讯享网<span style="font-family:宋体;">五款直流稳压电源电路图电路图一：整个电路通过单片机（AT89C51）控制，P0口和DAC0832的数据口直接相连，DA的CS和WR1连接后接P26，WR2和XFER接地，让DA工作在单缓冲方式下。DA的11脚接参考电压，通过调节可调电阻使LM336的输出电压为5.12V，所以在DAC的8脚输出电压的分辨率为5.12V/256=0.02V，也就是说DA输入数据端每增加1，电压增加0.02V。电路图二：电容降压的5V直流稳压电源，下面这个电源，可以约55mA电流：电容降压的5V直流稳压电源下面这个电源，可以约120mA电流：0-300v可调输出电路，这个电路为了与市电隔离加了一个1:1的变压器，可以不用这个变压器而直接输入市电，当然安全上会降低，但不影响使用。<br /> 

一﹑光缆产品用途及特点

<span style="font-family:宋体;">本产品适用于</span><span>485</span><span style="font-family:宋体;">等同性设备数据信号传输。</span><span></span> 

讯享网<span style="font-family:宋体;">二﹑执行标准</span><span></span> 

<span style="font-family:宋体;">参照</span><span>UL AWM 2919</span><span style="font-family:宋体;">文件</span> 

讯享网<span style="font-family:宋体;">三、使用特性</span><span></span> 

<span style="font-family:宋体;">1.</span><span style="font-family:宋体;">电缆长期使用温度：</span><span>-40</span><span style="font-family:宋体;">～</span><span>7</span><span style="font-family:宋体;">0</span><span style="font-family:宋体;">℃</span><span style="font-family:宋体;"></span> 

讯享网<span style="font-family:宋体;">2.</span><span style="font-family:宋体;">环境温度：固定敷设<span>-40</span>℃非固定敷设<span>-15</span>℃。<span></span></span> 

<span style="font-family:宋体;">3.</span><span style="font-family:宋体;">电缆敷设温度：<span><span>&nbsp;&nbsp; </span></span>不低于<span>0</span>℃<span></span></span> 

讯享网<span style="font-family:宋体;">4.</span><span> RS 485</span><span style="font-family:宋体;">通讯电缆</span><span style="font-family:宋体;">型电缆弯曲半径应不小于电缆直径的<span>10</span>倍。<span></span></span> 

<span style="font-family:宋体;">四、光缆型号、名称及用途<span></span></span> 

讯享网<span style="font-family:宋体;">型号：</span><span>RS 485</span> 

<span style="font-family:宋体;">规格：</span><span>3</span><span style="font-family:宋体;">×</span><span>2</span><span style="font-family:宋体;">×</span><span>0.75+1</span><span style="font-family:宋体;">×</span><span>0.2</span><span style="font-family:宋体;"></span> 

讯享网<span style="font-family:宋体;">名称：聚乙绝缘聚氯乙护套</span><span>485</span><span style="font-family:宋体;">通讯电缆</span><span></span> 

<span style="font-family:宋体;">光缆用途：用于</span><span>485</span><span style="font-family:宋体;">等同性设备数据信号传输，使</span><span style="font-family:宋体;">用或固定敷设</span> 

讯享网 <tr> <td style="border-bottom:windowtext 1pt solid;border-left:windowtext 1pt solid;border-top:windowtext 1pt solid;border-right:windowtext 1pt solid;" valign="top" width="152"> <p style="text-align:center;" align="center"> <span style="font-family:宋体;">项目</span> </p> </td> <td style="border-bottom:windowtext 1pt solid;border-left:windowtext 1pt solid;border-top:windowtext 1pt solid;border-right:windowtext 1pt solid;" valign="top" width="72"> <p style="text-align:center;" align="center"> <span style="font-family:宋体;">单位</span> </p> </td> <td style="border-bottom:windowtext 1pt solid;border-left:windowtext 1pt solid;border-top:windowtext 1pt solid;border-right:windowtext 1pt solid;" valign="top" width="74"> <p style="text-align:center;" align="center"> <span>0.2 mm</span><sup><span>2</span></sup> </p> </td> <td style="border-bottom:windowtext 1pt solid;border-left:windowtext 1pt solid;border-top:windowtext 1pt solid;border-right:windowtext 1pt solid;" valign="top" width="74"> <p style="text-align:center;" align="center"> <span>0.75 mm</span><sup><span>2</span></sup> </p> </td> </tr> <tr> <td style="border </div>