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18th November 2009, 08:50 PM
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#11 |
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diyAudio Member
Join Date: Apr 2009
Location: Gentofte
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Hi sexya,
I have output inductors, I just think you are mistaking them as a capacitor, but they are 47uF inductors and they are marked with the letter "L" for inductor. I haven't quite yet understood why the groundings for the LC filter also must be connected to negative supply. Isn't it supposed to filter both positive and negative signals since audio is AC? or does it still do its job with negative as ground? Regards, Simon H.A. |
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18th November 2009, 09:03 PM
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#12 |
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diyAudio Member
Join Date: Feb 2004
Location: Anonymityville
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On your PCB layout you have the upper right most 470uF cap straddling two grounds that aren't even connected together.
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"If you don't like funerals don't kick sand in ninja's face." Last edited by theAnonymous1; 18th November 2009 at 09:06 PM. |
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18th November 2009, 09:11 PM
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#14 |
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diyAudio Member
Join Date: Feb 2004
Location: Anonymityville
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No. It's the one with the arrow pointing at it in the below pic.
You have it's + side connected to the output ground and its - side connected to the input ground. The input and output grounds are not connected anywhere on the layout. EDIT: Same goes for the 10uF next to it. I would get rid of both of those caps and connect the two grounds at that point. Also, as previously stated, you don't have any DC blocking caps in series with the output (unless you plan to add them externally).
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"If you don't like funerals don't kick sand in ninja's face." Last edited by theAnonymous1; 18th November 2009 at 09:17 PM. |
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18th November 2009, 09:20 PM
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#15 |
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diyAudio Member
Join Date: Apr 2009
Location: Gentofte
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lol I was dumb right there.
So actually it is the best not to have any of these on the pcb? So I should just have the speakers connected to the speakerground from my powersupply? Here is a new layout where the filter is connected to the negative supply, is it correct now? Edit: I will also add the DC blocking caps. Does they also improve the performance? |
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18th November 2009, 09:26 PM
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#16 |
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diyAudio Member
Join Date: Feb 2004
Location: Anonymityville
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I'm not an expert on grounding (or anything for that matter), but I would put the ground connecters back on the PCB like you had them. You have room to put the two output caps next to the inductors connected in series.
__________________
"If you don't like funerals don't kick sand in ninja's face." |
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18th November 2009, 09:50 PM
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#18 |
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diyAudio Member
Join Date: Oct 2003
Location: Near the sea
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Where is the double sided PCB with a good ground plane and the ceramic SMD decoupling caps? This is class D, no TDA2030
 the difference between working or not working may be just some PCB track and capacitor lead parasitic inductance :P
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I use to feel like the small child in The Emperor's New Clothes tale 
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18th November 2009, 09:58 PM
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#19 | |
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diyAudio Member
Join Date: Feb 2004
Location: Anonymityville
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Quote:
Maybe looking over the evaluation module datasheet will help you out some as well. http://focus.ti.com/lit/ug/slou214a/slou214a.pdf
__________________
"If you don't like funerals don't kick sand in ninja's face." |
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18th November 2009, 11:14 PM
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#20 |
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diyAudio Member
Join Date: Apr 2009
Location: Gentofte
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I get it all now how it works.
Thanks to you all for using your time to help me. I have created a new layout and I will try make it and just cross my fingers for that it is stable. I have made a good ground plane now, and I really like this new layout. I think it will be stable with this board layout. Thanks a lot for all the help everyone, this forum is very nice. Regards, Simon H.A. |
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