Meant to be Seen

Was starting to hijack another thread, so I made a new one.

Took some research, but I actually found one for power cords. They make them for other cord types according to the PDF.


[youtube]http://www.youtube.com/watch?v=f6vej5N2uD4[/youtube]


pdf

I think I see a problem or two with this:
1. It looks like there may be 2 or 3 contacts through this which wouldn't be anywhere near enough for digital video and control signals.
2. Looks far too heavy for what you're trying to achieve. You want the swivel to be as light as possible to prevent the feeling that you're trying to turn something with your head.

There was another thread about this very thing, except using something called "slip rings":

http://www.mtbs3d.com/phpBB/viewtopic.p ... 33&p=89279



Might be a good place to start looking.

Thanks cyber, heard about slip rings, but didn't know about the thread. Looked at the page looks good, but maybe the other system is useful too if we need retractable. Might combine the rings with a retractable system. At least we got options.

Oh yeah, they said they make custom swivels too. I'm sure they could make a smaller commercial version.

Those slip ring connectors were available with up to 10 wires, but looked expensive. It would be interesting to see what kind of signal cross-talk or signal impedance mismatches they might have (if that is even important on HDMI-speed digital signals). Depending on their construction, they may have signal integrity or lifespan issues.

As a though experiment, you can picture a slip ring connector as a variation on a headphone jack, which can be rotated in its connector without losing signal. However, you may hear scratchy noises due to friction and signal degradation. Real slip rings require special interface metals such as Tungsten/Gallium, or lubricated fiber contacts. Insufficient lubrication (such as in a rotating headphone jack) would cause poor signal integrity and premature wear.

Here is a slip ring connecter designed for ROV (underwater robot) use, which combiner fiber-optic, power, and signal lines:
http://www.electro-miniatures.com/Fiber_Optic.html


And how they work:
http://www.electro-miniatures.com/HowSl ... orks.shtml


Here is a 6-wire slip ring posted by adafruit for DIY use ($17.50):
http://www.adafruit.com/products/736
[youtube]http://www.youtube.com/watch?v=cngf_eyV_l8[/youtube]

And another they have, with 12-wires ($24.95):
http://www.adafruit.com/products/1195


The adafruit slip rings appear identical to cybereality's posted photo.

The wires can each carry 2A at up to 240V. Not sure about HDMI or USB signal integrity though (possible signal crosstalk at the slip rings).

Never mind, Rift only has a single cable to the HMD. Ethernet might be useful for going to the control box.

Direlight wrote:Isn't it possible to have the Rift do everything (even power) via Ethernet?

http://www.trustedreviews.com/news/HDMI ... o-Standard

That comparison table was truncated, losing most of the HDBase-T info. Here is that table (intact):


Interesting. Thanks for this welcome news!

However, you may hear scratchy noises due to friction and signal degradation. Real slip rings require special interface metals such as Tungsten/Gallium, or lubricated fiber contacts. Insufficient lubrication (such as in a rotating headphone jack) would cause poor signal integrity and premature wear.

Well said. For any sort of long term usage (arcade setting), you really wouldn't want to cheap out on the contacts. I'd imagine there would be a bit of a tradeoff between connection integrity and resistance to turning. This could possibly be overcome with an active solution (motor drive that attempts to keep the twist out of the cable).

For those of you young enough to have not known about land lines without wireless handsets, there were phone-cord de-tangler connectors available They are cheap to play with. I don't recall if they have 2 or 4 wires.

However, I would think that any sort of rotary data connector is going to be a problem at today's high data rates. I wonder if an optical rotary is a better choice for the data line?

But, perhaps I am getting ahead of my self. What is the application? How many potential spins of the cable?

If you just need a data and power cord real and the end device is not rotating much, then you don't actually need to have a swivel connection. There are plenty of examples in the dollar store, where the earphone cord wraps around a device that is always in the middle of the length of the cord.

An old-fashioned telephone handset cord can swivel without a swivel connector... at least it can for a good number of turns. If you aren't connecting to a ballet dancer wearing a head set, then such a connection may be all that you need. They typically have 4 connectors.

Can you tell that I am unemployed? I tend to stay up at night hunting for something to design!

Joe Dunfee

This looks expensive,




http://www.uea-inc.com/products/slip-ri ... slip-rings

This one would suitable for you, details as follows:
http://www.arslipring.com