Nixie Tube Calculator!
How Nixie Tubes Work
A nixie tube is a small tube that is filled with neon gas. There is a grid that is charged to 180V, and filaments shaped like the numbers 0-9, one of which is connected to ground. Electrons travel through the neon from the grid to the filament, and when they strike the filament the neon around it glows with a warm orange light.
How the Display Works
There are ten tubes, and each tube has ten filaments. To save component count, I use a technique called multiplexing. This means I light one tube at a time, but switch the tube that's lit so quickly that the eye can't follow it, so it seems like all the tubes are lit, albeit more dimly.
The switching is done with high voltage transistors that are connected to I/O pins.
The Arduino sketch for the calculator is here. This github link also contains the eagle files for the board.
I am redesigning the board to handle some issues I found with the previous rev. I had swapped the Base and Emitter leads of the high voltage PNPs, and miscalculated the resistor values for the PNPs.
There will be 3 boards that comprise the calculator:
- A high voltage board will have the 9V-180V boost supply and high voltage transistors
- A logic board will contain the microcontroller circuit (ATMega328) and shift registers
- A Nixie carrier board will allow me to support all the popular tube types
I also want to add in fuses and other safety considerations, since there will be 180V on this board.