--- /dev/null
+<!doctype html>
+<html lang="en">
+<head>
+<title>Adjustable resistor / indicator</title>
+<!-- 2020-08-22 L 15:39 -->
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<meta name="generator" content="Org-mode">
+<meta name="author" content="Svjatoslav Agejenko">
+<link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
+<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
+<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
+<style type="text/css">
+footer {background-color: #111 !important;}
+pre {background-color: #111; color: #ccc;}
+</style>
+<style type="text/css">
+/* org mode styles on top of twbs */
+
+html {
+ position: relative;
+ min-height: 100%;
+}
+
+body {
+ font-size: 18px;
+ margin-bottom: 105px;
+}
+
+footer {
+ position: absolute;
+ bottom: 0;
+ width: 100%;
+ height: 101px;
+ background-color: #f5f5f5;
+}
+
+footer > div {
+ padding: 10px;
+}
+
+footer p {
+ margin: 0 0 5px;
+ text-align: center;
+ font-size: 16px;
+}
+
+#table-of-contents {
+ margin-top: 20px;
+ margin-bottom: 20px;
+}
+
+blockquote p {
+ font-size: 18px;
+}
+
+pre {
+ font-size: 16px;
+}
+
+.footpara {
+ display: inline-block;
+}
+
+figcaption {
+ font-size: 16px;
+ color: #666;
+ font-style: italic;
+ padding-bottom: 15px;
+}
+
+/* from twbs docs */
+
+.bs-docs-sidebar.affix {
+ position: static;
+}
+@media (min-width: 768px) {
+ .bs-docs-sidebar {
+ padding-left: 20px;
+ }
+}
+
+/* All levels of nav */
+.bs-docs-sidebar .nav > li > a {
+ display: block;
+ padding: 4px 20px;
+ font-size: 14px;
+ font-weight: 500;
+ color: #999;
+}
+.bs-docs-sidebar .nav > li > a:hover,
+.bs-docs-sidebar .nav > li > a:focus {
+ padding-left: 19px;
+ color: #A1283B;
+ text-decoration: none;
+ background-color: transparent;
+ border-left: 1px solid #A1283B;
+}
+.bs-docs-sidebar .nav > .active > a,
+.bs-docs-sidebar .nav > .active:hover > a,
+.bs-docs-sidebar .nav > .active:focus > a {
+ padding-left: 18px;
+ font-weight: bold;
+ color: #A1283B;
+ background-color: transparent;
+ border-left: 2px solid #A1283B;
+}
+
+/* Nav: second level (shown on .active) */
+.bs-docs-sidebar .nav .nav {
+ display: none; /* Hide by default, but at >768px, show it */
+ padding-bottom: 10px;
+}
+.bs-docs-sidebar .nav .nav > li > a {
+ padding-top: 1px;
+ padding-bottom: 1px;
+ padding-left: 30px;
+ font-size: 12px;
+ font-weight: normal;
+}
+.bs-docs-sidebar .nav .nav > li > a:hover,
+.bs-docs-sidebar .nav .nav > li > a:focus {
+ padding-left: 29px;
+}
+.bs-docs-sidebar .nav .nav > .active > a,
+.bs-docs-sidebar .nav .nav > .active:hover > a,
+.bs-docs-sidebar .nav .nav > .active:focus > a {
+ padding-left: 28px;
+ font-weight: 500;
+}
+
+/* Nav: third level (shown on .active) */
+.bs-docs-sidebar .nav .nav .nav {
+ padding-bottom: 10px;
+}
+.bs-docs-sidebar .nav .nav .nav > li > a {
+ padding-top: 1px;
+ padding-bottom: 1px;
+ padding-left: 40px;
+ font-size: 12px;
+ font-weight: normal;
+}
+.bs-docs-sidebar .nav .nav .nav > li > a:hover,
+.bs-docs-sidebar .nav .nav .nav > li > a:focus {
+ padding-left: 39px;
+}
+.bs-docs-sidebar .nav .nav .nav > .active > a,
+.bs-docs-sidebar .nav .nav .nav > .active:hover > a,
+.bs-docs-sidebar .nav .nav .nav > .active:focus > a {
+ padding-left: 38px;
+ font-weight: 500;
+}
+
+/* Show and affix the side nav when space allows it */
+@media (min-width: 992px) {
+ .bs-docs-sidebar .nav > .active > ul {
+ display: block;
+ }
+ /* Widen the fixed sidebar */
+ .bs-docs-sidebar.affix,
+ .bs-docs-sidebar.affix-bottom {
+ width: 213px;
+ }
+ .bs-docs-sidebar.affix {
+ position: fixed; /* Undo the static from mobile first approach */
+ top: 20px;
+ }
+ .bs-docs-sidebar.affix-bottom {
+ position: absolute; /* Undo the static from mobile first approach */
+ }
+ .bs-docs-sidebar.affix .bs-docs-sidenav,.bs-docs-sidebar.affix-bottom .bs-docs-sidenav {
+ margin-top: 0;
+ margin-bottom: 0
+ }
+}
+@media (min-width: 1200px) {
+ /* Widen the fixed sidebar again */
+ .bs-docs-sidebar.affix-bottom,
+ .bs-docs-sidebar.affix {
+ width: 263px;
+ }
+}
+</style>
+<script type="text/javascript">
+$(function() {
+ 'use strict';
+
+ $('.bs-docs-sidebar li').first().addClass('active');
+
+ $(document.body).scrollspy({target: '.bs-docs-sidebar'});
+
+ $('.bs-docs-sidebar').affix();
+});
+</script>
+</head>
+<body>
+<div id="content" class="container">
+<div class="row"><div class="col-md-9"><h1 class="title">Adjustable resistor / indicator</h1>
+
+<div id="outline-container-sec-1" class="outline-2">
+<h2 id="sec-1"><span class="section-number-2">1</span> General</h2>
+<div class="outline-text-2" id="text-1">
+<ul class="org-ul">
+<li>DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE
+COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE
+DESIGNS AT YOUR OWN RISK.
+</li>
+
+<li>This design is released under Creative Commons Zero (CC0) license.
+</li>
+
+<li>Author:
+<ul class="org-ul">
+<li>Svjatoslav Agejenko
+<ul class="org-ul">
+<li>Homepage: <a href="https://svjatoslav.eu">https://svjatoslav.eu</a>
+</li>
+<li>Email: <a href="mailto://svjatoslav@svjatoslav.eu">svjatoslav@svjatoslav.eu</a>
+</li>
+</ul>
+</li>
+</ul>
+</li>
+
+<li>See also:
+<ul class="org-ul">
+<li><a href="../../index.html">Other physical projects in this repository</a>
+</li>
+<li><a href="https://www.svjatoslav.eu/projects/">Other projects hosted at svjatoslav.eu</a>
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+
+<div id="outline-container-sec-2" class="outline-2">
+<h2 id="sec-2"><span class="section-number-2">2</span> Project description</h2>
+<div class="outline-text-2" id="text-2">
+<p>
+I needed a way to experimentally find resistance that works best in
+certain circuits. Usual potentiometers could not handle required power
+dissipation and were not precise enough.
+</p>
+
+<p>
+Solution is to build adjustable resistor:
+</p>
+
+
+<figure>
+<p><img src="make.png" class="img-responsive" alt="make.png">
+</p>
+</figure>
+
+<p>
+Logically there is series of resistors that increase in resistance in
+the power of 2: 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512. Each
+resistor can be enabled or disabled by a switch. This makes entire
+range of 0 – 1023.5 ohms available with the 0.5 ohms precision.
+</p>
+
+<p>
+Schematic:
+<img src="schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+
+<p>
+Here is front panel for switches:
+<img src="front%20panel.png" class="img-responsive" alt="front%20panel.png">
+</p>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="front%20panel.FCStd">FreeCAD project</a>
+</li>
+<li><a href="front%20panel.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+Sometimes I would like to use lightbulbs with various parameters as
+test load/indicator. Current device has 4 of them included.
+</p>
+
+<p>
+Here is front panel for light bulbs:
+<img src="indicator%20panel.png" class="img-responsive" alt="indicator%20panel.png">
+</p>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="indicator%20panel.FCStd">FreeCAD project</a>
+</li>
+<li><a href="indicator%20panel.stl">STL file</a>
+</li>
+</ul>
+
+
+<p>
+After assembly using prototype PCB:
+<img src="make,%202.png" class="img-responsive" alt="make,%202.png">
+</p>
+
+
+<p>
+Following body is used as a case and PCB support:
+<img src="body.png" class="img-responsive" alt="body.png">
+</p>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="body%20and%20back%20cover.FCStd">FreeCAD project (body + back cover)</a>
+</li>
+<li><a href="body.stl">STL file for body</a>
+</li>
+</ul>
+
+<p>
+Result:
+<img src="make,%203.png" class="img-responsive" alt="make,%203.png">
+</p>
+
+<p>
+Cover on the back:
+<img src="back%20cover.png" class="img-responsive" alt="back%20cover.png">
+</p>
+
+<p>
+Download: <a href="back%20cover.stl">STL file</a>
+</p>
+
+<p>
+Button covers:
+<img src="button.png" class="img-responsive" alt="button.png">
+</p>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="button.FCStd">FreeCAD project</a>
+</li>
+<li><a href="button.stl">STL file</a>
+</li>
+</ul>
+</div>
+</div>
+</div><div class="col-md-3"><nav id="table-of-contents">
+<div id="text-table-of-contents" class="bs-docs-sidebar">
+<ul class="nav">
+<li><a href="#sec-1">1. General</a></li>
+<li><a href="#sec-2">2. Project description</a></li>
+</ul>
+</div>
+</nav>
+</div></div></div>
+<footer id="postamble" class="">
+<div><p class="author">Author: Svjatoslav Agejenko</p>
+<p class="date">Created: 2020-08-22 L 15:39</p>
+<p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 26.1 (<a href="http://orgmode.org">Org-mode</a> 9.1.9)</p>
+</div>
+</footer>
+</body>
+</html>
projects / physical.git / blobdiff