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document.write('    	<td height="18" bgcolor="#EDECE9">·[aa] 发表评论于 2009/4/10 22:36:11</td>');
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document.write('    	<td style="line-height:24px;font-size:14px;">&nbsp;确实，因为TL494最大工作电压可以到40V，不过取消7812以后需要调整电路参数，特别是场效应管驱动</td>');
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document.write('    	<td height="18" bgcolor="#EDECE9">·[] 发表评论于 2009/4/10 12:25:02</td>');
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document.write('    	<td style="line-height:24px;font-size:14px;">&nbsp;设计的太差了，7812根本可以不用。</td>');
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