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General Question

I am wondering, is it possible to use a 5.5 x 2.1 mm male plug inside a 5.5 x 2.5 mm jack for transferring 12 Vdc?

My thoughts are just that it may just be a tight fit on the inner conductor. It may also just not fit. I figured before spending money and waiting a few days to try it out, it was worth asking here.

My Use Case

I have an Intel NUC, which can be powered off 12 Vdc via a 5.5 mm x 2.5 mm jack:

The back panel DC connector is compatible with a 5.5 mm/OD (outer diameter) and 2.5 mm/ID (inner diameter) plug, where the inner contact is +12-19 (±10%) V DC and the shell is GND.

Source

And it seems the 5.5 x 2.1 mm plugs are much more common, so I would like to use that.

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    \$\begingroup\$ Not reliably. \$\endgroup\$ – Hearth Oct 1 '19 at 16:30
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    \$\begingroup\$ Without more specific information about the mechanical arrangement of the plug and jack, as well as their nominal dimensions and tolerances, I don't think anyone can give a better answer than the one you provided yourself: maybe, maybe not. \$\endgroup\$ – Elliot Alderson Oct 1 '19 at 16:32
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    \$\begingroup\$ In a 5.5x2.1 plug, 2.1mm is a hole diameter. Forcing a 2.5 dia centre pin into it .... no. Other way round you get a sloppy fit and unreliable contact. \$\endgroup\$ – Brian Drummond Oct 1 '19 at 18:35
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This must be evaluated on a case by case basis, as sometimes the spring loaded tabs will allow for a few 0.1mm's of play. However, 0.4mm is most likely too far and a the right jack\plug combination with less than 0.4mm between the barrel and outer diameter of the plug needs to be found.

Whenever I do product testing with jacks\plugs, I usually buy several options and make sure that customers (boss, product development team) are happy with the plug\jack combination before I build a prototype.

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I have tried fitting a 2.1 mm barrel plug in a 2.5 mm jack (by accident or consciously) many times and it has never fit. Both sides are rigid and there is not enough clearance.

Size adapters are available; I recommend having some around for use when you have a device that doesn't come with a power adapter and an adapter with the right voltage. They do have the disadvantage of making the plug longer, hence more awkward and vulnerable to damage.

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    \$\begingroup\$ I seen instance in which they do fit and make an electrical connection, but it is extremely unreliable. \$\endgroup\$ – Caleb Reister Oct 1 '19 at 16:54
  • \$\begingroup\$ @CalebReister Are you perhaps thinking of putting a 2.5 mm plug in a 2.1 mm jack? That is what I would expect to be an unreliable fit since the jack's pin is too small. \$\endgroup\$ – Kevin Reid Oct 1 '19 at 23:09
  • \$\begingroup\$ Okay I went ahead and bought some connectors, and also found everything was too rigid and it didn't fit. Thanks for your input @KevinReid! \$\endgroup\$ – Intrastellar Explorer Oct 7 '19 at 18:02

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