RJ45 woes: how many incompatible flavours are there?

I used to use RJ11s in the good ol' days, and now would like to use RJ45s as my go-to modular connector for attaching remote sensors to 'duino project boxes -- neat, convenient, easy to terminate -- but lately I've had a couple of frustrating experiences.

  1. bought a bag of "RJ45" connectors online, only to find that I could not fit my cat5 wires into the plugs. I struggled for hours but could never install even one connector... So that was a waste of money and time. Bought "cat5" connectors from local ISP and they worked great, termination was a breeze.

  2. bought a bag of "RJ45" jacks (breakouts) to incorporate into projects. First batch I bought worked great w/ the plugs I bought from the ISP. Liking them so much, I bought another batch off Ebay. But when I tried one of the second batch I purchased, I found that my RJ45 plug would not seat properly in the jack! There is no "click" and I don't get a reliable connection at all.

Looking with a new and suspicious eye at the jack I can see that the opening does seem a tad wider than the older one that works. But that makes it even stranger that the plug doesn't fit properly :slight_smile:

I do have a few of the first batch of jacks left, so I can (sigh) replace the bogus one, with a bit of unsoldering and cussing. What I'd really like to know is how to identify the jacks and plugs I want to use, so I can stop buying these subtly different ones that don't work. Does anyone know how many flavours there are of these puppies, and which ones will play nice with which ones?

Oh, there's a lot of those.

Things to check that come to mind:

  • Stranded or solid wires in your cable ?
  • Round or flat cable ?
  • Shielded or not ?

There's a suiting RJ45 plug for any type of twisted pair networking cable.
They aren't necessarily exchangeable.
I'm not sure how you can determine what plug is compatible to what cable and to what mate (plug wise).

I worked for myself for a long time, installing Cat5 networks.

I bought all my RJ45s, must have used many thousands of them, from a reputable UK supplier. The plugs and sockets were often form multiple (known) manufacturers, I never has a problem with interchange ability.

Thanks for the warning about RJ45s from eBay.

There are non-interchangeable versions, but I think here its basically cheap fake connectors that is the issue.

'RJ' means 'Registered Jack" which means there is a specification. All plugs & jacks that are in-spec WILL fit and WILL work.

But of course, cheap Chinese stuff sold on eBay or Alibaba is exempt from any and all specs! :smiley: :smiley: :smiley:

FYI
https://forum.arduino.cc/index.php?topic=445951.msg3146617#msg3146617

4.jpg

larryd:
FYI
https://forum.arduino.cc/index.php?topic=445951.msg3146617#msg3146617

4.jpg

I haven’t crimped a lot of my own RJ45 connectors in my time but I’ve done enough for this photo to be embarrasing. I’ve been cutting the wires to length before crimping them, it never occured to me to bring them on through and trim them after crimping. Doh!

GilchristT:
I haven't crimped a lot of my own RJ45 connectors in my time but I've done enough for this photo to be embarrasing. I've been cutting the wires to length before crimping them, it never occured to me to bring them on through and trim them after crimping. Doh!

On most (all) connecters I have seen (many thousands) you dont push them through to cut, you cannot as there is a stop inside the connector stopping this happening.

GilchristT:
I haven't crimped a lot of my own RJ45 connectors in my time but I've done enough for this photo to be embarrasing. I've been cutting the wires to length before crimping them, it never occured to me to bring them on through and trim them after crimping. Doh!

If you click on the link provided, you see how to drill out the 8 holes in the RJ45 connector.

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larryd:
If you click on the link provided, you see how to drill out the 8 holes in the RJ45 connector.

I just swa it, I cannot believe anyone would have enough time to waste doing that, making an easy job heaps longer and more difficult.

srnet:
On most (all) connecters I have seen (many thousands) you dont push them through to cut, you cannot as there is a stop inside the connector stopping this happening.

Ah, thank goodness for that. I was wondering how I’d managed to miss that :slight_smile:

srnet:
I just swa it, I cannot believe anyone would have enough time to waste doing that, making an easy job heaps longer and more difficult.

Waste time ;), if you crimp these you will ‘never’ good back to the old versions.
I have done many hundreds of crimps.
For old stock, you drill connectors ahead of time, 10 RJ45 take < 7 minutes, 10 min if you drink wine while you are doing it :wink:
For new purchases buy through hole versions. ~$25 for 50 pieces.

The holes speed up crimping greatly (more than makes up for the drilling time) plus the crimp quality is way improved over the fussy old way.

100 for $4.00

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