Yesterday I cut the Eye of Mine Camera Housing composite video cable to length and proceeded to strip off the outer jacket and then the inner rubber jacket that encompasses the video signal wire and it accompanying stranded ground wire. I will cut the stranded ground wire near where it exits from the cable penetrator and attach a 22 gauge stranded silicone wire that will accompany the video signal wire into the Navigation Controller WTC.
This morning I thoroughly cleaned the outer jacket of the video cable and the inner surfaces of a Blue Robotics (BR) 6 mm cable penetrator. Then following the BR cable potting instructions I potted the video cable into the cable penetrator. The potted cable and penetrator are presently curing and should be available to handle sometime this afternoon.
I will provide some pictures of the potted cable assembly tomorrow:
Camera Housing modified composite video Cable and Cable Penetrator
Rear view of Camera Housing modified composite video cable and Cable Penetrator
Now that I have the ROV Chassis camera, housing, and cable attachments pretty much put to bed I have been thinking about lighting for the camera.
The turbidity of the water usually limits the range of underwater vision and can vary greatly depending on where the ROV is being used. In the depths that I will be operating, green, yellow, and blue have the least absorption down to around 50 meters while red hardly makes it down to 5 meters.
I have done an internet search for homemade underwater lights and have come across several interesting underwater lighting construction projects. The homebuiltrovs.com website has a forum devoted to underwater lighting, but there does not seem to be any real consensus on what works the best for a hobby ROV. Most of the homemade underwater lighting projects require a fair amount of flag waving to put together a decent 5 - 10 watt underwater Led light that will work at a depth of 33 meters or so.
I have a pair of these Flood Led lights manufactured by Mike's Subworks, that were originally intended for the SRV-II R/C submarine, and they seem to work well on 12 vdc and consume a reasonably low level of current. The homemade Led Lights usually require a heat sink for the 5 - 10 watt Led, a constant current source and obviously a waterproof housing for the Led to be mounted in.
Concerning the waterproof led post above, OpenROV is selling a 700 lumen external light cube that runs off of 7 - 17 vdc, consumes 6.5 watts (540 ma) at 12 vdc, and has been tested to 200 meters for $75 each.
On the other hand Mike's Subworks waterproof flood light puts out 570 lumen, consumes 200 ma at 12 vdc, has no depth rating, and sells for $40 each or two for $75.
Two of the Mike's Subworks flood lights would provide around 1140 lumens, consume only 400 ma versus 540 ma, for roughly the same price as one OpenROV external light cube.
The two external lights are virtually the same size, however the Mike's Subworks flood lights come with mounting brackets unlike the OpenROV external light cubes.
The lighting is a tricky part, I'm making my own using T6 leds with reflectors in aluminum housings. I got a few with different lumen and color temperature that I am gonna try out. I have no idea what works best so I am going with quantity (6 lights in total), it's hard to guess how much light you need and how well they will work so I am doing a trail and error approach on the matter . The housing is a really tight fit to the reflector so I am counting on heat not being an issue with the aluminum housing but I guess I'll find out eventually.
Hi Jaman42,
Thanks for the input on the lighting. Much appreciated.
Yes, the biggest concern is the cooling of the led and if you are not using a metallic housing, then you need to heat sink the led with an aluminum plate.
Regards,
SSN626B/TCIII
Well, I completed potting the Eye of Mine GoPro Camera Housing's composite video cable in its cable penetrator last Sunday and ordered another Enclosure Vent Plug from BR to be able to use one of my spare WTCs to vacuum test the Camera Housing. The Enclosure Vent Plug should be here on Thursday.
Except for some minor cleanup work on the ROV Chassis I am presently at a stand still until the beta versions of the Tether and Navigation Controller become available sometime in January.
Hope that you all had a nice holiday and are looking forward to a great New Years!
The USPS was a little slow in getting my Blue Robotics order to me so it did not arrive until yesterday and today is the first day that I have had the time to check the vacuum integrity of the Eye of Mine GoPro Camera Housing with one of my spare WTCs.
In my order from BR was a WTC Vent and Plug used to vent the WTC when installing and removing the End Caps. The Vent can also be used to vacuum test a WTC when used in conjunction with the BR Vacuum Plug adapter.
So I installed the Vent, three blank Cable Penetrators, and the composite video cable penetrator from the Eye of Mine Camera Housing into a 4" Series five hole End Cap and proceeded to pump down the WTC.
Since the air in the Camera Housing is leaking through the center wire of the composite video cable into the WTC, it took several pump downs to get a stable vacuum at 560 mm Hg. A check of the vacuum level at 1/2 hour after the final pump down indicated no change in the vacuum level of 560 mm Hg. So presently I am waiting for an hour to see if there is any vacuum loss from the initial 560 mm Hg.
If all goes well and the vacuum level is still at 560 mm Hg after an hour, I can declare victory and move on to completing some of the little odds and ends left with the ROV Chassis.
It looks like I can declare victory as the Camera Housing video cable/WTC vacuum test passed with flying colors. After one hour the vacuum still indicated 560 mm Hg which was the final pump down value.
I must say that I am impressed with the vacuum seal quality of the GoPro Hero 3/4 Camera Housing and the quality of the Eye of Mine video cable seal in the back of the Camera Housing.
Below is a picture of my vacuum test setup for vacuum testing the Camera Housing and Video Cable Penetrator:
Camera Case and Video Cable Penetrator vacuum Test Setup
When I decided to break vacuum on my Eye of Mine Camera Housing/WTC vacuum test setup I found that I could not get the back of the Camera Housing to open due to the residual internal vacuum in the housing.
It turned out that I had to wait for around 20 hours for the air in the open WTC to leak back up the composite video cable into the Camera Housing before the vacuum was low enough to get the back open.
I believe that this speaks well for the integrity of the Camera Housing seals and the leak proof quality of the composite cable and fittings.
. The housing is a really tight fit to the reflector so I am counting on heat not being an issue with the aluminum housing but I guess I'll find out eventually.
