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+<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
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+F1 "Amplifier_Audio_TDA2030" 150 150 50 H V C CNN
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+F3 "" 0 0 50 H I C CNN
+ALIAS TDA2050
+$FPLIST
+ TO*220*StaggerOdd*
+$ENDFPLIST
+DRAW
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+#
+# Connector_Conn_01x01_Male
+#
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+ Connector*:*
+$ENDFPLIST
+DRAW
+S 34 5 0 -5 1 1 6 F
+P 2 1 1 6 50 0 34 0 N
+X Pin_1 1 200 0 150 L 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
+# Device_C
+#
+DEF Device_C C 0 10 N Y 1 F N
+F0 "C" 25 100 50 H V L CNN
+F1 "Device_C" 25 -100 50 H V L CNN
+F2 "" 38 -150 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
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+X ~ 1 0 150 110 D 50 50 1 1 P
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+ENDDRAW
+ENDDEF
+#
+# Device_D
+#
+DEF Device_D D 0 40 N N 1 F N
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+F1 "Device_D" 0 -100 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
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+ *_Diode_*
+ *SingleDiode*
+ D_*
+$ENDFPLIST
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+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
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+F2 "" -70 0 50 V I C CNN
+F3 "" 0 0 50 H I C CNN
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+ENDDEF
+#
+# power_GND
+#
+DEF power_GND #PWR 0 0 Y Y 1 F P
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+F1 "power_GND" 0 -150 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
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+DRAW
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+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
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+PcbTextSizeH=1.500000000000
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+ModuleTextSizeThickness=0.150000000000
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+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
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<html lang="en">
<head>
<title>Physical projects</title>
-<!-- 2020-05-07 N 22:21 -->
+<!-- 2020-05-16 L 21:12 -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="generator" content="Org-mode">
<h2 id="sec-2"><span class="section-number-2">2</span> Projects</h2>
<div class="outline-text-2" id="text-2">
</div><div id="outline-container-sec-2-1" class="outline-3">
-<h3 id="sec-2-1"><a id="ID-0482740b-0f2e-4138-804d-37c7025124d3" name="ID-0482740b-0f2e-4138-804d-37c7025124d3"></a><span class="section-number-3">2.1</span> Miscellaneous</h3>
+<h3 id="sec-2-1"><span class="section-number-3">2.1</span> Audio</h3>
<div class="outline-text-3" id="text-2-1">
<ul class="org-ul">
-<li><a href="misc/Portable%20stereo%20active%20speaker/index.html">Portable stereo speaker</a>
+<li><a href="audio/Portable%20stereo%20active%20speaker/index.html">Portable stereo speaker</a>
<ul class="org-ul">
-<li><img src="misc/Portable%20stereo%20active%20speaker/make.png" class="img-responsive" alt="make.png">
+<li><img src="audio/Portable%20stereo%20active%20speaker/make.png" class="img-responsive" alt="make.png">
</li>
</ul>
</li>
+</ul>
+</div>
+</div>
+<div id="outline-container-sec-2-2" class="outline-3">
+<h3 id="sec-2-2"><a id="ID-0482740b-0f2e-4138-804d-37c7025124d3" name="ID-0482740b-0f2e-4138-804d-37c7025124d3"></a><span class="section-number-3">2.2</span> Miscellaneous</h3>
+<div class="outline-text-3" id="text-2-2">
+<ul class="org-ul">
<li><a href="misc/CAT%20B30%20phone%20cover/index.html">Cover for CAT B30 phone</a>
<ul class="org-ul">
<li><img src="misc/CAT%20B30%20phone%20cover/make.png" class="img-responsive" alt="make.png">
</div>
</div>
-<div id="outline-container-sec-2-2" class="outline-3">
-<h3 id="sec-2-2"><span class="section-number-3">2.2</span> Optics</h3>
-<div class="outline-text-3" id="text-2-2">
+<div id="outline-container-sec-2-3" class="outline-3">
+<h3 id="sec-2-3"><span class="section-number-3">2.3</span> Optics</h3>
+<div class="outline-text-3" id="text-2-3">
<ul class="org-ul">
<li><a href="optics/35mm%20film%20copying%20device/index.html">35mm film copying device</a>
<ul class="org-ul">
</div>
</div>
-<div id="outline-container-sec-2-3" class="outline-3">
-<h3 id="sec-2-3"><span class="section-number-3">2.3</span> Organizers / boxes / covers</h3>
-<div class="outline-text-3" id="text-2-3">
+<div id="outline-container-sec-2-4" class="outline-3">
+<h3 id="sec-2-4"><span class="section-number-3">2.4</span> Organizers / boxes / covers</h3>
+<div class="outline-text-3" id="text-2-4">
<ul class="org-ul">
<li><a href="organizers/cable%20organizer/index.html">Cable organizer</a>
<ul class="org-ul">
</div>
</div>
-<div id="outline-container-sec-2-4" class="outline-3">
-<h3 id="sec-2-4"><span class="section-number-3">2.4</span> Radio</h3>
-<div class="outline-text-3" id="text-2-4">
+<div id="outline-container-sec-2-5" class="outline-3">
+<h3 id="sec-2-5"><span class="section-number-3">2.5</span> Radio</h3>
+<div class="outline-text-3" id="text-2-5">
<ul class="org-ul">
<li><a href="RF/NanoVNA%20case/index.html">NanoVNA case</a>
<ul class="org-ul">
</li>
<li><a href="#sec-2">2. Projects</a>
<ul class="nav">
-<li><a href="#sec-2-1">2.1. Miscellaneous</a></li>
-<li><a href="#sec-2-2">2.2. Optics</a></li>
-<li><a href="#sec-2-3">2.3. Organizers / boxes / covers</a></li>
-<li><a href="#sec-2-4">2.4. Radio</a></li>
+<li><a href="#sec-2-1">2.1. Audio</a></li>
+<li><a href="#sec-2-2">2.2. Miscellaneous</a></li>
+<li><a href="#sec-2-3">2.3. Optics</a></li>
+<li><a href="#sec-2-4">2.4. Organizers / boxes / covers</a></li>
+<li><a href="#sec-2-5">2.5. Radio</a></li>
</ul>
</li>
</ul>
</div></div></div>
<footer id="postamble" class="">
<div><p class="author">Author: Svjatoslav Agejenko</p>
-<p class="date">Created: 2020-05-07 N 22:21</p>
+<p class="date">Created: 2020-05-16 L 21:12</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>
: git clone https://www2.svjatoslav.eu/git/physical.git
* Projects
+** Audio
++ [[file:audio/Portable%20stereo%20active%20speaker/index.html][Portable stereo speaker]]
+ + [[file:audio/Portable%20stereo%20active%20speaker/make.png]]
+
** Miscellaneous
:PROPERTIES:
:ID: 0482740b-0f2e-4138-804d-37c7025124d3
:END:
-+ [[file:misc/Portable%20stereo%20active%20speaker/index.html][Portable stereo speaker]]
- + [[file:misc/Portable%20stereo%20active%20speaker/make.png]]
-
+ [[file:misc/CAT%20B30%20phone%20cover/index.html][Cover for CAT B30 phone]]
+ [[file:misc/CAT%20B30%20phone%20cover/make.png]]
+++ /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>
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-footer {background-color: #111 !important;}
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-</style>
-<style type="text/css">
-/* org mode styles on top of twbs */
-
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-
-body {
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-
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- width: 100%;
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-}
-
-footer > div {
- padding: 10px;
-}
-
-footer p {
- margin: 0 0 5px;
- text-align: center;
- font-size: 16px;
-}
-
-#table-of-contents {
- margin-top: 20px;
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- padding-left: 19px;
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-
-/* 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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-</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_*
-$ENDFPLIST
-DRAW
-P 2 0 1 20 -80 -30 80 -30 N
-P 2 0 1 20 -80 30 80 30 N
-X ~ 1 0 150 110 D 50 50 1 1 P
-X ~ 2 0 -150 110 U 50 50 1 1 P
-ENDDRAW
-ENDDEF
-#
-# Device_D
-#
-DEF Device_D D 0 40 N N 1 F N
-F0 "D" 0 100 50 H V C CNN
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-ENDDRAW
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-#
-# Device_R
-#
-DEF Device_R R 0 0 N Y 1 F N
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-$FPLIST
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-#
-# power_GND
-#
-DEF power_GND #PWR 0 0 Y Y 1 F P
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-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
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-ENDDRAW
-ENDDEF
-#
-#End Library
+++ /dev/null
-update=22/05/2015 07:44:53
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-[general]
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-[cvpcb]
-version=1
-NetIExt=net
-[eeschema]
-version=1
-LibDir=
-[eeschema/libraries]
+++ /dev/null
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-EELAYER 30 0
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-F 2 "" H 2338 2450 50 0001 C CNN
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-F 3 "" H 4150 3750 50 0001 C CNN
- 1 4150 3750
- 1 0 0 -1
-$EndComp
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-$Comp
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- 1 3800 4450
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projects / physical.git / commitdiff
