DIY transformer and two-component epoxy adhesive

[SemperFi]

Originally Posted by Elerion

Now I have 1 mm wire, and winding a pair of this wire, using CT, would do the job, and probably make tighter winding.

Does it make sense?

Yes it does. Good luck. Picture of your tranny?

[Elerion]

Yes.

The first image is with bells on. This is how I tested it.

The second image is with nothing on. I'm making much better finishes in my last two trannies. The buzzing is much loader (obvious)

The third image is with a new hardware I'm testing. Similar buzz noise level than with bells. The idea is to place bells on top, which lack the "L" shaped on the bottom to bolt to the chassis.

Something strange (to me) is this: when I hold the transformer in the air with one hand (I use an insulated+leather globe), the buzzing noise almost fades away completely.
Any idea why?

I also tried to press hard over the filament winding, but the buzz doesn't change. If those thick wires were producing the buzz, this should have alleviated it, shouldn't it?

[SemperFi]

100Hz vibrations are not loud from a transformer that size. Placing it on a table or other large area increases the sound because the heavy transformer manages to get the whole surface to vibrate. So more sound from the big area. Holding it ur hand the only surface area to emit sound is relatively small and that produces less sound. Think big speaker vs small vibrating so lttle u cant feel it with ur fingers. Only the big speaker will be audible.
I think...

[SemperFi]

Are u sure the core is big enough for the power u are taking off it? The more of the metal that gets magnetically aligned the more the metal flexes. Or is the buzz the same with or without a load?

[Elerion]

The same with and without load.
By the way, it is a 45 mm stack EI96 core.

I checked the calculations, and the magnetization is around 1.3T. It isn't low, but being GOSS laminations, it isn't very high either.

[SemperFi]

Originally Posted by Elerion

The same with and without load.
By the way, it is a 45 mm stack EI96 core.

I checked the calculations, and the magnetization is around 1.3T. It isn't low, but being GOSS laminations, it isn't very high either.

OK now I am beyond my knowledge limit so I finding this interesting. I thought u needed some current thru the windings for magnetostriction to become active enough so as to become a problem.
What is the primary inductance? Is the magnitization (primary idle) current pretty high?
Are all the inductances as expected? Could a winding be the wrong way as to work against some of the other?

[TonyTecson]

what i do is to wedge a wooden shim between the center leg cores and the bobbin,
i use popsicle ticks to do that...

then a complete submerge in a vat of varnish...dry and dip again..

[TonyTecson]

Originally Posted by Elerion

That red piece is cardboard?
How could cardboard or soft materials be useful?

i use them all the time...

[TonyTecson]

Originally Posted by Elerion

The same with and without load.
By the way, it is a 45 mm stack EI96 core.

I checked the calculations, and the magnetization is around 1.3T. It isn't low, but being GOSS laminations, it isn't very high either.

1T is high enough, the RDH4 computations are just 0.9T
that 1.3T could be the cause of buzzing, not enough turns in the primary...

[TonyTecson]

How do you finish your power transformers?

like so....