How can you Arduino drive 81 nixie tubes? It’s easy with open source hardware. I was inspired by two excellent projects: the Arduinix and the Ogilumen Nixie Duo and Nixie Driver kit. I highly recommend both to anybody who wants to start playing with nixie tubes.
What’s so great about Arduinix? It has a simple, inexpensive 555-based boost converter to generate the high voltage necessary to operate the tubes, and it lets you multiplex the tubes. The power supply is on the right. On the left are four high voltage anode pins and 20 cathode pins connected to two 74141 driver ICs. In between the drive ICs and the power supply are high voltage transistors that enable multiplexing. This configuration allows you to control up to 8 tubes.
What’s so great about the Ogilumen kit? It puts the tubes on top of the drive components, and it lets you cascade multiple drive boards. Each driver board has a shift register that enables the cascading. With a high current power supply, you can control up to 12 tubes.
I decided to combine my favorite features from these projects and have mutliplexed tubes on top of cascable drive boards. I designed a board that allows you to control 9 tubes multiplexed in a 3×3 configuration. It uses a 555-based boost converter power supply, multiplexing high voltage transistors, shift registers, and of course 74141 driver ICs. Of course I still needed an easy way to control 9 driver boards…
I decided the simplest way to control everything (and get instant blog cred) was to use an Arduino. 9 digital outputs control three banks of shift registers, 5 digital I/Os get information from the keypad, and two analog inputs get information from potentiometer knobs. (I’ll talk more about the control software in a later post.)
To increase the mechanical stability, portability, and awesomeness of the project, I ordered a custom case from Ponoko. The case really takes the project to the next level, and it hides all of my crazy wiring. Designing and ordering it was a learning experience, but these days no project is complete until it has a custom case.
And that’s all the hardware you need! Simple really. If anybody is interested in building their own I have some spare development boards around here somewhere…