"Will this work?"

[Eridger]

So the specs of the Pandora say that the host USB port is capable of supplying up to 5V, and the OTG port is designed to supply up to 5V as well. Is this true? I ask because I bought a portable DVD burner today that is powered by two USB 2.0 ports (one supplies power and one is used as a data cable) and would love to be able to burn discs from my Pandora once I get it.


The device's info is here:


http://wize.com/cd-and-dvd-burners/p1411256-gear-head-8xdvdext-dvd-external-slim-burner


I can't find any really technical specs on the device just yet. But hopefully someone will be able to help me out. If not I could just buy a ac adapter for it, but I'd really like to be as mobile as possible with my Pandora as I can.

 

[gruso]

I've heard this idea discussed before, but I can't remember if anyone has tried it. There are two things to take into account:


- Both USB ports can supply the standard 5V, but what's more important is the current they can supply. The standard USB port (the bigger one) can supply 500mA, the maximum according to the USB standard. The OTG port (the smaller one) can only supply about 100mA. 600mA total may not be enough.


- The OTG port needs an OTG adapter to act as a host. Basically it's just a plug adapter or short cable that converts from mini USB to standard female USB and ties a pin down to ground so the port knows to go into host mode. The last bit is important; and old adapter won't do.


Having said all that, I don't even know if this is electrically safe to do. I believe that answer is somewhere in the forums already though, and someone will have better recollection than me. And if it does all work, it will absolutely slay your battery.


If you do end up going with a mains adapter, my suggestion is that a powered USB hub will be much more flexible than a power supply just for the DVD burner.

 

[Prometheus]

Someone please correct me if I'm wrong, but I don't think that the OTG port can supply 5v - I thought it was something like 3.3v...


Speaking from my experience with a LaCie 3.5" USB-powered hard disk drive, though, I don't think that this will work. That device was designed to be powered over just one USB port, and tried to draw too much power, which had an effect on the display much like you would get by holding a magnet up to a CRT. I would imagine that a DVD burner may require as much or more power than that.


Of course, your mileage may vary, and I'd love to be wrong, but given the above my educated guess is that an AC adapter might be a better bet for this.


EDIT: Ninja'd. h34r: And it looks like I slightly misremembered the part about the OTG port's power output.

 

[gruso]

^ Actually you could be completely right. Specific memories tend to trump lazy assumptions. I'm just posting half asleep from work.


We need a third opinion.

 

[ProfChaos]

Perhaps a DIY MintyBoost or similar?

 

[Eridger]

^That's exactly what I was thinking, although the idea of using an Altoids tin as a case is a much better idea than what I had in mind. I think in theory using something like that could work. And besides, I only plan on using something like this for quick burns. I certainly wouldn't have it plugged in 24/7. I think the battery-based USB would be fantastic if it works. I mean, people would be wondering why I'm plugging my DVD burner into mints, but... worse things have happened.


I'm gonna give this a try within the next few days. I'll let you guys know if I get anywhere.

 

[darfgarf]

if you're hooking up an external current source aswell to provide the needed juice, don't forget to connect the negative side/ground of whatever your circuit is to the pandoras ground, otherwise there's no way to be sure that the external power will be at the same level as the pandoras usb power, and weird things could start to happen, from odd behaviour to frying everything and it trying to charge the pandora from the external source (should take care of itself in the ground for the burners lead though)

 

[WizardStan]

You may be able to get away with it if you used a powered USB hub. Of course, that means plugging in the hub, not the most portable solution: you may as well go with a powered burner.


Because it uses a split connection, there is one other possible solution: use a battery USB charger as the second connection. That should definitely be able to supply enough power, though it still may not work.