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Nixie Power Supplies: have I been doing it all wrong?

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NivagSwerdna:
So the requirement is a 170V PSU of say 10W..
 To date I have just followed the standard approach of a boost converter from a 9V or 12V supply... It works... But...

.. and then in the mailbag there was a similar design for 100W... Which got me thinking...

Perhaps we are doing this all wrong!

This isn't for a Nixie watch so there will be a mains supply available... 240V in old blighty, 120V in the EU  ;) so it seems a bit stupid to use a wall wart switching supply to decrease 240V to 12V and then just boost it back up again?

Are there any transformer based designs that make more sense? Is is possible to have one that could operate at both continental  and UK voltages?

Thanks in advance

SiliconWizard:
Nah, it's 230/240V in most of the EU. I actually don't know of a country member of the EU that is @120V, but I may have missed it. If it exists, show me that weird beast  ;D
OTOH, you may have meant the US.

Anyway, even though your idea makes sense from an efficiency POV, there's the practicality of it to consider. In many applications these days using Nixie tubes (mostly for the vintage/design look), the PS comes from a separate mains adapter. Unless you really have to, you usually don't want to mess with the mains part yourself for several reasons including safety/CE marking/cost/etc. So all you may have at your disposal is a relatively low DC voltage. You'll have to go the boost converter path.

Now if your device includes a mains supply section, you could indeed generate the high voltage for the Nixie tubes directly. Thing is, it'd likely require a custom-made transfomer, which is not cost-effective at all unless you go for high quantities.

Additionally, I haven't worked with those tubes before, so I don't know how important that would be that the supply voltage be well regulated or not? If so, there would be little advantage using the above solution IMO, as you would still need a regulating stage.

Just a few thoughts.

NivagSwerdna:

--- Quote from: SiliconWizard on November 25, 2019, 07:59:04 pm ---Nah, it's 230/240V in most of the EU.
--- End quote ---
My mistake.  In fact looking at a list it's only USA, Canada, Japan and a few others that have the lower voltages.



--- Quote from: SiliconWizard on November 25, 2019, 07:59:04 pm ---Unless you really have to, you usually don't want to mess with the mains part yourself for several reasons including
--- End quote ---
So that's the crux... not worth frying any customer so don't bother?

David Hess:

--- Quote from: NivagSwerdna on November 25, 2019, 07:17:43 pm ---Are there any transformer based designs that make more sense? Is is possible to have one that could operate at both continental  and UK voltages?
--- End quote ---

Production quantity transformers do not cost any more than standard off-the-shelf transformers so in the past, it was common to just include a separate low current high voltage winding for the Nixie supply.  Several of my old salvaged transformers include such a winding.

Regulation is not critical because the current limiting resistor ballasts the Nixie element.

What I might do for simplicity if my design already has a power transformer is to add another small power transformer and wire it backwards to one of the low voltage AC outputs to produce an isolated 120 volts AC.  Alternatively it could be driven with a simple inverter circuit from a low voltage DC supply.

james_s:
Nixie tubes are just glorified neon glow lamps, regulation is not critical at all. Most real equipment that used them back in their day used a simple single diode rectifier on a transformer winding. I've used a resistor directly off rectified and filtered mains on a few designs. With others I used a dual primary transformer with one of the primaries used as a secondary in series with one of the other secondaries to get around 180VDC after rectifying and filtering. You can also use two back to back transformers, it's not critical. The advantage of a boost converter is that it's isolated from the mains and you need low voltage to power the electronics anyway. For a commercial product you can also have a UL or whatever certified wall wart and the device itself doesn't need to be compliant.

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