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'[EE] DC Power jacks'
2007\09\07@040756 by Hector Martin

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Here am I, trying to figure out what the deal is with DC power jacks.
What do PICListers use most commonly?

My experience indicates that there are relatively few commonly used DC
jack types, mostly the ones included with common universal adaptors.
There's the "standard" DC barrel which seems to be the most common (~5mm
outer diameter), EIAJ (yellow tip) plugs, the miniature version of the
standard jack (I've seen this in virtually every USB hub and USB
external HDD), and a few others.

However, when I actually go to buy some, there seem to  be 30 or 40
different types and sizes. Even Radio Shack seems to have come up with
21 different types.

The type I'm most concerned with is the common DC jack, with an outer
diameter of around 5mm. Note that I say "around", because there seem to
be several variants with slightly different sizes that are common. I've
seen 4.5mm, 5.0mm, 5.5mm, etc, with different combinations of inner
diameters.

How do I navigate through all this mess? What sizes should I use to try
to be compatible with the largest number of devices and adapters, both
for plugs and for sockets? What are the consequences of slightly
differing connectors? And why in the hell is there no standard for all
this that people actually use?

I have quite a collection of adapters of different voltages which I use
for several projects. Incidentally, the reason why I'm asking about this
is because I'm about to build a clone of a certain device that was just
fried by an adapter that claimed to output 12V but instead put out 18V.


--
Hector Martin (spam_OUThectorTakeThisOuTspammarcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc

2007\09\07@044632 by wouter van ooijen

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> Here am I, trying to figure out what the deal is with DC
> power jacks. What do PICListers use most commonly?

2.5 mm inner pin. slightly more robuust than the 2.1 inner pin.

I prefer center pin = positive because that reminds me of coax cable
(ground is outer).

> However, when I actually go to buy some, there seem to  be 30
> or 40 different types and sizes. Even Radio Shack seems to
> have come up with 21 different types.

Check what is supplied when you buy a universal wall-wart, here I get
some 10 plugs with it.

> Incidentally, the reason
> why I'm asking about this is because I'm about to build a
> clone of a certain device that was just fried by an adapter
> that claimed to output 12V but instead put out 18V.

For an unregulated adapter that is quite normal. When I put a power
connector on anything I make sure that is accepts a wide range of
voltage, and survives inverse polarity. Most gadgets I see seem to be
designed likewise, but I recently got a USB hub that uses a stabilised
5V DC wall-wart. That gives me the creeps.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu



2007\09\07@044806 by Tony Smith

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> Here am I, trying to figure out what the deal is with DC power jacks.
> What do PICListers use most commonly?
>
> However, when I actually go to buy some, there seem to  be 30
> or 40 different types and sizes. Even Radio Shack seems to
> have come up with
> 21 different types.
>
> How do I navigate through all this mess? What sizes should I
> use to try to be compatible with the largest number of
> devices and adapters, both for plugs and for sockets? What
> are the consequences of slightly differing connectors? And
> why in the hell is there no standard for all this that people
> actually use?


...and then there are the short / long barrel varieties too.

I believe the methodology is:

1. Hang part list on wall.
2. Throw dart.
3. Flip coin to set polarity.

Or

1. What's surplus today?

As you say, most seem to use a 5mm OD, not sure on ID, and negative to
exterior.  The only solution for maximum compatibility is to do what those
replacement transformers do, and supply 6 or 7 adapter tips.  They let you
reverse polarity too.  (Remember when power conector were often 3.5mm, and
you had those 'star' connectors with the bonus 9v plug?)

See what those transformers use, they should cover most of it.  I know Sony
like to invent a new plug every few years.

I've to a bunch of plugs / sockets with allicator clips on the end.  Comes
in handy with oddball stuff, like people using RCA as a power connector.  It
would be nice if the sizes actually meant something, like different
voltages.

Tony

2007\09\07@045517 by Jinx

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> What sizes should I use to try to be compatible with the largest
> number of devices and adapters, both for plugs and for sockets?

I think the most common is the 2.1mm

http://www.powersuppliesonline.co.uk/public/ranges/images/27/JR94C.jpg

with its corresponding PCB or panel socket

Lower profile devices that haven't the physical room for a 2.1mm
might use a 1.3mm

On one of my products I have a 2.1mm panel socket as the power
connector and a 2.5mm socket as a switched outlet. That way,
although they look similar, they can't be plugged into incorrectly

> And why in the hell is there no standard for all this that people
> actually use ?

No standard for polarity either. Probably there are commercial
reasons. Your average Joe Blow doesn't know that they could
use a cheap wall wart instead of the expensive 'recommendation'

For example my nephew was about to spend a small fortune on
battery eliminators for his guitar effects pedals. "Whoa there", I
says, and showed him how you could do the whole lot for $10

I've made him an LM317-based variable voltage outlet for the
cigarette lighter socket in his car so he can pretty much power
any small video or audio appliance. I had to include a bagfull
of adaptors (with a common connector type on one end - they
come supplied with some transformers) and they fit most devices.

Not an iPod of course, you have to spend up specially for one of
those. When I was in an appliance store last week, I was hovering
around the iPod/mp3 player cabinet and thought some of the
prices were quite reasonable. Then I realised I was looking at
accessories in boxes with iPods on, not actual iPods. They didn't
seem so cheap after that. A bit of a rip-off really for what they
were (designer covers, straps etc)

2007\09\07@101758 by Brian B. Riley

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 I would say that the 2.1 x 5.5 mm (Radio Shack type "M" tip)  with  
positive center is as close to a standard as there is , with  
2.5x5.5mm (Radio Shack type "N" tip) a close second and  1.3x3.5mm an  
equally close third.

The 1.3x3.5mm seems to be THE choice when real estate is an issue.

---
cheers ... 73 de brian  riley,  n1bq , underhill center, vermont
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On Sep 7, 2007, at 4:07 AM, Hector Martin wrote:

{Quote hidden}

> --

2007\09\07@113207 by Hector Martin

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Tony Smith wrote:
> ...and then there are the short / long barrel varieties too.
Of course.
> 3. Flip coin to set polarity.

Sadly, inside positive makes sense from a coaxial perspective and seems
to be the most common, but a standard PCB mount DC socket has a NC
contact on the barrel contact which makes it impossible to use that
functionality to switch between internal and external power when you
can't switch ground instead of positive! I had this dilemma once with a
dual USB/External powered device. Ended up using a switch.

> (Remember when power conector were often 3.5mm, and
> you had those 'star' connectors with the bonus 9v plug?)
Yes, they made nice little sparks when plugged/unplugged since they
shorted out in the process!

At least they were standardized though.

> See what those transformers use, they should cover most of it.  I know Sony
> like to invent a new plug every few years.

All of the ones I'm concerned with use the 5mm OD. I just want (for my
current project) a panel mount socket that will accept most plugs of the
5mm variety.

> I've to a bunch of plugs / sockets with allicator clips on the end.  Comes
> in handy with oddball stuff, like people using RCA as a power connector.  It
> would be nice if the sizes actually meant something, like different
> voltages.
That's the point of EIAJ plugs (the yellow tip ones). Size means voltage
IIRC. Few people use them though.


--
Hector Martin (hectorspamKILLspammarcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc

2007\09\07@113556 by Hector Martin

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wouter van ooijen wrote:
> For an unregulated adapter that is quite normal. When I put a power
> connector on anything I make sure that is accepts a wide range of
> voltage, and survives inverse polarity. Most gadgets I see seem to be
> designed likewise, but I recently got a USB hub that uses a stabilised
> 5V DC wall-wart. That gives me the creeps.

I have a rather large number of recent devices that all use regulated 5V
switching wall warts.

- FPGA board (Digilent Spartan-3E Starter Kit)
- PDA (Sharp Zaurus, all models IIRC)
- Nintendo DS
- 2.5" USB hard drives (pretty much every model)
- some small USB hubs
- La Fonera (That small, cheap, somewhat poorly designed locked-in
router that people like me like to hack and use as a general purpose
access point/router)

All use 5V stabilized power. The wall warts are convenient for PIC
projects though :)

>
> Wouter van Ooijen

--
Hector Martin (.....hectorKILLspamspam.....marcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc

2007\09\07@114938 by Herbert Graf

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On Fri, 2007-09-07 at 11:35 -0400, Hector Martin wrote:
{Quote hidden}

Which has been great for the surplus market. A local electronics store
has sold 5V 1A regulated switching wall warts for $2/each for quite a
while now, I've got tons... :) TTYL

2007\09\07@115020 by Mike Hord

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> Here am I, trying to figure out what the deal is with DC power jacks.
> What do PICListers use most commonly?

Do NOT use the audio jack type connectors (tip/ring/sleeve, usually
found in 1/8" or 2.5mm sizes).  It is VERY easy for the tip/sleeve
or tip/ring to short to one another during insertion of that sort- not
an issue for some uses, but when that shorts out a power supply
it can be less than desirable.

Mike H.

2007\09\07@164044 by alan smith

picon face
Depends on how its going to be used or mounted.  2.5mm barrel jacks can accept most power supplies, or 2 pin stick headers (or 3...if you sometimes tend to plug in backwards).  For proto boards...its usually 2 wires tacked onto the board someplace

Mike Hord <EraseMEmike.hordspam_OUTspamTakeThisOuTgmail.com> wrote:  > Here am I, trying to figure out what the deal is with DC power jacks.
> What do PICListers use most commonly?

Do NOT use the audio jack type connectors (tip/ring/sleeve, usually
found in 1/8" or 2.5mm sizes). It is VERY easy for the tip/sleeve
or tip/ring to short to one another during insertion of that sort- not
an issue for some uses, but when that shorts out a power supply
it can be less than desirable.

Mike H.

2007\09\09@113043 by Rich Satterlee

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Hi-

I have used the "RCA" type audio connectors with mixed sucess.  It was
convienent because I had a lot of both plugs and jacks.  There are downsides
that include:

There is a possiblity of shorting the tip (which protrudes) to the ring
when the wall wart is left plugged in and the connector is left lying on
the bench with various bits of metal around.......

Some people might confuse the purpose of the jack as it typically is used
as a "line" input/output to audio which might provide some surprises to
those not clued in.

The connector is not the most robust method of interconnection and there is
a chance with wear that it will fail to make good contact.

All in all, if you want to standarize with a power connector, I might suggest
looking at the polarized Molex type connectors with pins and jack pins.  It
might be a tad bit more work crimping on the pins and plugs, but each pin
is rated at an amp, they can reasonably isolate the plugs, female (sourcing
power) from accidental shorting.  There are a variety of them available,
one common example is the 4 connector version that are used for disk drives in
PCs. Note that you can get both PC mount versions and crimps for both sides.
Also, they seem to mechanically connect fairly well with each other and
not come apart unexpectedly.  One downside that I've seen with these
is that the housing tend to darken and more importantly harden and turn
brittle when to much current passes through the pins and the temperature
of the junction rises.  The other is that they are rather big. Other than
that, they seem to work pretty well.

 Cheers,

  Rich S.




{Quote hidden}

2007\09\12@083844 by Howard Winter

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Hector,

On Fri, 07 Sep 2007 11:31:25 -0400, Hector Martin wrote:

>...
> That's the point of EIAJ plugs (the yellow tip ones). Size means voltage
> IIRC. Few people use them though.

However, I have a Sony in-car adaptor which has such a plug, but which is switchable between 4.5 and 6V, so that clobbers that standard!  :-)

Incidentally, I concur with an earlier post which said that 2.5 x 5.5mm and 2.1 x 5.5mm are the most common, but I have a little box of 16 plugs in various sizes to get
round awkward situations, and even then there are some things that are so non-standard that I can't find anything to fit.  For example a Smith Corona labeller,
which has 6 AA batteries inside that run down rather fast, and to get round an obvious design flaw they supply a little plastic "battery saver" plug to go into the DC
socket that operates the in-socket switch to disconnect the batteries "when not in use"!  I would use an external PSU but I can't find a plug to fit - seems to be
about 6.3 x 2.5mm and I haven't seen those anywhere.

Cheers,



Howard Winter
St.Albans, England



'[EE] DC Power jacks'
2007\10\07@110510 by peter green
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> - FPGA board (Digilent Spartan-3E Starter Kit)
>
>  
mmm I'm sure those boards run just fine of a 7.5V unregulated supply
despite what it says on the silkscreen.

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