Wind Your Own Mains Transformer

[niclaspa]

Turbon, I think that you should section the bobbin in two halves with a wall of the material in the picture to separate them.  Use one section for the primary and the other section for the secondaries.

First wind one 320 V secondary.  Add a layer of isolation, i.e., Nomex, and then wind the other 320 V secondary.  You don't want two wires with only enamel isolation running next to each other with a large voltage difference.  I have done that and it shorted after a while.   For the same reason, it is important that you add extra isolation to the wire that goes from the beginning of the winding and out.

[Turbon]

Yes Niclas. I understand and separate the windings.
Btw, the first intersecting wall has seen light .

Regards

[Turbon]

I think of yet another wall. I will totally separate the HT windings if possible. It is either the nomex or the epoxy walls stealing window space. Flexibility is important to me so I can add or subtract windings if I decide so.

Regards

[Turbon]

I will have 3 sections. HT-MAINS-HT.
The bobbins are almost done.

Regards

[niclaspa]

Turbon, your bobbins look very neat!  Well done! 

[Turbon]

Thanks Niclas.

Still, it is far more work than I expected. 

Regards

[niclaspa]

Still, it is far more work than I expected. 

That seems to be the case with all my projects!   

[low pitch]

Looking good - what kind of sheet did you use for the bobbins? Is it available on ebay? 

High temp Kapton tape and brown kraft paper card is useful  http://www.ebay.com.au/itm/New-20mmx-100ft-Kapton-Tape-High-Temperature-Heat-Resistant-Polyimide-Adhesive/141861762820?_trksid=p2385738.c100677.m4598&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20160908110712%26meid%3Def8441866f0849a694819407a3b84359%26pid%3D100677%26rk%3D7%26rkt%3D15%26sd%3D321884489935
http://www.ebay.com.au/itm/Kraft-Brown-Card-and-Paper-20-150gsm-230gsm-335gsm-A4-100-Recycled-210x297mm-/291212836662?var=&hash=item43cda33f36:m:m3JzXAsCd-SsOyO8WBl0-PQ

[Turbon]

Hi Martin.

Thanks

I used epoxysheets from Conrad.de
The core and outer walls are 1mm and 0,5mm for the intersections.

Regards

[niclaspa]

How about distributing the taps equally?  Then, you will have 60 V between the taps.  I assume that you will make two windings to allow usage of a full wave rectifier.  If so, each winding will deliver 0.2 A.  You can drop 60 V with two 50 W resistors.  That means that you can get any voltage in the range.

[Turbon]

Hi Niclas.

Thanks for the tips on taps . This has been answered in the past but I don't remember where or by whom. The solution for experiments is a variable input transformer (vridtrafo) .
Almost forgot it - again I'm afraid...

Regards

[low pitch]

Windings can be used in 'buck' or 'boost'  (add or subtract voltage) so that can be a way to get more output choices.

Not  sure if anyone posted a link to Rod Elliot's guide - essential reading..

http://sound.whsites.net/xfmr.htm
http://sound.whsites.net/xfmr2.htm

[Turbon]

That was good reading Martin. Not that I understand it all - yet.
I have seen parts of the theory in other places but here it was in one place.

Regards

[Turbon]

Right, some minor adjustments as there seems to be some slack. The stack is doable to 81mm as planned. The next step is to make the holder that mimics the core of the transformer to be fitted to a winding setup ala Niclas setup. I bought an resetable counter that triggers on gnd. I haven't tested it yet but as it costed less than a fiver - what can one expect? It handles 180r/min - I have to be patient.

[Turbon]

Ok, my summer leave became longer than I hoped for.
Anyway, I got the itch again and have this as one of my winter projects

I believe I have everything gathered now to get going in a few weeks.

The hw looks as left in early summer.



Regards