X-Git-Url: http://www2.svjatoslav.eu/gitweb/?p=physical.git;a=blobdiff_plain;f=misc%2FPortable%20stereo%20active%20speaker%2Findex.org;fp=misc%2FPortable%20stereo%20active%20speaker%2Findex.org;h=0000000000000000000000000000000000000000;hp=e85fa1fa350fa37a35560c5a3ed30c32ac0b1565;hb=93328c1287d8ad9d802e3fef2fe807855734a74c;hpb=069fde206926a43efc051c63f55555f668520f73 diff --git a/misc/Portable stereo active speaker/index.org b/misc/Portable stereo active speaker/index.org deleted file mode 100644 index e85fa1f..0000000 --- a/misc/Portable stereo active speaker/index.org +++ /dev/null @@ -1,276 +0,0 @@ -#+TITLE: Portable stereo speaker -#+AUTHOR: Svjatoslav Agejenko -#+LANGUAGE: en - -* (document settings) :noexport: -** use dark style for TWBS-HTML exporter -#+HTML_HEAD: -#+HTML_HEAD: -#+HTML_HEAD: -#+HTML_HEAD: - -* 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]]