are these small guys flybacks?

[Alberto]

Hi everyone.

It has benn a long time.

At work, the printer has died. A HP m605. And I have dissasembled it, and I found theses



Are flybacks?

I have look up in the internet the numbers but no clue.

Thank you

best regards

[Mads Barnkob]

I would agree with you, those are most likely the tiny negative charge high voltage transformers.

I once tried to run one with a ZVS drivers, it burned to the ground Watch from 1:00 in this video

[Alberto]

Thank you.

Yes I saw your video long time ago. I love these small guys. They are very tiny but very big sparks!

But for example, in an older printer I got these



but they have the ferrite core exposed and I was able to put other coil. So one question

Why do we put other external primary coil in the flybacks instead using the existing one?

Thank you

[Mads Barnkob]

but they have the ferrite core exposed and I was able to put other coil. So one question

Why do we put other external primary coil in the flybacks instead using the existing one?

We want fewer primary turns, to get a higher primary current and thus a more powerful high voltage output. Usually we also like to use lower voltage and higher current rated MOSFETs/IGBTs and operate the drivers at a lower supply voltage.

The internal primary winding has more windings and needs a higher voltage to run, which is working with the popular self oscillating mazilli driver. It also has a bigger chance of breakdown/flashover due to the transformers being overdriven and mistreated for drawing arcs.

[Alberto]

Ahh ok ok. Thank you