<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="">Hi JP,<div class=""><br class=""></div><div class="">Harry Bissell's envelope follower is well thought of for its combination of speed and accuracy.</div><div class=""><br class=""></div><div class=""><a href="https://modwiggler.com/forum/viewtopic.php?t=109067" class="">https://modwiggler.com/forum/viewtopic.php?t=109067</a></div><div class=""><br class=""></div><div 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.</div><div class=""><br class=""></div><div 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.</div><div class=""><br class=""></div><div class="">HTH,</div><div class="">Tom</div><div class=""><br class=""><div class="">
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<div><br class=""><blockquote type="cite" class=""><div class="">On 15 Dec 2021, at 01:34, Jean-Pierre Desrochers <<a href="mailto:jpdesroc@oricom.ca" class="">jpdesroc@oricom.ca</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; 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;"><div style="margin: 0cm; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-CA" class="">Hi all,<o:p class=""></o:p></span></div><div style="margin: 0cm; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-CA" 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 ?<o:p class=""></o:p></span></div><div style="margin: 0cm; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-CA" 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)<o:p class=""></o:p></span></div><div style="margin: 0cm; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-CA" class="">Any known & reliable circuits ?<o:p class=""></o:p></span></div><div style="margin: 0cm; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-CA" class="">JP<o:p class=""></o:p></span></div></div><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="">_______________________________________________</span><br style="caret-color: rgb(0, 0, 0); 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