<html lang="en">
<head>
<title>Physical projects</title>
-<!-- 2020-12-27 Sun 01:44 -->
+<!-- 2020-12-27 Sun 02:00 -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="generator" content="Org-mode">
</div>
<div id="outline-container-sec-3" class="outline-2">
-<h2 id="sec-3"><span class="section-number-2">3</span> Projects</h2>
+<h2 id="sec-3"><span class="section-number-2">3</span> Miscellaneous</h2>
<div class="outline-text-2" id="text-3">
-</div><div id="outline-container-sec-3-1" class="outline-3">
-<h3 id="sec-3-1"><span class="section-number-3">3.1</span> Audio</h3>
-<div class="outline-text-3" id="text-3-1">
<ul class="org-ul">
-<li>Portable stereo speaker
-<br/><a href="audio/Portable%20stereo%20active%20speaker/index.html"><img style="width:100%; max-width:500px;" src=" audio/Portable%20stereo%20active%20speaker/make.png"></a>
-</li>
-
-<li>Headphone hub
-<br/><a href="audio/Headphone%20hub/index.html"><img style="width:100%; max-width:500px;" src=" audio/Headphone%20hub/make.png"></a>
+<li>12V Lead-Acid battery charger and terminal
+<br/><a href="misc/12V%20Lead-Acid%20battery%20changer%20and%20terminal/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/12V%20Lead-Acid%20battery%20changer%20and%20terminal/make.png
+ "></a>
</li>
-</ul>
-</div>
-</div>
-<div id="outline-container-sec-3-2" class="outline-3">
-<h3 id="sec-3-2"><a id="ID-0482740b-0f2e-4138-804d-37c7025124d3" name="ID-0482740b-0f2e-4138-804d-37c7025124d3"></a><span class="section-number-3">3.2</span> Miscellaneous</h3>
-<div class="outline-text-3" id="text-3-2">
-<ul class="org-ul">
-<li>Charging terminal alternative cover for CAT B30 phone
-<br/><a href="misc/CAT%20B30%20phone%20cover/index.html"><img style="width:100%; max-width:500px;" src="
- misc/CAT%20B30%20phone%20cover/make.png
+<li>adjustable resistor / indicator
+<br/><a href="misc/adjustable%20resistor/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/adjustable%20resistor/make.png
"></a>
</li>
-</ul>
-
-
-<ul class="org-ul">
-<li>Trekology camping chair leg tip
-<br/><a href="misc/camping%20chair%20leg%20tip/index.html"><img style="width:100%; max-width:500px;" src="
- misc/camping%20chair%20leg%20tip/make.png
+<li>battery tester
+<br/><a href="misc/battery%20tester/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/battery%20tester/make.png
"></a>
</li>
-<li>Toy robot
-<br/><a href="misc/
Robot%20toy/index.html"><img style="width:100%; max-width:500px;" src="
- misc/Robot%20toy/make.png
+<li>Lab heater and cooler
+<br/><a href="misc/
lab%20heater%20and%20cooler/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/lab%20heater%20and%20cooler/make.png
"></a>
</li>
misc/USB%20desk%20fan%20mod/make.png
"></a>
</li>
-</ul>
-</div>
-</div>
-<div id="outline-container-sec-3-3" class="outline-3">
-<h3 id="sec-3-3"><span class="section-number-3">3.3</span> Power</h3>
-<div class="outline-text-3" id="text-3-3">
-<ul class="org-ul">
-<li>12V Lead-Acid battery charger and terminal
-<br/><a href="power/12V%20Lead-Acid%20battery%20changer%20and%20terminal/index.html"><img style="width:100%; max-width:500px;" src="
- power/12V%20Lead-Acid%20battery%20changer%20and%20terminal/make.png
+<li>Window fixator
+<br/><a href="misc/window%20fixator/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/window%20fixator/make.png
"></a>
</li>
+</ul>
+</div>
-<li>battery tester
-<br/><a href="power/battery%20tester/index.html"><img style="width:100%; max-width:500px;" src="
- power/battery%20tester/make.png
+
+<div id="outline-container-sec-3-1" class="outline-3">
+<h3 id="sec-3-1"><span class="section-number-3">3.1</span> Audio</h3>
+<div class="outline-text-3" id="text-3-1">
+<ul class="org-ul">
+<li>Portable stereo speaker
+<br/><a href="misc/portable%20stereo%20active%20speaker/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/portable%20stereo%20active%20speaker/make.png
"></a>
</li>
-<li>adjustable resistor / indicator
-<br/><a href="
power/adjustable%20resistor/index.html"><img style="width:100%; max-width:500px;" src="
- power/adjustable%20resistor/make.png
+<li>Headphone hub
+<br/><a href="
misc/headphone%20hub/index.html"><img style="width:100%; max-width:500px;" src="
+ misc/headphone%20hub/make.png
"></a>
</li>
</ul>
</div>
</div>
+</div>
-
-<div id="outline-container-sec-3-4" class="outline-3">
-<h3 id="sec-3-4"><a id="ID-0ff5c7f6-e08d-4cdf-923f-3aa75d050b1c" name="ID-0ff5c7f6-e08d-4cdf-923f-3aa75d050b1c"></a><span class="section-number-3">3.4</span> Optics</h3>
-<div class="outline-text-3" id="text-3-4">
+<div id="outline-container-sec-4" class="outline-2">
+<h2 id="sec-4"><span class="section-number-2">4</span> Optics</h2>
+<div class="outline-text-2" id="text-4">
<ul class="org-ul">
<li>35mm film copying device
<br/><a href="optics/35mm%20film%20copying%20device/index.html"><img style="width:100%; max-width:500px;" src="
optics/35mm%20film%20copying%20device/make.png
"></a>
</li>
-</ul>
-</div>
-
-
-<div id="outline-container-sec-3-4-1" class="outline-4">
-<h4 id="sec-3-4-1"><span class="section-number-4">3.4.1</span> Microscopy</h4>
-<div class="outline-text-4" id="text-3-4-1">
-<ul class="org-ul">
<li>Fujifilm X-mount to microscope adapter
<br/><a href="optics/Fujifilm%20X-mount%20microscope%20adapter/index.html"><img style="width:100%; max-width:500px;" src="
optics/Fujifilm%20X-mount%20microscope%20adapter/make.png
"></a>
</li>
-</ul>
-</div>
-</div>
-
-<div id="outline-container-sec-3-4-2" class="outline-4">
-<h4 id="sec-3-4-2"><span class="section-number-4">3.4.2</span> Fujifilm</h4>
-</div>
-</div>
-
-<div id="outline-container-sec-3-5" class="outline-3">
-<h3 id="sec-3-5"><span class="section-number-3">3.5</span> Organizers / boxes / covers</h3>
-<div class="outline-text-3" id="text-3-5">
-<ul class="org-ul">
-<li>Window fixator
-<br/><a href="organizers/window%20fixator/index.html"><img style="width:100%; max-width:500px;" src="
- organizers/window%20fixator/make.png
+<li>Gyroscope stabilizer for binoculars
+<br/><a href="optics/gyro%20for%20binoculars/index.html"><img style="width:100%; max-width:500px;" src="
+ optics/gyro%20for%20binoculars/make.png
"></a>
</li>
</ul>
</div>
</div>
-<div id="outline-container-sec-3-6" class="outline-3">
-<h3 id="sec-3-6"><span class="section-number-3">3.6</span> Radio</h3>
-<div class="outline-text-3" id="text-3-6">
-<ul class="org-ul">
-<li>DIY Yagi antenna connector
-<br/><a href="RF/Yagi%20antenna%20connector/index.html"><img style="width:100%; max-width:500px;" src="
- RF/Yagi%20antenna%20connector/make.png
- "></a>
-</li>
-</ul>
-</div>
-</div>
-</div>
-<div id="outline-container-sec-4" class="outline-2">
-<h2 id="sec-4"><span class="section-number-2">4</span> See also</h2>
-<div class="outline-text-2" id="text-4">
+<div id="outline-container-sec-5" class="outline-2">
+<h2 id="sec-5"><span class="section-number-2">5</span> See also</h2>
+<div class="outline-text-2" id="text-5">
<ul class="org-ul">
<li>Jay Doscher blog: <a href="https://back7.co/">https://back7.co/</a>
</li>
<li><a href="#sec-2-4">2.4. Cable / wire</a></li>
</ul>
</li>
-<li><a href="#sec-3">3. Projects</a>
+<li><a href="#sec-3">3. Miscellaneous</a>
<ul class="nav">
<li><a href="#sec-3-1">3.1. Audio</a></li>
-<li><a href="#sec-3-2">3.2. Miscellaneous</a></li>
-<li><a href="#sec-3-3">3.3. Power</a></li>
-<li><a href="#sec-3-4">3.4. Optics</a></li>
-<li><a href="#sec-3-5">3.5. Organizers / boxes / covers</a></li>
-<li><a href="#sec-3-6">3.6. Radio</a></li>
</ul>
</li>
-<li><a href="#sec-4">4. See also</a></li>
+<li><a href="#sec-4">4. Optics</a></li>
+<li><a href="#sec-5">5. See also</a></li>
</ul>
</div>
</nav>
</div></div></div>
<footer id="postamble" class="">
<div><p class="author">Author: Svjatoslav Agejenko</p>
-<p class="date">Created: 2020-12-27 Sun 01:44</p>
+<p class="date">Created: 2020-12-27 Sun 02:00</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>
cases/roll/make.png
)}}}
-* Projects
-** Audio
-+ Portable stereo speaker
- {{{imglnk(audio/Portable%20stereo%20active%20speaker/index.html, audio/Portable%20stereo%20active%20speaker/make.png)}}}
-
-+ Headphone hub
- {{{imglnk(audio/Headphone%20hub/index.html, audio/Headphone%20hub/make.png)}}}
-
-** Miscellaneous
-:PROPERTIES:
-:ID: 0482740b-0f2e-4138-804d-37c7025124d3
-:END:
-
-+ Charging terminal alternative cover for CAT B30 phone
- {{{imglnk(
- misc/CAT%20B30%20phone%20cover/index.html,
- misc/CAT%20B30%20phone%20cover/make.png
+* Miscellaneous
++ 12V Lead-Acid battery charger and terminal
+ {{{imglnk(
+ misc/12V%20Lead-Acid%20battery%20changer%20and%20terminal/index.html,
+ misc/12V%20Lead-Acid%20battery%20changer%20and%20terminal/make.png
)}}}
++ adjustable resistor / indicator
+ {{{imglnk(
+ misc/adjustable%20resistor/index.html,
+ misc/adjustable%20resistor/make.png
+ )}}}
-
-+ Trekology camping chair leg tip
- {{{imglnk(
- misc/camping%20chair%20leg%20tip/index.html,
- misc/camping%20chair%20leg%20tip/make.png
++ battery tester
+ {{{imglnk(
+ misc/battery%20tester/index.html,
+ misc/battery%20tester/make.png
)}}}
-+ Toy robot
++ Lab heater and cooler
{{{imglnk(
- misc/Robot%20toy/index.html,
- misc/Robot%20toy/make.png
+ misc/lab%20heater%20and%20cooler/index.html,
+ misc/lab%20heater%20and%20cooler/make.png
)}}}
+ USB Fan modification
misc/USB%20desk%20fan%20mod/make.png
)}}}
-** Power
-+ 12V Lead-Acid battery charger and terminal
- {{{imglnk(
- power/12V%20Lead-Acid%20battery%20changer%20and%20terminal/index.html,
- power/12V%20Lead-Acid%20battery%20changer%20and%20terminal/make.png
++ Window fixator
+ {{{imglnk(
+ misc/window%20fixator/index.html,
+ misc/window%20fixator/make.png
)}}}
-+ battery tester
- {{{imglnk(
- power/battery%20tester/index.html,
- power/battery%20tester/make.png
+
+** Audio
+
++ Portable stereo speaker
+ {{{imglnk(
+ misc/portable%20stereo%20active%20speaker/index.html,
+ misc/portable%20stereo%20active%20speaker/make.png
)}}}
-+ adjustable resistor / indicator
- {{{imglnk(
- power/adjustable%20resistor/index.html,
- power/adjustable%20resistor/make.png
++ Headphone hub
+ {{{imglnk(
+ misc/headphone%20hub/index.html,
+ misc/headphone%20hub/make.png
)}}}
-** Optics
-:PROPERTIES:
-:ID: 0ff5c7f6-e08d-4cdf-923f-3aa75d050b1c
-:END:
+* Optics
+
+ 35mm film copying device
{{{imglnk(
optics/35mm%20film%20copying%20device/index.html,
optics/35mm%20film%20copying%20device/make.png
)}}}
-
-
-*** Microscopy
+ Fujifilm X-mount to microscope adapter
{{{imglnk(
optics/Fujifilm%20X-mount%20microscope%20adapter/index.html,
optics/Fujifilm%20X-mount%20microscope%20adapter/make.png
)}}}
-
-*** Fujifilm
-
-** Organizers / boxes / covers
-
-+ Window fixator
++ Gyroscope stabilizer for binoculars
{{{imglnk(
- organizers/window%20fixator/index.html,
- organizers/window%20fixator/make.png
+ optics/gyro%20for%20binoculars/index.html,
+ optics/gyro%20for%20binoculars/make.png
)}}}
-** Radio
-+ DIY Yagi antenna connector
- {{{imglnk(
- RF/Yagi%20antenna%20connector/index.html,
- RF/Yagi%20antenna%20connector/make.png
- )}}}
* See also
+ Jay Doscher blog: https://back7.co/
+ Valera Perinski designs:
+++ /dev/null
-<!doctype html>
-<html lang="en">
-<head>
-<title>Headphone hub</title>
-<!-- 2020-12-25 Fri 23:48 -->
-<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">Headphone hub</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
-</li>
-<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>
-
-<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>
-Simple hub that allows connecting up to 4 devices via headphone
-jack. For example single laptop or mp3 player can power up to 3
-headphones.
-</p>
-
-
-<figure>
-<p><img src="make.png" class="img-responsive" alt="make.png">
-</p>
-</figure>
-
-<p>
-Schematic diagram:
-<img src="schematic.png" class="img-responsive" alt="schematic.png">
-</p>
-
-<p>
-Warning: All devices are connected in parallel. Make sure that audio
-producing device can handle combined load. See:
-<a href="https://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistance_units_2">https://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistance_units_2</a>
-</p>
-
-
-<figure>
-<p><img src="make,%202.png" class="img-responsive" alt="make,%202.png">
-</p>
-</figure>
-
-<p>
-Device consists of body and cover that are held together by single
-screw at the center:
-</p>
-
-
-<figure>
-<p><img src="cover,%202.png" class="img-responsive" alt="cover,%202.png">
-</p>
-</figure>
-</div>
-</div>
-
-<div id="outline-container-sec-3" class="outline-2">
-<h2 id="sec-3"><span class="section-number-2">3</span> Download</h2>
-<div class="outline-text-2" id="text-3">
-<ul class="org-ul">
-<li><a href="hub.FCStd">FreeCAD project</a>
-</li>
-</ul>
-
-
-<p>
-Body <a href="body.stl">STL file</a>
-<img src="body.png" class="img-responsive" alt="body.png">
-</p>
-
-
-
-<hr >
-<p>
-Cover <a href="cover.stl">STL file</a>
-</p>
-
-
-<figure>
-<p><img src="cover.png" class="img-responsive" alt="cover.png">
-</p>
-</figure>
-</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>
-<li><a href="#sec-3">3. Download</a></li>
-</ul>
-</div>
-</nav>
-</div></div></div>
-<footer id="postamble" class="">
-<div><p class="author">Author: Svjatoslav Agejenko</p>
-<p class="date">Created: 2020-12-25 Fri 23:48</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>
+++ /dev/null
-#+TITLE: Headphone hub
-#+AUTHOR: Svjatoslav Agejenko
-#+LANGUAGE: en
-
-* (document settings) :noexport:
-** use dark style for TWBS-HTML exporter
-#+HTML_HEAD: <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
-#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
-#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
-#+HTML_HEAD: <style type="text/css">
-#+HTML_HEAD: footer {background-color: #111 !important;}
-#+HTML_HEAD: pre {background-color: #111; color: #ccc;}
-#+HTML_HEAD: </style>
-
-* General
-+ 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.
-
-+ This design is released under Creative Commons Zero (CC0) license.
-
-+ Author:
- - Svjatoslav Agejenko
- - Homepage: https://svjatoslav.eu
- - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
-
-+ See also:
- - [[../../index.html][Other physical projects in this repository]]
- - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
-
-* Project description
-Simple hub that allows connecting up to 4 devices via headphone
-jack. For example single laptop or mp3 player can power up to 3
-headphones.
-
-[[file:make.png]]
-
-Schematic diagram:
-[[file:schematic.png]]
-
-Warning: All devices are connected in parallel. Make sure that audio
-producing device can handle combined load. See:
-https://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistance_units_2
-
-[[file:make,%202.png]]
-
-Device consists of body and cover that are held together by single
-screw at the center:
-
-[[file:cover,%202.png]]
-
-* Download
-
-- [[file:hub.FCStd][FreeCAD project]]
-
-
-Body [[file:body.stl][STL file]]
-[[file:body.png]]
-
-
-
------
-Cover [[file:cover.stl][STL file]]
-
-[[file:cover.png]]
+++ /dev/null
-EESchema-LIBRARY Version 2.4
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-# Connector_AudioJack3
-#
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-#
-#End Library
+++ /dev/null
-EESchema Schematic File Version 4
-EELAYER 30 0
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-$Descr A4 11693 8268
-encoding utf-8
-Sheet 1 1
-Title ""
-Date ""
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-$EndDescr
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-L Connector:AudioJack3 J1
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- 0 1 1 0
-$EndComp
-$Comp
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- 1 4850 3300
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-$EndComp
-Wire Wire Line
- 3000 3500 3000 3800
-Wire Wire Line
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-Wire Wire Line
- 3900 3800 3900 3500
-Wire Wire Line
- 3900 3800 4750 3800
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-Wire Wire Line
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- 3100 3750 4000 3750
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-$Comp
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-Connection ~ 4750 3800
-Connection ~ 4850 3750
-Connection ~ 4950 3700
-$EndSCHEMATC
+++ /dev/null
-<!doctype html>
-<html lang="en">
-<head>
-<title>Portable stereo speaker</title>
-<!-- 2020-04-12 P 23:58 -->
-<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>
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-/* org mode styles on top of twbs */
-
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- position: relative;
- min-height: 100%;
-}
-
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- font-size: 18px;
- margin-bottom: 105px;
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- position: absolute;
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-}
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- margin: 0 0 5px;
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-.footpara {
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-
-/* from twbs docs */
-
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- position: static;
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-@media (min-width: 768px) {
- .bs-docs-sidebar {
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-/* All levels of nav */
-.bs-docs-sidebar .nav > li > a {
- display: block;
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-.bs-docs-sidebar .nav > li > a:hover,
-.bs-docs-sidebar .nav > li > a:focus {
- padding-left: 19px;
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- border-left: 1px solid #A1283B;
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-.bs-docs-sidebar .nav > .active:hover > a,
-.bs-docs-sidebar .nav > .active:focus > a {
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- color: #A1283B;
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-.bs-docs-sidebar .nav .nav {
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- padding-bottom: 10px;
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-.bs-docs-sidebar .nav .nav > li > a {
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-.bs-docs-sidebar .nav .nav .nav > li > a:hover,
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- padding-left: 39px;
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-.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,
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- position: fixed; /* Undo the static from mobile first approach */
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- .bs-docs-sidebar.affix .bs-docs-sidenav,.bs-docs-sidebar.affix-bottom .bs-docs-sidenav {
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-
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-});
-</script>
-</head>
-<body>
-<div id="content" class="container">
-<div class="row"><div class="col-md-9"><h1 class="title">Portable stereo speaker</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
-</li>
-<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>
-
-<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 had pair of good compact stereo speakers lying uselessly around as
-well as secondhand TDA2030 Chinese knockoff audio amplifier chips.
-Also I wanted to test modular construction approach: motherboard with
-shared bus and functionality realized via pluggable modules. So I
-built stereo speaker:
-</p>
-
-
-<figure>
-<p><img src="make.png" class="img-responsive" alt="make.png">
-</p>
-</figure>
-
-<p>
-Indicator on the front panel shows available power within the
-system. Ideally it should be at the maximum. It drops when batteries
-run empty or when consumed power (too loud music) is greater than
-onboard power supply or batteries can handle. It has on/off switch and
-stereo audio input. Audio input impedance is about 100 ohms.
-</p>
-
-
-<figure>
-<p><img src="make,%20side.png" class="img-responsive" alt="make,%20side.png">
-</p>
-</figure>
-
-<p>
-Idea for the holes on the top and smaller ones on the bottom back is
-to enable air flow for passive cooling.
-</p>
-
-
-<figure>
-<p><img src="make,%20back.png" class="img-responsive" alt="make,%20back.png">
-</p>
-</figure>
-
-<p>
-Entire construction is made of parts, no larger than
-120x120x120mm. Maximum for my printer.
-</p>
-</div>
-</div>
-
-<div id="outline-container-sec-3" class="outline-2">
-<h2 id="sec-3"><span class="section-number-2">3</span> Battery holder</h2>
-<div class="outline-text-2" id="text-3">
-<p>
-Device is powered by 4 times AA NiMH batteries (1.2V each).
-</p>
-
-
-<figure>
-<p><img src="battery%20holder/schematic.png" class="img-responsive" alt="schematic.png">
-</p>
-</figure>
-
-<p>
-I happened to have AA battery adapters lying around with different
-bottom hole configurations. Therefore this weird hole design:
-</p>
-
-
-<figure>
-<p><img src="battery%20holder/battery%20holder.png" class="img-responsive" alt="battery%20holder.png">
-</p>
-</figure>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="battery%20holder/battery%20holder.FCStd">FreeCAD file</a>
-</li>
-<li><a href="battery%20holder/battery%20holder.stl">STL file</a>
-</li>
-</ul>
-
-<p>
-Result:
-<img src="battery%20holder/make.png" class="img-responsive" alt="make.png">
-</p>
-
-<p>
-Attaches to the back of the body:
-<img src="battery%20holder/mounted%20on%20the%20back.png" class="img-responsive" alt="mounted%20on%20the%20back.png">
-</p>
-</div>
-</div>
-
-<div id="outline-container-sec-4" class="outline-2">
-<h2 id="sec-4"><span class="section-number-2">4</span> 20V up-step module</h2>
-<div class="outline-text-2" id="text-4">
-<p>
-Battery pack voltage is routed through main on/off switch on the front
-panel, and then it goes to the 20V up-step module.
-</p>
-
-
-<figure>
-<p><img src="20V%20upstep%20module/schematic.png" class="img-responsive" alt="schematic.png">
-</p>
-</figure>
-
-<p>
-It uses ready made upstep module, but adds extra voltage filtering via
-inductor and capacitors.
-</p>
-
-
-<figure>
-<p><img src="20V%20upstep%20module/make.png" class="img-responsive" alt="make.png">
-</p>
-</figure>
-</div>
-</div>
-
-<div id="outline-container-sec-5" class="outline-2">
-<h2 id="sec-5"><span class="section-number-2">5</span> Main board</h2>
-<div class="outline-text-2" id="text-5">
-<p>
-Voltage upstep above sits on top of main board (motherboard). It has
-uniform central bus that spans all connectors.
-</p>
-
-
-<figure>
-<p><img src="main%20board/internal%20bus.png" class="img-responsive" alt="internal%20bus.png">
-</p>
-</figure>
-
-
-<figure>
-<p><img src="main%20board/bus%20on%20the%20bottom,%202.png" class="img-responsive" alt="bus%20on%20the%20bottom,%202.png">
-</p>
-</figure>
-
-<p>
-First row of the main board is special IO terminal (for connecting
-speakers, front panel, etc..)
-</p>
-
-
-<figure>
-<p><img src="main%20board/IO%20terminal.png" class="img-responsive" alt="IO%20terminal.png">
-</p>
-</figure>
-
-<p>
-Remaining rows are for connecting boards:
-</p>
-
-
-<figure>
-<p><img src="main%20board/1.png" class="img-responsive" alt="1.png">
-</p>
-</figure>
-
-<p>
-To provide structural support, main board is attached to frame:
-</p>
-
-
-<figure>
-<p><img src="main%20board/board%20fixator%20body.png" class="img-responsive" alt="board%20fixator%20body.png">
-</p>
-</figure>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="main%20board/board%20fixator%20body.FCStd">FreeCAD file</a>
-</li>
-<li><a href="main%20board/board%20fixator%20body.stl">STL file</a>
-</li>
-</ul>
-
-<p>
-And boards plugged into main board are fixed at the top, using clip:
-</p>
-
-
-<figure>
-<p><img src="main%20board/board%20fixator%20top%20clip.png" class="img-responsive" alt="board%20fixator%20top%20clip.png">
-</p>
-</figure>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="main%20board/board%20fixator%20top%20clip.FCStd">FreeCAD file</a>
-</li>
-<li><a href="main%20board/board%20fixator%20top%20clip.stl">STL file</a>
-</li>
-</ul>
-
-<p>
-Result:
-</p>
-
-
-<figure>
-<p><img src="main%20board/bus%20on%20the%20bottom,%201.png" class="img-responsive" alt="bus%20on%20the%20bottom,%201.png">
-</p>
-</figure>
-
-
-<figure>
-<p><img src="main%20board/board%20fixator.png" class="img-responsive" alt="board%20fixator.png">
-</p>
-</figure>
-</div>
-</div>
-
-<div id="outline-container-sec-6" class="outline-2">
-<h2 id="sec-6"><span class="section-number-2">6</span> Mono audio amplifier module</h2>
-<div class="outline-text-2" id="text-6">
-<p>
-Design uses scavenged secondhand Chinese TDA2030 audio amp
-clones. Each chip is mono audio amplifier. Therefore 2 almost
-identical audio amp modules had to be built, one for left speaker, one
-for right.
-</p>
-
-
-<figure>
-<p><img src="mono%20audio%20amp%20module/schematic.png" class="img-responsive" alt="schematic.png">
-</p>
-</figure>
-
-<p>
-I like to build on top of prototype PCBs. Gives results much faster
-for one-off projects. Before soldering, I solve component layout on
-paper:
-</p>
-
-
-<figure>
-<p><img src="mono%20audio%20amp%20module/PCB%20layout.png" class="img-responsive" alt="PCB%20layout.png">
-</p>
-</figure>
-
-<p>
-Result - front:
-</p>
-
-
-<figure>
-<p><img src="mono%20audio%20amp%20module/assembled%20front.png" class="img-responsive" alt="assembled%20front.png">
-</p>
-</figure>
-
-<p>
-Result - back:
-</p>
-
-
-<figure>
-<p><img src="mono%20audio%20amp%20module/assembled%20back.png" class="img-responsive" alt="assembled%20back.png">
-</p>
-</figure>
-
-<p>
-Here copper tape is used as improvised heatsink.
-</p>
-</div>
-</div>
-
-<div id="outline-container-sec-7" class="outline-2">
-<h2 id="sec-7"><span class="section-number-2">7</span> Speakers</h2>
-<div class="outline-text-2" id="text-7">
-<p>
-High frequency small speaker and medium frequency bigger speaker are
-combined.
-</p>
-
-
-<figure>
-<p><img src="speakers/schematic.png" class="img-responsive" alt="schematic.png">
-</p>
-</figure>
-
-<p>
-Capacitor acts as high-pass filter on top of tiny PCB:
-</p>
-
-
-<figure>
-<p><img src="speakers/PCB%20layout.png" class="img-responsive" alt="PCB%20layout.png">
-</p>
-</figure>
-
-<p>
-Speaker enclosure:
-</p>
-
-
-<figure>
-<p><img src="speakers/speaker%20enclosure.png" class="img-responsive" alt="speaker%20enclosure.png">
-</p>
-</figure>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="speakers/speaker%20enclosure.FCStd">FreeCAD file</a>
-</li>
-<li><a href="speakers/speaker%20enclosure.stl">STL file</a>
-</li>
-</ul>
-
-<p>
-Speaker enclosure cover:
-</p>
-
-
-<figure>
-<p><img src="speakers/speaker%20enclosure%20cover.png" class="img-responsive" alt="speaker%20enclosure%20cover.png">
-</p>
-</figure>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="speakers/speaker%20enclosure%20cover.FCStd">FreeCAD file</a>
-</li>
-<li><a href="speakers/speaker%20enclosure%20cover.stl">STL file</a>
-</li>
-</ul>
-
-<p>
-Result:
-</p>
-
-
-<figure>
-<p><img src="speakers/make.png" class="img-responsive" alt="make.png">
-</p>
-</figure>
-</div>
-</div>
-
-<div id="outline-container-sec-8" class="outline-2">
-<h2 id="sec-8"><span class="section-number-2">8</span> Front panel</h2>
-<div class="outline-text-2" id="text-8">
-<p>
-Initial idea was really simple panel:
-</p>
-<ul class="org-ul">
-<li>on/off switch
-</li>
-<li>system power indicator
-</li>
-<li>stereo audio input
-</li>
-</ul>
-
-<p>
-But, since I'm using "agile" approach, during load-testing, it become
-clear that active fan based cooling would be nice (when playing loud
-music). I found tiny cooler fan that needs 5 volts to operate. Also I
-need to power backlight for power indicator. For both of these cases,
-I decided to add another voltage up-step module (target voltage output
-set to 6V). This time directly on the front panel.
-</p>
-
-
-<figure>
-<p><img src="front%20panel/schematic.png" class="img-responsive" alt="schematic.png">
-</p>
-</figure>
-
-<p>
-Front panel case:
-</p>
-
-
-<figure>
-<p><img src="front%20panel/front%20panel,%20front.png" class="img-responsive" alt="front%20panel,%20front.png">
-</p>
-</figure>
-
-
-<figure>
-<p><img src="front%20panel/front%20panel,%20back.png" class="img-responsive" alt="front%20panel,%20back.png">
-</p>
-</figure>
-
-<p>
-Electronics fits inside:
-</p>
-
-
-<figure>
-<p><img src="front%20panel/front%20panel,%20back,%20make.png" class="img-responsive" alt="front%20panel,%20back,%20make.png">
-</p>
-</figure>
-
-<p>
-Front view:
-</p>
-
-
-<figure>
-<p><img src="front%20panel/front%20panel,%20front,%20make.png" class="img-responsive" alt="front%20panel,%20front,%20make.png">
-</p>
-</figure>
-
-<p>
-And attaches to the remaining components:
-</p>
-
-
-<figure>
-<p><img src="front%20panel/attachment.png" class="img-responsive" alt="attachment.png">
-</p>
-</figure>
-</div>
-</div>
-
-
-<div id="outline-container-sec-9" class="outline-2">
-<h2 id="sec-9"><span class="section-number-2">9</span> Extra capacitors</h2>
-<div class="outline-text-2" id="text-9">
-<p>
-Another thing that become clear during load-testing: output
-power/volume can be further enhanced by adding high power capacitors
-to even out load on primary 20V up-step module.
-</p>
-
-
-<figure>
-<p><img src="extra%20capacitors/extra%20caps.png" class="img-responsive" alt="extra%20caps.png">
-</p>
-</figure>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="extra%20capacitors/extra%20caps.FCStd">FreeCAD project</a>
-</li>
-<li><a href="extra%20capacitors/extra%20caps.stl">STL file</a>
-</li>
-</ul>
-
-<p>
-Extra caps are mounted on top of the speaker and electrically attached
-to the main board.
-</p>
-
-
-<figure>
-<p><img src="extra%20capacitors/make.png" class="img-responsive" alt="make.png">
-</p>
-</figure>
-</div>
-</div>
-
-<div id="outline-container-sec-10" class="outline-2">
-<h2 id="sec-10"><span class="section-number-2">10</span> Center box</h2>
-<div class="outline-text-2" id="text-10">
-<p>
-Last physical part, to attach it all together: central body.
-</p>
-
-<p>
-Front:
-<img src="center%20box/front.png" class="img-responsive" alt="front.png">
-</p>
-
-<p>
-Back:
-<img src="center%20box/back.png" class="img-responsive" alt="back.png">
-</p>
-
-<p>
-Download:
-</p>
-<ul class="org-ul">
-<li><a href="center%20box/center%20box.FCStd">FreeCAD file</a>
-</li>
-<li><a href="center%20box/center%20box.stl">STL file</a>
-</li>
-</ul>
-</div>
-</div>
-
-
-<div id="outline-container-sec-11" class="outline-2">
-<h2 id="sec-11"><span class="section-number-2">11</span> Conclusions / TODO</h2>
-<div class="outline-text-2" id="text-11">
-<p>
-These things could be done better:
-</p>
-
-<ul class="org-ul">
-<li>Instead of using undersized heatsinks on the audio amplifiers and
-need for active cooling as a consequence, it would be better to try
-to mount audio amplifier chip on top of speaker metallic body. It
-would provide plenty of cooling and reduces power losses within
-cable, since amplifier would be as close to the speaker as possible.
-</li>
-
-<li>I used agile design. That is, implemented functionality ad-hoc. If I
-had done design in advance, then I could have had smarter connector
-layout between main board and front panel. That is: Instead of
-multiple smaller cables, one wide (multi connector) cable.
-</li>
-
-<li>Screw holes are too close to the edges on the front panel.
-</li>
-
-<li>It would be better if screw heads were slightly buried within
-construction body.
-</li>
-</ul>
-
-
-<p>
-Overall, it was good learning experience and I was able to test
-various ideas on it. Will add cooler later :)
-</p>
-
-
-<p>
-Photo of initial PSU + audio amp test:
-</p>
-
-
-<figure>
-<p><img src="initial%20test.png" class="img-responsive" alt="initial%20test.png">
-</p>
-</figure>
-</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>
-<li><a href="#sec-3">3. Battery holder</a></li>
-<li><a href="#sec-4">4. 20V up-step module</a></li>
-<li><a href="#sec-5">5. Main board</a></li>
-<li><a href="#sec-6">6. Mono audio amplifier module</a></li>
-<li><a href="#sec-7">7. Speakers</a></li>
-<li><a href="#sec-8">8. Front panel</a></li>
-<li><a href="#sec-9">9. Extra capacitors</a></li>
-<li><a href="#sec-10">10. Center box</a></li>
-<li><a href="#sec-11">11. Conclusions / TODO</a></li>
-</ul>
-</div>
-</nav>
-</div></div></div>
-<footer id="postamble" class="">
-<div><p class="author">Author: Svjatoslav Agejenko</p>
-<p class="date">Created: 2020-04-12 P 23:58</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>
+++ /dev/null
-#+TITLE: Portable stereo speaker
-#+AUTHOR: Svjatoslav Agejenko
-#+LANGUAGE: en
-
-* (document settings) :noexport:
-** use dark style for TWBS-HTML exporter
-#+HTML_HEAD: <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
-#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
-#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
-#+HTML_HEAD: <style type="text/css">
-#+HTML_HEAD: footer {background-color: #111 !important;}
-#+HTML_HEAD: pre {background-color: #111; color: #ccc;}
-#+HTML_HEAD: </style>
-
-* General
-+ 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.
-
-+ This design is released under Creative Commons Zero (CC0) license.
-
-+ Author:
- - Svjatoslav Agejenko
- - Homepage: https://svjatoslav.eu
- - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
-
-+ See also:
- - [[../../index.html][Other physical projects in this repository]]
- - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
-
-* Project description
-I had pair of good compact stereo speakers lying uselessly around as
-well as secondhand TDA2030 Chinese knockoff audio amplifier chips.
-Also I wanted to test modular construction approach: motherboard with
-shared bus and functionality realized via pluggable modules. So I
-built stereo speaker:
-
-[[file:make.png]]
-
-Indicator on the front panel shows available power within the
-system. Ideally it should be at the maximum. It drops when batteries
-run empty or when consumed power (too loud music) is greater than
-onboard power supply or batteries can handle. It has on/off switch and
-stereo audio input. Audio input impedance is about 100 ohms.
-
-[[file:make,%20side.png]]
-
-Idea for the holes on the top and smaller ones on the bottom back is
-to enable air flow for passive cooling.
-
-[[file:make,%20back.png]]
-
-Entire construction is made of parts, no larger than
-120x120x120mm. Maximum for my printer.
-
-* Battery holder
-Device is powered by 4 times AA NiMH batteries (1.2V each).
-
-[[file:battery%20holder/schematic.png]]
-
-I happened to have AA battery adapters lying around with different
-bottom hole configurations. Therefore this weird hole design:
-
-[[file:battery%20holder/battery%20holder.png]]
-
-Download:
-+ [[file:battery%20holder/battery%20holder.FCStd][FreeCAD file]]
-+ [[file:battery%20holder/battery%20holder.stl][STL file]]
-
-Result:
-[[file:battery%20holder/make.png]]
-
-Attaches to the back of the body:
-[[file:battery%20holder/mounted%20on%20the%20back.png]]
-
-* 20V up-step module
-Battery pack voltage is routed through main on/off switch on the front
-panel, and then it goes to the 20V up-step module.
-
-[[file:20V%20upstep%20module/schematic.png]]
-
-It uses ready made upstep module, but adds extra voltage filtering via
-inductor and capacitors.
-
-[[file:20V%20upstep%20module/make.png]]
-
-* Main board
-
-Voltage upstep above sits on top of main board (motherboard). It has
-uniform central bus that spans all connectors.
-
-[[file:main%20board/internal%20bus.png]]
-
-[[file:main%20board/bus%20on%20the%20bottom,%202.png]]
-
-First row of the main board is special IO terminal (for connecting
-speakers, front panel, etc..)
-
-[[file:main%20board/IO%20terminal.png]]
-
-Remaining rows are for connecting boards:
-
-[[file:main%20board/1.png]]
-
-To provide structural support, main board is attached to frame:
-
-[[file:main%20board/board%20fixator%20body.png]]
-
-Download:
-+ [[file:main%20board/board%20fixator%20body.FCStd][FreeCAD file]]
-+ [[file:main%20board/board%20fixator%20body.stl][STL file]]
-
-And boards plugged into main board are fixed at the top, using clip:
-
-[[file:main%20board/board%20fixator%20top%20clip.png]]
-
-Download:
-+ [[file:main%20board/board%20fixator%20top%20clip.FCStd][FreeCAD file]]
-+ [[file:main%20board/board%20fixator%20top%20clip.stl][STL file]]
-
-Result:
-
-[[file:main%20board/bus%20on%20the%20bottom,%201.png]]
-
-[[file:main%20board/board%20fixator.png]]
-
-* Mono audio amplifier module
-
-Design uses scavenged secondhand Chinese TDA2030 audio amp
-clones. Each chip is mono audio amplifier. Therefore 2 almost
-identical audio amp modules had to be built, one for left speaker, one
-for right.
-
-[[file:mono%20audio%20amp%20module/schematic.png]]
-
-I like to build on top of prototype PCBs. Gives results much faster
-for one-off projects. Before soldering, I solve component layout on
-paper:
-
-[[file:mono%20audio%20amp%20module/PCB%20layout.png]]
-
-Result - front:
-
-[[file:mono%20audio%20amp%20module/assembled%20front.png]]
-
-Result - back:
-
-[[file:mono%20audio%20amp%20module/assembled%20back.png]]
-
-Here copper tape is used as improvised heatsink.
-
-* Speakers
-
-High frequency small speaker and medium frequency bigger speaker are
-combined.
-
-[[file:speakers/schematic.png]]
-
-Capacitor acts as high-pass filter on top of tiny PCB:
-
-[[file:speakers/PCB%20layout.png]]
-
-Speaker enclosure:
-
-[[file:speakers/speaker%20enclosure.png]]
-
-Download:
-+ [[file:speakers/speaker%20enclosure.FCStd][FreeCAD file]]
-+ [[file:speakers/speaker%20enclosure.stl][STL file]]
-
-Speaker enclosure cover:
-
-[[file:speakers/speaker%20enclosure%20cover.png]]
-
-Download:
-+ [[file:speakers/speaker%20enclosure%20cover.FCStd][FreeCAD file]]
-+ [[file:speakers/speaker%20enclosure%20cover.stl][STL file]]
-
-Result:
-
-[[file:speakers/make.png]]
-
-* Front panel
-
-Initial idea was really simple panel:
-+ on/off switch
-+ system power indicator
-+ stereo audio input
-
-But, since I'm using "agile" approach, during load-testing, it become
-clear that active fan based cooling would be nice (when playing loud
-music). I found tiny cooler fan that needs 5 volts to operate. Also I
-need to power backlight for power indicator. For both of these cases,
-I decided to add another voltage up-step module (target voltage output
-set to 6V). This time directly on the front panel.
-
-[[file:front%20panel/schematic.png]]
-
-Front panel case:
-
-[[file:front%20panel/front%20panel,%20front.png]]
-
-[[file:front%20panel/front%20panel,%20back.png]]
-
-Electronics fits inside:
-
-[[file:front%20panel/front%20panel,%20back,%20make.png]]
-
-Front view:
-
-[[file:front%20panel/front%20panel,%20front,%20make.png]]
-
-And attaches to the remaining components:
-
-[[file:front%20panel/attachment.png]]
-
-
-* Extra capacitors
-Another thing that become clear during load-testing: output
-power/volume can be further enhanced by adding high power capacitors
-to even out load on primary 20V up-step module.
-
-[[file:extra%20capacitors/extra%20caps.png]]
-
-Download:
-+ [[file:extra%20capacitors/extra%20caps.FCStd][FreeCAD project]]
-+ [[file:extra%20capacitors/extra%20caps.stl][STL file]]
-
-Extra caps are mounted on top of the speaker and electrically attached
-to the main board.
-
-[[file:extra%20capacitors/make.png]]
-
-* Center box
-
-Last physical part, to attach it all together: central body.
-
-Front:
-[[file:center%20box/front.png]]
-
-Back:
-[[file:center%20box/back.png]]
-
-Download:
-+ [[file:center%20box/center%20box.FCStd][FreeCAD file]]
-+ [[file:center%20box/center%20box.stl][STL file]]
-
-
-* Conclusions / TODO
-
-These things could be done better:
-
-+ Instead of using undersized heatsinks on the audio amplifiers and
- need for active cooling as a consequence, it would be better to try
- to mount audio amplifier chip on top of speaker metallic body. It
- would provide plenty of cooling and reduces power losses within
- cable, since amplifier would be as close to the speaker as possible.
-
-+ I used agile design. That is, implemented functionality ad-hoc. If I
- had done design in advance, then I could have had smarter connector
- layout between main board and front panel. That is: Instead of
- multiple smaller cables, one wide (multi connector) cable.
-
-+ Screw holes are too close to the edges on the front panel.
-
-+ It would be better if screw heads were slightly buried within
- construction body.
-
-
-Overall, it was good learning experience and I was able to test
-various ideas on it. Will add cooler later :)
-
-
-Photo of initial PSU + audio amp test:
-
-[[file:initial%20test.png]]
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--- /dev/null
+<!doctype html>
+<html lang="en">
+<head>
+<title>Headphone hub</title>
+<!-- 2020-12-25 Fri 23:48 -->
+<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">Headphone hub</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
+</li>
+<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>
+
+<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>
+Simple hub that allows connecting up to 4 devices via headphone
+jack. For example single laptop or mp3 player can power up to 3
+headphones.
+</p>
+
+
+<figure>
+<p><img src="make.png" class="img-responsive" alt="make.png">
+</p>
+</figure>
+
+<p>
+Schematic diagram:
+<img src="schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+
+<p>
+Warning: All devices are connected in parallel. Make sure that audio
+producing device can handle combined load. See:
+<a href="https://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistance_units_2">https://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistance_units_2</a>
+</p>
+
+
+<figure>
+<p><img src="make,%202.png" class="img-responsive" alt="make,%202.png">
+</p>
+</figure>
+
+<p>
+Device consists of body and cover that are held together by single
+screw at the center:
+</p>
+
+
+<figure>
+<p><img src="cover,%202.png" class="img-responsive" alt="cover,%202.png">
+</p>
+</figure>
+</div>
+</div>
+
+<div id="outline-container-sec-3" class="outline-2">
+<h2 id="sec-3"><span class="section-number-2">3</span> Download</h2>
+<div class="outline-text-2" id="text-3">
+<ul class="org-ul">
+<li><a href="hub.FCStd">FreeCAD project</a>
+</li>
+</ul>
+
+
+<p>
+Body <a href="body.stl">STL file</a>
+<img src="body.png" class="img-responsive" alt="body.png">
+</p>
+
+
+
+<hr >
+<p>
+Cover <a href="cover.stl">STL file</a>
+</p>
+
+
+<figure>
+<p><img src="cover.png" class="img-responsive" alt="cover.png">
+</p>
+</figure>
+</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>
+<li><a href="#sec-3">3. Download</a></li>
+</ul>
+</div>
+</nav>
+</div></div></div>
+<footer id="postamble" class="">
+<div><p class="author">Author: Svjatoslav Agejenko</p>
+<p class="date">Created: 2020-12-25 Fri 23:48</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>
--- /dev/null
+#+TITLE: Headphone hub
+#+AUTHOR: Svjatoslav Agejenko
+#+LANGUAGE: en
+
+* (document settings) :noexport:
+** use dark style for TWBS-HTML exporter
+#+HTML_HEAD: <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
+#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
+#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
+#+HTML_HEAD: <style type="text/css">
+#+HTML_HEAD: footer {background-color: #111 !important;}
+#+HTML_HEAD: pre {background-color: #111; color: #ccc;}
+#+HTML_HEAD: </style>
+
+* General
++ 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.
+
++ This design is released under Creative Commons Zero (CC0) license.
+
++ Author:
+ - Svjatoslav Agejenko
+ - Homepage: https://svjatoslav.eu
+ - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
+
++ See also:
+ - [[../../index.html][Other physical projects in this repository]]
+ - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
+
+* Project description
+Simple hub that allows connecting up to 4 devices via headphone
+jack. For example single laptop or mp3 player can power up to 3
+headphones.
+
+[[file:make.png]]
+
+Schematic diagram:
+[[file:schematic.png]]
+
+Warning: All devices are connected in parallel. Make sure that audio
+producing device can handle combined load. See:
+https://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistance_units_2
+
+[[file:make,%202.png]]
+
+Device consists of body and cover that are held together by single
+screw at the center:
+
+[[file:cover,%202.png]]
+
+* Download
+
+- [[file:hub.FCStd][FreeCAD project]]
+
+
+Body [[file:body.stl][STL file]]
+[[file:body.png]]
+
+
+
+-----
+Cover [[file:cover.stl][STL file]]
+
+[[file:cover.png]]
--- /dev/null
+EESchema-LIBRARY Version 2.4
+#encoding utf-8
+#
+# Connector_AudioJack3
+#
+DEF Connector_AudioJack3 J 0 20 Y Y 1 F N
+F0 "J" 0 350 50 H V C CNN
+F1 "Connector_AudioJack3" 0 250 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ Jack*
+$ENDFPLIST
+DRAW
+S -200 -200 -250 -100 0 1 10 F
+S 100 150 -200 -200 0 1 10 f
+P 4 0 1 10 0 -100 25 -125 50 -100 100 -100 N
+P 5 0 1 10 -75 -100 -50 -125 -25 -100 -25 0 100 0 N
+P 5 0 1 10 100 100 -100 100 -100 -100 -125 -125 -150 -100 N
+X ~ R 200 0 100 L 50 50 1 1 P
+X ~ S 200 100 100 L 50 50 1 1 P
+X ~ T 200 -100 100 L 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
+#End Library
--- /dev/null
+EESchema Schematic File Version 4
+EELAYER 30 0
+EELAYER END
+$Descr A4 11693 8268
+encoding utf-8
+Sheet 1 1
+Title ""
+Date ""
+Rev ""
+Comp ""
+Comment1 ""
+Comment2 ""
+Comment3 ""
+Comment4 ""
+$EndDescr
+$Comp
+L Connector:AudioJack3 J1
+U 1 1 5FE65EA5
+P 3100 3300
+F 0 "J1" V 3036 3488 50 0000 L CNN
+F 1 "AudioJack3" V 3127 3488 50 0000 L CNN
+F 2 "" H 3100 3300 50 0001 C CNN
+F 3 "~" H 3100 3300 50 0001 C CNN
+ 1 3100 3300
+ 0 1 1 0
+$EndComp
+$Comp
+L Connector:AudioJack3 J2
+U 1 1 5FE6658D
+P 4000 3300
+F 0 "J2" V 3936 3488 50 0000 L CNN
+F 1 "AudioJack3" V 4027 3488 50 0000 L CNN
+F 2 "" H 4000 3300 50 0001 C CNN
+F 3 "~" H 4000 3300 50 0001 C CNN
+ 1 4000 3300
+ 0 1 1 0
+$EndComp
+$Comp
+L Connector:AudioJack3 J3
+U 1 1 5FE66E55
+P 4850 3300
+F 0 "J3" V 4786 3488 50 0000 L CNN
+F 1 "AudioJack3" V 4877 3488 50 0000 L CNN
+F 2 "" H 4850 3300 50 0001 C CNN
+F 3 "~" H 4850 3300 50 0001 C CNN
+ 1 4850 3300
+ 0 1 1 0
+$EndComp
+Wire Wire Line
+ 3000 3500 3000 3800
+Wire Wire Line
+ 3000 3800 3900 3800
+Wire Wire Line
+ 3900 3800 3900 3500
+Wire Wire Line
+ 3900 3800 4750 3800
+Wire Wire Line
+ 4750 3800 4750 3500
+Connection ~ 3900 3800
+Wire Wire Line
+ 3100 3500 3100 3750
+Wire Wire Line
+ 3100 3750 4000 3750
+Wire Wire Line
+ 4000 3750 4000 3500
+Wire Wire Line
+ 4000 3750 4850 3750
+Wire Wire Line
+ 4850 3750 4850 3500
+Connection ~ 4000 3750
+Wire Wire Line
+ 3200 3500 3200 3700
+Wire Wire Line
+ 3200 3700 4100 3700
+Wire Wire Line
+ 4100 3700 4100 3500
+Wire Wire Line
+ 4100 3700 4950 3700
+Wire Wire Line
+ 4950 3700 4950 3500
+Connection ~ 4100 3700
+$Comp
+L Connector:AudioJack3 J4
+U 1 1 5FE687FA
+P 5700 3300
+F 0 "J4" V 5636 3488 50 0000 L CNN
+F 1 "AudioJack3" V 5727 3488 50 0000 L CNN
+F 2 "" H 5700 3300 50 0001 C CNN
+F 3 "~" H 5700 3300 50 0001 C CNN
+ 1 5700 3300
+ 0 1 1 0
+$EndComp
+Wire Wire Line
+ 4750 3800 5600 3800
+Wire Wire Line
+ 5600 3800 5600 3500
+Wire Wire Line
+ 4850 3750 5700 3750
+Wire Wire Line
+ 5700 3750 5700 3500
+Wire Wire Line
+ 4950 3700 5800 3700
+Wire Wire Line
+ 5800 3700 5800 3500
+Connection ~ 4750 3800
+Connection ~ 4850 3750
+Connection ~ 4950 3700
+$EndSCHEMATC
--- /dev/null
+<HTML>
+<HEAD>
+ <meta HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8"/>
+</HEAD>
+<BODY bgcolor="#000000" alink="#50ffff" link="#50ffff" vlink="#ff50ff" text="#ffffff">
+<!-- DirListGen -->
+<!-- Directory Listing Generator by Svjatoslav Agejenko. E-mail: svjatoslav@svjatoslav.eu, homepage: http://svjatoslav.eu -->
+<font color="#ffffff">
+<CENTER><H1>Gallery</H1></CENTER>
+<CENTER><H2></H2></CENTER>
+<TABLE>
+
+<TR><TD><br></TD></TR>
+</TABLE>
+<div style="float:left; margin: 10px;"><a href="body%2C%201.png">
+<img border="0" src=".thumbnails/body%2C%201%20(4FE5B061).jpeg"/></a><br/>
+<b>body, 1</b><br/>(<a href="body, 1.png">914x739</a>)
+</div><div style="float:left; margin: 10px;"><a href="body%2C%202.png">
+<img border="0" src=".thumbnails/body%2C%202%20(6930C5AD).jpeg"/></a><br/>
+<b>body, 2</b><br/>(<a href="body, 2.png">863x707</a>)
+</div><div style="clear: both;"><a href="body.FCStd">body.FCStd</a>
+ (455 KiB)</div><br/>
+<div style="clear: both;"><a href="body.stl">body.stl</a>
+ (692 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="bottom%20cover.png">
+<img border="0" src=".thumbnails/bottom%20cover%20(888C2041).jpeg"/></a><br/>
+<b>bottom cover</b><br/>(<a href="bottom cover.png">839x767</a>)
+</div><div style="clear: both;"><a href="bottom%20cover.stl">bottom cover.stl</a>
+ (2384 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="make%2C%20bottom.png">
+<img border="0" src=".thumbnails/make%2C%20bottom%20(77EF885B).jpeg"/></a><br/>
+<b>make, bottom</b><br/>(<a href="make, bottom.png">800x695</a>)
+</div><div style="float:left; margin: 10px;"><a href="make.png">
+<img border="0" src=".thumbnails/make%20(BCD5D41).jpeg"/></a><br/>
+<b>make</b><br/>(<a href="make.png">800x1033</a>)
+</div><div style="clear: both;"><a href="schematic-cache.lib">schematic-cache.lib</a>
+ (3351 b)</div><br/>
+<div style="float:left; margin: 10px;"><a href="schematic.png">
+<img border="0" src=".thumbnails/schematic%20(5FA81873).jpeg"/></a><br/>
+<b>schematic</b><br/>(<a href="schematic.png">930x552</a>)
+</div><div style="clear: both;"><a href="schematic.sch">schematic.sch</a>
+ (4547 b)</div><br/>
+<div style="clear: both;"><a href="schematic.sch-bak">schematic.sch-bak</a>
+ (4546 b)</div><br/>
+<div style="float:left; margin: 10px;"><a href="top%20cover.png">
+<img border="0" src=".thumbnails/top%20cover%20(1A1B8AED).jpeg"/></a><br/>
+<b>top cover</b><br/>(<a href="top cover.png">842x755</a>)
+</div><div style="clear: both;"><a href="top%20cover.stl">top cover.stl</a>
+ (322 KiB)</div><br/>
+</font></BODY></HTML>
--- /dev/null
+<!doctype html>
+<html lang="en">
+<head>
+<title>Portable stereo speaker</title>
+<!-- 2020-04-12 P 23:58 -->
+<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">Portable stereo speaker</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
+</li>
+<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>
+
+<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 had pair of good compact stereo speakers lying uselessly around as
+well as secondhand TDA2030 Chinese knockoff audio amplifier chips.
+Also I wanted to test modular construction approach: motherboard with
+shared bus and functionality realized via pluggable modules. So I
+built stereo speaker:
+</p>
+
+
+<figure>
+<p><img src="make.png" class="img-responsive" alt="make.png">
+</p>
+</figure>
+
+<p>
+Indicator on the front panel shows available power within the
+system. Ideally it should be at the maximum. It drops when batteries
+run empty or when consumed power (too loud music) is greater than
+onboard power supply or batteries can handle. It has on/off switch and
+stereo audio input. Audio input impedance is about 100 ohms.
+</p>
+
+
+<figure>
+<p><img src="make,%20side.png" class="img-responsive" alt="make,%20side.png">
+</p>
+</figure>
+
+<p>
+Idea for the holes on the top and smaller ones on the bottom back is
+to enable air flow for passive cooling.
+</p>
+
+
+<figure>
+<p><img src="make,%20back.png" class="img-responsive" alt="make,%20back.png">
+</p>
+</figure>
+
+<p>
+Entire construction is made of parts, no larger than
+120x120x120mm. Maximum for my printer.
+</p>
+</div>
+</div>
+
+<div id="outline-container-sec-3" class="outline-2">
+<h2 id="sec-3"><span class="section-number-2">3</span> Battery holder</h2>
+<div class="outline-text-2" id="text-3">
+<p>
+Device is powered by 4 times AA NiMH batteries (1.2V each).
+</p>
+
+
+<figure>
+<p><img src="battery%20holder/schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+</figure>
+
+<p>
+I happened to have AA battery adapters lying around with different
+bottom hole configurations. Therefore this weird hole design:
+</p>
+
+
+<figure>
+<p><img src="battery%20holder/battery%20holder.png" class="img-responsive" alt="battery%20holder.png">
+</p>
+</figure>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="battery%20holder/battery%20holder.FCStd">FreeCAD file</a>
+</li>
+<li><a href="battery%20holder/battery%20holder.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+Result:
+<img src="battery%20holder/make.png" class="img-responsive" alt="make.png">
+</p>
+
+<p>
+Attaches to the back of the body:
+<img src="battery%20holder/mounted%20on%20the%20back.png" class="img-responsive" alt="mounted%20on%20the%20back.png">
+</p>
+</div>
+</div>
+
+<div id="outline-container-sec-4" class="outline-2">
+<h2 id="sec-4"><span class="section-number-2">4</span> 20V up-step module</h2>
+<div class="outline-text-2" id="text-4">
+<p>
+Battery pack voltage is routed through main on/off switch on the front
+panel, and then it goes to the 20V up-step module.
+</p>
+
+
+<figure>
+<p><img src="20V%20upstep%20module/schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+</figure>
+
+<p>
+It uses ready made upstep module, but adds extra voltage filtering via
+inductor and capacitors.
+</p>
+
+
+<figure>
+<p><img src="20V%20upstep%20module/make.png" class="img-responsive" alt="make.png">
+</p>
+</figure>
+</div>
+</div>
+
+<div id="outline-container-sec-5" class="outline-2">
+<h2 id="sec-5"><span class="section-number-2">5</span> Main board</h2>
+<div class="outline-text-2" id="text-5">
+<p>
+Voltage upstep above sits on top of main board (motherboard). It has
+uniform central bus that spans all connectors.
+</p>
+
+
+<figure>
+<p><img src="main%20board/internal%20bus.png" class="img-responsive" alt="internal%20bus.png">
+</p>
+</figure>
+
+
+<figure>
+<p><img src="main%20board/bus%20on%20the%20bottom,%202.png" class="img-responsive" alt="bus%20on%20the%20bottom,%202.png">
+</p>
+</figure>
+
+<p>
+First row of the main board is special IO terminal (for connecting
+speakers, front panel, etc..)
+</p>
+
+
+<figure>
+<p><img src="main%20board/IO%20terminal.png" class="img-responsive" alt="IO%20terminal.png">
+</p>
+</figure>
+
+<p>
+Remaining rows are for connecting boards:
+</p>
+
+
+<figure>
+<p><img src="main%20board/1.png" class="img-responsive" alt="1.png">
+</p>
+</figure>
+
+<p>
+To provide structural support, main board is attached to frame:
+</p>
+
+
+<figure>
+<p><img src="main%20board/board%20fixator%20body.png" class="img-responsive" alt="board%20fixator%20body.png">
+</p>
+</figure>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="main%20board/board%20fixator%20body.FCStd">FreeCAD file</a>
+</li>
+<li><a href="main%20board/board%20fixator%20body.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+And boards plugged into main board are fixed at the top, using clip:
+</p>
+
+
+<figure>
+<p><img src="main%20board/board%20fixator%20top%20clip.png" class="img-responsive" alt="board%20fixator%20top%20clip.png">
+</p>
+</figure>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="main%20board/board%20fixator%20top%20clip.FCStd">FreeCAD file</a>
+</li>
+<li><a href="main%20board/board%20fixator%20top%20clip.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+Result:
+</p>
+
+
+<figure>
+<p><img src="main%20board/bus%20on%20the%20bottom,%201.png" class="img-responsive" alt="bus%20on%20the%20bottom,%201.png">
+</p>
+</figure>
+
+
+<figure>
+<p><img src="main%20board/board%20fixator.png" class="img-responsive" alt="board%20fixator.png">
+</p>
+</figure>
+</div>
+</div>
+
+<div id="outline-container-sec-6" class="outline-2">
+<h2 id="sec-6"><span class="section-number-2">6</span> Mono audio amplifier module</h2>
+<div class="outline-text-2" id="text-6">
+<p>
+Design uses scavenged secondhand Chinese TDA2030 audio amp
+clones. Each chip is mono audio amplifier. Therefore 2 almost
+identical audio amp modules had to be built, one for left speaker, one
+for right.
+</p>
+
+
+<figure>
+<p><img src="mono%20audio%20amp%20module/schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+</figure>
+
+<p>
+I like to build on top of prototype PCBs. Gives results much faster
+for one-off projects. Before soldering, I solve component layout on
+paper:
+</p>
+
+
+<figure>
+<p><img src="mono%20audio%20amp%20module/PCB%20layout.png" class="img-responsive" alt="PCB%20layout.png">
+</p>
+</figure>
+
+<p>
+Result - front:
+</p>
+
+
+<figure>
+<p><img src="mono%20audio%20amp%20module/assembled%20front.png" class="img-responsive" alt="assembled%20front.png">
+</p>
+</figure>
+
+<p>
+Result - back:
+</p>
+
+
+<figure>
+<p><img src="mono%20audio%20amp%20module/assembled%20back.png" class="img-responsive" alt="assembled%20back.png">
+</p>
+</figure>
+
+<p>
+Here copper tape is used as improvised heatsink.
+</p>
+</div>
+</div>
+
+<div id="outline-container-sec-7" class="outline-2">
+<h2 id="sec-7"><span class="section-number-2">7</span> Speakers</h2>
+<div class="outline-text-2" id="text-7">
+<p>
+High frequency small speaker and medium frequency bigger speaker are
+combined.
+</p>
+
+
+<figure>
+<p><img src="speakers/schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+</figure>
+
+<p>
+Capacitor acts as high-pass filter on top of tiny PCB:
+</p>
+
+
+<figure>
+<p><img src="speakers/PCB%20layout.png" class="img-responsive" alt="PCB%20layout.png">
+</p>
+</figure>
+
+<p>
+Speaker enclosure:
+</p>
+
+
+<figure>
+<p><img src="speakers/speaker%20enclosure.png" class="img-responsive" alt="speaker%20enclosure.png">
+</p>
+</figure>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="speakers/speaker%20enclosure.FCStd">FreeCAD file</a>
+</li>
+<li><a href="speakers/speaker%20enclosure.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+Speaker enclosure cover:
+</p>
+
+
+<figure>
+<p><img src="speakers/speaker%20enclosure%20cover.png" class="img-responsive" alt="speaker%20enclosure%20cover.png">
+</p>
+</figure>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="speakers/speaker%20enclosure%20cover.FCStd">FreeCAD file</a>
+</li>
+<li><a href="speakers/speaker%20enclosure%20cover.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+Result:
+</p>
+
+
+<figure>
+<p><img src="speakers/make.png" class="img-responsive" alt="make.png">
+</p>
+</figure>
+</div>
+</div>
+
+<div id="outline-container-sec-8" class="outline-2">
+<h2 id="sec-8"><span class="section-number-2">8</span> Front panel</h2>
+<div class="outline-text-2" id="text-8">
+<p>
+Initial idea was really simple panel:
+</p>
+<ul class="org-ul">
+<li>on/off switch
+</li>
+<li>system power indicator
+</li>
+<li>stereo audio input
+</li>
+</ul>
+
+<p>
+But, since I'm using "agile" approach, during load-testing, it become
+clear that active fan based cooling would be nice (when playing loud
+music). I found tiny cooler fan that needs 5 volts to operate. Also I
+need to power backlight for power indicator. For both of these cases,
+I decided to add another voltage up-step module (target voltage output
+set to 6V). This time directly on the front panel.
+</p>
+
+
+<figure>
+<p><img src="front%20panel/schematic.png" class="img-responsive" alt="schematic.png">
+</p>
+</figure>
+
+<p>
+Front panel case:
+</p>
+
+
+<figure>
+<p><img src="front%20panel/front%20panel,%20front.png" class="img-responsive" alt="front%20panel,%20front.png">
+</p>
+</figure>
+
+
+<figure>
+<p><img src="front%20panel/front%20panel,%20back.png" class="img-responsive" alt="front%20panel,%20back.png">
+</p>
+</figure>
+
+<p>
+Electronics fits inside:
+</p>
+
+
+<figure>
+<p><img src="front%20panel/front%20panel,%20back,%20make.png" class="img-responsive" alt="front%20panel,%20back,%20make.png">
+</p>
+</figure>
+
+<p>
+Front view:
+</p>
+
+
+<figure>
+<p><img src="front%20panel/front%20panel,%20front,%20make.png" class="img-responsive" alt="front%20panel,%20front,%20make.png">
+</p>
+</figure>
+
+<p>
+And attaches to the remaining components:
+</p>
+
+
+<figure>
+<p><img src="front%20panel/attachment.png" class="img-responsive" alt="attachment.png">
+</p>
+</figure>
+</div>
+</div>
+
+
+<div id="outline-container-sec-9" class="outline-2">
+<h2 id="sec-9"><span class="section-number-2">9</span> Extra capacitors</h2>
+<div class="outline-text-2" id="text-9">
+<p>
+Another thing that become clear during load-testing: output
+power/volume can be further enhanced by adding high power capacitors
+to even out load on primary 20V up-step module.
+</p>
+
+
+<figure>
+<p><img src="extra%20capacitors/extra%20caps.png" class="img-responsive" alt="extra%20caps.png">
+</p>
+</figure>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="extra%20capacitors/extra%20caps.FCStd">FreeCAD project</a>
+</li>
+<li><a href="extra%20capacitors/extra%20caps.stl">STL file</a>
+</li>
+</ul>
+
+<p>
+Extra caps are mounted on top of the speaker and electrically attached
+to the main board.
+</p>
+
+
+<figure>
+<p><img src="extra%20capacitors/make.png" class="img-responsive" alt="make.png">
+</p>
+</figure>
+</div>
+</div>
+
+<div id="outline-container-sec-10" class="outline-2">
+<h2 id="sec-10"><span class="section-number-2">10</span> Center box</h2>
+<div class="outline-text-2" id="text-10">
+<p>
+Last physical part, to attach it all together: central body.
+</p>
+
+<p>
+Front:
+<img src="center%20box/front.png" class="img-responsive" alt="front.png">
+</p>
+
+<p>
+Back:
+<img src="center%20box/back.png" class="img-responsive" alt="back.png">
+</p>
+
+<p>
+Download:
+</p>
+<ul class="org-ul">
+<li><a href="center%20box/center%20box.FCStd">FreeCAD file</a>
+</li>
+<li><a href="center%20box/center%20box.stl">STL file</a>
+</li>
+</ul>
+</div>
+</div>
+
+
+<div id="outline-container-sec-11" class="outline-2">
+<h2 id="sec-11"><span class="section-number-2">11</span> Conclusions / TODO</h2>
+<div class="outline-text-2" id="text-11">
+<p>
+These things could be done better:
+</p>
+
+<ul class="org-ul">
+<li>Instead of using undersized heatsinks on the audio amplifiers and
+need for active cooling as a consequence, it would be better to try
+to mount audio amplifier chip on top of speaker metallic body. It
+would provide plenty of cooling and reduces power losses within
+cable, since amplifier would be as close to the speaker as possible.
+</li>
+
+<li>I used agile design. That is, implemented functionality ad-hoc. If I
+had done design in advance, then I could have had smarter connector
+layout between main board and front panel. That is: Instead of
+multiple smaller cables, one wide (multi connector) cable.
+</li>
+
+<li>Screw holes are too close to the edges on the front panel.
+</li>
+
+<li>It would be better if screw heads were slightly buried within
+construction body.
+</li>
+</ul>
+
+
+<p>
+Overall, it was good learning experience and I was able to test
+various ideas on it. Will add cooler later :)
+</p>
+
+
+<p>
+Photo of initial PSU + audio amp test:
+</p>
+
+
+<figure>
+<p><img src="initial%20test.png" class="img-responsive" alt="initial%20test.png">
+</p>
+</figure>
+</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>
+<li><a href="#sec-3">3. Battery holder</a></li>
+<li><a href="#sec-4">4. 20V up-step module</a></li>
+<li><a href="#sec-5">5. Main board</a></li>
+<li><a href="#sec-6">6. Mono audio amplifier module</a></li>
+<li><a href="#sec-7">7. Speakers</a></li>
+<li><a href="#sec-8">8. Front panel</a></li>
+<li><a href="#sec-9">9. Extra capacitors</a></li>
+<li><a href="#sec-10">10. Center box</a></li>
+<li><a href="#sec-11">11. Conclusions / TODO</a></li>
+</ul>
+</div>
+</nav>
+</div></div></div>
+<footer id="postamble" class="">
+<div><p class="author">Author: Svjatoslav Agejenko</p>
+<p class="date">Created: 2020-04-12 P 23:58</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>
--- /dev/null
+#+TITLE: Portable stereo speaker
+#+AUTHOR: Svjatoslav Agejenko
+#+LANGUAGE: en
+
+* (document settings) :noexport:
+** use dark style for TWBS-HTML exporter
+#+HTML_HEAD: <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
+#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
+#+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
+#+HTML_HEAD: <style type="text/css">
+#+HTML_HEAD: footer {background-color: #111 !important;}
+#+HTML_HEAD: pre {background-color: #111; color: #ccc;}
+#+HTML_HEAD: </style>
+
+* General
++ 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.
+
++ This design is released under Creative Commons Zero (CC0) license.
+
++ Author:
+ - Svjatoslav Agejenko
+ - Homepage: https://svjatoslav.eu
+ - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
+
++ See also:
+ - [[../../index.html][Other physical projects in this repository]]
+ - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
+
+* Project description
+I had pair of good compact stereo speakers lying uselessly around as
+well as secondhand TDA2030 Chinese knockoff audio amplifier chips.
+Also I wanted to test modular construction approach: motherboard with
+shared bus and functionality realized via pluggable modules. So I
+built stereo speaker:
+
+[[file:make.png]]
+
+Indicator on the front panel shows available power within the
+system. Ideally it should be at the maximum. It drops when batteries
+run empty or when consumed power (too loud music) is greater than
+onboard power supply or batteries can handle. It has on/off switch and
+stereo audio input. Audio input impedance is about 100 ohms.
+
+[[file:make,%20side.png]]
+
+Idea for the holes on the top and smaller ones on the bottom back is
+to enable air flow for passive cooling.
+
+[[file:make,%20back.png]]
+
+Entire construction is made of parts, no larger than
+120x120x120mm. Maximum for my printer.
+
+* Battery holder
+Device is powered by 4 times AA NiMH batteries (1.2V each).
+
+[[file:battery%20holder/schematic.png]]
+
+I happened to have AA battery adapters lying around with different
+bottom hole configurations. Therefore this weird hole design:
+
+[[file:battery%20holder/battery%20holder.png]]
+
+Download:
++ [[file:battery%20holder/battery%20holder.FCStd][FreeCAD file]]
++ [[file:battery%20holder/battery%20holder.stl][STL file]]
+
+Result:
+[[file:battery%20holder/make.png]]
+
+Attaches to the back of the body:
+[[file:battery%20holder/mounted%20on%20the%20back.png]]
+
+* 20V up-step module
+Battery pack voltage is routed through main on/off switch on the front
+panel, and then it goes to the 20V up-step module.
+
+[[file:20V%20upstep%20module/schematic.png]]
+
+It uses ready made upstep module, but adds extra voltage filtering via
+inductor and capacitors.
+
+[[file:20V%20upstep%20module/make.png]]
+
+* Main board
+
+Voltage upstep above sits on top of main board (motherboard). It has
+uniform central bus that spans all connectors.
+
+[[file:main%20board/internal%20bus.png]]
+
+[[file:main%20board/bus%20on%20the%20bottom,%202.png]]
+
+First row of the main board is special IO terminal (for connecting
+speakers, front panel, etc..)
+
+[[file:main%20board/IO%20terminal.png]]
+
+Remaining rows are for connecting boards:
+
+[[file:main%20board/1.png]]
+
+To provide structural support, main board is attached to frame:
+
+[[file:main%20board/board%20fixator%20body.png]]
+
+Download:
++ [[file:main%20board/board%20fixator%20body.FCStd][FreeCAD file]]
++ [[file:main%20board/board%20fixator%20body.stl][STL file]]
+
+And boards plugged into main board are fixed at the top, using clip:
+
+[[file:main%20board/board%20fixator%20top%20clip.png]]
+
+Download:
++ [[file:main%20board/board%20fixator%20top%20clip.FCStd][FreeCAD file]]
++ [[file:main%20board/board%20fixator%20top%20clip.stl][STL file]]
+
+Result:
+
+[[file:main%20board/bus%20on%20the%20bottom,%201.png]]
+
+[[file:main%20board/board%20fixator.png]]
+
+* Mono audio amplifier module
+
+Design uses scavenged secondhand Chinese TDA2030 audio amp
+clones. Each chip is mono audio amplifier. Therefore 2 almost
+identical audio amp modules had to be built, one for left speaker, one
+for right.
+
+[[file:mono%20audio%20amp%20module/schematic.png]]
+
+I like to build on top of prototype PCBs. Gives results much faster
+for one-off projects. Before soldering, I solve component layout on
+paper:
+
+[[file:mono%20audio%20amp%20module/PCB%20layout.png]]
+
+Result - front:
+
+[[file:mono%20audio%20amp%20module/assembled%20front.png]]
+
+Result - back:
+
+[[file:mono%20audio%20amp%20module/assembled%20back.png]]
+
+Here copper tape is used as improvised heatsink.
+
+* Speakers
+
+High frequency small speaker and medium frequency bigger speaker are
+combined.
+
+[[file:speakers/schematic.png]]
+
+Capacitor acts as high-pass filter on top of tiny PCB:
+
+[[file:speakers/PCB%20layout.png]]
+
+Speaker enclosure:
+
+[[file:speakers/speaker%20enclosure.png]]
+
+Download:
++ [[file:speakers/speaker%20enclosure.FCStd][FreeCAD file]]
++ [[file:speakers/speaker%20enclosure.stl][STL file]]
+
+Speaker enclosure cover:
+
+[[file:speakers/speaker%20enclosure%20cover.png]]
+
+Download:
++ [[file:speakers/speaker%20enclosure%20cover.FCStd][FreeCAD file]]
++ [[file:speakers/speaker%20enclosure%20cover.stl][STL file]]
+
+Result:
+
+[[file:speakers/make.png]]
+
+* Front panel
+
+Initial idea was really simple panel:
++ on/off switch
++ system power indicator
++ stereo audio input
+
+But, since I'm using "agile" approach, during load-testing, it become
+clear that active fan based cooling would be nice (when playing loud
+music). I found tiny cooler fan that needs 5 volts to operate. Also I
+need to power backlight for power indicator. For both of these cases,
+I decided to add another voltage up-step module (target voltage output
+set to 6V). This time directly on the front panel.
+
+[[file:front%20panel/schematic.png]]
+
+Front panel case:
+
+[[file:front%20panel/front%20panel,%20front.png]]
+
+[[file:front%20panel/front%20panel,%20back.png]]
+
+Electronics fits inside:
+
+[[file:front%20panel/front%20panel,%20back,%20make.png]]
+
+Front view:
+
+[[file:front%20panel/front%20panel,%20front,%20make.png]]
+
+And attaches to the remaining components:
+
+[[file:front%20panel/attachment.png]]
+
+
+* Extra capacitors
+Another thing that become clear during load-testing: output
+power/volume can be further enhanced by adding high power capacitors
+to even out load on primary 20V up-step module.
+
+[[file:extra%20capacitors/extra%20caps.png]]
+
+Download:
++ [[file:extra%20capacitors/extra%20caps.FCStd][FreeCAD project]]
++ [[file:extra%20capacitors/extra%20caps.stl][STL file]]
+
+Extra caps are mounted on top of the speaker and electrically attached
+to the main board.
+
+[[file:extra%20capacitors/make.png]]
+
+* Center box
+
+Last physical part, to attach it all together: central body.
+
+Front:
+[[file:center%20box/front.png]]
+
+Back:
+[[file:center%20box/back.png]]
+
+Download:
++ [[file:center%20box/center%20box.FCStd][FreeCAD file]]
++ [[file:center%20box/center%20box.stl][STL file]]
+
+
+* Conclusions / TODO
+
+These things could be done better:
+
++ Instead of using undersized heatsinks on the audio amplifiers and
+ need for active cooling as a consequence, it would be better to try
+ to mount audio amplifier chip on top of speaker metallic body. It
+ would provide plenty of cooling and reduces power losses within
+ cable, since amplifier would be as close to the speaker as possible.
+
++ I used agile design. That is, implemented functionality ad-hoc. If I
+ had done design in advance, then I could have had smarter connector
+ layout between main board and front panel. That is: Instead of
+ multiple smaller cables, one wide (multi connector) cable.
+
++ Screw holes are too close to the edges on the front panel.
+
++ It would be better if screw heads were slightly buried within
+ construction body.
+
+
+Overall, it was good learning experience and I was able to test
+various ideas on it. Will add cooler later :)
+
+
+Photo of initial PSU + audio amp test:
+
+[[file:initial%20test.png]]
--- /dev/null
+EESchema-LIBRARY Version 2.4
+#encoding utf-8
+#
+# Amplifier_Audio_TDA2030
+#
+DEF Amplifier_Audio_TDA2030 U 0 5 Y Y 1 F N
+F0 "U" 150 250 50 H V C CNN
+F1 "Amplifier_Audio_TDA2030" 150 150 50 H V C CNN
+F2 "Package_TO_SOT_THT:TO-220-5_P3.4x3.7mm_StaggerOdd_Lead3.8mm_Vertical" 0 0 50 H I C CIN
+F3 "" 0 0 50 H I C CNN
+ALIAS TDA2050
+$FPLIST
+ TO*220*StaggerOdd*
+$ENDFPLIST
+DRAW
+P 4 0 1 10 -200 200 200 0 -200 -200 -200 200 f
+X + 1 -300 100 100 R 50 50 1 1 I
+X - 2 -300 -100 100 R 50 50 1 1 I
+X -Vs 3 -100 -300 150 U 50 40 1 1 W
+X ~ 4 300 0 100 L 50 50 1 1 O
+X +Vs 5 -100 300 150 D 50 40 1 1 W
+ENDDRAW
+ENDDEF
+#
+# Connector_Conn_01x01_Male
+#
+DEF Connector_Conn_01x01_Male J 0 40 Y N 1 F N
+F0 "J" 0 100 50 H V C CNN
+F1 "Connector_Conn_01x01_Male" 0 -100 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ Connector*:*
+$ENDFPLIST
+DRAW
+S 34 5 0 -5 1 1 6 F
+P 2 1 1 6 50 0 34 0 N
+X Pin_1 1 200 0 150 L 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
+# Device_C
+#
+DEF Device_C C 0 10 N Y 1 F N
+F0 "C" 25 100 50 H V L CNN
+F1 "Device_C" 25 -100 50 H V L CNN
+F2 "" 38 -150 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ C_*
+$ENDFPLIST
+DRAW
+P 2 0 1 20 -80 -30 80 -30 N
+P 2 0 1 20 -80 30 80 30 N
+X ~ 1 0 150 110 D 50 50 1 1 P
+X ~ 2 0 -150 110 U 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
+# Device_D
+#
+DEF Device_D D 0 40 N N 1 F N
+F0 "D" 0 100 50 H V C CNN
+F1 "Device_D" 0 -100 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ TO-???*
+ *_Diode_*
+ *SingleDiode*
+ D_*
+$ENDFPLIST
+DRAW
+P 2 0 1 8 -50 50 -50 -50 N
+P 2 0 1 0 50 0 -50 0 N
+P 4 0 1 8 50 50 50 -50 -50 0 50 50 N
+X K 1 -150 0 100 R 50 50 1 1 P
+X A 2 150 0 100 L 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
+# Device_R
+#
+DEF Device_R R 0 0 N Y 1 F N
+F0 "R" 80 0 50 V V C CNN
+F1 "Device_R" 0 0 50 V V C CNN
+F2 "" -70 0 50 V I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ R_*
+$ENDFPLIST
+DRAW
+S -40 -100 40 100 0 1 10 N
+X ~ 1 0 150 50 D 50 50 1 1 P
+X ~ 2 0 -150 50 U 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
+# power_GND
+#
+DEF power_GND #PWR 0 0 Y Y 1 F P
+F0 "#PWR" 0 -250 50 H I C CNN
+F1 "power_GND" 0 -150 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+DRAW
+P 6 0 1 0 0 0 0 -50 50 -50 0 -100 -50 -50 0 -50 N
+X GND 1 0 0 0 D 50 50 1 1 W N
+ENDDRAW
+ENDDEF
+#
+#End Library
--- /dev/null
+update=22/05/2015 07:44:53
+version=1
+last_client=kicad
+[general]
+version=1
+RootSch=
+BoardNm=
+[pcbnew]
+version=1
+LastNetListRead=
+UseCmpFile=1
+PadDrill=0.600000000000
+PadDrillOvalY=0.600000000000
+PadSizeH=1.500000000000
+PadSizeV=1.500000000000
+PcbTextSizeV=1.500000000000
+PcbTextSizeH=1.500000000000
+PcbTextThickness=0.300000000000
+ModuleTextSizeV=1.000000000000
+ModuleTextSizeH=1.000000000000
+ModuleTextSizeThickness=0.150000000000
+SolderMaskClearance=0.000000000000
+SolderMaskMinWidth=0.000000000000
+DrawSegmentWidth=0.200000000000
+BoardOutlineThickness=0.100000000000
+ModuleOutlineThickness=0.150000000000
+[cvpcb]
+version=1
+NetIExt=net
+[eeschema]
+version=1
+LibDir=
+[eeschema/libraries]
--- /dev/null
+EESchema Schematic File Version 4
+EELAYER 30 0
+EELAYER END
+$Descr A4 11693 8268
+encoding utf-8
+Sheet 1 1
+Title ""
+Date ""
+Rev ""
+Comp ""
+Comment1 ""
+Comment2 ""
+Comment3 ""
+Comment4 ""
+$EndDescr
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+ 1 0 0 -1
+$EndComp
+$Comp
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+ 0 -1 -1 0
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+$Comp
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+ 1 2450 3900
+ 1 0 0 -1
+$EndComp
+Wire Wire Line
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+$Comp
+L Connector:Conn_01x01_Male J2
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+$Comp
+L Device:C C3
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+ 1 2750 3900
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+$EndComp
+Wire Wire Line
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+Wire Wire Line
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+Wire Wire Line
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+Connection ~ 2750 4200
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+L power:GND #PWR03
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+ 1 2750 4350
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+$EndComp
+Wire Wire Line
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+$Comp
+L Device:C C2
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+Wire Wire Line
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+L Connector:Conn_01x01_Male J1
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+Wire Wire Line
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+Wire Wire Line
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+L power:GND #PWR01
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+Wire Wire Line
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+L power:GND #PWR05
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+Wire Wire Line
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+Wire Wire Line
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+Wire Wire Line
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+L power:GND #PWR04
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+ 1 3800 5100
+ 1 0 0 -1
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+Wire Wire Line
+ 3800 5100 3800 5000
+$Comp
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+Wire Wire Line
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+Wire Wire Line
+ 3800 4200 3800 3500
+Wire Wire Line
+ 4500 4200 4600 4200
+Wire Wire Line
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+Wire Wire Line
+ 4600 3400 4550 3400
+$Comp
+L Device:D D2
+U 1 1 5E95E389
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+F 0 "D2" V 4554 4579 50 0000 L CNN
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+F 2 "" H 4600 4500 50 0001 C CNN
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+ 1 4600 4500
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+$EndComp
+$Comp
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+U 1 1 5E9303C6
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+F 0 "U1" H 4594 3446 50 0000 L CNN
+F 1 "TDA2030" H 4594 3355 50 0000 L CNN
+F 2 "Package_TO_SOT_THT:TO-220-5_P3.4x3.7mm_StaggerOdd_Lead3.8mm_Vertical" H 4250 3400 50 0001 C CIN
+F 3 "http://www.st.com/resource/en/datasheet/cd00000128.pdf" H 4250 3400 50 0001 C CNN
+ 1 4250 3400
+ 1 0 0 -1
+$EndComp
+Wire Wire Line
+ 4600 4350 4600 4200
+Connection ~ 4600 4200
+$Comp
+L power:GND #PWR06
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+$EndComp
+Wire Wire Line
+ 4600 4800 4600 4650
+$Comp
+L Device:D D1
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+F 0 "D1" V 4554 2679 50 0000 L CNN
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+F 2 "" H 4600 2600 50 0001 C CNN
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+Wire Wire Line
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+ 4600 2350 4150 2350
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+L Device:R R7
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+F 2 "" V 4930 3750 50 0001 C CNN
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+ 1 5000 3750
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+$Comp
+L Device:C C6
+U 1 1 5E967648
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+F 2 "" H 5038 4000 50 0001 C CNN
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+ 1 5000 4150
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+$Comp
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+ 1 5000 4400
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+$EndComp
+$Comp
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+Wire Wire Line
+ 5000 3600 5000 3400
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+ 5000 3400 5200 3400
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+Wire Wire Line
+ 5000 4300 5000 4400
+$Comp
+L Connector:Conn_01x01_Male J3
+U 1 1 5E96C10D
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+F 0 "J3" H 5772 3332 50 0000 R CNN
+F 1 "7 / 9: speaker signal out" H 5772 3423 50 0000 R CNN
+F 2 "" H 5800 3400 50 0001 C CNN
+F 3 "~" H 5800 3400 50 0001 C CNN
+ 1 5800 3400
+ -1 0 0 1
+$EndComp
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+ 5500 3400 5600 3400
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+ 2300 2350 3100 2350
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+ 3750 2450 3750 2350
+Connection ~ 3750 2350
+Wire Wire Line
+ 3750 2350 4150 2350
+$Comp
+L Connector:Conn_01x01_Male J4
+U 1 1 5E989AED
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+F 0 "J4" H 2108 4931 50 0000 C CNN
+F 1 "1, 2: GND" H 2108 4840 50 0000 C CNN
+F 2 "" H 2000 4750 50 0001 C CNN
+F 3 "~" H 2000 4750 50 0001 C CNN
+ 1 2000 4750
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+$Comp
+L power:GND #PWR08
+U 1 1 5E98A1F3
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+F 0 "#PWR08" H 2350 4650 50 0001 C CNN
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+F 3 "" H 2350 4900 50 0001 C CNN
+ 1 2350 4900
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+$EndComp
+Wire Wire Line
+ 2350 4900 2350 4750
+Wire Wire Line
+ 2350 4750 2200 4750
+$EndSCHEMATC
--- /dev/null
+<HTML>
+<HEAD>
+ <meta HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8"/>
+</HEAD>
+<BODY bgcolor="#000000" alink="#50ffff" link="#50ffff" vlink="#ff50ff" text="#ffffff">
+<!-- DirListGen -->
+<!-- Directory Listing Generator by Svjatoslav Agejenko. E-mail: svjatoslav@svjatoslav.eu, homepage: http://svjatoslav.eu -->
+<font color="#ffffff">
+<CENTER><H1>Gallery</H1></CENTER>
+<CENTER><H2></H2></CENTER>
+<TABLE>
+
+<TR><TD><br></TD></TR>
+</TABLE>
+<div style="float:left; margin: 10px;"><a href="binocular%20mount.png">
+<img border="0" src=".thumbnails/binocular%20mount%20(5470FA5E).jpeg"/></a><br/>
+<b>binocular mount</b><br/>(<a href="binocular mount.png">1207x822</a>)
+</div><div style="clear: both;"><a href="binocular%20mount.stl">binocular mount.stl</a>
+ (1013 KiB)</div><br/>
+<div style="clear: both;"><a href="body.FCStd">body.FCStd</a>
+ (640 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="bottom%20cover.png">
+<img border="0" src=".thumbnails/bottom%20cover%20(46C5509).jpeg"/></a><br/>
+<b>bottom cover</b><br/>(<a href="bottom cover.png">889x720</a>)
+</div><div style="clear: both;"><a href="bottom%20cover.stl">bottom cover.stl</a>
+ (1289 KiB)</div><br/>
+<div style="clear: both;"><a href="disk%20momunt.FCStd">disk momunt.FCStd</a>
+ (38 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="disk%20mount%20body.png">
+<img border="0" src="disk mount body.png"/></a><br/>
+<b>disk mount body</b><br/>(<a href="disk mount body.png">515x431</a>)
+</div><div style="clear: both;"><a href="disk%20mount%20body.stl">disk mount body.stl</a>
+ (1255 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="disk%20mount%20top%20ring.png">
+<img border="0" src=".thumbnails/disk%20mount%20top%20ring%20(5145D798).jpeg"/></a><br/>
+<b>disk mount top ring</b><br/>(<a href="disk mount top ring.png">818x565</a>)
+</div><div style="clear: both;"><a href="disk%20mount%20top%20ring.stl">disk mount top ring.stl</a>
+ (49 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="main%20body%2C%201.png">
+<img border="0" src=".thumbnails/main%20body%2C%201%20(CED4849B).jpeg"/></a><br/>
+<b>main body, 1</b><br/>(<a href="main body, 1.png">807x652</a>)
+</div><div style="float:left; margin: 10px;"><a href="main%20body%2C%202.png">
+<img border="0" src=".thumbnails/main%20body%2C%202%20(BBE5D47).jpeg"/></a><br/>
+<b>main body, 2</b><br/>(<a href="main body, 2.png">880x649</a>)
+</div><div style="clear: both;"><a href="main%20body.stl">main body.stl</a>
+ (1023 KiB)</div><br/>
+<div style="float:left; margin: 10px;"><a href="make%2C%201.png">
+<img border="0" src=".thumbnails/make%2C%201%20(F0B1B465).jpeg"/></a><br/>
+<b>make, 1</b><br/>(<a href="make, 1.png">885x740</a>)
+</div><div style="float:left; margin: 10px;"><a href="make%2C%202.png">
+<img border="0" src=".thumbnails/make%2C%202%20(F6EEB15).jpeg"/></a><br/>
+<b>make, 2</b><br/>(<a href="make, 2.png">839x642</a>)
+</div><div style="float:left; margin: 10px;"><a href="make%2C%203.png">
+<img border="0" src=".thumbnails/make%2C%203%20(B2562273).jpeg"/></a><br/>
+<b>make, 3</b><br/>(<a href="make, 3.png">1311x1023</a>, <a href=".thumbnails/make%2C%203%20(2BEF1B03).jpeg">655x511</a>)
+</div><div style="float:left; margin: 10px;"><a href="make%2C%204.png">
+<img border="0" src=".thumbnails/make%2C%204%20(E33553C2).jpeg"/></a><br/>
+<b>make, 4</b><br/>(<a href="make, 4.png">969x1050</a>, <a href=".thumbnails/make%2C%204%20(9EE76D6F).jpeg">484x525</a>)
+</div><div style="float:left; margin: 10px;"><a href="make.png">
+<img border="0" src=".thumbnails/make%20(A3EAEADD).jpeg"/></a><br/>
+<b>make</b><br/>(<a href="make.png">1008x1008</a>, <a href=".thumbnails/make%20(66C48D60).jpeg">504x504</a>)
+</div><div style="float:left; margin: 10px;"><a href="top%20cover.png">
+<img border="0" src=".thumbnails/top%20cover%20(4D38AF67).jpeg"/></a><br/>
+<b>top cover</b><br/>(<a href="top cover.png">827x705</a>)
+</div><div style="clear: both;"><a href="top%20cover.stl">top cover.stl</a>
+ (1351 KiB)</div><br/>
+</font></BODY></HTML>
projects / physical.git / commitdiff
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