Wall Wart Woes!

Yep - I took a punt once with a cordless phone and let the smoke out. Now I pull alpart and check to be sure!

I know this is high level rocket science, but...

1. The label on the unit tells the voltage. Always.

1. The polarity can be determined with a visual inspection of the board at the connector, they will have at least one filter capacitor, with a marked plus lead.

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I'm never going to grow up.

The polarity of the connector is also almost always on the AC powered product ID label as well. OR it can be ID'd from the cord feeding the plug sometimes too. The 'icon' on the device being powered sometimes shows the polarity 'desired' by it as well. Look closely at the logo at the power pin, if there is one.

The standard is typically "center positive" because the connector design is usually such that the barrel (outer) connects first. Or for whatever reason, it has been pretty much the de-facto method.

There are, however "center negative" versions as well. So much for adopting and maintaining standards. Maybe we should ring the necks of all the dopes who stubbornly did it "their way" anyway.

I have also used in a design, types which have a threaded ferrule on them and actually attach to the device the get plugged into. I would want that exposed ferrule to be chassis, which is usually negative.

If you but a model K901 Ethernet switch, why doesn't the wart have a label "For model K901" ?

I volunteer at a non-profit that actually *receives* such kit for recycling. If you think its bad trying to chase down *your* wall wart for *your* piece of kit, imagine the problem when donors drop off random bits of kit with the wall warts in a knotted tangle -- which often doesn't include *the* wall wart for the item of interest!

(We have, literally, garbage *cans* full of wall warts whose mates are unknown)

Some vendors will mark the product with the voltage and polarity of the expected power source. Then, it's "just" a matter of finding the appropriate barrel diameter and center post diameter to "fit".

One gripe *I* have is that the standard scheme for indicating polarity doesn't fare well as it is scaled. Something like:

• ----* )---- -

where the ")" signifying the barrel contact actually wraps around the "*" signifying the center post. Ink bleed at small scales often turns this into a guessing game: "is that a '-' or a '+'? Is the line from that +/- symbol going to the center *pin*? Or, the enclosing curve??"

Why not a simple circle with a sign inside? Takes LESS space on the label (so it could be printed at a larger scale) and removes some of the ambiguity!

Or, design devices that are tolerant of polarity reversals! (ideally,

*functioning* with either polarity or at least not giving up the ghost with "reversed" polarity!)

For my own, personal items, I label each wall wart with the name of its mate and write the power requirements on the mate with a "Sharpie" using the "circled sign" graphic I described accompanied by voltage and amperage. I have a *white* pen for those items that have black cases.

A vendor once made the observation that center positive is common for US market while many other markets have center negative. I suspect that is *not* universally true (as I have encountered lots of kit with center negative).

Let's see... how many souls currently on the planet?

I've just had a look at the two wallwart-powered ADSL modems on my desk, and though they both specify the required DC supply voltages, neither one shows the polarity. They are neither moulded nor printed anywhere.

A high majority of the devices I've worked with and on over the years use the outer ring as the positive contact, with the opposite polarization being occasional exceptions. I've always considered the more common practice illogical.

I write the name of the gizmo on the wall wart using gold paint marker. (It isn't going to make a wall wart any uglier.)

Cheers

Phil

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Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Because they are usually generic, for multiple models in a company's product line. Big companies like to reduce stock numbers. In some cases there are several revisions of 'K901', each requiring different wall warts. Linksys was good at that. Not only do they change them, but they delete the old information from their support documents.

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You can't have a sense of humor, if you have no sense.

How long would it take to slap a sticker on a wart before they ship it? I'd be happy if they'd spend their time doing that, and eliminate some of the zillion twist-ties on everything, and the plastic junk taped all over the line plug.

I think there is a trend towards a universal power scheme, namely the USB thing.

Mostly because the wall wart is used for everything the company makes and is usually an off-the-shelf item.

They can't slap a sticker on it? We do.

It's a Phihong switcher, and we sticker it as a "Highland model J12". The main box has the female power connector labeled "+12V" and the manual and web site say that it works with a J12.

I wonder how many returns people get from their customers using the wrong wart. You'd think they'd come out ahead by using some stickers.

-- A host is a host from coast to snipped-for-privacy@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433

Because K's builder bought the wallwarts from Delta or another wallwart supplier....and they charge real money for custom labels. Further, they also fit K950's, L111's and etc. What label should they pay Delta to use?

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Because Linksys bought each version from a different supplier, I bet.

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

And what happens when the wall wart gets misplaced?

Wall wart (applies to bricks as well) *and* device need to clearly indicate their power requirements. ON THE DEVICES (since you can't expect a user to hold onto any printed documentation that came with the original product -- nor can you rely on vendors to maintain this information on web sites, help desks, etc.).

Ink is cheap (or, raised lettering on a mold).

(though this still ignores the issue of protecting that device from "inappropriate" power adapter choices on the part of the user!)

WoolyBully Inscribed thus:

What about the ones that actually require an AC supply. Granted you are unlikely to cause any damage irrespective of the polarity of a DC supply.

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Best Regards:
                          Baron.

The EU, tired of tens of millions of junked smartphone chargers per year, mandated 5VDC/microUSB. The phone builders balked at first, then grokked then no longer need to ship one with each phone.

Apple, of course, is upset. They make big money selling replacement chargers.

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Because the companies are run by MBAs who want you to fry the junk, once it's out of warranty. I was keeping a list of the model and power supply numbers for everything, but it was one of the files corrupted when that Seagate 1 TB drive failed during a backup and trashed the existing backup copy.

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You can't have a sense of humor, if you have no sense.

i have several routers in the same case, but with different power connectors. The early versions used a three pin plug & dual voltage. It also had a fan. The later boards used two different coaxial connectors.

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You can't have a sense of humor, if you have no sense.