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    <TD align=left height=30><A 
      href="http://www.dzjs.com/default.asp">电子技术天地</A> &gt;&gt; <FONT 
      color=black>实验制作 &gt;&gt; 影视通信&gt;&gt;</FONT><B><FONT 
      color=#ff9900>四、不用电感的调频发射器</FONT></B></TD></TR>
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    <TD align=left height=30><A href="http://www.dzjs.com/"><IMG height=8 
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      录入日期:2003-7-19&nbsp;阅读：3102 次 &nbsp;文章来源：&nbsp;原作者：&nbsp;&nbsp;<FONT 
      color=black> 关键词：无线发射电路</FONT> </TD></TR>
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                  <P style="LINE-HEIGHT: 150%" 
                  align=left>&nbsp;&nbsp;&nbsp;&nbsp;以上介绍的几款发射电路虽然电路形式比较简单，但在电路中都使用了电感，制作难度较大，下面介绍一款不用电感的调频发射电路，电路如图所示。<IMG 
                  hspace=10 src="spmain.files/showimg.htm" align=left 
                  vspace=10><BR>&nbsp;&nbsp;&nbsp;&nbsp;驻极体话筒接收到的音频信号经过C1耦合到反相器IC1-A组成的放大器进行放大，放大后的音频信号加到变容二极管VD1（30V，4～32pF）两端使其电容量随着声音的变化而改变，达到调频的目的。三端陶瓷滤波器与IC1-B共同构成载波信号振荡电路。调制后的音频信号经过L1-C反相、IC1-D、IC1-E、IC-F放大，然后经过C7耦合到天线发射到空中。在该电路中，IC1-C不但内部将信号反相，还能够降低输出阻抗，使前置电路与后级放大电路能够更好地匹配，有效地提高发射频率。<BR>&nbsp;&nbsp;&nbsp;&nbsp;图电路中，六个反相器IC1-A～IC1-F采用CMOS六反相器集成电路CD4069。该机发射频率约为96.3MHz，天线为700mm时发射效果最佳。 
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    <TD align=middle height=40><FONT 
    color=#ff9900>版权归原作者所有;如需转载请先联系原作者！</FONT></TD></TR>
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            target=_blank>能否一些介绍一些……</A> 由<FONT 
            color=#000099>冯裕辉</FONT>发表于3.1&nbsp;<BR><IMG 
            src="spmain.files/4.gif"><A 
            href="http://www.dzjs.com/view.asp?ReviewID=79&amp;ID=798" 
            target=_blank>NO</A> 由<FONT 
            color=#000099>MIC</FONT>发表于8.12&nbsp;<BR><IMG 
            src="spmain.files/1.gif"><A 
            href="http://www.dzjs.com/view.asp?ReviewID=172&amp;ID=798" 
            target=_blank>ytyt</A> 由<FONT 
            color=#000099>Fugue</FONT>发表于12.20&nbsp;<BR><BR></P></TD></TR></TBODY></TABLE></TD></TR>
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