Below is a wall wart with ratings 5V 2A. I'd like to buy a DC adapter of some kind for this wall wart, so I can easily wire things to a circuit or bread board. What is the name of the DC side of this wall wart and what are possible adapters I can buy for it? I'd like to either use alligator clips or just plain jumper cables (female or male is fine). If I need to solder it, that's fine, but I'd prefer not to do that.


enter image description here

I'd like something similar to this:


Or this:



1 Answer 1


It is a DC Coaxial Power Connector:


You will see on that page that there are many different sizes - there are a few ways to find the correct size. Once you have the correct size then you can look for adapters. I have sometimes bought just the necessary matching connector and attached a cable; sometimes bought the PCB-mount version for the "wall wart" to connect.

If you have a set of vernier calipers, that will quickly show the outside diameter of your specific connector. Depending on that measurement, there may be a choice of inner (pin) diameters too. Depending on what equipment you have available, that can be more of a challenge to measure, in my experience.

Updated to add: According to an Ebay listing for the same D-Link part number, the connector is a 5.5mm x 2.5mm DC coaxial connector


If that information is correct, then neither of the Pololu adapters which you linked is appropriate, since they are for 5.5mm x 2.1mm plugs :-(

Updated to add: Although I can't find any Pololu adapters for 5.5mm x 2.5mm plug to terminal block, I have found some on Ebay, so they are available if you want to go down that route (if you accept the statement of the connector size in the Ebay listing which I linked above).

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    \$\begingroup\$ I have been known to buy a bunch of female connectors, and use whichever one fits. In particular, the 2.5mm and 2.1mm ones look very similar. \$\endgroup\$
    – Simon B
    Commented Apr 23, 2016 at 22:00
  • \$\begingroup\$ @SimonB - Yes (+1) - Funnily enough I was just going to suggest that i.e. consider replacing the cable-mounted female to match whatever male part is more easily available. However it seems that the OP here is trying to avoid soldering, which replacing the female part will likely require :-( Agreed about the 2.5mm vs 2.1mm issue. The good news is that one is bigger than the other, so depending on what connectors the OP has on other equipment, it might be possible to find that answer by "trial fitting" (that is what I did in a similar situation recently). \$\endgroup\$
    – SamGibson
    Commented Apr 23, 2016 at 22:05
  • \$\begingroup\$ Measuring the outside diameter is trivial, measuring the inside diameter is not. The two most widespread sizes are 5.5/2.5mm & 5.5/2.1mm, and without having a mating female socket of each size to test, it's not easy to distinguish them. \$\endgroup\$ Commented Apr 23, 2016 at 22:06
  • \$\begingroup\$ @LaszloValko - Agreed. Once the OP finds the outside diameter (OD), we can see whether the inside diameter (ID) is an issue, or whether it can be easily decided e.g. if the female has a 4mm OD, then there is only one standard ID size. \$\endgroup\$
    – SamGibson
    Commented Apr 23, 2016 at 22:11
  • \$\begingroup\$ A set of metric drill bits in 0.5 mm steps makes finding the ID easy. Also note the barrel length. I got caught when I bought some short ones by mistake. \$\endgroup\$
    – Transistor
    Commented Apr 23, 2016 at 22:27

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