How to mount a toiroid on the chassis?

[sdk]

Hi guys,

Received a call from the chap who is making my toiroid transformer to take delivery this week.

He said that he's going to fill the centre of the toiroid with black epoxy and leave a hole for mounting

Most videos show toiroids with no filling, bolted to the chassis between rubber gaskets with a metal plate on top

How do I mount a filled core with a ready hole in the centre?

Mount it directly? Or go searching for gaskets and plates?

What other precautions do I take? Since space is at a premium can it touch the sides of the metal cabinet? Or not?

The bolt is supposed to touch only the bottom and not both ends to metal?

Regards

 

[jls001]

Gasket + metal plates should be included with the transformer. Bolt it securely to the bottom of cabinet.

 

[frend2001]

I don't think the bolt touching the washer / plate would have any problem.

Since isolation is important you may mount the torroid on a gasket put on the cabinet floor and secured from a washer from bottom.

Similar idea for top of torroid too. A rubber gasket or thick rubber washer followed by a metal washer and that's it.

That's my understanding and 2 paisa.

Hope this helps

 

[surfatwork]

If your toroid is potted, then don't use any metal plate on top. Rubber sheet on the bottom., then toroid, then through bolt. You can use a washer.
Using a metal plate compresses the windings of a potted transformer and is not good.

 

[sdk]

Collected my transformer from the manufacturer

A very heavy monster built to the dimensions that I had specified, due to my cabinet and board dimensions

I feel he's done a great job

Will test for voltages later, after my back and neck recovers from lugging them back home.

It took longer than usual because I was constrained by the space I had and the core required by him.

He had to specifically order narrow and tall cores for me. Compared to the wider and shorter cores that people generally order to make slim looking amps

He's done a great job except for two things that I wanted

One was a copper shield around the primary connected to ground. Since he almost never gets requests for that, he forgot, so he added it at the end over the secondaries. At least it will prevent leakage. At the cost of safety, if the primary shorts with no foil and connection to ground and leakage between primary and secondary.

I also wanted a thermal cut off switch. He said that he never gets orders for those either and could not source them in time. He asked me to add an external one later.

From what I saw, he's very busy with hundreds of EI as well as toiroids being packed during every visit.

If the core is in stock, he promises delivery within a week, if he has to order uncommon cores then almost two weeks like mine.

 

[surfatwork]

Who is the manufacturer? Torotrans?

 

[sdk]

Who is the manufacturer? Torotrans?

No

This was by a company called Be Tech India, Goregaon, Mumbai. Found him via a Google search. Very friendly and approachable. Will definitely do business with him again. He seems to be a OEM manufacturer for other brands and for dealers.

Not only was torotrans too expensive they don't pay attention to what the client wants. I asked for a quote for OD 115 mm and height 110 mm. They reply with 165/85 mm at three times the cost.

The only way I could fit it in would be by taking a hacksaw to my power amp board!!!

Other companies that I emailed, WhatsApped, SMSed did not bother to respond.

Which is why in my earlier post I had advised a FM that one should start a build by sourcing the transformer first. That was the most difficult part of it all. And then build the boards around it.

 

[quad]

Be careful to avoid a "shorted turn" when mounting -

https://www.edn.com/design/audio-de...wer-supply-types---transformer-considerations

 

[sdk]

Be careful to avoid a "shorted turn" when mounting -

https://www.edn.com/design/audio-de...wer-supply-types---transformer-considerations

Thank you so much for this resource

All diy enthusiasts should read this

Regarding a shorted turn via the bolt touching metal at both ends, can that be prevented by covering the bolt shaft and head with heat shrink tube and insulating the insides of the
Case with Heatlon or rubber sheet?

That way even if the cover bends due to some weight on the top there won't be metal contact

 

[quad]

Yes, you can prevent a shorted turn by good insulation. However it is best to have a gap
so that the top would not touch.