鎖定放大是微弱信號檢測的重要手段。基于相關(guān)檢測理論，利用開關(guān)電容的開關(guān)實(shí)現(xiàn)鎖定放大器中乘法器的功能，提出開關(guān)電容和積分器相結(jié)合以實(shí)現(xiàn)相關(guān)檢測的方法，并設(shè)計(jì)出一種鎖定放大器。該鎖定放大器將微弱信號轉(zhuǎn)化為與之相關(guān)的方波，通過后續(xù)電路得到正比于被測信號的直流電平，為后續(xù)采集處理提供方便。測量數(shù)據(jù)表明鎖定放大器前級可將10-6 A的電流轉(zhuǎn)換為10-1 V的電壓，后級通過帶通濾波器級聯(lián)可將信號放大1×105倍。該方法在降低噪聲的同時(shí)，可對微弱信號進(jìn)行放大，線性度較高、穩(wěn)定性較好。 Abstract: Lock-in Amplifying（LIA）is one of important means for weak signal detection. Based on cross-correlation detection theory， switch in the swithched capacitor was used as multiplier of LIA， and a new method of correlation detection was proposed combining swithched capacitor with integrator. A kind of LIA was designed which can convert the weak signal to square-wave， then DC proportional to measured signal was obtained through follow-up conditioning circuit， providing convenience for signal acquisition and processing. The measured data shows that the electric current（10-6 A） can be changed into voltage（10-1 V） by LIA， and the signal is magnified 1×105 times by cascade band-pass filter. The noise is suppressed and the weak signal is amplified. It has the advantages of good linearity and stability.
標(biāo)簽： 開關(guān)電容 鎖定放大器
上傳時(shí)間： 2013-11-29
上傳用戶：黑漆漆
設(shè)計(jì)了一種基于PIC16C71單片機(jī)的數(shù)字水溫配制閥。該配制閥采用NTC熱敏電阻作溫度傳感器，與固定電阻組成簡單分壓電路作為水溫測量電路，利用PIC16C71單片機(jī)內(nèi)置的8位A/D轉(zhuǎn)換器把熱敏電阻上的模擬電壓轉(zhuǎn)換為數(shù)字量，PIC16C71單片機(jī)控制直流電機(jī)驅(qū)動混水閥調(diào)節(jié)冷熱水的混合比例實(shí)現(xiàn)水溫調(diào)節(jié)。給出了控制電路圖，對水溫測量電路的參數(shù)選擇和測溫精度作了詳細(xì)討論。實(shí)驗(yàn)和分析表明，選用阻值較大的NTC熱敏電阻和分壓電阻可較好地解決熱敏電阻因功耗較大造成的熱擊穿問題。 Abstract: A digital valve for controlling water temperature based on PIC16C71 was presented in this paper.A bleeder circuit which consisted of a NTC thermistor as temperature sensor and a fixed resistance was designed as water temperature measuring circuit.The analog voltage on the thermistor was converted into digital signal by a 8-bit A/D converter embedded in PIC16C71. Based on the digital signal， the MCU PIC16C71 drived the valve by a DC motor to adjust the water temperature through adjusting the proportion of hot water and cold water.The circuit diagram of controller was given，the principle，the component parameters and the accuracy of measuring temperatures were also dissertated in detail. It was found by experiment and analysis that thermal breakdown of thermistor caused by high power could be solved by selecting thermistor and fixed resistance with high impedance value.
上傳時(shí)間： 2013-11-08
上傳用戶：Yue Zhong
The PCA9549 provides eight bits of high speed TTL-compatible bus switching controlledby the I2C-bus. The low ON-state resistance of the switch allows connections to be madewith minimal propagation delay. Any individual A to B channel or combination of channelscan be selected via the I2C-bus, determined by the contents of the programmable Controlregister. When the I2C-bus bit is HIGH (logic 1), the switch is on and data can flow fromPort A to Port B, or vice versa. When the I2C-bus bit is LOW (logic 0), the switch is open,creating a high-impedance state between the two ports, which stops the data flow.An active LOW reset input (RESET) allows the PCA9549 to recover from a situationwhere the I2C-bus is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C-busstate machine and causes all the bits to be open, as does the internal power-on resetfunction.
標(biāo)簽： switch Octal 9549 with
上傳時(shí)間： 2014-11-22
上傳用戶：xcy122677
the calculator s usage! after you have inputed 2 operators,choose + - * / function! But the only situation I did t deal with is that when you choos + fuction ,and the operaters signs is like this -A+B,just turn it to B-A!
標(biāo)簽： calculator the operators function
上傳時(shí)間： 2016-02-12
上傳用戶：lili123
The XML Toolbox converts MATLAB data types (such as double, char, struct, complex, sparse, logical) of any level of nesting to XML format and vice versa. For example, >> project.name = MyProject >> project.id = 1234 >> project.param.a = 3.1415 >> project.param.b = 42 becomes with str=xml_format(project, off ) "<project> <name>MyProject</name> <id>1234</id> <param> <a>3.1415</a> <b>42</b> </param> </project>" On the other hand, if an XML string XStr is given, this can be converted easily to a MATLAB data type or structure V with the command V=xml_parse(XStr).
標(biāo)簽： converts Toolbox complex logical
上傳時(shí)間： 2016-02-12
上傳用戶：a673761058
Implement the following integer methods: a) Method celsius returns the Celsius equivalent of a Fahrenheit calculation celsius = 5.0 / 9.0 * ( fahrenheit - 32 ) b) Method fahrenheit returns the Fahrenheit equivalent of a Celsius the calculation fahrenheit = 9.0 / 5.0 * celsius + 32 c) Use the methods from parts (a) and (b) to write an application either to enter a Fahrenheit temperature and display the Celsius or to enter a Celsius temperature and display the Fahrenheit equivalent.
標(biāo)簽： equivalent Implement the following
上傳時(shí)間： 2014-01-19
上傳用戶：jackgao
用AVR單片機(jī)設(shè)計(jì)的MP3播放器 功能： MP3 Player IDE ATA interface FAT 32 with long file name support USB interface On board power supply (input from 7v to 20v DC) Bootloader firmware upgradeable via USB port Infrared bi-directional interface Remote Control Back light graphic LCD worked with only 2x AA batteries In sleep mode sink less than 1uA (2.5mA in active mode) 5 buttons for easy navigation Long range (more than 20 feets)
標(biāo)簽： MP3 interface support Player
上傳時(shí)間： 2016-07-02
上傳用戶：fandeshun
常用電源類芯片Altium Designer AD原理圖庫元件庫CSV text has been written to file : 電源類芯片.csvLibrary Component Count : 70Name Description----------------------------------------------------------------------------------------------------78Lxx 線性穩(wěn)壓芯片78Mxx 線性穩(wěn)壓芯片78xx 線性穩(wěn)壓芯片79xx 線性穩(wěn)壓芯片AMC7135 大功率LED恒流芯片AMS1117 三端穩(wěn)壓芯片APW7075 電壓轉(zhuǎn)換器AS1015 可調(diào)升壓芯片CN3703 三節(jié)鋰電池充電芯片DW01 鋰電池過流保護(hù)ICFP6716 可調(diào)升壓芯片GS3525 開關(guān)電源管理ICHT71xx LDO線性穩(wěn)壓芯片HY2110 鋰電池保護(hù) ICHY2213 電池充電平衡 ICLM2576 DC降壓芯片LM2577 DC升壓芯片LM2596 DC降壓芯片LM2940 5V穩(wěn)壓芯片LM2991S 可調(diào)穩(wěn)壓芯片LM317 可調(diào)線性穩(wěn)壓芯片LTC4054 鋰電池充電芯片LTC4057 鋰電池充電管理ICMC34063 DC升降壓芯片ME2100 可調(diào)升壓芯片ME2149-5pin DC升壓芯片ME2149-8pin DC升壓芯片ME3149 IN:36V,OUT:0.8-33/3A,150MHzME4057 鋰電池充電管理ICME6203 低功耗LDOME6209 低功耗LDOME8323X 電源管理ICMP2303 IN:28V,OUT:0.8-25/3A,360MHzMP2359 DC降壓芯片PN8370 電源管理ICREF196 3V3基準(zhǔn)電壓源REF5040 高精度電壓基準(zhǔn)SD4923E 以太網(wǎng)受電設(shè)備控制器SDB628 DC升壓芯片SM7033 非隔離AD-DCSX1308 可調(diào)升壓芯片TL431-ID 可調(diào)基準(zhǔn)穩(wěn)壓芯片TL431_SMD 可調(diào)基準(zhǔn)穩(wěn)壓芯片TL432_SMD 可調(diào)基準(zhǔn)穩(wěn)壓芯片TL494 電源管理ICTP4056 鋰電池充電管理TPS3305 DSP電源管理TPS62400 電壓轉(zhuǎn)換器TPS63000 電壓轉(zhuǎn)換器TPS6735 負(fù)電壓轉(zhuǎn)換芯片UC3843 電源控制芯片XC6206P332MR 低壓差線性穩(wěn)壓芯片XL1410 DC降壓芯片XL1507 DC降壓芯片XL1509 DC降電壓芯片XL1513 DC降壓芯片XL1530 DC降壓芯片XL1583 DC降壓芯片XL4003 DC降壓芯片XL4005 DC降壓芯片XL4013 DC降壓芯片XL4015 DC降壓芯片XL4016 DC降壓芯片XL6005 LED恒流驅(qū)動XL6007 DC升壓芯片XL6008 DC升壓芯片XL6012 DC升壓芯片XL6013 DC升壓芯片XL6019 DC升壓芯片XL7015E1 DC降壓芯片
標(biāo)簽： 電源 Altium Designer
上傳時(shí)間： 2022-03-13
上傳用戶：
LED 線陣顯示裝置, 分為 LED 線性旋轉(zhuǎn)顯示主機(jī)和圖文錄入器兩部分。主機(jī)用直流電機(jī)帶動由紅綠 LED 組成的線陣旋轉(zhuǎn), 同時(shí)線陣按照時(shí)序依次切換顯示狀態(tài), 在固定區(qū)域利用視覺暫留效果形成 16×16 點(diǎn)陣, 用以顯示圖文;圖文錄入器用 HMI 觸控屏作為人機(jī)交互界面, 實(shí)現(xiàn)圖文錄入和回放功能。主機(jī)與圖文錄入器通過無線通信方式進(jìn)行信息交互,可由圖文錄入器控制主機(jī)切換不同工作任務(wù), 以及改變線陣顯示內(nèi)容。The LED linear array display device is divided into two parts:the one is the main unit used to display content,and the other one is used to input the contents.The main unit is driven by a DC motor to rotate the linear array composed by red and green light emitting diodes.At the same time,the 16×16 dot matrix that switching the display state according to the time sequence on the main unit displays pictures and texts in the fixed area,by using the visual temporary effect.The HMI touch screen is used as human machine interface to realize the function that input and playback pictures and texts.The two parts of the device communicate with each other through wireless communication.The image and text input controller can control the main unit to switch different tasks and change the content of linear array displayed.
標(biāo)簽： stc12c5a60s2 單片機(jī) led
上傳時(shí)間： 2022-03-28
上傳用戶：jiabin
Agenda■Motor Types Overview■BLDC Motor Applications■Comparison of DC to Brushless DC Motors■Hall Sensors■Six-Step Commutation■Sensorless Commutation with Back-EMFVector Motor Control basicsClosed-Loop Speed Control■Introduction to BLDC Motor Control Evaluation Kit■SummaryAll the popular motor types have their specific applications, and all can be controlled with microcontrollers.We wll talk about Brushless DC motors as it is the fast growing motor type today.Motors used in modern Air conditioners, home appliances, tools, even electric bikes are all going to Brushless DC.
標(biāo)簽： bldc 電機(jī)驅(qū)動
上傳時(shí)間： 2022-07-07
上傳用戶：
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