What is It
How often have you sent off a message in a bottle, only to realise, as it floats out of sight, that you regret the contents of your message? Well, with the Text Message in a Bottle (TM) that will no longer be a problem! You can update your message at any time, just by sending a text. Fantastic!
Why Did I Build It
I have been following the oodles of submissions to the LinkIt One MediaTek Collection, and most of them are without housings, even projects like weather stations that are ostensibly for use outdoors, so I decided to demonstrate a simple waterproof project with off the (kitchen) shelf parts.
Features (or, what you can learn in this Instructable)
My original plan was to make a completely self-contained, solar-powered, WiFi-hotspot-in-a-jar, that would allow people to connect and download files or leave notes on a web server or something, but unfortunately the LinkIt One does not support running the WiFi in Access Point (AP) mode.
My next idea was to the same sort of thing using Bluetooth, like some shops do, where they send you an image or message when you come in range (proximity marketing), but it seems that this is also not yet in the API.
The MediaTek LinkIt One is an Arduino-compatible board with some very cool features built in, in this project we are using the built-in GSM for receiving SMS messages as well as the built-in battery charger to charge the included battery.
A prepaid sim-card that can receive text messages. Preferably one without a PIN.
I used 3 long narrow 8-10V solar panels of approximately 1W output, I got them out of broken/obsolete equipment, so I don't have any info at all on them.
You should be able to buy things like this easily on sites such as Aliexpress if you don't mind waiting for the shipping.
I chose the Power Trends PT78ST105S because I had one lying around, here are its specs
Input Voltage: 9-38V
Output Voltage: 5V
Output Current: 1.5A
I used a knock-off of Duct Tape to turn the three solar panels into a foldable unit, as well as to attach the various modules to the back of the panels. It looks like a hack job when open, but when folded up it is rather neat.
Jars designed for pickling or jams are ideal, because they have wide necks. I couldn't find a large enough Mason Jar, which i think would be the best, so I chose a 1.5l swing top instead.