Electrical Slip Ring for the Tether


#1

I thought it would be good to start a Discussion on an Electrical Slip Ring so that the tether can be put on a spool and unwound as needed. I have ordered up the following item: http://www.ebay.com/itm/271157596689?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 which I would like to test.

This one has 12 circuits using 30AWG wire and my thought was to use 6 for each of the two wires on the tether. This in my mind will give a better connection with less noise and a higher current capability if needed, or you can use the extra contacts for any additional wires that you may be using in your theter.

There are many versions of these slip rings and I am not sure which would be the best to use and maybe someone has already gone down this road and done some testing.


#2

I've used sliprings from www.slipring.cn once. I transfered a pulsing 200V/6Mhz signal, and this worked quite good. you will see the benefit of paralleling more circuits. because sliprings often do get a bit more resistance than specified after a while. it depends alot on the enviroment its used in.

for an drum in our application this will not be a problem. you never constantly pay out cable on a small rov like openrov. I think the drum will primarily be standing still, and paying in/out on launch and recovery.


#3

I though that I would share my build of the tether and stand using a slip ring. The wire you see is 500' of 22AWG Teflon coated aircraft wire, this is a very tough coating which should stand up when rubbed against rocks or rough objects (time will tell :) ). The frame was made from1/2" CPVC plumbing tubing and fittings, I used a full 10' length of pipe with only a few inches to spare. You will also see the Slip ring that fit into the end of the 1/2' pipe after I drilled it out with a 1/2" bit. This went together better that I had expected and made it very easy to incorporate the slip ring. I still have to wire in the Slip Ring and do some testing hopefully all will work as planed. I also plan to mount the MediaLink close to the slip ring on the frame and put a top on the unit so that it becomes a stand for my laptop. If anyone wants more detail of this let me know.

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#4

One more picture

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#5

Dude! This is awesome! Would you mind if I reposted your photos on the main page?

Eric


#6

Sure go for it.


#7

Here is the final Build of the Tether stand with slip ring & MediaLink adapter, just need to terminate the tether with a connector which has yet to be determined which I will use.


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#8

More Pic's

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#9

More Pic's

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#10

Yahoo I did a simple test today using the Tether spool and slip ring and I am happy to say that everything seems to work well. As I unspooled the wire I could watch myself on the Cockpit Video and had no loss of connection to the BB so it looks like the slip ring is doing it's job. and this was with 500' of wire. I did notice a flicker on the viedo once in a while even when I was not unspooling the wire but for the most part it was fine.


#11

Wow. That's amazing. Eric and I were just talking about this yesterday: we've never empirically tested just how much tether length we can get away with, with the medialink. Keep us posted on how the 500' continues to work!


#12

David, I really like your slip ring solution and the tether stand!

Since I wanted to get a more compact solution for the tether (thinking of putting the ROV into a backpack to be able to access remote locations or caves), I built a rough prototype out of some parts I had lying around.

As the slip ring I used a quarter-inch audio jack plug which can be rotated with the cable plugged in. From the plug I made a hand grip using an aluminium tube and a neoprene grip which can be held in one hand while rotating the reel with teh other hand. Works perfectly. When unplugging the jack, the cable reel gets very compact for transport. The cable even can be disconnected and reconnected during operation! The cockpit software reconnects perfectly.

As soon as I have some practical experience with it, I will build a more lightweight solution using plasic parts for the reel instead of metal and wood.






#13

Great job!!!


#14

Great idea! ...Also, I love the compass mounted in front of the ROV! Haha-- navigating old school!

E


#15

Yes, the compass serves as a substitute until I get an electronic onboard version ready. And as it is often the case with old school things, it works perfectly. And it glows in the dark ;-). I took it from my Suunto sea kayak compass. The capsule is actually designed for scuba equipment and should work at any depth the ROV will operate at.

For those who are interested:

http://www.simplyscuba.com/products/Suunto/SK7CompassCapsuleZoneOne.aspx


#16

Great idea using the audio jack, I never thought of that. I notice the wire on the spool and was wondering if it was buoyant or not?


#17

The wire is the Cat5 single pair digital audio patch cable which was delivered with the first tranche of kits. Although it contains some air, it is not bouyant. I'm thinking of using some plastic or wooden beads with a hole in the middle to make it bouyant, but I haven't tried it yet.

I discovered that the audio jack would make a slip ring when I was looking for a robust tether connector in a box that I have since I used to work as an audio engineer. First, I did not think that the connector could also be a slip ring and I used an XLR microphone connector, which is very sturdy, too. But when I built the reel, I came across the jacks. They are used to connect musical instruments (like e-guitars) with the audio line, and the fact that they can rotate while plugged in is very handy on stage. And as it turned out, it is handy for the ROV, too ;-).


#18

And after the prototype - here comes the "reel thing" ;-)

The reel is now made from HDPE which is very robust. The jack was replaced by a locking one, so the plug won't come off by accident (you have to push the red knob for release). The whole construction is very compact and can take approx. 100m of the orange cable that came with the first kits (2.3).



The plug rotates easily, even when it is locked. Just hold the grip-plug with one hand and rotate the reel with the other! And if the cable has got twisted - just realease the jack, turn the reel a few times, plug the jack in again and continue (cockpit software reconnects automatically).

Low tech but high comfort ;-)

-Stefan


#19

Sounds great. Do you have feedback from the field?


#20

Great job!

What about the transportation?

How heavy is it?

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