[PSUBS-MAILIST] LED Lights

Thu Jul 23 15:47:24 EDT 2015

Backscatter is less a function of light intensity, and more one of incident angle. In addition to the wider beam dispersion,  vehicle fog lights work because they are typically mounted lower than the headlights, and thus reflected light off the water droplets doesn't come straight back at the driver. A similar effect could be achieved on your submarine by mounting lights on outboard extension arms.

Standard encapsulating epoxies are very good insulators. Coupling hot equipment to a heat sink with potting compound specifically requires one designed with thermal conductivity in mind.

Sean

On July 23, 2015 1:31:26 PM MDT, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Cliff, Ken,I like the dimming option. The 10,000 lumens may be too much
>light insome low visibility conditions where there is a lot of back
>scatter.The 5,000 lumen option may act like a fog light.Also I am
>thinking of having lights mounted to the side which may notneed to be
>as intense.Depth rating.... looking at the drawings of various 10,000
>meter light housings,it seems simple to achieve a reasonable depth
>without much more cost.Potting the board..... I would be careful about
>what was potted in case some of thecomponents needed to get rid of a
>bit of heat.Mechanical housing..... with you on that one Cliff. Like
>the idea of the recessed light.Alan
>From: Clifford Redus via Personal_Submersibles
><personal_submersibles at psubs.org>
>To: Personal Submersibles General Discussion
><personal_submersibles at psubs.org> 
> Sent: Friday, July 24, 2015 4:06 AM
> Subject: Re: [PSUBS-MAILIST] LED Lights
>   
>Ken, good first pass at the specs.  Below are comments.  BTW, I will
>post these here as I have not been able to get the activation code back
>yet on registering at the forum.
>Item 2.1 DC Voltage.  If it were me, I would stick with nominal battery
>bank voltages of 24 and 36 VDC.  When I switch to MK 101 thrusters, I
>dropped my main battery bank voltage to 36VDC my instrumentation bus is
>24VDC.  Would need a single fuse holder to accept fuses to
>handle different nominal voltages.
>Item 4.0 Depth Requirement.  In the spirit of keeping cost down, I
>think 500 meters (1640 ft) would be more than enough.  I know Scott is
>designing a deep diving boat but is any one else shooting for more than
>500m?
>6.0 Dimming.   I would omit the ability to dim the light.  Yes I know
>it is easy from an electrical point of view but it forces us to go with
>more pins on the subsea connector.  I am thinking on
>installing multiple lighs so I could just control on/off for each
>light.  I could go either way on this but in the spirit of KISS, I vote
>to omit dimming.
>8.3 Ports  I would change plastic to acrylic.  I don't think we will
>end up here but if we do, we can use PVHO flat view port calcs to size
>the acrylic lens.
>9.0 Printed Wiring Boards.  I really like the way the Minn-Kota motor
>controller PWBs are potted.  Rather than using the spray on hydrophobic
>coatings, to me we should pot the board (accept for access to fuse). 
>Therefore suggest changing the word coated to potted.
>11.0 Mechanical Housing.  I suggest.  The LED panel light and PCB shall
>be contained in a single 1-atm flange mounted cylindrical housing with
>a low profile that can be recessed in a FRP shell with attachment
>screws from the rear of the flange.  The housing should contain a
>single 29 LED Array rated at 10,000 lumens  with a rated power of
> 91-140 lumens/W (109-71W).  Mounting holes will be provided for an
>optional SS yoke style support bracket.  
>Material: Hard anodized 6061-T6 or 7071-T6  TBD (I have a grey beard
>machinist friend that owns a machine shop.  He loves 7071-T6 as it is a
>dream to machine and stronger than 6061-T6.
>On Thu, Jul 23, 2015 at 9:52 AM, Ken Martindale via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
>
>Cost is critical. The electronics should be a small part of the cost.
>The housing might be the most expensive. Hope you guys are reading the
>specification. Ken From: Personal_Submersibles
>[mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Clifford
>Redus via Personal_Submersibles
>Sent: Thursday, July 23, 2015 10:18 AM
>To: Personal Submersibles General Discussion
><personal_submersibles at psubs.org>
>Subject: Re: [PSUBS-MAILIST] LED Lights Jon, thanks for setting up the
>forum.  I am assuming we can post files as well.  I agree low cost is
>important but having a functioning light is as well.  OTS LED utility
>lights like that one you noted are not an option unless they can be
>potted.  To me the best way to keep the cost low, is to publish
>construction drawings of a 1-atm  DIY housing that a psubber could
>machine or have machined by a friend, and publish a design of a PCB
>that could be easily fabricated using  one of the PCB online sites like
> ExperessPCB www.expresspcb.com and DIY populate the board.  As a
>group, we design and build a prototype that I can test in my shop. If
>it works as designed, then we post to the psubs site a report, that
>includes the design drawings, circuit diagram, parts list and test
>results.  Getting a consciences on the design spec is the first
>step.  Cliff On Wed, Jul 22, 2015 at 10:11 PM, Jon Wallace via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>My three words of advice...cost, cost, cost.
>
>One measure of a success for this project will be how many people
>actually build/use it.  If it costs more to manufacture than just
>purchasing something like
>http://www.surpluscenter.com/Electrical/Lights/DC-Mobile-Equipment-Lights/12-24-VDC-3120-LUMEN-16-LED-UTILITY-FLOOD-LIGHT-12-999-B.axd
>off the shelf then it's real world application by psubbers may be
>limited.
>
>Over-spec'ing the design above requirements for typical recreational
>operations (ie 10,000 psi capability) is likely going to drive up the
>cost.  Also, let's remember that "cheap", "low cost", and "good price"
>are relative terms for a diverse group like PSUBS so include realistic
>estimates of parts and manufacturing especially if tooling is required.
>
>Jon
>
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