Model 2 of my solar-powered, ePaper digital photograph body
It’s been over two years since I began tinkering with the concept of a solar-powered, ePaper digital photograph body. My first version was practical however had various points that made me return to the drafting board.
As a reminder, my objectives had been to construct a digital photograph body that:
- Requires no electrical outlet connection.
- Requires no type of upkeep. You place it up and it really works “endlessly” (it turns into a heirloom system).
- Makes use of both open {hardware} and open requirements or {hardware} and requirements which are so widespread that it ought to be trivial to carry out modifications or updates “a few years sooner or later”.
The largest situation with model one was the battery. After a couple of hundred load/unload cycles, it went bust — as I anticipated. There are various tasks and even industrial merchandise on the market utilizing a bigger li-ion battery than the one I used for my v1, a few of which promise as much as two refreshes a day, for a whole yr, earlier than needing to recharge the battery.
Many individuals would suppose that it’s completely acceptable for an object that for 99.9% of its life will simply cling there and be stunning. Many individuals are usually not me. I need my system to “be alive”. Refresh as a lot or as little as it may well, following the cycles of nature (in essence: use as a lot mild because the panels obtain to energy the system). And naturally, there nonetheless isn’t a tool fairly prefer it on the market, so bonus factors for engaged on one thing novel.
One other situation with v1 was its wastefulness. A complete Raspberry Pi needed to be powered and booted to carry out the picture swap. There actually is not any want for all that {hardware} to alter an image.
V2 fixes these two major points. It does away with the battery, changed with an enormous, fats capacitor. And the Raspberry Pi is now slimmed right down to an ESP32 microcontroller. In a nutshell, the photo voltaic panels slowly cost the capacitor. When a sure voltage is reached, the circuit is opened, powering the ESP32 which boots a easy program that both downloads a photograph from a server, or retrieves it from an SD card, and shows it on the ePaper display screen. Shortly after the operation is concluded, the capacitor’s voltage drops under a sure threshold and the circuit closes, restarting the cycle.
This digital black magic known as a photo voltaic engine.
V2 requires fewer photo voltaic panels, performs its obligation quicker, and may doubtlessly preserve doing its job for a lot of, a few years (tremendous caps lifecycle is measured in tens of millions of cost and discharge cycles). My first V2 prototype is now 2 years sturdy and all the things seems to be in good form.
Thus far I’ve constructed three completely different prototypes for V2.
Issues appear to be working properly. Granted, I’ve solely examined this the place I lived, sun-bathed locations like California and Florida, the place I can get a number of photograph swaps a day even on a cloudy day (it stays paramount to choose a great spot for these frames, as shut as potential to a window with good solar publicity). It in all probability wouldn’t work as properly in Belgium or New Zeland, although even there the solar ultimately comes out. And the great thing about this design is which you can neglect concerning the system, till it astonishes you with a beautiful photograph that you just didn’t even bear in mind you took. As a result of, let’s face it, one of many curses of our age is being too busy taking footage, and hardly having any time to look at them.
I’m now engaged on the next decision, bigger 7-color display screen. One factor I’d prefer to check out is to get energy from an alternate supply. Two candidates: inductive charging, or a spring charging mechanism, like grampa’s clock. It’s a heirloom, in spite of everything! On the software program entrance, I’m cleansing up the server-side portion of the code, which robotically synchronizes with a media supplier resembling Google Photographs or Flickr (arguably the a part of the undertaking which is able to turn into out of date the quickest).
How a lot does it value to construct a type of? A superb rule of thumb is {that a} first rate picket photograph body with non-reflective glass prices as a lot as an ePaper display screen. So say you spend $100 for the body, and $100 for the display screen (plus management interface). Add about $50 for the ESP32, the panels, and the photo voltaic engine. You’re now at $250. Except you worth your time very low, you in all probability must consider simply as a lot for the manufacturing course of. There you’ve it, a $500 custom-made photo voltaic photograph body.
At that value level, limitations, and basic degree of curiosity, I doubt it is sensible to arrange an effort to commercialize one of these product, whilst a restricted version. One factor I can do, although, is to publish as a lot materials as potential to allow anybody to construct their very own. I began doing so on this repo.
One thing that might enormously simplify the duty can be to provide a PCB with the photo voltaic engine connecting the photo voltaic panels and the ESP32. However even then, assembling all the things collectively restricts this undertaking to tinkerers comfy with soldering irons, compiling ESP32 code, and customarily getting their fingers soiled.
Except you recognize one thing I don’t, and also you suppose each family ought to have one in all these, through which case, please ship me a message.