If I wanted to build something that can function underwater, what would I need to buy so that the spark core is protected? Or is this not possible?
the RF waves don’t place nice when things are under water…
You can place them in a water tight enclosure sold in hardware shops if you would like to try
I wonder if this would be a good scenario for an external antenna? I imagine you could run it up to a buoy or something floating on the water
This topic might be of interest:
Power will be an issue for anything enclosed and underwater. Depending on the depth of the device, you could look at a solar panel but getting the amps up and having a rechargeable battery will be another challenge. The other issue is the distance between the device and the signal tower. As mentioned earlier, water is a poor signal carrier. You could overcome the signal problem by attaching an antenna to the buoy above the waterline. Salt water messed things up bad though with rust. You could look at marine antennas built for such an environment.
If you were building a mesh system you could use other radio signals like UHF, VHF, FM or AM. Those signals could be gathered up by a communication box on dry land that translates the information and sends that data via 3G to your location. There are several ways to look at this project that would use minimal power, low costs, high availability and low maintenance requirements. I know of several Raspberry Pi projects that are also submerged to collect fish data, water temps and so forth. Talk about phishing, oh my.
Have you looked at potting electronics? Not sure if this is enough for your use case, but here is a video where silicone is used to completely encase and waterproof electronics:
I am not sure, but wouldn’t something like that create heat issues? The cc3000 chip gets pretty hot (I think in a topic it was 58 ish Celsius). Insulating might make it run too hot and cause damage and/or shutdown (don’t know if it has thermal protection build in).
It is possible to read the temperature sensor though so you could use that during testing and see if it gets too hot.
Internal temp topic : http://community.spark.io/t/core-internal-temperature-sensor/3515
Thanks for the link @Moors7.
RF Waves won’t travel very far underwater - we had a Bob (see linked post above) in a tank last week - with a small external stubby antenna in the dome we could keep a connection in the top 10cm of water. On a dive with the antenna about 50cm underwater it lost connection until it returned to the top - this is the reason our Bob and also the Argo Floats / Slocum gliders deployed at sea will always have to return to the surface periodically to connect and transmit data / receive instructions.
Heat can be an issue in an enclosed container - but prudent placing of the electronics can help alleviate it a bit. Water is very good at diffusing heat away (I think it has about 20 times better thermal diffusion than air) which is why you tend to wear wetsuits, when diving, even in relatively warm water - so placing the warmer parts of the electronics towards the skin of the container can help keep heat more controlled than having them towards the centre of the container or boxed in.
We ran tests from about 9am to 4:30pm for four days last week - whilst the inside “felt” warmer when we opened the containers afterwards - it wasn’t anything that concerned us - we had the Spark processor facing the heat sink of a power regulator in the centre of the container (pretty much the opposite of what I suggested above) to see if anything shut down.
We’re going to re-position things in the right places and run some longer tests in the next few months and will update, but if anyone has any questions or wants us to check anything out then please do shout.