Charging Via Usb?

[jpmatrix]

or this one :
http://www.wexim.com/cgi-bin/shop/UK-SPSP.html

come on, we have choices now

[jpmatrix]

what about this one :
http://shop.brando.com.hk/3in1chargerforpsp.php
3-in-1 charger for ... Zaurus ?
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well
i finally bought this one from Brando    with a SLC3000 brando case  
i'll let you know

[jpmatrix]

guys, ladies (?)

i've just received my whole package from Brando :
-pda air case, fit perfectly the Z, i've to try it further to be sure it is THE case
-psp usb charging cable : now it is charging the Z (at least I hope ! the orange led is lit

but i first tried to plug it with the Z lit and the orange led kept blinking....but if the Z is powered off it seems to charge....i've to check my usb power...perhaps not enough power to charge and power the Z ...
anyone got the same issue ?


i'll let you know more later
Jean-Paul

[euroclie]

but i first tried to plug it with the Z lit and the orange led kept blinking....but if the Z is powered off it seems to charge....i've to check my usb power...perhaps not enough power to charge and power the Z ...
anyone got the same issue ?

With my little USB hub and its AC adapter, I also get (almost) the same behavior. When the Zaurus is powered off, or powered on but idle (no hard disk activity), the orange LED is ON. But when there are some microdrive access, the orange LED blinks...

[daniel3000]

but i first tried to plug it with the Z lit and the orange led kept blinking....but if the Z is powered off it seems to charge....i've to check my usb power...perhaps not enough power to charge and power the Z ...
anyone got the same issue ?

With my little USB hub and its AC adapter, I also get (almost) the same behavior. When the Zaurus is powered off, or powered on but idle (no hard disk activity), the orange LED is ON. But when there are some microdrive access, the orange LED blinks...
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Yes, that is certainly an issue of USB power.

Remember: USB ports of a powered USB device (computer, active hub) are specified to provide 500mA per USB port. The Z needs 800mA (at least this is the requirement for an AC adapter).

You could work around this problem by using two USB plugs in parallel, plugged into two USB ports. Some external USB hard drives are powered that way.

daniel

[jfs.w]

Yes, that is certainly an issue of USB power.

Remember: USB ports of a powered USB device (computer, active hub) are specified to provide 500mA per USB port. The Z needs 800mA (at least this is the requirement for an AC adapter).

You could work around this problem by using two USB plugs in parallel, plugged into two USB ports. Some external USB hard drives are powered that way.

daniel
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sorry to bring up an old topic, but .. i believe this topic is still relevant to all of us Z users who might be interested in doing this.

Anyway, my question is, will the electrical potential between the two usb power lines create a problem when no Z is plugged in to the other end? I am not an electrical engineer, so i wouldnt know, but from my own "sense" of understanding things, it will be like two forces pushing against each other (electrons, or "current" wants to flow out) What if the current is unbalanced, with one usb port supplying slight more than the other? will that cause a "pushback" of current into the weaker usb port, thereby potentially causing damage to whatever equipment is behind the weaker usb port? And then what if the two are equal? will it cause any potential "strain", or damage still?

thanks for bearing with my electrical ignorance,
-jf

[daniel3000]

sorry to bring up an old topic, but .. i believe this topic is still relevant to all of us Z users who might be interested in doing this.

Anyway, my question is, will the electrical potential between the two usb power lines create a problem when no Z is plugged in to the other end? I am not an electrical engineer, so i wouldnt know, but from my own "sense" of understanding things, it will be like two forces pushing against each other (electrons, or "current" wants to flow out) What if the current is unbalanced, with one usb port supplying slight more than the other? will that cause a "pushback" of current into the weaker usb port, thereby potentially causing damage to whatever equipment is behind the weaker usb port? And then what if the two are equal? will it cause any potential "strain", or damage still?

thanks for bearing with my electrical ignorance,
-jf
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Well, it does not matter if a device is connected or not:
If there is realy a difference in potential, there will be current flow. But the current flows from one USB port with the higher potential to the one with the lower potential. Not through the connected device.

That current flow (or better: The connection of the two terminals with different potential) will make the two potentials on the terminal to the connected device equal. That means, the connected device will not know anything about that current flow / potential problem.
The only problem could be that the voltage on the Zaurus side of the cable will be modified so heavily that it is not suitable anymore for the Zaurus. but that had to mean that at least one of the two involved USB ports must have a voltage way too far from 5V that it can be called an USB port. ;-)

BUT: I seriouly doubt that there can be a significant potential difference between two ports of the same hub, becasue hub manufacturers will use the same voltage regulators for each port. So port voltage difference can only be a matter of component parameter tolerances. Since the ports are designed to stand 500mA, a few mA more or less due to little potential differences are probably neglectible.

However, the point may be important if you connect a Zaurus with such a two-USB-plug cable to to different hubs! I would not do that.

daniel

[jfs.w]

Well, it does not matter if a device is connected or not:
If there is realy a difference in potential, there will be current flow. But the current flows from one USB port with the higher potential to the one with the lower potential. Not through the connected device.

That current flow (or better: The connection of the two terminals with different potential) will make the two potentials on the terminal to the connected device equal. That means, the connected device will not know anything about that current flow / potential problem.
The only problem could be that the voltage on the Zaurus side of the cable will be modified so heavily that it is not suitable anymore for the Zaurus. but that had to mean that at least one of the two involved USB ports must have a voltage way too far from 5V that it can be called an USB port. ;-)

BUT: I seriouly doubt that there can be a significant potential difference between two ports of the same hub, becasue hub manufacturers will use the same voltage regulators for each port. So port voltage difference can only be a matter of component parameter tolerances. Since the ports are designed to stand 500mA, a few mA more or less due to little potential differences are probably neglectible.

However, the point may be important if you connect a Zaurus with such a two-USB-plug cable to to different hubs! I would not do that.

daniel
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just to further update/ask a question - what if (i think these devices are available, if i'm not mistaken) we add "one-way resistors" to the wires coming out from each usb port, so that these will help discourage the presence of flowback into any usb port? will this make a viable, or useful "dual-usb" zaurus charger?