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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span lang=EN-CA style='mso-fareast-language:EN-US'>></span><span lang=EN-CA> This would be the digital equivalent to the single pole RC. It should be possible to get better ripple suppression by using higher order filters. Harald showed that he got a better response using a fourth-order filter.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA><br>So.. how can I modify the C1 section to get for example a fourth-order filter ?<br>To do it the way the signal flows across C1 is a bit confusing..<br>The signal comes from the left side but the clamping comes from D1 at right side.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA>I know how to implement high order filters in circuits but only<br>if I know the signal flow direction..</span><span lang=EN-CA style='mso-fareast-language:EN-US'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><img width=608 height=460 style='width:6.3333in;height:4.7916in' id="Image_x0020_1" src="cid:image001.png@01D7F331.833F9BD0"></span><span style='mso-fareast-language:EN-US'><o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=FR>De :</span></b><span lang=FR> Synth-diy <synth-diy-bounces@synth-diy.org> <b>De la part de</b> Tom Wiltshire<br><b>Envoyé :</b> 17 décembre 2021 08:37<br><b>À :</b> Martin Klang <mars@pingdynasty.com><br><b>Cc :</b> synth-diy@synth-diy.org<br><b>Objet :</b> Re: [sdiy] Best & fastest envelope follower schematic.. anybody ?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This would be the digital equivalent to the single pole RC. It should be possible to get better ripple suppression by using higher order filters. Harald showed that he got a better response using a fourth-order filter.<o:p></o:p></p><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>On 16 Dec 2021, at 16:26, Martin Klang <<a href="mailto:mars@pingdynasty.com">mars@pingdynasty.com</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>I think an envelope follower with no lag is called a rectifier.<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>Jokes aside, there are a number of options available but ultimately it comes down to filtering.<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>For digital envelope followers, I like to use a simple exponential average (aka leaky integrator, a first-order IIR filter) on the fully rectified signal and tune the time constant to the expected input signal. Generally you want it to be fast, but not so fast as to track the waveform oscillations, even at say 20 Hz. This makes a computationally very efficient follower with predictable results.<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>best,<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>Martin<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;caret-color: rgb(0, 0, 0);font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px'><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>On 16/12/2021 01:36, Jean-Pierre Desrochers wrote:<o:p></o:p></span></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt;font-variant-caps: normal;orphans: auto;text-align:start;widows: auto;-webkit-text-size-adjust: auto;-webkit-text-stroke-width: 0px;word-spacing:0px'><div><p class=MsoNormal>Here is my goal..<o:p></o:p></p></div><div><p class=MsoNormal><span lang=EN-CA>I need a circuit that will take an AC signal and will shift level it from<br>a DC offset extracted from its min & max Peaks..<br>Ex: Suppose you have steady +/- 5v peak sine wave coming in this circuit,<br>The output would be the same waveform but shifted up to +5vdc.<span class=apple-converted-space> </span></span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=EN-CA>So 0 to +10vdc.<br>That final waveform would be much usable for a 0-5vdc control voltage input<br>than the original AC waveform.<br>Now the challenge is to do the same with a level changing AC signal.</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=EN-CA>In the case of a<span class=apple-converted-space> </span><u>steady waveform</u><span class=apple-converted-space> </span>this ‘level shifter’ could be an opamp that would add half of the peak to peak voltage as an offset DC voltage,<br>But here I’m looking for something that will be more versatile<br>to handle varying level waveform.<br><br><br></span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=EN-CA> </span><o:p></o:p></p></div></blockquote><p class=MsoNormal><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>_______________________________________________<br>Synth-diy mailing list<br><a href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a><br><a href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>Selling or trading? Use <a href="mailto:marketplace@synth-diy.org">marketplace@synth-diy.org</a></span><o:p></o:p></p></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p></div></div></div></body></html>