I have been reading how to make a flyback converter for my nixie clock.
This blog shows his design process: Nixie Tube 170 V flyback DC-DC power converter | Hackaday.io
But I wonder why I couldnt choose a much smaller 'flyback transformer'.
For example:
He used the DA2032-AL which can deal with the 3A peaks.
But why couldnt I use the CJ5143-ALB? (1.5A peaks).
The nixie tubes only use 2-5mA really. So why choose the big beefy part?
IF the inductances of the windings are them same, then there is no real difference.
Paul
10uH (DA2032-AL) vs 15uH (other)
So, it's not just current peaks.
Paul
As a flyback transformer you want a gapped core, since you need to store energy in the inductance (gapped cores store loads more energy). Without the gap you'll use an unnecessarily bulky part.
Normal transformers work by transfering energy immediately and directly between primary and secondary, not storing it (to a first approximation), inductors work by storing energy in a magnetic field, and are able to give it back later. A flyback transformer is a hybrid of the two.
[ paradoxically the energy stored in the magnetic field is mainly inside the air-gap, not the core - the core serves to concentrate the energy into the gap. ]
Something I think I am not quite understanding is where the inductance parameter on the datasheet is coming from.
Is it the combination of both windings? Or is it a representive of the energy that the core stores?
Please.
Gotta peel the onion, otherwise known as reading the datasheet. Carefully.
It says: Inductance at 0A2±10% (μH)
And when you find footnote 2:
https://www.coilcraft.com/getmedia/88ef6a9b-3558-4004-8c5f-af97c95c7e8c/da2032.pdf
Don’t be fooled by the 3 amp rating, that’s the primary peak current. Usable output current is probably less than 50ma.
Translation: That’s about as small a core as you would want to use.
If you want a small size Nixie power supply to build yourself, I have used a circuit similar to this for powering 6 IN-12 tubes in direct drive (not multiplexed) mode.
Do a Google search for "Nixie Power Supply 555" and lots will appear.
The only issue I had was with the layout. Keep the feedback circuit well away from the inductor.
What about this core: NA5920-ALD
I have made up a circuit and am going to experiment with it anyway.
Im interested what the different in inductance in the cores will show...
I've not got a problem finding/building a 180V PSU, I have already built my own voltage multiplier boost. I just want to experiment with a flyback converter, to build on my psu knowledge. Thanks tho 
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