It’s been a little while since the end of my latest Kickstarter, a kit to drive 2 IN-9 nixie tubes and it’s been a very busy time. However, after a few hurdles rewards are being shipped. To go along with the shipped rewards I have written a few example Arduino sketches and an assembly guide. These can be accessed from a new tab at the top. This will take you to a page covering how to assemble the kit and a link for the necessary Arduino sketches.
It was a pretty straightforward task to assemble the bits into a functioning 4×4 nixie matrix. The tubes are mounted on spray painted black MDF with the PWM driver mounted on the back. They are each held in place with a small square of double sided foam tape. Wires soldered on the back to the tubes create a small nest and will be more neatly managed of the bigger version. I programmed an Arduino with the Adafruit pwmtest example and it all works fine. In fact, it works much better than I expected and I think I’m ready to go full scale, with no real modifications. All seems too easy.
I did a measurement of power consumption and the 4×4 uses a power of 1.8W, so will need about 15W for going full scale. Not too bad really for 128 tubes.
I recently bought a few (200) IN-3 nixie bulbs. Unlike the familiar numeric tubes or the bargraphs I’m fond of, these are just little bulbs. They have commonly been used as dots between digits in clocks and alike. Not content to make just another run of the mill Nixie project I decided to build a Nixie matrix, much like an LED matrix but with the lovely orange glow. My eventual aim is an 8×16 matrix, enough to display basic numbers and graphics. Though I’m starting with a simpler 4×4. This does provide the first challenge, how to drive so many tubes? The common way is multiplexing, however, since this is a one-off build and additional electronics isn’t too important (I’m not trying to optimise a BOM and a bit of extra work is fine) I have opted to directly drive each IN-3 tube. Not only drive each tube on and off but with a PWM signal. This should allow nice brightness variations and fading effects across the matrix. Pretty sexy. So now I just need 128 PWM channels… For ease I’ve gone for a 16 channel LED PWM driver (PCA9685). There’s even a nice Adafruit library for quick Arduino testing. It’s I2C so I intend the chain 8 of them together, these are driving mosfets that switch the high voltage tubes. (I’m also putting together an IN-9 driver kit (watch out Kickstarter…) so I have an abundance of high voltage supplies.)
So far I’ve fully soldered up 4 boards and tested one with 16 tubes. All working nicely. Today I’ve cut out a small 4×4 MDF board to make up a little test board to get everything right before I go full scale. So far, it’s all be smooth sailing. Wonder how long that’ll last.
Being Christmas I wanted to make something for the festive table. I also haven’t made a carving for myself in a while. I decided to make a tealight candle holder out of some discarded mahogany I had. The design is the superposition of 3 functions, each ripple out from a point, where the candle sits. The waves interfere with each other over the wood and reflect the candlelight. Looks pretty neat.
Now the clock is finished and working beautifully I’ve decided to list it as a kit onTindie. In the kit, you’ll receive the populated board, nixie tubes and a battery. With this kit, all you have to do is mount it and make your own bargraph clock! Just click this link!