基本設(shè)計原理及實現(xiàn)方法，最后給出了詳細(xì)硬件構(gòu)成和軟件實現(xiàn)。該系統(tǒng)能滿足中小型變電站安全、可靠、自動運行的要求，并通過與上位機(jī)的串行通信實現(xiàn)變電站的遠(yuǎn)程管理和控制。 Abstract: The characters of the intelligent battery data logging system of the electric operation power are introduced.The basic design principle and the implemented methods of the special equipment which only designed for the middle or small transformer substation based on MSP430F149 are prescribed. Finally, the hardware block diagram and the software flow chart are also given. The function that the system finally needs to realize can basically meet with the middle or small transformer substation’s satisfy, reliably,and automatic running.And it can also realize the transformer substation long-distance management and control by serial communicating with the host computer.
上傳時間： 2013-11-25
上傳用戶：黃華強(qiáng)
介紹一種基于單片機(jī)的多路溫度采集及監(jiān)控系統(tǒng)，能夠測量6路溫度信號，具有計算機(jī)聯(lián)網(wǎng)功能，各測量點可以單獨監(jiān)控和設(shè)置，可根據(jù)用戶的需求自動控制。測量溫度范圍為-10 ℃～200 ℃，控制方式采用模擬量調(diào)壓模式。該系統(tǒng)具有控制精度高、沖擊小等特點。 Abstract: A temperature collecting and surveillance-controlling system based on sing-chip microcomputer is introduced. It can measure 6 channel signal of the temperature,and it has a function of network connection.The temperature measure points can be monitored and located, it can be controlled automatic according to user’s demand.The temperature range is -10℃ to 200℃.The model of control is adjustable voltage with simulation. It features high precision and little impact.
標(biāo)簽： 多路 溫度采集 監(jiān)控系統(tǒng)
上傳時間： 2013-10-23
上傳用戶：bjgaofei
TI半導(dǎo)體針對工業(yè)應(yīng)用推出了基于ARM926EJ-S內(nèi)核的低功耗ARM9處理器AM17xx和AM18xx。其中，AM17xx 和OMAPL137在軟件和引腳上兼容；AM18xx 和OMAPL138在軟件和引腳上兼容。基于本系列處理器，用戶可快速開發(fā)出具有強(qiáng)壯可靠操作系統(tǒng)、豐富用戶接口、高性能的處理能力的設(shè)備。
標(biāo)簽： ARM EJ-S 926 內(nèi)核
上傳時間： 2013-10-19
上傳用戶：9牛10
設(shè)計了一個工作在S波段矢量陣列的天線單元，利用HFSS軟件進(jìn)行優(yōu)化和仿真。實測結(jié)果表明，該天線在E面和H面的交叉極化電平分別小于-26 dB和-23 dB，兩個端口之間的隔離度大于32 dB。該數(shù)據(jù)滿足組成矢量陣列的要求。
上傳時間： 2013-11-17
上傳用戶：朗朗乾坤
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