Wallwart Question

[The Monkey]

I have a powered USB hub that I'd like to get up and running. However I don't have the wallwart for it. The input is marked DC 7.5V 2.1A. If I can't located the original wall wart, what rating range would be acceptable to use with this thing? Or does it have to be specifically 7.5V 2.1A?

[Fitz]

You'll need to replace it with a 7.5VDC wallwart with a current rating 2.1A or greater, so 2.5A, 3A, etc will be fine. It'll probably be cheaper/easier to just pick up a new USB hub though.

[cetoole]

You also need the right connector and polarity.

[The Monkey]

Yeah, I plan to get a new hub, but I'm at my parents' place in East Hampton and will get gouged. Would a 9V wall wart be a bad thing? I basically don't understand how these numbers work...

By the way, the unpowered HRT Music Streamer is a piece of shit because it basically needs to be run from a powered USB hub. Fuckers.

[Fitz]

Depends on the equipment, some stuff can tolerate a bit higher voltage, some stuff will say fuck you and go bye bye.

[cetoole]

9v might work, or might blow it, depends on the hub. I wouldn't risk it.

[The Monkey]

fucking electricity. Thanks guys. Much appreciated, as always.

[dsavitsk]

I wouldn't risk it.

I would -- if you don't risk it, you don't have a working hub. If you do, you might.

But, I wouldn't risk it if you are not in the room in case is burns up

[cetoole]

I would -- if you don't risk it, you don't have a working hub. If you do, you might.

But, I wouldn't risk it if you are not in the room in case is burns up

Less worried about the hub, and more about worst case and the computer.

[mrarroyo]

If you have a Radio Shack close by you may be in luck, check out: Enercell High-Power AC Adapter : AC Adapters | RadioShack.com

However at the $37 cost a new hub would be a better deal, good luck.

[n_maher]

I'd probably try a 6V unit before I tried a 9V one.

[kevin gilmore]

you know that the usb output voltage is 5 volts, so likely the power supply inside the hub is a simple ldo linear

regulator. Which means it probably won't work at 6 volts, and it might overheat at 9 volts if you are

going to pull full power out of it.

[n_maher]

you know that the usb output voltage is 5 volts, so likely the power supply inside the hub is a simple ldo linear

regulator. Which means it probably won't work at 6 volts, and it might overheat at 9 volts if you are

going to pull full power out of it.

My thinking was that just about any wallwart Dinny is likely to find laying around won't be regulated or exactly 2.1A. So odds are good that any 6V unit is probably pushing over 7V already and I'd rather undershoot than overshoot. If it's a simple LDO on the inside the worst case by feeding it too little voltage is that you get poor to no regulation and perhaps low voltage at the output, right? The consequences of too much V on the input seem much worse (burnout).

[The Monkey]

Thanks for your help, gang. I ended up getting a new hub. But it really is a pain in the ass when you misplace a wallwart, isn't it? Based on this thread, it seems like you really need to replace it with the same voltage rating, but can go with higher current rating, is that a fair summary?

[spritzer]

The component will only use as much current as it needs but higher voltage can overload internal parts. The rub here though is that if you have a say 12V/1.5A wallwart but the component draws only 300mA then the voltage the wallwart outputs will be higher than the rated 12V. The voltage output is at the rated current draw so it rises with less current demand.

[The Monkey]

Ah, that make sense now. Thanks for the clarification.

[spritzer]

Happy to help.