Nixiedisp is a 6-digit nixie tube numeric display, software-controlled over USB or RS232, that also functions standalone as a clock.
Features:
git repository: https://github.com/jtsiomb/nixiedisp
Copyright (C) 2020-2021 John Tsiombikas <nuclear@mutantstargoat.com>
All hardware designs and software in this project are free. Feel free to use, modify, and/or redistribute under the terms of the GNU General Public License v3, or at your option any later version published by the Free Software Foundation. See the full license text for details.
nixiedisp rev2 schematics (PDF)
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| main | nixie tube drivers | power supply |
nixiedisp rev2 gerbers (for PCB manufacturing)
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| front copper | back copper |
The BOM is available in CSV or open document spreadsheet format.
I have included mouser product ids to make it easy to order the components. Simply upload bom.csv to the mouser BOM tool, designate the quantity and mouser-id columns, and add everything to the cart. It's worth going over every item and changing the quantity to something that makes sense though. Mainly to have spares, but also because buying a single 0805 resistor is ridiculous.
| # | Description | Footprint | Mouser ID |
|---|---|---|---|
| 1 | CR2032 battery holder | SMD battery holder Keystone 1060 | 534-1060TR |
| 15 | 0.1uF capacitor | SMD 0805 | 581-08055C104K |
| 2 | 22pF capacitor | SMD 0805 | 80-C0805C220K1HACTU |
| 1 | 2.2nF capacitor | SMD 0805 | 187-CL21B222JBANNNC |
| 5 | 1uF electrolytic capacitor (RS232 option) | SMD electrolytic 4x5.4 | 710-865060640001 |
| 2 | 0.33uF electrolytic capacitor | SMD electrolytic 4x5.4 | 710-865230640003 |
| 1 | 220uF low-ESR electrolytic capacitor | SMD electrolytic 8x10 | 667-EEE-FP1V221AL |
| 1 | 10nF capacitor | SMD 0805 | 187-CL21B103JBANNNC |
| 1 | 2.2uF 250V electrolytic capacitor | Through-hole radial | 647-UVR2E2R2MED1TD |
| 1 | 1N4148 diode | SMD SOD-323 (0805) | 750-1N4148WS-HF |
| 1 | MUR160 diode | SMD DO-214A (SMB) | 821-MUR160SR5G |
| 1 | DB9 male connector (RS232 option) | Through-hole DB9 male | 523-L717SDE09P1ACH |
| 1 | Micro-USB connector | USB Micro-B Molex-105017-0001 | 538-105017-0001 |
| 1 | AVR programming header | 2x3 male pin header 2.54mm pitch | 710-61200621621 |
| 1 | DC barrel jack | barrel jack 2mm center pin | 490-PJ-202A |
| 1 | Hour-separator LED connector | 1x3 female socket 2.54mm pitch | 538-90147-1103 |
| 1 | power jumper/switch header | 1x2 male pin header 2.54mm pitch | 538-22-28-4112 |
| 1 | 220uH inductor | SMD inductor 14x18.3 | 652-SDR1806-221KL |
| 2 | MMBTA55 PNP transistor | SMD SOT-23 | 863-MMBTA55LT1G |
| 66 | MMBTA42 NPN transistor | SMD SOT-23 | 863-MMBTA42LT1G |
| 1 | IRF740A MOSFET | SMD TO-263-3 | 844-IRF740ASPBF |
| 4 | 10k resistor | SMD 0805 | 71-CRCW080510K0JNEAC |
| 66 | 47k resistor | SMD 0805 | 652-CR0805FX-4702ELF |
| 6 | 160k resistor | SMD 0805 | 660-RK73H2ATTD1603F |
| 3 | 1 ohm resistor | SMD 0805 | 603-RC0805FR-071RL |
| 2 | 1k resistor | SMD 0805 | 71-CRCW08051K00JNEAC |
| 6 | 24k resistor | SMD 0805 | 660-RK73H2ATTD2402F |
| 1 | 475k resistor | SMD 0805 | 667-ERJ-6ENF4753V |
| 1 | 3.32k resistor | SMD 0805 | 71-CRCW0805-3.32K-E3 |
| 1 | Right-angle tactile button | SMD right-angle | 113-TA34W2VTR |
| 1 | Atmega328PB-AU microcontroller | TQFP-32 | 556-ATMEGA328PB-AU |
| 6 | 74HC4514 demux | SOIC-24 wide | 771-74HC4514D-T |
| 1 | MAX232 level converter (RS232 option) | SOIC-16 | 595-MAX232DR |
| 1 | 74HC126 3-state buffer | SOIC-14 | 595-SN74HC126DR |
| 1 | DS1302Z+ RTC | SOIC-8 | 700-DS1302ZT&R |
| 1 | MC34063AD switching controller | SOIC-8 | 595-MC34063ADR |
| 1 | 7805 voltage regulator | SMD TO-252-2 DPAK | 863-MC7805CDTRKG |
| 1 | MCP2221AxSL USB interface IC | SOIC-14 | 579-MCP2221A-I/SL |
| 3 | 74HC164 shift register | SOIC-14 | 771-74HC164D-T |
| 1 | 14.7456MHz crystal | SMD crystal ECS CSM3X 2pin 7.6x4.1mm | 815-ABLS7M-14.745B2T |
| 1 | 32.768KHz crystal | SMD crystal 2-pin 2x1.2mm (alt.footprint Y3) | 815-ABS0632768KHZ61T |
| 1 | 32.768KHz crystal | Through-hole crystal 3x8mm (alt.footprint Y2) | 695-CFS-20632768EZBB |
| 2 | Amber 3mm LED (hour sep.) | Through-hole 3mm LED | 859-LTL-1CHA |
| 6 | IN-14 nixie tube |
You don't need both of the 32.768kHz crystals in this list. They are just alternative footprints. You should only populate one or the other.
Also, all items marked as (RS232 option) can be omitted if you don't need the serial port, in which case skip them, and also install a 10k pull-up resistor across the J7 pads (marked usbpwr on the silkscreen). The opposite (having only the serial port and no USB) should also be possible by leaving the USB connector and the MCP2221 chip unpopulated, but that's currently untested. Let me know if you try it.
With current (Feb 2021) prices, without the nixie tubes, these components cost around 30 euros.
ИН-14 (IN-14) nixie tubes obviously cannot be purchased through electronics distributors in the 21st century, but they usually go for around 10-15 euros each on ebay, desoldered from old equipment. Make sure the left-side decimal point wires are intact, because nixiedisp uses them. Some sellers have tubes with the decimal point wires cut very short.
The git repository contains only source code. If you want pre-compiled firmware images, you should download one of the official release archives.
To program the AVR microcontroller with the nixiedisp firmware, you'll need an in-system programmer with the standard AVR 6-pin programming header.
Under the sw/ directory of the project you will find various programs and scripts that can be used to manage the nixie display through USB or a serial port. Among them is a graphical tool called nixiedisp-gui which can be used to configure device settings, set the time and date for the clock mode, and more.
The git repo contains only source code, but you can download one of the release archives, which includes pre-compiled binaries for various systems.
A partial 3D-printable enclosure is included (base.stl), which covers the bottom of the PCB where most of the potentially dangerous high-voltage parts of the circuit are located, and also acts as a base for the device. Only a very small area of the top of the PCB has high voltage present, for extra safety a small cap which clips into the side of the enclosure is also included (hvcover_cap.stl).
If you intend to use the board without the bottom cover, an alternative version of the top-side high-voltage cap is provided which protrudes slightlty and clips onto the side of the PCB instead (hvcover_pcbclip.stl).
Download nixiedisp rev2 enclosure: contains OpenSCAD source code for the main part, Blender file for the top-side HV-cap, and pre-generated ready-to-print STL files for both parts.
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