USB Hub with external Power Source?

[electroRF]

Hi,
I'm in urgent need (due to a high-priority project) of USB Hub with an external power source, which has the following features:

1. The Power drawn by the devices that are connected to the Hub is taken from the Power supply and not from the PC

2. when the Power Supply is disconnected, there will be no USB communcation between the PC and the devices connected to the Hub.

Is there such USB Hub available?

I tried one store today but they had only regular Hubs.

I'll try looking for one first thing in the morning tomorrow in other stores (everything is close now), but I wonder whether there's such device available.

Thank you!

 

[MrAl]

Hello,


These are quite common these days. They powered ones come with a wall wart that powers the hub and also the devices plugged into the hub.
The USB 3.0 hubs will most likely have a bigger wall wart so you can get more current out of those hubs, so maybe look for a USB 3.0 powered hub.
I would think places like New Egg and Tiger Direct have these things.

You can also roll your own if you are good with building or modifying electronic circuits built on PC boards

 

[electroRF]

Hi MrAl,
Thanks a lot!

you mean a 5V wall wart right? (220/110AC -> 5V)

I found this one on the website, but I'm not sure if it's what serves the purpose:
**broken link removed**

I also found 3 USB Hubs here, but how can you tell if the USB Connection is disconnected once the power is off?
https://translate.google.com/transl...Id=-16&searchProfile=onlineshop&query=usb-hub

 

[dougy83]

This will not be true of all hubs, but the ones that connect the external power directly to the USB power will work it his fashion simply by cutting the trace that connects to the power once the device, or alternatively cutting the power wire in the USB cable if you don't want to modify the hub.

 

[electroRF]

hi dougy,
Thank you very much.

So, I take the USB cable that goes from the PC to the Hub, and disconnects only the 5V wire? and keep the other 4 wires connected?
including keeping the ground connected between the PC and the Hub?

Will it work?

 

[dougy83]

I have done this for a cheap hub (it had VUSB and the external power directly connected together inside) and yes it works. It may not work if VUSB and the ext. power are separated inside the hub.

There should be 4 wires in the cable + a shield. The red one is the power and the white, green, black and shield should remain intact.