'Wall wart' power supplies: voltage?

Addenda:

I should have noted that the '4.5V' 500mA Sony supply is the only one that has the right plug on the end: so if the problem is just the way I've been measuring it, this would be my logical first choice to try powering the oocket hub with...

S

"Steve H" wrote in news:tKBLh.12397$ snipped-for-privacy@newsfe2-gui.ntli.net:

It all depends on the design. Some may be simply a transformer w/a DC bridge rectifier. Others may be regulated after the DC rectifier, or provide AC-DC isolation. Others may be switching supplies, which require a load to get a true reading of the voltage. The cheapest one's are usually simple DC bridge rectifiers w/o regulation.

As for the devices they power....again, depends on the device.

Typically, a device will have an internal regulator that cuts the voltage down even more. If it calls for a 5V supply, there is probably a 3.3v regulator inside the device. While a 5v device will most likely function with a 9VDC supply, it may not for long. The regulator inside will get very hot, very quickly, and possibly burn up, if it is a standard 7805-like (linear) regulator.

This symbol: ____ ----

Means it is a DC output. Yes, I have seen AC output wall adapters.

It's best just to use one that you have that outputs the correct voltage right off the bat.

USB power is always 5.0VDC at whatever current is necessary. That's usually 0.5A per port. So, if your pocket hub has 4 ports, you'll need 2Amps of current capeability. Also note that there's a very big difference between a battery charger (as detailed in your cell phone and camera examples), and a battery eliminator (as required by this USB contrivance). I'll spare you the details (unless you want them).

Does $14 including shipping work for you?

You didn't say anything about the connector, so I can't be sure it will just plug into your Sitecom USB hub.

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

Hey Jeff,

Whenever I'm looking for a wall adapter, the first place I look is Hosfelt.

wall adapters are listed under 'Adapter' on the left side.

The stock constantly changes, and right now they don't have as much as usual, but worth looking at if you need one. this is where I bought the

18VAC output wall adapter I mentioned in my post.

Thanks again Jeff and Dan,

That clears up a few things, and reassures me me or my meter weren't going mad after all!

Here in the UK, things are not as cheap as they are out your way, so I will refrain from buying a dedicated new adapter just yet, as the adapter from my defunct D-Link router is correct for the USB hub bar the plug - which I will now swap over, and hopefully then prove that it was just lack of power that was the problem with my Buffalo USB wireless adaptor.

Cheers,

S

And the result is ... see back at the Buffalo adaptor thread...

S

The ones that measure as indicated are regulated. The ones that measure higher are unregulated. If it were possible to measure the voltage of the unregulated wall wart when it was plugged into the device it is intended for, it would be about the right voltage under that load.

The symbol with the line and three dashes is for DC.

Unregulated supplies save the manufacturer a few cents in manufacturing, and the device it powers (or charges) is designed to work with a wide enough voltage range so it doesn't affect it.

Here's one supply that should work, once you put on the proper tip "

"

Thanks for the extra info SMS: it is good to find so many helpful people about!

The allelectronics supply does look amazingly good value (though in the UK I won't be able to take advantage of this).

The Sitecom FAQ recommended a 2.5A supply, and this coincided with the supply I still had from a router recently replaced, so I used this to see if my pocket hub would power the troublesome Buffalo WLI-U2-KG54-AI USB wireless adaptor I have been trying to make work in my laptop (Inspiron

2600) - the subject of quite a long earlier thread you may have missed.

I can report back that even with the additional power to the USB hub, the wireless adaptor will not start on the laptop though it works fine on the pc. If you see the other thread you will find that that just about exhausts every avenue I can think of as to why the device may not work in the laptop. Buffalo still have not got back to me with any further suggestions either...

Thanks >

"

"

I'd suspect the laptop a lot more than the USB Wireless adapter.

I have a lot of experience troubleshooting USB issues, and often it's the host controller, the processor, or the USB driver that are the cause of USB problems, rather than the USB device. The problems are exacerbated when it goes through a hub. It can even work for a while just fine, then start screwing up.

I.e. see "http://81.5.185.34/tc-one-thousand/issues.html#USBFunc" which turned out to be a driver problem that was never discovered until a specific combination of processor and USB host controller exacerbated the problem. The processor would be servicing other PCI devices and the USB would time-out and disconnect when it should have waited for the processor, then the system would rediscover the USB device, and it would work for a while then disconnect again. This was a very difficult USB issue to troubleshoot, requiring renting an expensive USB analyzer to see what was going on. The failure didn't occur when connected directly to the USB port on the system, only when connected through a USB 2.0 hub which was in the docking station. Fortunately there was a fix in the processor's firmware that solved the problem, and was able to be downloaded and installed by the user.

You might want to check if there was ever an updated USB driver for that notebook.

In any case, I'd give up and buy a Cardbus wireless adapter, unless you need the CardBus slot for something else.

Thanks again for the additional info and link. I think I just about exhausted every possibility of updates to drivers and chip sets (though it is not very easy to swap drivers about as the device tends to just look for the same one whatever you point it at). The chip set in the 2600 is no longer updated by IBM unfortunately.

The 2600 only has USB1, and though others have suggested adding a USB2 PCMCIA card, I have followed the customer comments from those and found many people had similar problems with them as I have been experiencing with the Buffalo - that is why I tried the option of the powered hub first, before resorting to buying a PCMCIA wireless card. However, I have held back on laying out more cash on one of these, as I am far from certain that the laptop would work with the pcmcia version where it does not with the USB.

In case you want to read more of what I did try, here is the earlier thread link:

If you have any fresh thoughts they would be most welcome.

Cheers,

Right, don't add a USB 2.0 Cardbus card, add a Cardbus wireless card.

The Buffalo High Power Cardbus card is good, despite your problems with another Buffalo product.

Cheers, Seems to be the only avenue left in any case!

S

At least the 2600 has a CardBus slot, and not just a 16 bit slot, though they use the often troublesome O2 Micro OZ6912 CardBus controller.

CardBus is pretty robust, it's essentially the 32 bit PCI slot ported to an external connector. It's a lot more likely to work than USB.

In the U.S. you can buy an CardBus wireless card for less than $10, but I guess things aren't that cheap over where you are.

Thanks very much for all this. Will let you know how I get on, when I've sorted out the finances!

S