Power for US hub?

No. The voltage spec is tight. Try to find a unit 5.0V, 2.1A,switching type. Linksys routers use them, for one.

No. You really need 5 volts at 500ma for each port. Most things don't use

5 volts anymore, they use regulators for lower voltages and 4.5 is just at the border of 3.3 volt regulators working or not.

Besides a 4.5 volt unregulated supply could provide almost anything at no load (like 8 or 9 volts if it is really bad) which would be a problem.

Lucklily 5 volt supplies are easy to get and cheap. You can get a 5v 1amp switching supply as a charger for a music player/cell phone. That will do for

2-3 bus powered devices, or all 4 if they are self powered.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

5V at about 2+A -- for four *powered* ports; less if you can guarantee the devices plugged into the hub have their own power source(s). You won't be finding this in an old-fashioned "transformer" wall wart (you'll need a small switcher wall-wart)

Most hubs that I have seen, lately, use a ~0.100 dia barrel connector (center positive) -- though I have seen others.

Thanks all, glad I asked, as I hadn't realised it needed such a heavy duty supply. At worse, I'll get out to the shed and make one.

BTW, if you'll excuse a related question, is it usual for USB ports on the front of a PC case to be less reliable than ports on the back? Perhaps with lower current delivery? That's my motive for deploying this powered hub. An operation that failed from the front worked OK from the back (connecting an iPad to run an iTunes sync). That wasn't the only thing I changed, so it's not conclusive. But from subsequent googling I've seen several suggestions that this difference is a real one.

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Terry, East Grinstead, UK

Again, it only needs that sort of supply if you have devices that

1) need lots of power (e.g., a laptop disk drive powered from the USB port) and 2) don;t provide it themselves. Some devices (e.g., the sort of laptop drive I mentioned) have options for both. Mice, keyboards, etc. usually rely on the USB port for their (typically modest) power requirements.

A lot of this depends on the vintage/manufacturer of the PC.

All bets are off when it comes to an "add in" USB card (which would typically be USB2 or USB3 and most likely "powered" -- but, could just as easily be an ancient USB1.1 card, etc.)

Some manufacturers put "good" (fast, powered) ports on the front of the machine leaving slower ports on back for the keyboard/mouse and giving the user more flexibility in what he can CONVENIENTLY plug into the front of the machine. Other machines may be the exact opposite with the philosophy that the fast devices you are likely to use will be semi-permanently attached and you'll just need the front ports for things like thumb drives (modest power requirements).

The ports *in* keyboards are almost never capable of delivering and sort of power (I've seen some that won't support a thumb drive). And, of course, you are limited to the speed of the keyboard's connection to the PC (in addition to the hub/controller within the keyboard).

It is also not uncommon for connectors to be flakey -- the "pins"

*in* the USB connector as well as the pigtail that invariably connects the "front connectors" to the motherboard (the rear panel connectors are more often than not directly soldered to the motherboard).

And, of course, iPod cables are also notoriously flakey (not to mention the &*^!@#*&$% "charge only" cables!)

HTH

Terry Pinnell Inscribed thus:

Open up the machine and unplug the ten pin cable header for the front USB ports at the mainboard then plug it back in ! Could be the pins are dirty. Its surprising what a little oxidisation can do !

Don't forget to take anti static precautions !!

--
Best Regards:
                     Baron.

Well, it's 5V at 500 mA max on the USB pins; the power adapter could be 5V, 5.1V, 6V, and anything (for the max output power) from 2A to 2.5A (the hub could need some internal power, but probably not much).

The various hubs use different input voltages because the power-supply USB features are implemented in several different ways.

Thanks for those helpful follow-ups.

The good news is that after more rooting around in the shed I found the adapter. A 6V, 2.1 A unit.

Not so good is that the 'New Hardware Wizard' on my XP PC now reckons it's found new hardware and wants to install the darn thing. Why! The same USB devices are plugged into it as before, when it was running under PC power. And I'm darned if I have an installation CD for it. I thought USB hubs were simply plug'n play?

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Terry, East Grinstead, UK

Did you change the configuration? Is the hub plugged nto the same port on the PC, and are the otherUSB devices plugged into the same ports on the hub?

--
For the last time:  I am not a mad scientist, I'm just a very ticked off
scientist!!!

I wouldn't use any power supply that was not 5.0 volts regulated unless it was provided by the manufacturer. I had a strange problem on my system. I powered it down with a powered usb hub connected. When I powered it back up a few minutes later it wouldn't boot. It wouldn't even boot from a cdrom drive. Then I noticed the usb hub was still on (power led on) when my machine was off. So I unplugged the hub's power supply (which was 5.0 volt at 2.6 amp regulated) and the machine then booted up correctly. Apparently the powered hub was feeding 5 volts back on to the motherboard and not allowing all the circuits to reset properly on power down. I hate to think what a unregulated 5 or 6 volt power supply would have done to the 5 volt circuits on the motherboard.

YMMV

--

...Bob

I've seen several USB hubs that use a 6 volt supply. The hub has a built in LDO 5 V regulator. Terry said it was the supply that came with the hub.

The hub isn't supposed to put 5 volts to the input port. Either it was defective, or it was designed by a retired school teacher.

--
For the last time:  I am not a mad scientist, I'm just a very ticked off
scientist!!!

They are, it's trying to play it... So let it install and you'll probably do just fine.

It will "install" support for the (external) hub. In turn, that may (silently?) reinstall the devices that you plug into that hub as they are now connected "differently".

This shouldn't be a problem.

Be sure to note/verify any power indicator on the hub. Some will only illuminate when a device is plugged

*into* the hub.

You can also check in "Device Manager" to see where the hub appears (by connection) and whether it is seen as a 1.1 or 2.0 hub.