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Need Ideas for deep underwater LED light

  1. Apr 13, 2017 #1
    Hi guys,

    I am trying to build a underwater camera system with lights. The depth requirement is 1500 feet. I need to view the bottom well enough to understand what conditions exist. I need to know if the bottom is rock or sand or mud.

    I have solved the camera issue...well I think...lol
    ARJpCh4.jpg
    Qj9pf4P.jpg
    The housing in the above photos is rated to 5000 feet.

    The issue now is to provide lights. This next photo is what I have in mind. The issue is I can not find a housing rated the the required depth. I had in mind to try and use the LEDs and circuit from this housing or build something like it.

    As it is pretty dark at depths more than 500 feet so I was wondering if some circuit could be designed to turn on the LEDs. I can turn the light on and off at the surface by opening the housing but that is not very convenient.
    Ccr7FYx.jpg

    The camera and the light will be connected together and lowered to the sea floor by this electric reel with a 10 pound lead weight .
    3qOMkon.jpg

    I have owned this reel for a couple of years now and have learned how to prevent the lead weight from getting stuck on the bottom. At around $30 for the lead weight one gets good at this or spends a bunch of money...lol

    The issue becomes a bit more serious with at least $1000 invested in camera and lights!...lol

    Controlling the camera position will be difficult at best. The area I need to use this contraption in has currents around 2 knots and the wind moves the boat also. I am faced with this issue all the time when fishing and trying to keep the baited hooks just where I want them in relation to the bottom.

    So...the basic electronics question is about best design for the LED light circuit and ideas for ways to turn it off and on while inside the housing.

    Thanks,

    Billy
     
  2. jcsd
  3. Apr 13, 2017 #2

    anorlunda

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    That sounds like a cool project. Just a few questions to clarify.

    How will you trigger the camera shutter? I'm wondering if the same signal can trigger both the camera and the lights.

    Is the power supply at the surface or at the bottom?

    Does the cable include pairs of wires?

    Edit: still photos or videos?
     
  4. Apr 13, 2017 #3

    jim hardy

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    When i was a kid i read Jacque Cousteau's books. I recall his difficulties with underwater housings for flash photography.. How do you change the flashbulb after a shot ? He found out that ordinary flashbulbs withstood the pressure at his depths ( which were modest by today's standards) so he didn't need a housing at all.
    Thinking along the same line - since LED's are encapsulated in solid plastic i wonder whether the pressure housing for them is really necessary . I'd think a simple conformal coating dip would do the job.

    Hmmm what changes when it gets deep ? Gets dark, and absolute pressure increases one atmosphere every 32 feet.
    Looking at pressure first,
    500 feet would be roughly fifteen atmospheres more pressure than the one atmosphere at surface, call it 16 atmospheres absolute = 235 psia .
    One of these could measure that:
    http://www.ssi-sensors.com/pdfs/Pressure Sensors/P51/PS-AN2_FAMILY PRODUCT OVERVIEW.pdf
    about 160 bucks at Digikey

    I'd contact the manufacturer and explain you plan to use it for an underwater depth sensor , ask if his his seal around his wires good for 1500 feet of seawater ?
    Of course it it's inside a lamp housing that's a non-issue.

    Looking next a darkness sensor --- a photodiode looking backward, opposite direction from your LED's ?

    Lastly - surely nobody will accompany this thing down to 1500 feet ? But 500 is do-able. A magnet and reed switch could work through the housing.

    Sounds like fun.

    ps another pressure sensor

    http://www.mouser.com/ProductDetail/Measurement-Specialties/89-01KA-4R/?qs=sGAEpiMZZMtiz6SYu%2fjtS1p%2fV5%252blOzfhUHidWqX3UNjqZSXkoAe2rw%3d%3d [Broken]
     
    Last edited by a moderator: May 8, 2017
  5. Apr 13, 2017 #4

    rbelli1

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    Maybe talk to these guys:

    https://www.openrov.com/

    Their rover is not rated to the depth you need but they might have some ideas they could share.

    BoB
     
  6. Apr 14, 2017 #5
    Hi guys,

    The camera and lights will be self contained and run on batteries. The camera can shoot video for more than one hour on one charge and the housing is built and tested. No electrical cable from the surface is being used, at least at this time. The reason is cost. At two to four dollars a foot for typical cable used for this sort of work, cost get out of control pretty quick. I had looked at building a ROV but the final cost could be somewhere between five to eight thousand dollars. The diameter of typical cable using a ten to twenty pound weight will cause a large bow in the cable with a two knot current plus what ever wind drift effect is caused by the boat.

    The camera will be turned on at the surface then placed in the housing. Most likely that will take less than five minutes. Then another three to five minute trip to the bottom plus the return trip to the surface. The system will be on the bottom for around ten minutes. That is around 25 to 30 minutes in total, well within to battery life for the camera.

    I am considering making the light housing from a solid block of plexiglass. The camera housing was made from a solid block of aluminum. If I can make it work from plex I have in mind to install two screws through the plex and complete the battery connection via salt water. I need to design the LED/battery circuit to operate for the required 30 minute timeframe and produce enough light for the video.

    I also had considered Jim's idea of a photosensor to turn the light on. No switch is actually necessary if I design the battery system for the light large enough.

    My guess is that the LEDs would survive the pressure without any housing. Due to salt water being conductive any connection would cause a failure. I sort of assume that issue could be overcome but assume the batteries would be compressible and fail.

    The good news in the light problem is that cost of failure is not an issue.

    I also have to make a bracket to connect the camera to the light and make some sort of rudder device to keep the system from spinning around.

    Lots of issues to solve but I am almost there!! The pressure involved is large as 1500 feet = apx 46 atm or apx 680 psi.

    It will be interesting to see the first video and what detail I can get.

    Cheers,

    Billy
     
  7. Apr 14, 2017 #6

    anorlunda

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    OK, then the KISS principle should be the next priority. The simpler, the more reliable.

    Instead of a switch and circuitry, how about matching the battery duration of the light with that of the camera? Turn them both on at the surface, then seal, then launch.
     
    Last edited: Apr 14, 2017
  8. Apr 14, 2017 #7
    Here is what I am searching for with the camera idea.
    k4PX8JZ.jpg
    This is a Warsaw Grouper and lives in 500 to 1000 feet neat rockey ledges
    I7NU6Vz.jpg
    This is a Snowy Grouper lives on flatter bottom 600 to 1000 feet
    pvreB3X.jpg
    This is a Misty Grouper lives on flatter bottom 600 to 1200 feet
    7BJKZHk.jpg
    This is a Queen Snapper lives on rock bottom in around 1200 foot
    3iw9Ka4.jpg
    This is a Golden Tilefish and lives on mud bottom 600 to 1000 foot

    These are all great tasting fish to eat. Larger ones, say over 50 pounds can have high mercury content and the possibility of Ciguatera poison. I try to target these fish in the 25 to 30 pound range.

    There are lots of problems in "Deep Drop" fishing. Some grouper are endangered and prohibited. The problem is to try not to catch them. Any fish brought up from 1000 feet is going to die so there is no way to release them alive and you can not keep them. At least the sharks get to eat....

    So...all this camera stuff is an attempt at better fishing and better conservation.

    Billy
     
    Last edited by a moderator: Apr 14, 2017
  9. Apr 14, 2017 #8
    That looks like the less problematic solution. I am not sure how to size the battery but I can experiment here at the house.

    Absolutely nothing is simple when dealing with the marine environment!! BOAT is an abbreviation for Break Out Another Thousand...lol

    I am not in a huge hurry to get all this done but I want to have it all finished and working by the the end of May. May is the beginning of the prime fishing season.

    Fishing addiction, electronics addiction....at least I stopped drinking, chasing cars and howling at the moon...lol..lol

    Thanks for all the feedback guys,

    Billy
     
  10. Apr 14, 2017 #9

    jim hardy

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    Nice Fish !!!! But I thought Warsaws were on the protected list these days.

    I got an award in the 1959 Miami fishing tournament for a 112 pound Warsaw, caught about a mile off Miami Beach in way less deep water, maybe 150 feet. Live Blue Runner for bait. We ate grouper for months....

    old jim
     
  11. Apr 19, 2017 #10
    We can catch one per day in Florida. They have been on the protected list for a while now. They have come back in large numbers.

    The light project is coming along. I will start testing it offshore in a couple of weeks.

    I decided to bite the bullet and install a new sonar in the boat. Something called CHIRP. CHIRP is an acronym for Compressed High Intensity Radar Pulse. Deeper range and better target resolution. It is a sort of spread spectrum technology. I have been procrastinating for a couple of years due mainly to the cost and all the installation issues.

    Here is a screen shot of what it should look like.
    P0Z7EuZ.jpg

    I hope with the new sonar and the info I can get with the camera/light system I will have a much better chance of finding the fish.

    Cheers,

    Billy
     
  12. Apr 20, 2017 #11

    dlgoff

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  13. Apr 20, 2017 #12
    Can you get enough LEDs and battery into a second camera housing?
     
  14. Apr 20, 2017 #13

    Baluncore

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    Fill a soft plastic box housing the LEDs with a clear oil to displace all the air. You will then not have a pressure difference, so no sea water will enter.
     
  15. Apr 20, 2017 #14

    rbelli1

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    If you do this make sure there are no wet electrolytic capacitors in there. The oil will get in and that is probably not good for them.

    BoB
     
  16. Apr 20, 2017 #15
    You might be able to rig a photo transistor to only turn on the light, when the ambient light level was low, to save battery time.
     
  17. Apr 20, 2017 #16

    berkeman

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    Just curious -- Why do they call a sonar system Radar?
     
  18. Apr 20, 2017 #17
    I worked in the seismic industry in the 80's and they used something called naroma, but I think it was basically kerosene,
    and would damage many plastics.
     
  19. Apr 20, 2017 #18

    rbelli1

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  20. Apr 20, 2017 #19
    The LED light is very easy to waterproof just take the circuit board out and paint it with polyurethane varnish cover all the exposed metal and components screw it back in BEFORE it is dry. Then wait for the varnish to dry and finish closing the case
     
  21. Apr 21, 2017 #20
    To switch the light on/off: since there is a lead weight which is supposed to hit the bottom the switching might be made with magnet/magnetic switch.
    However, I'm not sure that common reed relays are OK for that pressure, so it requires some thinking and a decent depth-rated housing still might be needed.
     
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