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	文章列表 - Hardware Desing

	(转)电子工程术语与定义
	<table style="border-collapse: collapse;" align="center" border="1" bordercolor="#dddddd" cellpadding="0" cellspacing="0" width="360"> <tbody><tr height="60"><td align="center" width="60"><img src="/fileicon/pdf.gif" alt="" border="0"></td><td> <table style="border-collapse: collapse;" border="0" cellpadding="0" cellspacing="0" width="100%"> <tbody><tr height="20"><td align="center" width="40">文件:</td><td>电子工程术语与定义列表.pdf</td></tr> <tr height="20"><td align="center" width="40">大小:</td><td>407KB</td></tr> <tr height="20"><td align="center" width="40">下载:</td><td><a href="http://blogimg.chinaunix.net/blog/upfile2/080817215718.pdf">下载</a></td></tr> </tbody></table> </td></tr> </tbody></table>
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	发表于:2008-08-17 ┆ 阅读(61) ┆ 评论(0)

	纹波和浪涌
	一、纹波(ripple)的定义<br> <br>1. 纹波(ripple)的定义 <br>     <br>   由于直流稳定电源一般是由交流电源经整流稳压等环节而形成的，这就不可避免地在直流稳定量中多少带有一些交流成份，这种叠加在直流稳定量上的交流分量就称之为纹波。纹波的成分较为复杂，它的形态一般为频率高于工频的类似正弦波的谐波，另一种则是宽度很窄的脉冲波。对于不同的场合，对纹波的要求各不一样。对于电容器老练来说，无论是那一种纹波，只要不是太大，一般对电容器老练质量不会构成影响。而对程控机电源或音响设备中所使用的电源，由于宽度很窄的脉冲没有足够的能量来推动喇叭的纸盆或话机的听筒而形成杂音。因此对于这种窄脉冲的要求可以放宽。 <br>    而对于音频范围内的类似正弦波的纹波信号，虽然其幅度不是太高，但其能量却使喇叭或听筒发生嗡嗡的杂音。因此对这种形态的纹波应有一定的要求，而对于用于一些控制的场合，由于窄脉冲达到一定的高度会干扰数字或逻辑控制部件，使设备运行的可靠性降低，因此对这种窄脉冲的幅度应有一定的限制，而对类似正弦波的纹波，一般由于其幅度较低，对控制部件的干扰不大。 <br>  &……
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	发表于:2008-08-15 ┆ 阅读(57) ┆ 评论(0)

	PC104总线
	<DIV>PC/104总线是嵌入式PC机所用的总线标准.有两个总线插头.其中P1 有64个引脚, P2 有40个引脚共有104个引脚,这也是PC/104 名称的由来.PC104有两个版本，8位和16位，分别与PC和PC/AT相对应。PC104PLUS 则与PCI总线相对应.<BR>    PC/104模块本质上就是尺寸缩小为3.8英寸 3.9英寸的ISA总线板卡。它的总线与ISA 在IEEE-P996中定义基本相同。具有16位数据宽度，最高工作频率为8MHz数据传输速率达到8MB/s，地址线24 条，可寻访16M字节地址单元。　</DIV> <DIV>所有PC/104总线信号定义和功能与它们在ISA总线相应部分是完全相同的。104根线分为 5类：地址线，数据线，控制线，时钟线，电源线。简要介绍如下：　</DIV> <DIV>(1)地址线</DIV> <DIV>SA0～SA19 和 LA17～LA23<BR>　SA0～SA19是可锁存的地址信号, LA17～LA23是非锁存信号由于没有锁存延迟因而给外设插板提供了一条快捷途径。SA0～SA19加上LA17～LA23可实现 16MB 空间寻址（其中 SA17～SA19 和 LA17～LA19 是重复的）</DIV> <DIV>(2)数据线</DIV> <DIV>数据线 SD0～SD7 和 SD8～SD15 其中 SD0～SD7 位为低 8位数据，SD8～SD15 为高 8 位数据　</DIV> <DIV>(3)控制线　</DIV> <DIV>AEN： ……
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	发表于:2008-05-20 ┆ 阅读(298) ┆ 评论(0)

	(转)接地与浮地技术
	<DIV>接地与浮地技术 </DIV> <DIV><BR>“地”是电子技术中一个很重要的概念。由于“地”的分类与作用有多种，容易混淆,故总 <BR>结一下“地”的概念。 <BR>    “接地”有设备内部的信号接地和设备接大地，两者概念不同，目的也不同。“地”的 <BR>经典定义是“作为电路或系统基准的等电位点或平面”。  <BR>　  <BR>    一：  信号“地”又称参考“地”，就是零电位的参考点，也是构成电路信号回路的公 <BR>共端。 <BR>      (1) 直流地：直流电路“地”，零电位参考点。 <BR>      (2) 交流地：交流电的零线。应与地线区别开。 <BR>      (3) 功率地：大电流网络器件、功放器件的零电位参考点。 <BR>      (4) 模拟地：放大器、采样保持器、A/D转换器和比较器的零电位参考点。 <BR>      (5) 数字地：也叫逻辑地，是数字电路的零电位参考点。 <BR>      (6) “热地”：开关电源无需使用工频变压器，其开关电路的“地”和市电电网有 <BR>关，即所谓的“热地”，它……
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	发表于:2008-05-07 ┆ 阅读(282) ┆ 评论(0)

	Eurocard (PCB)
	<P><B>Eurocard</B> is a <A title=Europe href="http://en.wikipedia.org/wiki/Europe"><FONT color=#0000ff>European</FONT></A> standard format for <A title="Printed circuit board" href="http://en.wikipedia.org/wiki/Printed_circuit_board"><FONT color=#0000ff>PCBs</FONT></A>, which can be plugged together into a standardized <A class=mw-redirect title=Subrack href="http://en.wikipedia.org/wiki/Subrack"><FONT color=#0000ff>subrack</FONT></A>. The subrack consists of a series of slotted card guides on the top and bottom, into which the cards are slid so they stand on end, like books on a shelf. At the "back" of each card is one or more connectors, which plug into mating connectors on a backplane which closes the rear of the subrack.</P> <DIV> <P>The Eurocard packaging system is a complex mixture of English and metric dimensions. Although this may seem confusing, widespread conformance to the standard dimensions means that users are not troubled by these issues.</P> <P><A id=Standard_pitch n……
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	发表于:2008-05-05 ┆ 阅读(180) ┆ 评论(0)

	(转)RS232C, V.24, V.28, X.21bis and EIA-232
	<DIV> <H1 style="TEXT-ALIGN: center" align=center><A name=top></A>RS232C, V.24, V.28, X.21bis and EIA-232<BR>Connector and Signaling Standards</H1> <HR> <BR> <H3>Interface Standards</H3> <P>V.24 is a specification for single-ended communications that includes the definition of connector pin allocations. It is used together with V.28 to define a specification for serial asynchronous or synchronous communications. <BR><BR>V.28 is a specification for single-ended communications that defines signal electrical characteristics. It is used together with V.24 to define a serial communications specification used for asynchronous or synchronous communications. V.28 signals are used in V.24 and part of V.35 interfaces.<BR><BR>RS-232C is essentially equivalent to a combination of V.24 and V.28. Note that the EIA standards have effectively replaced the RS standards.<BR><BR>X.21bis is a standard that incorporates a subset of V.24 but its use is in decline.</P> <H3 align=left><B>Interface Chara……
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	发表于:2008-03-17 ┆ 阅读(339) ┆ 评论(0)

	(转)PCB设计基础知识
	<DIV>刷电路板（Printed circuit board，PCB）几乎会出现在每一种电子设备当中。如果在某样设备中有电子零件，那么它们也都是镶在大小各异的PCB上。除了固定各种小零件外，PCB的主要功能是提供上头各项零件的相互电气连接。随着电子设备越来越复杂，需要的零件越来越多，PCB上头的线路与零件也越来越密集了。裸板（上头没有零件）也常被称为「印刷线路板Printed Wiring Board（PWB）」。 <BR>    板子本身的基板是由绝缘隔热、并不易弯曲的材质所制作成。在表面可以看到的细小线路材料是铜箔，原本铜箔是覆盖在整个板子上的，而在制造过程中部份被蚀刻处理掉，留下来的部份就变成网状的细小线路了。这些线路被称作导线（conductor pattern）或称布线，并用来提供PCB上零件的电路连接。<BR>    为了将零件固定在PCB上面，我们将它们的接脚直接焊在布线上。在最基本的PCB（单面板）上，零件都集中在其中一面，导线则都集中在另一面。这么一来我们就需要在板子上打洞，这样接脚才能穿过板子到另一面，所以零件的接脚是焊在另一面上的。因为如此，PCB的正反面分别被称为零件面（Component Side）与焊接面（Solder Side）。 <BR>   ……
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	发表于:2008-02-27 ┆ 阅读(351) ┆ 评论(0)

	(转)8255 PPI Tutorial
	<DIV> <H3>8255 PPI Tutorial</H3> <P>The 8255 Programmable Peripheral Interface (PPI) is a very popular and versatile input / output chip that is easily configured to function in several different configurations. The 8255 is used on several of our range of cards that plug into an available slot in your IBM PC. This chip allows you to do both digital input and output (DIO) with your PC. For example, you may want to have your PC turn on a switch, or have a switch electronically activate your PC to execute a program. Each 8255 has 3 off 8-bit TTL-compatiable I/O ports which will allows the control of up to 24 individual outputs or to read 24 individual inputs, or indeed a mixture of both input or output. For example, you could attach this to a robotic device to control movement by use of motors to control motion and switches to detect position etc.</P> <P>Our range of cards utilising the 8255</P> <UL> <LI><A href="http://www.decisioncards.com/io/8255_53.html"><FONT color=#0000ff>DC-06……
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	发表于:2007-12-04 ┆ 阅读(528) ┆ 评论(0)

	(转)PCB Design tools
	<DIV> <H3>PCB Design tools<BR><BR></H3> <P><A href="http://www.cadsoft.de/" target=_blank><FONT color=#ff0000><B>EAGLE</B><BR></FONT></A>Nice, easy to use CAD/CAM software for PCB schematic and routing.<B> We accept .BRD files for prototyping.</B> You can donwload free evaluation version. <BR><BR><A href="http://www.protel.com/" target=_blank><FONT color=#ff0000><B>PROTEL</B><BR></FONT></A>CAD/CAM software for schematic and routing. You can download 30 days free trial. Protel offers free old-DOS based software called EasyTrax. <BR><BR><A href="http://www.cadstarworld.com/" target=_blank><FONT color=#ff0000><B>CADSTAR</B><BR></FONT></A>CAD/CAM software for schematic and routing. Have free for download limited demo version. <BR><BR><A href="http://www.orcad.com/" target=_blank><FONT color=#ff0000><B>ORCAD</B><BR></FONT></A>CAD/CAM software. No demo/evaluation version. <BR><BR><A href="http://www.microcode.com/" target=_blank><FONT color=#ff0000><B>CIRCUIT MAKER</B><BR></FONT></A>CAD/CA……
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	发表于:2007-11-26 ┆ 阅读(593) ┆ 评论(0)

	RS232标准
	<h2> <center> <a name="anchor367782"></a> <table style="width: 23px; height: 20px;" bgcolor="#e8e8e8" border="0" cellpadding="0" cellspacing="2"> <tbody><tr> <td><a onmouseover="changeImages('home_tab','../Tab_Graphics/home_tab_blue.gif');CSAction(new Array(/CMP/'C1299C886'));return true;" onmouseout="changeImages('home_tab','../Tab_Graphics/home_tab.gif');CSAction(new Array(/CMP/'C1299C887'));return true" href="http://www.camiresearch.com/welcome.html" csout="C1299C887" csover="C1299C886"><br></a></td> <td><a onmouseover="changeImages('contact_tab','../Tab_Graphics/contact_tab_blue.gif');return true" onmouseout="changeImages('contact_tab','../Tab_Graphics/contact_tab.gif');return true" href="http://www.camiresearch.com/about_us.html"><br></a></td> <td><a onmouseover="changeImages('products_tab','../Tab_Graphics/products_tab_blue.gif');return true" onmouseout="changeImages('products_tab','../Tab_Graphics/products_tab.gif');return true"……
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	发表于:2007-08-25 ┆ 阅读(1140) ┆ 评论(0)

	Zener Diode
	Refer to the characteristic curve of a typical rectifier(diode) in the figure below. The forward characteristic of the curve we have previously described above in the <A href="http://www.americanmicrosemi.com/tutorials/diode.htm"><U><FONT color=#800080>DIODE</FONT></U></A> section. It is the reverse characteristics we<FONT size=2> </FONT>will discuss here<FONT size=2>.</FONT> <DIV> <DIV align=center><IMG src="http://blogimg.chinaunix.net/blog/upfile/070720133901.jpg" onload="javascript:if(this.width>500)this.width=500;" border=0></DIV></DIV> <DIV>Notice that as the reverse voltage is increased the leakage current remains essentially constant until the breakdown voltage is reached where the current increases dramatically. This breakdown voltage is the zener voltage for zener diodes. While for the conventional rectifier or diode it is imperative to operate below this voltage; the zener diode is intended to operate at that voltage, and so finds its greatest application as a voltage reg……
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	发表于:2007-07-20 ┆ 阅读(800) ┆ 评论(0)