<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Here's a link to that page of the discussion:<div class=""><br class=""></div><div class=""><a href="https://modwiggler.com/forum/viewtopic.php?f=17&t=109067&start=175" class="">https://modwiggler.com/forum/viewtopic.php?f=17&t=109067&start=175</a></div><div class=""><br class=""></div><div class="">TBH, Harald, I think the comparison is a bit unfair. You're comparing a 24dB active SK filter to a passive RC. Clearly one is going to have better filtering response to the other. </div><div class=""><br class=""></div><div class=""><div class="">Whether the FWR gives better performance than the peak-hold method is an interesting question, but that's not really dealt with. Also the test signal is very artificial. The slower decay on the Bissell envelope (not that slow - 150msecs?) actually matches typical guitar envelopes rather well, so perhaps that's why many people rate it highly, at least in the pedal world.</div><div class=""><div class=""><br class=""></div><div class="">I do think your experiment makes a good point though - if you want a smoother output, you need better filtering. Many designs get by with a simple passive RC and leave it at that. With such a simple filter there *will* always be a trade-off between speed and ripple.</div><div class=""><br class=""></div>
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<div><br class=""><blockquote type="cite" class=""><div class="">On 15 Dec 2021, at 09:44, Harald <<a href="mailto:sdiy@haraldswerk.de" class="">sdiy@haraldswerk.de</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">Well,</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">scroll a little back in this thread to page 7/8 and have a look at my comparison. Harry Bissell' envelope follower is in no way better than the classical approach. It is slower, has more ripple and is about 500mV off.</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">Harald</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">Am 15.12.21 um 10:08 schrieb Tom Wiltshire:</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">Hi JP,<br class="">Harry Bissell's envelope follower is well thought of for its combination of speed and accuracy.<br class=""><a href="https://modwiggler.com/forum/viewtopic.php?t=109067" class="">https://modwiggler.com/forum/viewtopic.php?t=109067</a><span class="Apple-converted-space"> </span><<a href="https://modwiggler.com/forum/viewtopic.php?t=109067" class="">https://modwiggler.com/forum/viewtopic.php?t=109067</a>><br class="">It's a good circuit, but pretty complicated, especially for an effect pedal design. So like you, I thought "PIC!", and had a go at implementing it in firmware.<br class="">The round-robin three peaks detectors are easy enough. Doing the output filtering is more demanding on a chip with no multiply, but I managed it by being choosy about the filter coefficients and keeping things binary friendly. The end result was pretty good and used a little PIC to the maximum extent.<br class="">HTH,<br class="">Tom<br class="">==================<br class=""> Electric Druid<br class="">Synth & Stompbox DIY<br class="">==================<br class=""><blockquote type="cite" class="">On 15 Dec 2021, at 01:34, Jean-Pierre Desrochers <<a href="mailto:jpdesroc@oricom.ca" class="">jpdesroc@oricom.ca</a>> wrote:<br class=""><br class="">Hi all,<br class="">I’m looking for a fast and accurate voltage follower circuit.<br class="">There are plenty of them on the web to build but they all<br class="">suffer of inaccuracy and lag on the final DC output (final stage of low pass to smooth off the incoming peaks).<br class="">The incoming voltage will be a varying 0 to +/-5v peak.<br class="">I thought about implementing a solution using a small PIC with ADC/DAC<br class="">but even if these micros are very cheap this solution would be overkill.. would it be ?<br class="">So far the available circuits have too much lag on their DC output.<br class="">(The envelope takes too much time to get back to zero after a fast incoming peak)<br class="">Any known & reliable circuits ?<br class="">JP<br class="">_______________________________________________<br class="">Synth-diy mailing list<br class=""><a href="mailto:Synth-diy@synth-diy.org" class="">Synth-diy@synth-diy.org</a><span class="Apple-converted-space"> </span><<a href="mailto:Synth-diy@synth-diy.org" class="">mailto:Synth-diy@synth-diy.org</a>><br class=""><a href="http://synth-diy.org/mailman/listinfo/synth-diy" class="">http://synth-diy.org/mailman/listinfo/synth-diy</a><span class="Apple-converted-space"> </span><<a href="http://synth-diy.org/mailman/listinfo/synth-diy" class="">http://synth-diy.org/mailman/listinfo/synth-diy</a>><br class="">Selling or trading? 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