High Voltage Nixie Power Supply: from idea to production Part 1: The Idea

This is a multipart series on how to design an efficient and modern high voltage nixie power supply, from the idea to shipping it to customers worldwide.

Summary

The idea to build a good power high voltage DC/DC converter simply comes from my own need for it. Anything dealing with power management that comes from dodgy Chinese source is a potential for disaster. There has been some dramatic incident in the 3D printing community for instance. Add to this the high voltage element and I honestly would not leave for one second a nixie clock that is powered by these modules unattended.

Luckily for me, no drama happened: the power supply just crapped out without warning.

So how to build a quality power supply capable of boosting up to 170V?

First and foremost let’s not reinvent the wheel. I like to think that there has to be a solution for this problem that is supported by a big semiconductor company. In the case of nixies though, not so much! If you study old designs, they’re all powered by mains and a big old transformer. A solution that is not hobby friendly.

That being said, there is at least one modern application that needs high voltage DC/DC transformation: capacitor chargers. They are typically the main source of power for photography using flash.

So after doing some more research, I found two key components that would fit the bill:

The power transformer

There are surprisingly not a whole lot of “stock” transformers out there, most of them are ordered custom made. However I dug up some interesting beauties from Coilcraft doing research:

Coilcraft’s description for the DA203x series of flyback transformers

I quickly found out that to generate high voltage, all semiconducators companies use a flyback transformer. No one uses a typical boost converter. The boost ratio is too great to have something safe and stable.

A transformer with 3/24V input used to generate 300V? Surely it can do 12 to 170V easily then right?

The switching regulator

Coilcraft mentions LT3750 / LT3751 which are capacitor chargers, not switching regulators. They work on the same principle but have a few goodies like telling you when the capacitor is fully charged so that you can stop pumping high voltage.

Digging around though I came across the LT3757, a real switching regulator which includes a reference design for… a high voltage power supply!

5V to 350V as a “typical application” you say? Sign me up!

The idea is all there, we are in business!

Move on to Part 2: Design and Simulation

References

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