The only component that significantly heats up without cooling in our dropcam is the gear360 camera. If not cooled, it will go past 50 degrees Celsius and will cause it to stop recording. This should have no impact on the function of the burnwire as these systems are independent.
Thank you! And we fixed the issue of the circuit to activate the relay. We are feeding it with the same 11.5V of the LiPo battery and the transistor makes it work. It is simple but we were doing a big mistake putting the transistor before and not after the coil. Now, all our electronics work and it is time to do more testing about temperature inside the enclosure.
We have a humidity and temperature sensor and we are looking into ways to measure condensation.
Hi Ivan, we have a new challenge and need your insights. Now that the Arduino-controlled electronic circuit that activates the burn wire works well, the issue is that the wire doesn’t burn when tested inside water. We did a few tests with salt water (tap water with a couple of spoons of salt, it could had salt in 300 ppt) and the nichrome wire doesn’t burn. Are we missing something?
Dear @rjehangir, @WorkshopScience and all, we are ready to test our drop cam (now named Blue Eye) and the only thing that doesn’t work is the burnwire. Our circuit gets activated and the wire gets a lot of current but it doesn’t get burned as the one I can see in @WorkshopScience 's video. In the meantime, we will use a reel to recover the camera but this is not what we want.
Any clue? Suggestion?
Hello Pau,
Have you tried activating the burnwire in freshwater? If it works under these conditions then the most likely cause behind the error you mention is too much exposed metal on either side of the wire’s connection points. This leads to most of the current flowing through the saltwater rather than through the wire. We encountered this error when using large metal thumb screws and switching to plastic-ended ones seemed to have solved the issue. If the burnwire doesn’t work in freshwater either then the it is most likely just not receiving enough current. Can I confirm what the capacity and discharge rating of the battery is?
Kind regards,
Ivan
Thank you Ivan. Yes, we tried in freshwater and it didn’t work, but I was optimistic about salt water because of its electric conductivity. I understand your point about too much metal exposed to water. I will share pictures of our burnwire later, and will rethink how to make it using less metal.
Dear @WorkshopScience and @rjehangir, we did several tests of our drop cam, named “Blue Eye”, in Menorca, and it was really great. The burn-wire is not working properly but we believe we can fix it, and the only thing that is pending (for next summer!) is to do some tests in the deep sea. It was impossible to arrange a trip to the deep sea. We did drop the camera in several places, between 25 and 45 m depth, and it worked very well. We are sharing some pictures and videos of the experiments. Now, in addition to fix the burn-wire, we want to refine the design of the enclosure and the mechanism to attach the lights.
In this video, you can see the footage of the camera while it is landing into the seabed.
In these videos, you can see some footage of the drop-cam:
We will make everything open source during the Fall.
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Dear @rjehangir and @WorkshopScience, please see a short video to describe our project and work in progress so far
Still more work to do to fix the burn wire and we plan to make everything open source in GitHub.
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Hello Pau,
Thank you so much for sharing, it is awesome to see your work and the footage looks great! The burn wire is definitely quite a tricky aspect to properly refine, in early trials we attached the entire drop-cam to a fishing line in order to have an emergency option of recovering it. If you are planning on trying it out at great depths where a fishing line wouldn’t be appropriate, I’d definitely recommend you take a look into galvanic releases as those are a cheap and easy method to guarantee a release if all else fails (albeit somewhat inconsistent timing-wise). I really look forward to seeing where you take this project and please let me know if these is anything I can help you with!
Kind regards,
Ivan
Nice work, @Paucam! This is a really awesome video and overview of your adventure! Thanks for sharing here.
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This is sweet, @Paucam! It’s been super fun to watch your project take life and we can’t wait for future updates 
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Very cool project! I’m still hoping to put together a drop cam of my own, so I’ll be keeping an eye out for the GitHub.
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Thank you! We will let you know when it is posted!
Hi Ivan, yes, we conducted our tests with the drop cam tied to a line, and also have galvanic time releases as a backup plan!
Dear @rjehangir and all, after three years since my last post here (I was pursuing other projects), I am happy to announce that I published the assembly guide and software to build the dropcam (called blue_eye) on GitHub. With this, anyone can contribute to the global movement of citizen science and ocean exploration. And the burnwire took a lot of work but now works fine!
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Hi @Paucam,
It’s great to see an update on this project - thanks for sharing, and great work on all your development and testing so far! 
Some comments, questions, and suggestions for potential future improvements:
- With our new Locking Enclosures (which you mention in the assembly guide) and WetLink Penetrators (which don’t seem to be mentioned), it could indeed achieve depths up to 500m
- potted penetrators may not consistently maintain a seal all the way to 500m - it depends a fair amount on the potting conditions
- note that it may be worth epoxy-coating (potting) the exposed end of the cable jacket (and/or use cable with a water-blocking filler) and the ends of the wires, to avoid the high pressure water pushing in past the insulation
- using a water-blocked connector could also resolve this issue, although is more expensive to do
- to get beyond 500m would require a thicker and/or smaller dome (perhaps the electronics could fit into a 3" enclosure?), as well as new lights (at some point we’ll be releasing a new iteration of our Lumens, which should be able to go deeper)
- It’s really cool to have a reference for a tested burnwire setup!
- I noticed that the guide example mentions it should burn for ~1 minute (section 4.16), but the code seems to tell it to burn for ~10 minutes - are these both just examples that depend on the wire being used, or were they supposed to both be the same?
- if an external pressure sensor or an accelerometer were integrated, it may be possible to “burn” until a consistent lifting starts occurring, with the timeout used as a backup to avoid excessively running down the battery if it doesn’t seem to be working properly
- I’m not sure how much current the burnwire setup uses when switched on
- if it’s significant, it may be worth providing a close or even direct connection to the battery terminals, to avoid burning out the breadboard traces
- for additional robustness, it may be worth covering the anode in moldable sealant, as electrical tape alone could still fail to keep the water out and end up corroding things
- I noticed that the guide example mentions it should burn for ~1 minute (section 4.16), but the code seems to tell it to burn for ~10 minutes - are these both just examples that depend on the wire being used, or were they supposed to both be the same?
- The “blue_eye” name is apt and interesting, but may be a bit confusing because there’s an ROV company called Blueye, so it could incidentally seem like this project is affiliated with them
- The photos and wiring layout diagrams in the assembly guide should be useful for replicating your setup
- it may also be worth creating an actual schematic, to better share the logical intent behind the circuit connections, and help people to understand which connections are being made and why
- there are free softwares that can make electrical schematics - Kicad is one for electronics design, and there are also a variety of online options, including just general diagram creation software that includes electrical symbols
- it may also be worth creating an actual schematic, to better share the logical intent behind the circuit connections, and help people to understand which connections are being made and why
- The usage guide refers to our Switch as an “electronic switch”, but I would personally consider it (and the reed switch) to be electrical switches (because they are not electronically actuated), while your relay would be an example of an electronic switch
- Given the two Lumen lights are sharing the same signal, it may be worth daisy-chaining them (or just getting a pre-connected set), to save a penetrator spot in the enclosure
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Dear Eliot, thank you so much for your feedback, it is terrific and you touch on several details that are critical for the device and also details to improve/correct the assembly guide. Will work on all them.
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Hi @Paucam! We’d love to feature this on our social media - is there anything you’d like us to highlight? Thank you in advance!
-Taylor
Blue Robotics
Customer Success and Subsea Social
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