Advice on Smallest Circular Connector with >=3 Poles

I am looking for the smallest/lowest profile connector(plug and socket), based on the following criteria:

  • In the ballpark of 2.1mm/3.5mm sized connectors
  • Must be circular/round
  • Able to be panel mounted
  • Have >=3 poles
  • Able to be plugged and unplugged while power is on without shorting, and hence, able to support not only signal, but power transmission(max 12v)

Here is what I have found. The size of the 3.5mm connector is almost perfect, but it doesn't fulfill the 5th criteria. While for mini din/xlr connectors, the "handle" of the plug connector makes it too long/large. For RJ11/45 jacks, they are not circular, which makes cutouts and mounting difficult on metal panels, and also plastic ones when you need to add many. Although special made rounded RJ45 sockets could be found for panel mounts, they are costly in huge amounts and increases the connector size multiple times.

If anyone knows of a connector which fits all the criteria above, input is appreciated.

Able to be plugged and unplugged while power is on without shorting, and hence, able to support not only signal, but power transmission(max 12v)

Can't you use a 3.5mm jack if you are "clever" about which pieces have power on them? If TIP is your +V, I don't see how it gets a chance to short against anything else...

Thanks but no, it will not work. I have thought of that, and I have tested the crap out of it before posting this, it still shorts. I guess that is the way 3.5mm jack is designed, not for power. Here is another topic on to back my claim http://forum.arduino.cc/index.php?topic=27760.0 Using 3.5mm, the only way is to plug them in before supplying power, which does not meet criteria number 5.

There's basiscally only two types of circular power connectors available as consumer products:

A- a cylinder with a hole in the center (This type will never have more than 2 "poles" (correct terminology is "terminals", not "poles")

B- audio type plugs that can have as many as three contacts, (one GND , one left channel and one right channel) These are commonly called stereo audio connectors.

Sounds like what you need is something like XLR connectors but they're not small.

There's something called Mini XLR

A “circular connector” usually has an array of pins inside a circular shell. A “TRS” or tip-ring-sleeve connector is ring shaped contacts on a common axle. It’s also called a “phone connector” because it was originally designed for plugboard type telephone exchanges.

If your TRS is shorting then you can look for a different socket. There are a number of variations, some with extra contacts that are closed when the plug is removed. Look carefully at the insides of your socket to see what stage of insertion causes the short.

Proper arrangement of the power connections should also be considered. The sleeve is usually ground but maybe it should be Vcc?

Then you might consider a 4-way TRRS. That will put one more ring in as an isolator. They are less common - mostly you will find the 2.5mm version (or is that 2.1?)

Hi

What about "mini DIN 3pin" or 3+shield as GND?

I use "normal" DIN size for data lines and aviation connector for power line.

You can get them with plugs, sockets, etc.

And remember, do not consider only voltage, take more care about amperage ( current ).

"DIN"? Deutsch Industries Normal, which is the German standard. That was my thought when he said "circular" but I think he wants smaller than that.

DIN is useful when you want true panel mount. Each socket has a version with screw holes on the sides so it can be screwed directly to the panel, with flying leads on the inside. TRS connectors are usually on a PCB behind the panel.

MorganS: "DIN"? Deutsch Industries Normal, which is the German standard. That was my thought when he said "circular" but I think he wants smaller than that. I think he wants smaller than that.

Hi.

My bad, typo error. Just corrected it.

Smaller than that? and easy to plug and unplug as a mini DIN... not sure

Byork: I am looking for the smallest/lowest profile connector(plug and socket), based on the following criteria:

  • In the ballpark of 2.1mm/3.5mm sized connectors
  • Must be circular/round
  • Able to be panel mounted
  • Have >=3 poles
  • Able to be plugged and unplugged while power is on without shorting, and hence, able to support not only signal, but power transmission(max 12v)

Here is what I have found. The size of the 3.5mm connector is almost perfect, but it doesn't fulfill the 5th criteria. While for mini din/xlr connectors, the "handle" of the plug connector makes it too long/large. For RJ11/45 jacks, they are not circular, which makes cutouts and mounting difficult on metal panels, and also plastic ones when you need to add many. Although special made rounded RJ45 sockets could be found for panel mounts, they are costly in huge amounts and increases the connector size multiple times.

If anyone knows of a connector which fits all the criteria above, input is appreciated.

Use a current-limited supply. ie Constant current source circuit, then shorting the supply isn't a problem.

If the power comes from the socket: Use 3.5mm TRRS, tip=power, ring = NC, ring2=GND, sleeve = signal.

If the power comes from the plug: Use 3.5MM TRRS, tip = signal, ring = GND, ring2 = NC, sleeve = power.

Test it of course - there is still risk of power getting onto the signal depending on precise connector geometry.

MorganS: Then you might consider a 4-way TRRS. That will put one more ring in as an isolator. They are less common - mostly you will find the 2.5mm version (or is that 2.1?)

Less common?

Not nowadays - 3.5 mm version practically universal thanks to smartphones.

I suppose I'd vote for mini-DIN connectors. Small, nonshorting, and can get them in panel mount.

I appreciate all the replies, especially Mark's detailed one. I am reporting back with the tested results of the TRRS suggestion, and MarkT is right on the money. Isolating the ring right after power solves the issue for these 3.5mm connectors. This solves my issue for power + 1 signal devices. So I guess for more than 1 signal with power, the next best thing does have to be mini-din connectors, but at the expense of its larger profile. Thanks again.