| joeling39 |
Hi,
I am thinking of adding a separate power supply to a USB powered device. Do I have to connect the ground(i.e. 0V) of the new power supply to the ground of the supply coming from the PC ?
The signal will come from the PC USB port, the power supply from the PC USB port will be severed & replaced with a external power supply. The ground of the new external power supply (the 0V) will be tied to the ground of the USB port supply. Is this OK?
Thanks.
Regards,
Joe Ling |
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| Fin |
| Why not use a small powered USB hub? |
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| joeling39 |
Dear Fin,
Thanks for the query. Maybe it's time for me to disclose more :
The USB device in question is a sound card mated to a clock conditioner (Apogee Big Ben). I want a very good quality 5V power supply to the USB sound card.
My guess is that a power USB hub is not much better than the power supply from the PC.
Please assist. Thanks.
Regards,
Joe Ling |
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| Fin |
Hi Joe
I'm no expert on this but would think that the PC, soundcard and external psu would need to have their grounds connected at some point in order to share the same 0V.
In a CDP with separate audio/dac board and decoder board, the 0V are connected from one board to the other. This is often done using the screen of the signal cable.
Does the 0V provide a screen in the USB cable?
Maybe a computer guru can help. |
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| apolon34 |
you have to connect the ground, of course !
just make sure your 5v supply is floating to avoid any problems (ie not connected to earth) |
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| joeling39 |
ok did a check on my USB HDD & found that the 0V reference is connected like the after picture. Used that as the basis & managed to get the whole thing to work. Please find attached some photos.
Regards,
Joe Ling |
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| joeling39 |
more photos. This one is shows how the power connectes to the USB. Would actually prefer to use a box that is shielded but this this all I have lying around.
Regards,
Joe Ling |
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| joeling39 |
The display of my clock conditioner showing input frequency from the PC
Regards,
Joe Ling |
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| joeling39 |
My PC. I am using it as a transport (CD transport)
Regards,
Joe Ling |
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| joeling39 |
more showoff pics. This is the view from behind my listening chair
Regards,
Joe Ling |
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| joeling39 |
last one. Equipment placed to the right of listening chair.
Regards,
Joe Ling |
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| maxlorenz |
where's the beer?? :D :D :D
I deduce you are single :)
Sorry, I couldn't resist. I'm also unable to add further advise.
Good luck!!
Mauricio |
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| TNT |
I'm actually planning to do something similar. I would like to galvanically separate my usb audio box from my laptop. The power coming from the laptop when laptop connected to mains seems to be really polluted.
I'm planning / searching for a trafo solution where the 12 mhz digital usb stream is coupled between the usb box and the laptop via a trafo. This of cource negiates any power feeding from the laptop but I also get rid of any intreconnected grounds.
Could this work?
I was planning to use this trafo ..
http://www.lundahl.se/pdfs/datash/1575.pdf
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| joeling39 |
Dear maxlorenz,
Contrary to your guess, I am happily married with 2 young kids. The room in the photos is a dedicated (small) listening area out of bounds to all (wife excepted but she cannot bear to walk into the room without the urge to tidy up everything but that will take months) :)
Dear TNT,
I am not expert in this area. However, if you want to separate the power supply, there shouldn't be any need to transformer couple the data stream. Just get rid of the power supply from the notebook & feed a clean +5V to your USB device (like I did refer to "after" pic in the first post). The whole assumption here is of course the data stream is not affected by the power from the notebook (nothing you can do about that anyway) & that you would like to improve the power supply to the USB device. I hope I make sense but don't take my word for it as I am also a novice.
Regards,
Joe Ling |
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| TNT |
| quote: | Originally posted by joeling39
Dear maxlorenz,
Contrary to your guess, I am happily married with 2 young kids. The room in the photos is a dedicated (small) listening area out of bounds to all (wife excepted but she cannot bear to walk into the room without the urge to tidy up everything but that will take months) :)
Dear TNT,
I am not expert in this area. However, if you want to separate the power supply, there shouldn't be any need to transformer couple the data stream. Just get rid of the power supply from the notebook & feed a clean +5V to your USB device (like I did refer to "after" pic in the first post). The whole assumption here is of course the data stream is not affected by the power from the notebook (nothing you can do about that anyway) & that you would like to improve the power supply to the USB device. I hope I make sense but don't take my word for it as I am also a novice.
Regards,
Joe Ling |
But the earths wold still have to be connected and it is on the earth that all the dirt is ;-) |
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