NixieNet is a Wi-Fi enabled Nixie Tube clock. The retro appeal of these 1960's era vacuum tubes is combined with the convenience of being able to automatically set your clock using an internet hotspot. One extra feature is a mini-forecast of the next 12 hours around a chosen zip code, allowing you to plan the next part of your day at a glance.
This project is a stopgap on my way to building a ground-up "Internet of Things" base design around the ESP8266 SoC WiFi solution. I started by taking a few nixie tubes I've had lying around from a past project, and connecting them to a Nixie Power supply I found on ebay http://www.ebay.com/itm/Berkeley-CA-NCH6100HV-High-Voltage-DC-Power-Supply-for-Nixie-Tubes-MagicEye-/181788483994?hash=item2a5370219a
. After making sure they lit up, I wired the Nixies up to a HV5622 chip (which anyone who makes Nixie clocks should really consider for their designs) http://ww1.microchip.com/downloads/en/DeviceDoc/HV5622%20C072313.pdf
. This chip is basically 4 '595 shift registers in one package with HV current sink outputs, meaning you can control 32 nixie elements using just this chip and 3 microcontroller pins. For this clock, I used 30 outputs for driving the 0-9 digit elements on three of the nixie tubes, with the leftmost tube only having 1 and 2 driven by the chip, making a 24 hour clock possible with a single chip (midnight looks like 0:00). After testing out driving the chip with an ESP8266 and a simple level shifter from SparkFun https://www.sparkfun.com/products/12009?gclid=CMz2qujL_scCFcOQHwodiIwF4w
, I took 6 nixie bulbs and wired them to a Russian 74141 clone chip that came with the bulbs http://tubehobby.com/datasheets/k155id1.pdf
. These would become the colon of the clock, giving me 4 bulbs to use for displaying the weather forecast. Using the OpenWeather API (after signing up for it and getting an API key), I was able to pull in the weather forecast for the next 9 hours in 3 hour intervals using a simple HTTP GET. Checking the JSON data returned using simple string matching functions is a snap, and I programmed the clock to light up a bulb for the 'worst-case' forecast for the next 9 hours. Meaning, if it's going to rain and then be cloudy, the bulb for rain will light up. After everything worked great on the breadboard, I designed a PCB in Eagle and a nice case in FreeCAD, then shipped off the parts to be made by my favorite services (OSHpark for PCBs and Ponoko for the laser-cut acrylic and walnut). I chose the silver acrylic and walnut MDF to give my piece a 'wood/metal/glass' motif, but cutting out an actual aluminum panel would be way beyond the cost of this simple project, and the silver acrylic honestly looks really good. The bulb for telling you the weather shines through the cutout for the weather's symbol (I should work on diffusing it a bit, but I'm happy with how it works for myself). The schematic makes heavy use of SparkFun's level shifter schematic for the ESP8266 -> everything else, and the HV section should be interfaced with a suitable Nixie driver. Also there's some confusion with using GPIO15 for anything, so if you're going to remake this, I would suggest playing around with the pin mapping (none of the pins need to necessarily be the ones I used, play around with them and see what works for you :) ).