USB Cable Questions

[SezMe]

The cable on the left came with my Canon DSLR. The cable on the right came with my Kindle. First, what is the little "barrel" on the Canon cable? There is not one on the other cable. And, more importantly, can I use these cables interchangeably or should I use them only on the devices they came with.

http://forums.randi.org/imagehosting/thum_19574e680b02b5fa5.jpg (http://forums.randi.org/vbimghost.php?do=displayimg&imgid=24058)

[Wowbagger]

The "barrel" is called a Ferrite Core. It's used to reduce electromagetic noise on the wire. Here is the Wiki article about it: http://en.wikipedia.org/wiki/Ferrite_bead

I think in most cases you can use these cables interchangeably, assuming they have the same plug shapes on the end. I often get lazy, and plug things into other things that didn't come with those things, and suffered no ill effects, so far. Though, it doesn't hurt to keep them with the devices they belong to, anyway.

[dtugg]

No idea and yes.

[SezMe]

Thanks, Wowbagger, OM. :)

[jj]

The cable with the wart means it's intended for something that has less EMI rejection. You can probably switch with impugnity as long as they are both truly USB connectors and you don't live next door to Radio Free Europe.

[SezMe]

The cable with the wart means it's intended for something that has less EMI rejection. You can probably switch with impugnity as long as they are both truly USB connectors and you don't live next door to Radio Free Europe.
My favorite typo of the week. :) It's not a word, but it damn well ought to be. It just looks right, somehow.

[gph]

I have come across some plug ends, I think for phones, that are the same shape but with different amounts of pins. Other than that I think it's fine.

[SezMe]

I don't think USB cable have pins at all.

[gph]

Have a look inside a phone end. I have 2 types of Samsung and a Motorola here and they have little pins in them.

I think the incompatibility I'm remembering is a Motorola 4-ish years ago that had the same shape as a standard micro (I think it's called) usb but the pins were different.

[epepke]

It seems strange to me that a DSLR should require a ferrite core on the cable. That's usually to clean up the power; the digital lines don't require it. So I can see a ferrite core if you're using it to power an AM radio or something like that, but why a DSLR? EMI might conceivably affect the CCD, but when it's hooked up, you're just downloading images, right?

[SezMe]

I think, epepke, that it will recharge the battery. I'm not sure. I KNOW the Kindle uses the USB port to recharge its battery so your post suggests that the Kindle ought to be the one with the ferrite core. Hmmmm.....

ETA: Actually, I take it back on the camera. It has a separate battery recharge unit.

[SezMe]

Have a look inside a phone end. I have 2 types of Samsung and a Motorola here and they have little pins in them.
A quick scan of the Wiki article (http://en.wikipedia.org/wiki/USB_cable#Cables) on USB cables doesn't show any with pins. Maybe a heavy weight USB guru can weigh in.

[LTC8K6]

No pins with usb as far as I know. Pins are unreliable and have gone out of style, iirc.

[gph]

A quick scan of the Wiki article (http://en.wikipedia.org/wiki/USB_cable#Cables) on USB cables doesn't show any with pins. Maybe a heavy weight USB guru can weigh in.Scroll a little less than half way down that page to a picture captioned "Types of USB connectors left to right". The pins I'm talking about are those little copper coloured things inside the ends.

[LTC8K6]

Scroll a little less than half way down that page to a picture captioned "Types of USB connectors left to right". The pins I'm talking about are those little copper coloured things inside the ends.

They may be generically referred to as pins, but I don't think they are literally pins that fit inside a socket. Contacts is a better term, imo.

[SezMe]

LTC8K6 is right. Those are all contacts on the side of the connector. Using the word "pins" to describe them is a misnomer.

[Rasmus]

It is possible to use the dslr while it is connected to the usb to store images on the computer directly, the cameras I.ve worked with still needed a separate charger.

I know there are some usb cables for my samsung phone that have special writing to activate cart modus or tell the device it is in a cradle - but the phone works with any stansart cobble too

[gph]

One of them is labelled "Mini-B plug (5-pin)".

ETA: and the illustration below that image is captioned "Pin configuration of the USB connectors"

[LTC8K6]

One of them is labelled "Mini-B plug (5-pin)".

ETA: and the illustration below that image is captioned "Pin configuration of the USB connectors"

Yes, but they are not pins imo.

We might refer to Pin 1 rather than contact 1, for example, but that would not be technically correct imo. It's convenient though.

[LTC8K6]

http://wiki.s1mp3.org/Temp:USB_cables

They are called pins here too, but you can see they are sliding contacts. Note the offset, so that one set always makes contact first.

There are some oddball proprietary connectors out there.

Literal "pins" tend to quickly get out of alignment and stop the connector from going in. or break off.

This one appears to use actual pins and sockets in a opposed setup to get 8 connections.

http://wiki.s1mp3.org/images/d/d0/Otherusb2.jpg

[Cuddles]

And, more importantly, can I use these cables interchangeably or should I use them only on the devices they came with.

The "U" in "USB" stands for universal. The whole point is that it's all completely interchangeable. Although with enough different connectors that you still end up with a big pile of wires instead of just needing one. The power supplies are not necessarily the same, so a USB charger for one device won't necessarily work for another, but when you're just dealing with a cable it shouldn't matter where it's from - if you can plug it in, it should work.

It seems strange to me that a DSLR should require a ferrite core on the cable. That's usually to clean up the power; the digital lines don't require it. So I can see a ferrite core if you're using it to power an AM radio or something like that, but why a DSLR? EMI might conceivably affect the CCD, but when it's hooked up, you're just downloading images, right?

The camera probably charges through the USB cable as well. However, a bit of Googling suggests that it's most likely there to reduce noise during data transfer, not charging. There were also some suggestions that it might actually be to reduce RF interference caused by the camera, since the wire would effectively act as an aerial and broadcast any noise. If cameras are covered by different regulations from things like media players this would make sense, so I've never seen ferrite cores on any USB cables other than those for cameras but they've been on all the camera ones I've seen. So it's not actually an issue of clean power or data, but simply radio broadcast regulations.

However, most of what I could find was people asking similar questions on other forums and public question sites, so none of that is an official answer from the people who actually put them there.

[JWideman]

Cameras invariably use the USB cable for transferring to a computer. Any USB to mini-USB cable will do.
The Kindle comes with a little dongle that fits on the end of the USB side and plugs directly into the wall outlet, allowing you to charge it without a computer. The cable itself is just a generic USB to mini-usb cable.
So yes, the cables are completely interchangeable.

[not daSkeptic]

From Intel's EMI Design Guidelines for USB Components (http://www.ti.com/sc/docs/apps/msp/intrface/usb/emitest.pdf):

The inside of a PC chassis is a very noisy environment, and care must be taken to minimize the noise coupling from sources inside the PC chassis to USB signals.

...

Power supply noise conduction into the USB cable power conductors can be reduced by the use of ferrite beads on both the VBUS and Gnd leads. Due to the large difference between the low speed signal bandwidth (< 4x the bit rate) and the lower limit of class B emissions range (30 Mhz), ferrite beads may also be used on the D+ and D- lines, if necessary.

[Christian Klippel]

The "U" in "USB" stands for universal. The whole point is that it's all completely interchangeable.

Sorry, but that's just plain wrong. The "universal" part here has nothing much to do with the cables or the connectors (of which there are quite a lot by now), but mostly with the devices and the way the host (computer) recognizes them and communicates with them. It simply means that a) the same bus can be used for a multitude of devices (mice, keyboards, cameras, soundcards, storage, etc.) and that b) there is a defined protocol layer for all of them, so that on the PC the core driver is always the same (and only depending on the device class an extra driver is needed). It just so happens that the USB specs also define how the connectors must look like and what the minimum specs for the cables itself must be. But again, its becoming more and more connectors, micro-USB being the latest one for "regular" USB.

Ferrite beads on such cables are generally a good idea to reduce emitted/feceived EMI. You will find them on monitor (VGA, DVI, HDMI, ...) cables as well, for example. Its just that with stuff that gets produced at the lowest cost, such extra parts are often left out, purely to save a few cent.

Greetings,

Chris

[epepke]

There were also some suggestions that it might actually be to reduce RF interference caused by the camera, since the wire would effectively act as an aerial and broadcast any noise. If cameras are covered by different regulations from things like media players this would make sense, so I've never seen ferrite cores on any USB cables other than those for cameras but they've been on all the camera ones I've seen. So it's not actually an issue of clean power or data, but simply radio broadcast regulations.

Maybe class C regulations, then. Probably ignorable.

[Kopji]

In addition to the number of pins there is a current limit to how much can be pulled from each USB connection. Have seen many problems related to this, usually solved with a dual head usb cable that lets you pull power from two connectors on the PC.

My Motorola cellphone with USB connector, (someone mentioned Motorola earlier) will not charge when connected via USB cable to a PC but charges ok with a dedicated USB charger.

The other 'problem' device was a Blackberry, which required one of the dual head USB connectors to charge, but once the Blackberry drivers were loaded onto the PC it charged ok with a regular single head USB cable.

The only time I've seen the ferrite cores really matter is when the connection is made to a hub port on a display. Displays are notorious for picking up electrical noise.

Something to beware of, if you purchase an AC charger with a USB connector on it, the cable that comes with it often only has the two power lines and not the data lines, a regular USB cable will work in the charger, but the charger cable won't work for other things because it is not a full USB cable.

[Verde]

Cameras invariably use A USB cable for transferring to a computer. Any USB to mini-USB cable will do.
The Kindle comes with a little dongle that fits on the end of the USB side and plugs directly into the wall outlet, allowing you to charge it without a computer. The cable itself is just a generic USB to mini-usb cable.
So yes, the cables are completely interchangeable.

Bolding mine.

Nope, there are many.

http://en.wikipedia.org/wiki/USB

I resisted the urge to post the Wiki-link, but it has some good information. Scrolldown the page and see how many 'standard' connectors there are. The big four-connector device we all use to plug into the computer is pretty much a standard, but when it comes to plugging into other devices there is a big range of options.
The connections may be the same, but the shield configuration is such that they cannot be mated without the use of a hammer. I do not recommend this.
My camera, my Android phone, my BT40 GPS, my Kindle, probably something else, all talk USB, but none of the connectors are compatible.

Oh, and putting ferrets on the leads is a very good idea for those of us that run high power ham radio stations.

V.

[Verde]

Something to beware of, if you purchase an AC charger with a USB connector on it, the cable that comes with it often only has the two power lines and not the data lines, a regular USB cable will work in the charger, but the charger cable won't work for other things because it is not a full USB cable.

I have a flexible lamp for illuminating my laptop keyboard. I have seen someone actually using a USB cable to power a coffee warmer. At 5v/500mA that's not a lot of power, as you mentioned upstream.
No data transfer needed, but an interesting niche market.

V.