Page 57: of Marine Technology Magazine (September 2023)

heat transfer material behind the PCB letters are bare aluminum. components, and do lots of testing pre- to carry the heat away from the LEDs deployment. Cree LEDs produce more (google “CREE LED Luminaire Design Many parts can be purchased by an light per watt, so less heat, and their

Guide”). LEDs are completely pressure experimenter very cheaply. Those footprint is smaller, so the housing is tolerant as they have no compressible are the best to learn with. One failure smaller. LUXdrive and Meanwell make volume. A pressure compensating ? uid, doesn’t cost a lot. When it really mat- small and ef? cient LED drivers. Check such as mineral oil may be used. Avoid ters, though, spend the money on better out www.ledsupply.com.

silicone oil has the cast dome on an LED is often silicone, and may be affected by

Further Reading immersion in a ? uid of a similar nature.

DeepSea Power & Light (San Diego, CA) has published numerous articles on un- dersea lighting and imaging.

Tip: A reasonably good 30-watt, 2600

Go to: https://www.deepsea.com/knowledgebase/ lumen LED array is <$10 and 12-24vdc input LED driver is <$9 plus shipping at

Other good references (Tip: try www.book? nder.com): .

• Christ, Bob; Wernli, Bob, The ROV Manual, Second Edition,

If using a MOSFET as a high-power

Waltham, MA, Butterworth-Heinemann, 2014 switch to control the lights, look for • Moore, Steven; Bohm, Harry; Jensen, Vicki, Underwater Robotics, the RDS(ON) value, “Static Drain-to-

Hong Kong, Marine Advanced Technology Education (MATE), 2010

Source On-Resistance.” This is the volt- age (VGS) that needs to be applied to • Cross, E.R., Underwater Photography and Television, New York, the gate to fully switch the MOSFET

Exposition Press, 1954, a seminal early text on. Depending on the part you select,

Readers are encouraged to share their experience, inventions, and feedback by this will be between 4v to 10v. I look writing the author at [email protected] for MOSFETS that fully saturate at logic levels of 5v, such as the IRL540.

A helpful review of MOSFET circuits is found at . A useful MOSFET

HMS-620 BUBBLE GUN worksheet is at

MARINE SEISMIC SYSTEM APPLICATIONS

CONCLUSIONS • Shallow Gas Hazard Surveys • Oi shore Wind Turbine

Building you own underwater imag- • Geotechnical InvesO gaO on • Sand Resource InvesO gaO on ing system provides insight to what manufacturers have faced, and what questions to ask sales reps. You can see the engineering behind a commercial design because you’ve done it. You can also spot mistakes. Cameras for ROVs, which are in and out of the water fre-

Portable System Requires only quently, can get away with some dis-

Wavelet 2KW at 250ms Ping Rate

CorrelaO on > 0.96 similar materials, such as a 316SS snap ring to hold a viewport into an anod- ized aluminum body, as the vehicle gets rinsed off after every dive. Not great design practice, but manageable. The same camera on an IOOS node will see constant exposure right through to fail-

Sand Reclamation Data Collected Using HMS-620 ure by galvanic corrosion. I’ve also seen

Courtesy URI Graduate School of Oceanography a manufacturer who laser engraved the

Falmouth Scienti¿ c, Inc.

company logo and serial number right

Pocasset, MA USA 02559 • Tel: +1-508-564-7640 • Fax: +1-508-564-7643 through the black anodize layer to the [email protected] • www.falmouth.com aluminum substrate. Those shiny silver www.marinetechnologynews.com 57

MTR #7 (50-65).indd 57 10/2/2023 3:40:42 PM