High Voltage Power Supply for Nixie Tube Projects


This project is a HVPSU (High-Voltage Power Supply) that generates up to 220V from a 12V input. In addition to that, it also provides 2*Vout (so, up to 440V, for dekatrons), and two outputs for powering digital logic: 5V and 3.3V. The primary HV boost circuit reaches 88% efficiency when going from 12V to 185V at 55mA, with a 3% output ripple.

I designed it because I couldn’t find anything that would make sense for my Nixie projects. There are plenty of tiny power supply modules available on eBay, but most of them end up being impractical: no 3.3V (for my microcontroller) and 5V (for my 74141 nixie drivers), no mounting holes, no >400V output for powering dekatrons. Some supplies make a token gesture towards practicality by sticking a 7805 on the same board, but you quickly find out that the current draw of 6×74141 is enough to require a large heat sink on a 12V-powered 7805 (one 74141 consumes 12.5mA!). This means that instead of a single-board power supply you end up routing your input power all over the place, implementing your power supply in several places.

I wanted to have something versatile enough so that I could use it in a number of projects: with nixies, dekatrons, other tubes, VFDs, phone ringers, etc. I also wanted it to fit on a 5x5cm PCB, so that I can order 10 PCBs for $10 at iteadstudio.

The version I’m posting online is not perfect, but works quite well in a number of my projects. I decided I’d rather publish it as it is now rather than keep it locked forever.

High Voltage Power Supply for Nixie Tube Projects

The circuit and PCB you see are the result of multiple iterations. I started out with a design based on MAX1771, which turned out to have stability problems, mostly due to EMI on the feedback pin. I then went through seven board designs, trying to make it work. I ended up with a design that mostly worked, but exhibited uncontrolled behavior in some conditions (load transients, overcurrent, EMI). I finally got tired of the MAX1771 chip and decided to look for another solution.

I chose the TPS40210 from Texas Instruments, which seemed to be a solid performer in high-voltage boost applications, was easily available, not too expensive. The existence of an automotive-grade version also means that the chip won’t disappear anytime soon. I went through three board revisions with the TPS40210, which were mostly about shrinking the design and adding the TPS62160 buck converter instead of a 7805 to produce 5V.

n the process I learned a lot and discovered that there is a lot of stuff about boost converters that I didn’t even know I didn’t know. Here are a few examples:

  • Loop stability: I had no idea why it was an issue or how to design loop compensation (TI’s SwitcherPro is really helpful).
  • CCM vs DCM and transitions inbetween.
  • Current-mode control sub-harmonic instability in continuous conduction mode.
  • RC snubber: do you know about parasitic ringing on the switching node? That ringing that your scope probably won’t show, because it’s above 500MHz?

I now know slightly more, but the circuit certainly isn’t perfect. I don’t even have the equipment to measure some of its properties, so I have to leave it as it is.

There are two principal reasons for making this available as an open-hardware project:

  • I learned a lot by studying the designs of others, and I felt I owe the community something in return (Nick de Smith’s Nixie HV Switching PSU page was especially helpful).
  • Most Nixie PSU designs I saw online are based on the MAX1771, and apart from people hacking crude 555 supplies, there seems to be little variation. I thought an alternative should be out there.


  • Generates 4 voltages from 12V input:
    • Vout: up to 220V at up to 80mA, 2-3% voltage ripple
    • 2*Vout (optional): up to 440V at up to 30mA
    • 5V at up to 1A at ~85% efficiency for older digital logic such as 74141 Nixie drivers (compare to about 40% efficiency if a 7805 is used)
    • 3.3V for modern digital logic (microcontrollers, etc)
  • High-voltage DC-DC converter can be shut down digitally to save power
  • Can be used with many different power inductors, depending on desired output power:
    • SMD 12.5×12.5mm
    • THT vertical barrel type, rasters of 5mm, 8mm, 11mm
    • THT vertical toroidal type, 8mm raster, up to 23.5x11mm
  • Known & fixed switching frequency (50kHz)
  • Nominal input is 12V, can be up to 16V
  • Safety features: overcurrent protection, thermal shutdown, slow-start.

Downloads, Release Notes and Licensing

  • Schematic as a PDF file
  • A zipfile containing the schematic, PCB, Eagle .sch and .brd files, and Gerbers prepared for manufacturing at iteadstudio.
  • There is also a partlist, as generated by Eagle. Not a real BOM, but at least you’ll know what to need and what resistor sizes to use.

Version 2.2 is what I use in all my projects. Version 2.3 has several tiny fixes: adjusted position of mounting holes, added comments in the schematic, but is otherwise identical to 2.2.

I wanted to pick an Open-Source Hardware license, but couldn’t find one. There is lots of talk about Open-Source Hardware, but when you actually want to open-source something, it turns out it isn’t easy.


For more detail: High Voltage Power Supply for Nixie Tube Projects

About The Author

Ibrar Ayyub

I am an experienced technical writer with a Master's degree in computer science from BZU Multan University. I have written for various industries, mainly home automation, and engineering. I have a clear and simple writing style and am skilled in using infographics and diagrams. I am a great researcher and is able to present information in a well-organized and logical manner.

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