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<title>HwB: Active Filter: Butterworth 12dB Lowpass</title>
<meta name="Author" content="Joakim Ögren">
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content="Formulas for a 2nd order Butterworth active lowpass filter.">

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content="HwB, pinout, hardware, butterworth, filter, active, lowpass, 2nd, 12">



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<h1>Active Filter: Butterworth<br>
(2nd order, 12 dB/octave, Lowpass)</h1>

<p><img src="images/misc_ActiveFilter2L.GIF"
alt="2nd order Butterworth Lowpass" align="bottom" width="231"
height="111"></p>

<p>R=4.7k-10 kOhm<br>
Ca=1.414/(2*pi*Fc*R)<br>
Cb=0.7071/(2*pi*Fc*R)</p>

<p><font size="2"><i>Units: R [Ohm], Cx [F], Fc [Hz]</i></font></p>

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    <font size="2">Contributor: </font><a
    href="mailto:qtech@mailhost.net"><font size="2">Joakim Ögren</font></a>
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    <font size="2">Source:&nbsp;?</font>
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    <font size="1">Please send any comments to </font><a
    href="mailto:qtech@mailhost.net"><font size="1">Joakim Ögren</font></a><font
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