This one's still a work in progress, but I figure I'm far enough along now to post some information about it.
I love nixie tubes. I also have made a few timepieces in the past and have been looking for a good project to familiarize myself with the efm32 line of microcontrollers (I just started here at SiLabs a few months ago, and have been working solely with em35x silicon so far). So I decided that my desk needed an efm32 based nixie clock as a piece of office flair
The first step to this project was getting the electrics managed. Each of those tubes requires 180V DC to ignite the filament, which is slightly higher than the an efm32 can tolerate as input voltage. I designed a circuit board that uses an inductor, a 555 timer, and a feedback resistor to take in 9V drom a wall wart and 1) boost it to 180V for the tubes and 2) pass it through an LDO to power the micro controller. I added a 16 pin 100 mil header for each set of two tubes, which in turn goes to a duplex daughter board.
Each daughter board contains all the tube specific hardware for two IN-12A tubes (the idea being I can make a different daughter board for different types of tubes in the future without having to re-spin the main board).
Once I had my circuits made, it was time to write the software. I used a wonder gecko starter kit, because it is roughly the size of my booster board and has enough GPIOs that I didn't have to rely on an external shift register to handle the tube control (please forgive the choice in case here, it was the best I could do in 10 minutes with an x-acto knife : )
I eventually want to use a Blue Gecko for this project so I can add some fun controls over phone via BLE. Once I get the software for that good to go, I plan on spinning either a version of the boost board that has the gecko on board or one that is compatible with the 100 mil headers on the Gecko kits, which will obviate the need for all the messy wires.
Once I had all the software done and the tubes working, it was time to make a housing. My goal is to have the tubes mounted on side lit etched acrylic, with all of the circuitry visually exposed behind the tubes. First step here was to do a quick design using the Silicon Labs logo and the Gecko emblem. I'm still considering making some changes here, so if anyone reading this has graphic design experience and can provide feedback, I'd be very open to constructive criticism or assistance. Once the design was made, it was off to the laser cutter to etch the design and cut out the acrylic. I was pretty happy with the results.
On a side note, I can not use a laser cutter without marveling at what a huge feat of engineering achievement they are.
I was unfortunately very rushed when doing the acrylic design (I was running at the end of a borrowed half hour's time on the laser cutter), so mistakes were definitely made with respect to sizing and boundaries. It was still good enough to get the tubes to fit in the holes, though, which was the primary objective.
For the prototype, I decided to use red oak to hold the acrylic. I cut a channel a bit bigger than the acrylic and will eventually be gluing everything together. I'm very happy with the results so far, especially considering this is the first attempt at doing an enclosure of this type. My WS2812b LED strips arrived in the mail over the weekend, so hopefully I'll have the software to drive them done soon. I also have better acrylics and a t-slot router bit on the way in the mail, which will (hopefully) allow me to get a better mounting solution in place. I'll update this post as I make more progress, but feedback is certainly welcome at this stage
I'd like to show and get feedback from the community for a project I started some time ago.
I intend to use the Si504 as the local oscillator in ham radio projects.
The main project page is here. The first version of the firmware is made to run on an Arduino
board but I intend to have a standalone module which can receive commands over I2C and
then internally talks to the Si504.
There are some concerns about the phase noise of the Si504 for which I will have some (hopefully
promising ) measurements ready in the months to come.