Barrel connectors

[Don Y]

Hi Matt,

There is a Japanese standard for these, that Sony and Nintendo equipment
seems to follow. http://en.wikipedia.org/wiki/EIAJ_connector The
diameter goes up with voltage.

Ah, OK.

The standard doesn't seem to require it,
but it seems popular for the defined voltage to not be an even number.
The insulator at the tips of these plugs is usually yellow, at least on
Sony and Nintendo gear.

I've seen numerous colors: yellow, red, ubiquitous_black, etc.
At first, I was excited thinking there might be some color code
that would make sorting out what's what easier. But, that didn't
pan out.

So, a micrometer and selection of drill bits are my only real way of
figuring out what the characteristics of a particular connector are.

For "regular" plugs, the most common OD is probably 5.5 mm, with either
a 2.1 mm or 2.5 mm ID. The voltage and current can be anything at all,
up to maybe 50 W, +/- 50 W.

Great tolerance there! :>

If you want your customers to be able to improvise a supply, pick a
common size. If you want to sell them power supplies and/or cause them
to go to the competition, pick a weird size.

I am more interested in understanding how/why particular sizes
are chosen as there doesn't seem to be any sense to it all.

It *seems* US firms have the barrel negative wrt center post.
And, many far east firms the opposite.

Except when they aren't! :<

I don't know what brands are good or bad, but I'd probably look for a
"name brand" like Switchcraft or Hirose first, and then look for
something cheaper when the bean counters scream.

A lot of smaller devices seem to have standardized on USB connectors,
which are almost always good for 5 V, 0.5 A; higher currents are
available but you can't always count on this. The main advantage is
that you can be pretty sure that the voltage will be between 5.0 and
5.5 V, and that the polarity will be right.

Yes, but the connectors are more fragile and harder to mate.

I've actually had more failures of the wire right behind the plug than
I have had of the plugs or the jacks. I would tend to trust a through-
hole jack more than a surface mount one, especially if the plug will
be disconnected and reconnected often.

I've had to replace a number of jacks -- laptops, organs/"keyboards",
etc. Usually devices that ither see lots of motion while in use
*or* have heavy cords dangling off the connection, unsupported.
I've also encountered broken "wipers" in the jack (the contact
that mates with the O.D.)

I figured connectors with a *longer* and *wider* barrel might be
more mechanically secure -- not just because of the increased
size but, also, because they could be more readily "supported"
by bits of the device into which they mate (even if that support
is non-conductive)

I've also seen connectors that have quarter-turn locks built in.
Insert and rotate to keep it from falling out (or being PULLED out)

These are more of a design thing, but: one "failure mode" might be that
if the plug even remotely sort of fits, people will try to cram it into
the socket, so you might get all kinds of unexpected voltages coming in.

I think the biggest risk, there, is a "plug" with a "too large" I.D.
being *apparently* mated to one with the correct O.D. but smaller
I.D. -- not a very robust connection (if at all!)

A fuse with a "backwards" diode after it guards against wrong polarity;
guarding against too-high voltage is a little trickier. If you can
stand the voltage drop, board space, and budget, put in a bridge
rectifier and a capacitor, so the user can use any AC or DC power supply
of some minimum voltage.

Exactly my thoughts (electrically). Let it feed anoher (set of)
converters inside the device. More assurance that you have *all*
the right supplies instead of HOPING to have the *one* right input
supply.

Also, some of the jacks have switches that open or close on plug
insertion. Some devices use these to switch between internal or
external power. Some users, though, might prefer to leave the plug
connected all the time, and remove the AC power from the power supply
instead; your device might not be able to rely on the switch contact
in the jack.

Ah, hadn't thought of that! Hadn't *planned* on such a connector,
though. Worth remembering for future encounters!

Are you talking about the ones that have a pin inside the barrel? As

Yes. Looks sort of like the *mate* to the "original style"
(hence my reason to call it "inverse")

far as I know, this is to offer an extra "data" channel to the power
supply; these are really 3-circuit connectors. The outside surface of
the barrel is one side of the power supply (usually negative), the
inside surface of the barrel is the other (usually positive), and the

Ahhhhh! Yes, that makes perfect sense! I'd simply assumed the outside
of the barrel was one conductor (like it had been for the "original"
plugs) and the pin was there just to "be different". The larger
diameter and length that typically are associated with these being
mechanical "enhancements" -- e.g., laptops see a fair bit of motion
reflected to that connection!

pin is "data". The "data" can be as simple as a resistor to one side
of the power supply, which the connected device measures and interprets,
or as complex as a serial bus to a microcontroller or ROM inside the
power supply.

OK. Allows the PS to be "identified" by the device using it.
Presumably, could also ensure the supply isn't powered up if
t is "wrong"!

Could also be used to power *down* the power supply when the device
doesn't need it any longer!

Or, could just be there to sell "special powersupplies" :-(

The "data" can be used for good or for evil. A good use is that the
cheap 20 volt 3 amp supply has (say) a 1K resistor to ground, and the
more expensive 20 volt 5 amp supply has (say) a 2K resistor to ground.
The connected device has an A/D that tells it what resistor is there,
and then it can adjust its internal switching power supply appropriately
to only draw as much current as the external supply is capable of.
(Laptops often do this; they *have* to power the CPU and then the
battery gets whatever is "left over".)

Ah, OK. Clever. So, charge time depends on power supply and not
something inherent in the device! Yes, that makes perfect sense!

An evil use is to require the
power supply to authenticate to the connected device, in order to sell
power supplies at inflated prices^W^W^W^W^W^Wprotect the consumer.

And, of course, the truth is probably somewhere in between.

Thanks! That makes things a lot clearer! I will have to get a bright
light and loupe and peer *in* the end of the plug. There should be
a conductive surface there in addition to the pin.

(and, *probing* would obviously be something done with care lest
"something" get shorted to the pin!)

 

[Don Y]

Hi Jasen,

Sturgeons law?

Isn't that CARP? :>

You mean like current limits and mating cycle counts?

Yeah but most of the issues I've seen have been mechanical
related. Hence "CRAP".

The cable seems to die first in my experience.

Often lots of fatigue just past the strain relief. But, I
have seen the device into which the cable plugs also experience
failures -- "jacks" snapping off or developing intermittents
as they lose their adhesion to the solder pads. Very annoying
on laptops (as they are often a PITA to disassemble without breaking
ots of little plastic things!)

AFAICT three contacts.

Yes, I realized that from Matt's post just now. Thanks.
Previously, anything with more than 2 contacts had been
obvious in a plastic molded plug. IBM & Dell made several
laptops like this. I'd always assumed the extra pin was
another supply -- much like it is on many external (USB) disk
enclosures. I will have to make a point of gutting one next
time I come across a "spare".

 

[Phil Allison]

"Don Y"

** The most annoying and expensive ( for owners) to fix falure is when
sockets develop cracked joints on the PCB. Single sided boards are the main
culprits, as there is so little strength in the copper foil to resist
movement.

Some makers try to wedge socket inlets into a hole in the case - that helps
a bit.

But far better is to use sockets that fasten to the case with a nut OR a
pair of bolts to the case or PCB.

If I see a keyboard instrument with a broken DC inlet - I usually fit a
whole new connector that fastens to the case.

2 or 4 pins "CB mic" connectors with locking rings are ideal



..... Phil

 

[Tauno Voipio]

Digikey has these at $20 a pair ( one male/one female ) !!!!!

Just for power ?!?!

If you're not happy with the price, have a look at Lemo
<http://www.lemo.com/en>.

 

[[email protected]]

It would be the female part that sorta resembles a gun barrel but I
doubt that's where it got its name, though.

It also refers to the common DC power connector.

Well, you seem to think that I'm an American, based on your poorly-aimed
insults. Guess again.

I'm amazed to see you as the target of Phyllis' psychotic rage.

 

[amdx]

Phil you seem to be free of all medication at this point and now have
demons running around in your mind. It doesn't seem like it is working well.
Please use some new abusive terms for me, your same old line is,
well, get old.
Thanks, Mike

 

[amdx]

Doesn't this connector seem confused about its gender?

Joe Gwinn

That's just being politically correct.

 

[[email protected]]

The way to tell a Canadian from a USian is to get them to say "about."

OK, I can tell you're USAian. Now all we have to do is get Phil to
say it, 'ay?

 

[[email protected]]

I've seen numerous colors: yellow, red, ubiquitous_black, etc. At
first, I was excited thinking there might be some color code that
would make sorting out what's what easier. But, that didn't pan out.

Rat Shock color-codes their replacement connectors, but hardly anybody
else does.

I am more interested in understanding how/why particular sizes
are chosen as there doesn't seem to be any sense to it all.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This is the relevant part here.

The reasons probably include:

People's Shining Power Supply Factory #7 had a blowout sale on adapters
with a certain size plug. (For 5 cents extra, PSPSF7 will download the
UL or TUeV artwork from the net and print that on there, too!)

The previous product had that size, and there are still lots of adapters
in stock.

The previous product had a different size, but greater sales of
replacement power supplies are now desired.

The competition uses that size and they wanted to be plug-compatible.

The competition uses a different size and they wanted to be plug-
incompatible.

The device has some other hole that should not have a power supply
connected to it, so the power supply is chosen to not fit the wrong
hole.

Marketing wanted the device to be 0.5 mm thinner, so the first power
supply plug wouldn't fit.

Dumping 100 watts through the previous, smaller, plug didn't work, so
they picked a bigger one with more contact area.

It *seems* US firms have the barrel negative wrt center post.
And, many far east firms the opposite.

Except when they aren't! :<

I've noticed that too. I sort of like tip-positive, if for no other
reason that the barrel part is more exposed, and I'd rather have that
be ground. In a house it doesn't matter so much, as DC ground should
be isolated from AC ground, but in a car, DC ground is everywhere...
it's nice if a cigarette-lighter cord doesn't blow its fuse when the
plug end flops against the seat track or something.

I think the biggest risk, there, is a "plug" with a "too large" I.D.
being *apparently* mated to one with the correct O.D. but smaller
I.D. -- not a very robust connection (if at all!)

Yeah, I've had that happen before. It depends on how much travel and
tension the spring in the ID of the connector has.

Some other notes on barrel connectors:

You can get adapters from both male and female barrels to screw
terminals, which is handy for prototyping. Mouser JACK21-F-TERM and
JACK21-M-TERM; Sparkfun https://www.sparkfun.com/products/10287
and https://www.sparkfun.com/products/10288 ; All Electronics
http://www.allelectronics.com/make-a-store/item/SDP-S/RETRO-FIT-2.1MM-COAX-SOCKET/1.html
and
http://www.allelectronics.com/make-a-store/item/SDP-P/RETRO-FIT-2.1MM-COAX-PLUG/1.html
..

You can get adapters from one size to another:
http://www.digikey.com/product-detail/en/6872340FG/271-2628-ND
http://www.allelectronics.com/make-a-store/category/198300/Connectors-DC-Power-Coax/Adapters/1.html

You can get "extension cords" and cables with barrel connectors on one
end:
http://www.allelectronics.com/make-a-store/category/123/Cables-Co-Ax-Power-Plugs/1.html

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

Matt Roberds

 

[Don Y]

Hi Matt,

Rat Shock color-codes their replacement connectors, but hardly anybody
else does.

So, it's only helpful if you are replacing one RS product
with another?

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This is the relevant part here.

The reasons probably include:

People's Shining Power Supply Factory #7 had a blowout sale on adapters
with a certain size plug. (For 5 cents extra, PSPSF7 will download the
UL or TUeV artwork from the net and print that on there, too!)

The previous product had that size, and there are still lots of adapters
in stock.

The previous product had a different size, but greater sales of
replacement power supplies are now desired.

The competition uses that size and they wanted to be plug-compatible.

The competition uses a different size and they wanted to be plug-
incompatible.

The device has some other hole that should not have a power supply
connected to it, so the power supply is chosen to not fit the wrong
hole.

Marketing wanted the device to be 0.5 mm thinner, so the first power
supply plug wouldn't fit.

Dumping 100 watts through the previous, smaller, plug didn't work, so
they picked a bigger one with more contact area.

Or, none of the above. Someone just *picked* a size and let
someone else chase down the actual adapter, etc.

I've noticed that too. I sort of like tip-positive, if for no other
reason that the barrel part is more exposed, and I'd rather have that
be ground. In a house it doesn't matter so much, as DC ground should
be isolated from AC ground, but in a car, DC ground is everywhere...
it's nice if a cigarette-lighter cord doesn't blow its fuse when the
plug end flops against the seat track or something.

I repair/rescue lots of kit (from lots of places -- not uncommon
to see something with a european power plug, etc.). So, a big
part of the "project" is often sorting out what the hell you
need to *provide* (power) to the device -- before you can even see
if it is working! (wall warts and bricks tend to get misplaced
or separated fromtheir "mates")

Early on, the solution I came up with was to unceremoniously *cut*
the plugs off a variety of "power supplies" (which were headed for
the tip) and wire them to a digitally programmable PS. So, when
I have a bit of kit that *might* be worth rescuing, I can hunt
down the power requirements (USUALLY written SOMEWHERE on the
device *or* a WWW search -- or, GUESS!), type in V & I and then
hunt for which of the multiple "ends" of my homegrown octopus
cable happen to fit the device. If the results look promising,
*then* worry about finding/making a real PS to marry to it!

Yeah, I've had that happen before. It depends on how much travel and
tension the spring in the ID of the connector has.

Some other notes on barrel connectors:

You can get adapters from both male and female barrels to screw
terminals, which is handy for prototyping. Mouser JACK21-F-TERM and
JACK21-M-TERM; Sparkfun https://www.sparkfun.com/products/10287
and https://www.sparkfun.com/products/10288 ; All Electronics
http://www.allelectronics.com/make-a-store/item/SDP-S/RETRO-FIT-2.1MM-COAX-SOCKET/1.html
and
http://www.allelectronics.com/make-a-store/item/SDP-P/RETRO-FIT-2.1MM-COAX-PLUG/1.html

Ah, that might be nice to have on hand (one of each size).
Currently, I keep "common" plug sizes on hand so I can
butcher PS's that have the right V/I but wrong connector!

You can get adapters from one size to another:
http://www.digikey.com/product-detail/en/6872340FG/271-2628-ND
http://www.allelectronics.com/make-a-store/category/198300/Connectors-DC-Power-Coax/Adapters/1.html

Hmmm... that sounds like it might be "iffy". The connectors seem
pretty crappy to begin with and that just adds aother "wiggle"
to the equation.

You can get "extension cords" and cables with barrel connectors on one
end:
http://www.allelectronics.com/make-a-store/category/123/Cables-Co-Ax-Power-Plugs/1.html

Someone made a device (laptop?) in which the cord *to* the device
(from the PS) ws replaceable. Either it was done to allow a single
PS to be used with multiple devices *or* anticipated the cord
failing (from use). Hard to imagine adding the second connector
without a *good* reason!

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

<grin> I notice all the "house numbers" are of the form MRI####
[Matt Roberds Industries? :>]

Thanks for the references and the effort you went thru! Take a few
bucks out of petty cash... ;-)

 

[John Devereux]

Autism is a birth defect. Why abuse people for a problem that they didn't cause?

Many tekkies are, to some degree, asperger-y. So what?

Yes quite, never heard it used as a term of abuse before hanging out
here. I don't know much about Autism, but it is ironic that those who
throw that "insult" around are *precisely* those who appear, shall we
say, a bit socially challenged.

Phil seems to have Tourettes. Probably another birth defect.

Hmm, does Tourettes still work with the written word?

 

[Phil Allison]

"amdx"

( snip more shite )

** **** off - you PATHETIC damn troll

 

[Phil Allison]

"John Devereux"
** Nonsense.

It is a mental disability typically accompanied by narcissism and
sociopathy.

Yes quite, never heard it used as a term of abuse

** It's not abuse to point out what someone IS.



.... Phil

 

[Spehro Pefhany]

I guess we'll have to abandon
round connectors once all the various polarity, pin, and barrel sizes
are exhausted, and switch to square or other odd shaped power
connectors.

One design flaw with some Dells is that their fat coaxial power
connector are in back, and right beside the RJ-45 Ethernet jack. The
Ethernet jack has low quality spring materials, so it gets bent out of
shape and will no longer work reliably if the power connector is
accidentally shoved into it.


Best regards,
Spehro Pefhany

 

[Don Y]

Hi Jeff,

True. However, replacement power supplies are fairly cheap on eBay.
In other words, lousy quality is acceptable if the replacement is
available and cheap.

I think its more fundamental than that! Laptops are typically
considered disposable. So, serviceability and longevity don't
enter into the design equation -- just price!

I absolutlety *hate* it when I encounter a really *nice* laptop
with a problem. Because it puts pressure (self-inflicted) on
me to *fix* it instead of scrapping it! Then begins the stressful
task of trying to get it apart without breaking anything or doing
any cosmetic damage. :<

ToughBooks are reasonably "easy" to work on -- as long as you don't
drop any screws!

OTOH, one of *my* laptops has a flakey keyboard and I just keep
tolerating it rather than deal with replacing it (and keyboards
tend to be *easy* fixes!). I guess I am hoping I decide to
discard it before that day comes :>

Buy the cheapest. By the time the customer realizes that it's junk,
you and the customers money are gone.

Sorry, I mean picking a connector for durability, etc.
I can't believe there is much money to be save in the
*connector* choice!

Of course. Everything can fail in some way. With laptops, it's
mechanical stress. I repair LOTS of broken power receptacle on
laptops. Some examples of design defects.

Right angle connector versus straight-in connector. The right angle
has the advantage of surviving having the laptop shoved against a wall
or back of desk.

Straight in can also be an issue on *side* entry. Set something
down on/near it and you put a lot of vertical stress on it.

The right angle versions of many power connectors are fairly good at
relieving some forms of connector stress, but not all of them. It is
still possible to destroy the receptacle by pulling on the power cord.
Maximum damage is assured by the fairly long plug length, providing
maximum leverage and torque.

I think that was part of what the "twist lock" connectors I mentioned
were designed to minimize (as well as preventing their accidental
removal)

Ideally, an "air core" transformer design so there is no connector
and no "hole" for materials to enter the device (liquids). But,
that tends to put you in a lower power category.

 

[Don Y]

Hi Spehro,

One design flaw with some Dells is that their fat coaxial power
connector are in back, and right beside the RJ-45 Ethernet jack. The
Ethernet jack has low quality spring materials, so it gets bent out of
shape and will no longer work reliably if the power connector is
accidentally shoved into it.

I've seen similar damage as the "modem" connector is often adjacent
to the "network" connector. As many folks (?) do things by feel,
if you end up with the plug in the wrong connector, it *will* fit
but will typically mangle the fingers on entry/withdrawal.

 

[Jasen Betts]

Of course. Everything can fail in some way. With laptops, it's
mechanical stress. I repair LOTS of broken power receptacle on
laptops. Some examples of design defects.

Right angle connector versus straight-in connector. The right angle
has the advantage of surviving having the laptop shoved against a wall
or back of desk.

It tends not to survive someone tripping over the lead though, straight-in
will ofter pull out.

I guess we'll have to abandon
round connectors once all the various polarity, pin, and barrel sizes
are exhausted, and switch to square or other odd shaped power
connectors.

Apple's patent on magnetic flush power connectors may have expired by then.

 

[[email protected]]

This particular connector is a problem.
<http://bixnet.net/images/Connector-D003.jpg>
[...] Of course, the connector is not available individually, so the
entire power supply has to be replaced.

DCP-7, DCP-6, or DCP-5, $1.50 each at All Electronics? I have no idea
if they are any good at not, just that they exist (found while doing
research for earlier posts in this thread).

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

I guess we'll have to abandon round connectors once all the various
polarity, pin, and barrel sizes are exhausted, and switch to square
or other odd shaped power connectors.

Cover the lid of the laptop or backside of the tablet with PV solar
cells. The "charger" will consist of a 60 watt 120 VAC to 12 VAC
transformer and a sealed-beam headlight.

Matt Roberds

 

[Jasen Betts]

This particular connector is a problem.
<http://bixnet.net/images/Connector-D003.jpg>
[...] Of course, the connector is not available individually, so the
entire power supply has to be replaced.

DCP-7, DCP-6, or DCP-5, $1.50 each at All Electronics? I have no idea
if they are any good at not, just that they exist (found while doing
research for earlier posts in this thread).

if you his one of the large suppliers (eg: digikey) they'll have links
to the maker's datasheet and giving capacity durability numbers.

 

[John Devereux]

"John Devereux"

** Nonsense.

It is a mental disability typically accompanied by narcissism and
sociopathy.

<http://en.wikipedia.org/wiki/Autism>

"...The diagnostic criteria require that symptoms become apparent before
a child is three years old..."

"...Parents usually notice signs in the first two years of their child's
life"

"...Overt symptoms gradually begin after the age of six months..."

Sure sounds like a birth defect to me. It's not like the babies make a
lifestyle choice.

** It's not abuse to point out what someone IS.

I think it is, when it is used in a derogatory way. In fact it is much
worse.