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
   <http://web.mac.com/brianbr/>  Tech Blog
   <http://www.wulfden.org/TheShoppe.shtml>
    Home of the
       K107 Serial LCD Controller Kit   FT817 Power Conditioner Kit
       Tab Robot Laser Tag Kit            MSP430 Chips and Connectors
       Propeller Robot Controller         SX48 "Tech Board" Kit



On Sep 7, 2007, at 4:07 AM, Hector Martin wrote:

> 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 (hector@marcansoft.com)
> Public Key: http://www.marcansoft.com/marcan.asc
>
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist