Dr. Scott M. Baker

Nixie Calculator Update – PCB availability, source code, design notes

by admin on Aug.21, 2016, under Electronics Projects

The nixie tube calculator project was not funded on kickstarter, and I recall some time ago promising to make the boards and other resources that I used for constructing the prototype available. Well, it’s taken a while but I’ve finally got around to it.

I’ve made the boards available on Osh Park, which is the same site I ordered my prototypes from. Osh Park always sells boards in quantity of 3. To build the same calculator I built as the prototype, you’ll need 2 nixie display boards, 2 4×4 keypads, 1 2×2 keypad, and one power supply board. You’ll also need a raspberry pi. Since the boards are sold in quantity three, you’ll generally have at least one board leftover. Put it to good use in some other project. ;)

Use these ordering links at your own risk. I make no money off of the Osh Park sales, and I accept no responsibility for the quality of the board or the accuracy of the layout or the proper functioning.

The link to the original blog post on the calculator is here: http://www.smbaker.com/nixie-tube-calculator-powered-by-a-raspberry-pi

Nixie Display board

Order from OSH Park

4×2 keypad

Order from OSH Park

4×4 keypad

Order from OSH Park

High voltage power supply

Order from OSH Park

Source code

The source code can be found at my github repository at https://github.com/sbelectronics/nixiecalc

Wiring the calculator

The I2C bus is daisy chained from one board to the next. A short cable connects the raspberry pi to the leftmost 4×4 keypad. There are five wires: 3.3V, SDA, SCL, G, and 5V. Right angle headers are used to connect that keypad to the middle 4xz4 keypad, and right angle headers are then used to connect the middle keypad to the rightmost 4×2 keypad. A short cable then goes from the rightmost 4×2 keypad to the rightmost nixie display board. Right angle headers connect the two nixie display boards together.

Setting the addresses of all of the I2C devices is important. Each board (keypad, nixie display board) includes two or three jumpers for this purpose. There can be eight devices on the I2C bus. Each display board consists of two devices. Each keypad has one device. This adds up to a total of 7 I2C devices.

TODO: add picture of jumper configurations for keypad boards and nixie display boards.

The power supply board includes a 5V output for powering the raspberry pi and the other boards. I spliced the 5V supply into the 5-wire cable that goes from the pi to the leftmost keypad.

A single high voltage wire goes from the power supply board to the rightmost nixie display board. The high voltage is daisy changed from the rightmost nixie board to the leftmost using right-angle headers.

There isn’t much space between the leftmost keypad and the rightmost keypad and the case edges to plug in the cables. For this reason, I made some right-angle adapters by soldering a male angle header to a female straight header.

The case

The case for the calculator was fabricated by Ponoko.It is constructed of laser cut acrylic and uses 4-40 fasteners.

TODO: Figure out if there’s a way to share it on the Ponoko site, provide material details.


1 Comment for this entry

  • Matt Greer

    My compliments on a great concept and implementation. I’m interested in taking on the project… would you be willing to provide a bill of materials and interconnect diagram on a paid or open source basis? I’m reasonably competent with electronics and Ardiuno projects, so feel confident in taking on the project with just a little more info. The Raspberry pi should be easy for me and I have nixies, pins, etc.

    Thanks

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