Unusual connectors - Embedded.com

Unusual connectors

You may remember I did a blog“Which PCB Connectors Are Best?” on connectors some time ago. Now I don’t mean to re-invent the wheel, but I thought it might be interesting to recall some of the more unusual connectors that I have come across in my meanderings through the electronics landscape.

It seems to me that I frequently write that a blog that I claim is different to a previous one, and then I immediately harp back to the original. Well this one is no different. If you go back you will see that I discussed a range of plug in terminals, one of which was a 0.2” (5.08 mm) spacing typical of the German connector industry. In this the plug (the male part in sexist terms) is the part that mounts on the PCB (printed circuit board) whilst the socket with the screw terminals is the plug – the part that the wires attach to. However this is not always the case. Some manufacturers also make a PCB mounted socket and a screw terminal plug. This opens the door to some creativity since there is no law that says that you have to have a PCB mount mated with a transition to wires. You can do PCB to PCB as shown in Figure 1 which gives you the benefit of a high current capability as well as the rigidity of a sturdy connector.


Figure 1. Mezzanine board arrangement using PCB mount plugs and sockets. A second board, identical to the small board in the left foreground, is mounted on the connectors at the rear of the larger board.

The converse also works in connecting wire to wire as shown in Figure 2. I find this great for testing multiple prototypes during development making for easy connection and detachment from the test equipment especially when you have a fairly complex setup.


Figure 2. A wire plug and socket makes for a great in-line connector.

There are also through-panel versions of these connectors like the PWO 16 or the PLW 16 or even 5.08 mm compatible ones. It would be nice if you could plug in on both sides of the through-panel connector – perhaps that does exist somewhere, however you can get it with D-sub connectors like the P-Q3-B3RX.

An interesting variation of a plug-in connector is the BLIDCB 3.5 range, which not only allows for insulation displacement connections to the connector, but like flat cable connectors, will allow for daisy chaining connectors.

When designing a family of modules that have common and even bus connections between them, you can get housings that include a built-in connector in the base that connect on an external bus structure so that the installer is saved a considerable amount of wiring saving time and reducing errors. The ME-MAX modular housings from Phoenix Contact embodies this idea.

If you want a PCB to move whilst still making contact with a second you could always use a flat cable or loom, but there is an alternative. FCI does a rotatable multi-way connector known as the “Rotaconnect” family that works like a hinge.

Sometimes you need to connect to some rotating equipment. Today there is always some form of wireless as a possibility, but an expensive alternative would be slip rings. These are rather like the armature on an electric motor allowing for continuous contact as the object moves without ending up with twisted wires. One option is from the Orbex Group or from Molex like this two-conductor one and this four-conductor one.

One of the dirty secrets of two part connectors (plug and socket) is the low number of make/break cycles leading to an increase in the contact resistance and eventually to open circuits. One of my favourite non-EE Times bloggers is Jason Sachs and he has a suggestion for this. Item #6 in his blog “10 More (Obscure) Circuit Components You Should Know” describes a high current, multiple-make “Powerpole” connector from Anderson Power Products. As an adjunct to his description you should also note that there are also housings available to group (“stack”) these individual connectors into a multi-pole connector.

Notwithstanding Mr Sachs’ choice, in the test jigs that I design I often have to arrange for a conductor to be “threaded” through a current transformer (CT). There is a connector for that! You can see an arrangement in Figure 3.


Figure 3. The plug on the right is mounted on a sliding rod and will mate with the socket on the left. The CT is positioned so that the pin passes through the CT opening.

The Y-series range of products from Hypertronics has a high current rating, low insertion force, and a large number of make/break cycles. You would think that because they are gold plated, Hypertronics treats them like they are in Fort Knox. They seem to completely disavow the product on their web site and in their catalog. I found their distributors more helpful, but you may have to deal with several to get to the pair that you want – a plug from one and a socket from another. Some distributors will have the relevant pages, but if you cannot get it from them raise the matter in the comments below and I will send you a pdf.

Tag-Connect makes a family of products to allow connection of programmers and emulators (or whatever is in your imagination) to your PCB using “Pogo” spring pins (like those used on a bed-of-nails) built into a connector. This means that you save the component cost of a programming header on every PCB as well as getting a robust connector that will last for many operations.

There are a series of heavy duty connectors with built in RFID. Harting suggests that their “Han” connectors could be used to self-identify if they break so that the correct replacement can be ordered. I am sure that there are more imaginative uses for this idea, or is this a solution looking for a problem?

My first project as an independent consultant way back in 1979 was to create a non-contact device that would synchronize the data from a petroleum tanker truck to the gas station since the delivery often happened at night when the gas station was un-manned. We managed to do this with a loosely coupled transformer, but the project was never completed and so I am not sure of the ultimate reliability of the system. Several years ago on the late, lamented forum “The Connecting Edge” I was introduced to the ARISO range of non-contact connectors. I knew exactly where I could have used them. There were several other instances as well, and they could quite possibly be used instead of slip rings in some circumstances. In summary these connectors will transfer both power and data across an air gap and I long to play with some, but the web page that you access above has not changed in years. Just last week I received a newsletter from Mouser that indicates that they intend to stock them – at long last! A newer variation on the same theme is from Keyssa, but there is little data on the web site.

I have only used some of the connectors in this blog, so I can’t vouch for all of them. Remember that many of the European style connectors that I described at the beginning may have multiple sources. On the other hand, some of them may be so hard to obtain you may even conclude that they are “vapourware.”

I do hope that I did give you some ideas anyway. Have you come across any other unusual connectors? Please add them to the conversation below.

16 thoughts on “Unusual connectors

  1. “Just today I got a newsletter from Digikey also now stocking the TE Ariso range. Quite pricey, especially since you need a pair!nnBoth Mouser and Digikey carry links to more detailed data sheets.”

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  2. “DavidnnI recently had this problem with my year-old air-conditioner unit at home. It was under warranty so I didn't try and solve the problem. It was replaced by a brand new board.”

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  3. “DavidnnAnother issue not mentioned much in data sheets is that connectors often have a minimum current rating (like the wetting current in relays) and below that your current may not flow. And if you think some of these connectors are rare, try and get

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  4. “Davidnn”do you remember the old Mercury-wetted contact relays beloved of teleprinter comms designers?”nnYes I do. I also remember mercury switches that I used to use for a snooze button on a few alarm clocks that I made for friends. I actually seem

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  5. “The Anderson Powerpole connectors are quite popular among Amateur radio operators for DC power. There is a standard configuration for this purpose and various commercially available distribution boxes and other accessories.nThese are much nicer than the

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  6. “The Weidmueller BLIDC 3.5mm IDC plugs aren't stocked by Digikey. A more common but somewhat similar choice would be TE MTA connectors, available in 0.1″ and 0.156” with gold or tin plating (although some combinations might not be as available, e.g. 0.1

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  7. “TonynnI think you should be writing some articles on connectors as well! I remember that you also had some valuable input in the blog I referred to at the beginning of this one.”

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  8. “These appear to be similar to many connectors made by several European connector manufacturers. I believe they are an industry standard format. In fact if you look at the D-sub connector I refer to in the article (P-Q3-B3RX) you will see it uses the same

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  9. “Nice coverage as always Aubrey. Years ago I had problems with under-specified connectors in some old terminals, they would overheat and oxidize and overheat some more, sometimes melting the connector body. Fortunately I could get spares for them, but it

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  10. “Aubrey…do you remember the old Mercury-wetted contact relays beloved of teleprinter comms designers? They had a bead of mercury on the contacts which kept the contact closed during bounce – once the contact had made, the mercury kept the circuit closed

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  11. “I had the “not enough solder” problem with relays on a washing machine control board, a year and a week after I purchased it with a 1-year guarantee. It was potted, so had to get a new board ($186). A week later I saw a recall notice for the problem.

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  12. “Aubrey… I found a beautiful mercury tilt switch the other day on some old stuff but did not have the right tools to remove it… must remember to.nnI heard somewhere that Zimbabwe's asbestos is particularly long-fibre compared to most of the world, wh

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