I'd like to buy a portable hard drive in Bangkok (the one that powered by a USB lead not the one with its own power source. I dont need too much space 300 Gig or 500 Gig would be enough as I don't want to put too much stuff on one drive in case it malfunctions. Can anybody suggest a cheap to mid ranged product, how much it is and where I can acquire one? Thanks

Hi, any IT mall with have them. Where are you in BKK? You can get 300 but might as well go for 750 or so, just a couple hundred Baht more. Should cost you a couple thousand Baht tops.

I'm sure you can get 500 GB refurbished one at around 1500 THB at Pantip Plaza Pratunam

or if you don't mind some buck you can check this German based retailer (English language available)

http://www.lazada.co.th/shop-external-hard-disks/?storage_capacity=500

Go to Fortune and look in Banana, they have lots.

Get a 1TB with USB 3.0, I've bought a few of these @ Bt2490.

http://www.bananait.com/product.php?productid=21600&cat=296&page=1

You can get Toshiba 1TB's a bit cheaper, but a 500Gb new is Bt1990 so I can't see the point unless you're really on a budget.

Heres a few online stores who wont rob your coin.

Invade IT

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Jedicool

Thanni

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My experience with the USB powered units is that they work when hooked directly to my computer, but not when hook to a powered hub. (The hub has it's own power cord to plug into the wall.)

That might just be my hub, but it's worth knowing that when I got my first one, I thought it was defective until I tried moving it from the hub to the computer.

My experience with the USB powered units is that they work when hooked directly to my computer, but not when hook to a powered hub. (The hub has it's own power cord to plug into the wall.)

That might just be my hub, but it's worth knowing that when I got my first one, I thought it was defective until I tried moving it from the hub to the computer.

I'm also some electrical engineer

this can cause mainly by 2 reasons

1: the power cord you plug into the wall (I call a power supply.) not have enough current(Amp) capability.

2. cause by internal electrical characteristic of hub.

reason 1 is easy to understand.

What interesting is reason 2.

When you buy a USB hub you think it'd be better if the hub can also take power from external adapter right?

but it has cons

The hub with external adapter slot has no switch for user to select which power source to use (from USB or from external source)

instead it'll select for you automatically (ease of use)

The problem is in the component they use to make it switch automatically.

Actually it's just diode. all type of diode introduce voltage drop. Silicon one would drop around 0.5~1 V.

The diode type using in USB hub usually be low voltage drop one called "Schottky diode".

Although Voltage drop across Schottky diode is small the output voltage is guarantee to less than 5 V

(It also depend on quality of diode.) that why some device may not work with this type of hub.

(USB hub that can't take power from external source doesn't have this diode.)

.

poor PCB design in USB hub can cause problem too; as the current flow to control harddisk's motor can interfere with data signal. (D+, D-)