Here’s a nice little project that tickled my fancy for a couple of reasons; mainly because it’s very nicely executed, but also because it’s quite complex (by yesterday’s standards) yet still quite simple (by today’s). It’s very well thought out and put together, but unfortunately you’ll need access to a 3D printer to be able to replicate it all yourself.
The basic function of the unit is to plug-up the receptacle of a cell-phone wall charger (when the cell phone is absent) to prevent the flow of electrons from trickling out all over the carpet. While performing this useful function, it also provides an up-to-the-minute weather report for your chosen area, using the magic of an ESP8266 module in conjunction with a small OLED display.
The weather display is something we’ve seen before in previous projects elsewhere, but the cute part of this particular project is the 3D printed case. Because the charger might be plugged into a wall socket near the ground, or perhaps into a kitchen counter-top socket (or somewhere even closer to eye-level), the creator has designed a case with a ball-joint coupling, to allow the display to be tilted to the optimum angle for viewing. Another neat feature is that the OLED will update to display in either landscape or portrait mode, initiated by a tilt switch attached to one of the ESP8266 pins.
All of the files for the project, both for the firmware and for the 3D print, are available from the author’s GitHub repository.
Possibly the only thing I’m not too keen on in this project is the author’s use of a couple of diodes, wired in series, as a method of supplying the ESP8266 and screen from the 5v charger output. This is what we used to call (many, many, many moons ago) the “wattless-dropper” method, but that was back when the alternative was a very large, wire-wound resistor. (Yes, I’m being wildly liberal with my use of the term, so does anyone care to expand on the critical difference between this usage and a real “wattless-dropper” application? Answers on a postcard…) .
At any rate, the actual drop across a silicon diode tends to vary somewhat when the current passing through it is very small, so if you do decide to replicate this build, I’d recommend going with something like the Holtek HT7333 (LDO regulator with an exceptionally low quiescent current), instead. Other than that, this is definitely a weekend-doable project, even if you house it in a used pastel tin and use a chopped-off bit of old USB cable for the connector (…and assuming that you don’t have to wait three weeks for parts to arrive from the Middle Kingdom).
Kudos to WillFly, aka Ardyesp for bringing together all of these elements into such a neat little device. Can I point you in the direction of Tindie? There’s a positive dearth of decent ESP projects over there at the moment.