Wet-connections - any one looked into it?


#1

I was thinking on... could we make some diy wet connections to the tether?

enabling disconnection of the tether from ROV under transport and lengthen the tether if needed?


#2

I have used and tested this one from Ebay:

Link


#3

looks good!


#4

With regards to lengthening the tether, what is the functional length before you start loosing more quality in the video feed?


#5

The guys in openrov HK said somewhere around 300 metre max…
’‘As is’’ I think the video quality could been better. …recording through VLC. .Any other ways to record?


#6

Yeah- a low-cost waterproof plug would be awesome to have. An interesting thought is that the tether may not even need to be electrically connected... it turns out that HomeplugAV communication is a sort of RF over tether, and signals can actually jump across gaps in wire when the wires are next to eachother. We found this out when someone trying to log into one ROV ended up seeing the video from a different nearby ROV instead. Very strange, but worth experementing with...

Other then that, I've also been working on some ideas involving non-newtonian fluids like silly putty which could surround a connection like a fluid, but could be removed easily when access is needed. The idea with non-newtonian fluids is that they act like a liquid when moving slowly, but like a solid when moved quickly.

I'll try to do some experementation later and will report the results.

E


#7

Seems inexpensive. Maybe too inexpensive. What were the results of testing?.

Anybody know what the average amp draw going through the umbilical? And thus any connector used.

Look into "Marsh Marine" dive communication connectors. The others, Burton , seacon etc seemed over kill (rated for thousands of feet) as well as cost prohibitive.


#8

Expensive? 5 USD including shipping. I have tested this one in a pressure chamber to 10 bar without any leak.


#9

Hi Erick:

If the HomeplugAV can really work as a RF TX/RX, ....

Making two coil-capacitor (LC circuit) one for the HomeplugAV and another for the tether, and arranging them isolated into a concentric connector, would work as a high gain pair of aerials.

Total lenght of each coil wire has to be an integer part of the carrier wavelenght. The capacitor must be choosen in order to set the LC circuit in resonance state with the carrier frequency.

For fine tunning a variable resistance can be fitted inside the LC loop.(see RLC circuit).

The connector could be as simple as a tube, where a coil is fitted, and a cylinder with the other coil.

Regards


#10

Cool stuff regarding AV, but signals for controlling the ROV must still enter through the cable I guess...


#11

Yes Tom, you're right.

Making a detachable cable is only a matter of better storage.

Regards


#12

I wrote "inexpensive". Just sayin sometimes the cheapest might not be so secure when we are talking bout the electronics.


#13

Someway I read expensive on my phone earlier today. I need to get some glasses or a larger phone :slight_smile: