Power supply 260V for tube preamp

[Gost22]

Hi guys!
For this power supply a little more detail on the HF-transformer ETD29-3C90.
Thanks for your help!

 

[DUG]

It looks like you need to wind 12 turns, bring that connection out for the FET and then wind an additional 80 turns continued in the same direction for the output.

What does the designer suggest as far as wire gauge and type?

 

[Gost22]

Happy New Year to all!
cheers!

 

[ballpencil]

Correct me if i'm wrong but i don't see why you can't use normal power transformer for it.
80T:12T is 6.67 ratio. Using something like 33 volt (30-35 volt) primary and 220 volt as secondary should work I think. 220:33 is 6.67 ratio. its only a step up transformer.

 

[Bibliophile]

ETD29-3C90 is the core material.
ETD29/16/10-3C90 - FERROXCUBE - FERRITE CORE, ETD, 3C90 | Farnell UK

It's an E-section so you need two of them.
You'll also need a former to wind on and a clamp to hold it all together.
ETD29/16/10-3C90 - FERROXCUBE - FERRITE CORE, ETD, 3C90 | Farnell UK

Probably best to buy a kit if you can.

You can't use a normal power transformer as it is running at about 33 KHz.

 

[Gost22]

I have such a transformer!
Can I use it?
How many turns of the primary and how the secondary?
Which cross section of copper wire!
thank you!

 

[DUG]

It looks like you need to wind 12 turns, bring that connection out for the FET and then wind an additional 80 turns continued in the same direction for the output.

What does the designer suggest as far as wire gauge and type?

Did you find this out?

 

[maton00]

The original schematic states it
you can use something like a EI-33 - EI40 to make that transformer, being a overkill with a EI-40.

 

[Gost22]

Take a look project:12AX7 Tube (valve) Preamplifier Kit
Best regards!

 

[kevinkr]

I believe Bibliophile is correct, use the recommended ferrite core.. An EI will be extremely lossy at these frequencies, and could kill the fet. As a total swag I would try something like 20 awg for the 12T and 30 awg for the 80T with the recommended core. (Magnet wire) Wind tight, and put the 80T directly on top of the 12T - if you are concerned about insulation breakdown in the wire use a single layer of plumber's teflon tape between the two windings. Make sure the windings are phased correctly!

 

[jcx]

er - no don't use plumbers tape for electrical insulation - it is soft teflon and will flow/creep forever under the slightest stress - like winding pressure - could easily thin to nothing over time where wires cross and magnify stress

in this case it is less critical since its not being used for mains isolation

you should be able to find the real temperature rated Mylar transformer insulating tape with silicone adhesive

 

[Gost22]

Hi kevinkr!
Which cross section of copper wire for the primary and which the secondary?
N1:N2=?
d1/d2=?