Folks:
I know this might sound crazy, but I am contemplating taking the big risk of trying to wind my own output transformers (modifying a lathe to make a winding lathe with counter and all).
My big question is where can I get the core plates (either E-I or C as I have not decided yet) and the wire? I am willing to invest in decent materials so I am not looking for the cheapest materials from China.
I am also looking for what you folks consider the best articles or books on designing output transformers.
I am willing to try to read this stuff through and try to do this right. I have all the time in the world as this is my own project and not a work or business related item.
I do have an electronics engineering background and am verse in working with vacuum tube gear (assistant curator at the
Spark Museum here in Bellingham, Washington fixing and restoring period radios).
Thank you very much for your help.
Truly,
Mark Allyn
Bellingham, Washington
I know this might sound crazy, but I am contemplating taking the big risk of trying to wind my own output transformers (modifying a lathe to make a winding lathe with counter and all).
My big question is where can I get the core plates (either E-I or C as I have not decided yet) and the wire? I am willing to invest in decent materials so I am not looking for the cheapest materials from China.
I am also looking for what you folks consider the best articles or books on designing output transformers.
I am willing to try to read this stuff through and try to do this right. I have all the time in the world as this is my own project and not a work or business related item.
I do have an electronics engineering background and am verse in working with vacuum tube gear (assistant curator at the
Spark Museum here in Bellingham, Washington fixing and restoring period radios).
Thank you very much for your help.
Truly,
Mark Allyn
Bellingham, Washington
A quick Google search turned up 2 sources, whose URLs follow.
Transformer laminations of all shapes and sizes | Tempel
https://www.thomas-skinner.com/transformerlaminations.htm
I did not deeply review the "hits". What you need is M6 grain oriented silicon steel (GOSS) E/I scrapless laminations. Small, hobbiest, orders may not be welcomed by the suppliers.
You are about to endure a very difficult learning curve. The winding of magnetics is a complex mix of science, art, and experience. Avoiding substantial monetary outlay is most unlikely.
Transformer laminations of all shapes and sizes | Tempel
https://www.thomas-skinner.com/transformerlaminations.htm
I did not deeply review the "hits". What you need is M6 grain oriented silicon steel (GOSS) E/I scrapless laminations. Small, hobbiest, orders may not be welcomed by the suppliers.
You are about to endure a very difficult learning curve. The winding of magnetics is a complex mix of science, art, and experience. Avoiding substantial monetary outlay is most unlikely.
ThomasNet - Product Sourcing and Supplier Discovery Platform, search for transformer laminations and go from there.
If you can decipher German I can point you to some good articles there. E
ps: your museum is absolutely fabulous and I will visit again when in Bellingham!
If you can decipher German I can point you to some good articles there. E
ps: your museum is absolutely fabulous and I will visit again when in Bellingham!
Bridgeport Magnetics in Connecticut may be worth checking out.
Amorphous C-Cores by Bridgeport Magnetics
http://www.bridgeportmagnetics.com/contents/en-us/d42_C-Cores.html (Note that the core material is M4 which is pretty good.)
I have at least two friends who wind their own output transformers and one also winds his own power transformers. AJT, a fellow moderator here is very well versed in both, and has shared some tips on winding transformers here. (Use search)
Amorphous C-Cores by Bridgeport Magnetics
http://www.bridgeportmagnetics.com/contents/en-us/d42_C-Cores.html (Note that the core material is M4 which is pretty good.)
I have at least two friends who wind their own output transformers and one also winds his own power transformers. AJT, a fellow moderator here is very well versed in both, and has shared some tips on winding transformers here. (Use search)
Could I use cores from discarded power transformers?
Noting that one of the replies suggest that some suppliers may not honor small hobbyist orders, I am curious if I can get away with using the cores of discarded power transformers? I have a source for old power transformers which I could rip out the windings but then re-use the laminations. Do power transformers of vacuum tube gear use compatable metals as those for audio output transformers? I am wondering if I could do this as a cost savings while I do my initial learning by doing/smoking/zapping, etc
Noting that one of the replies suggest that some suppliers may not honor small hobbyist orders, I am curious if I can get away with using the cores of discarded power transformers? I have a source for old power transformers which I could rip out the windings but then re-use the laminations. Do power transformers of vacuum tube gear use compatable metals as those for audio output transformers? I am wondering if I could do this as a cost savings while I do my initial learning by doing/smoking/zapping, etc
Use what you have.
Transformer winding involves some practicing, so go ahead and reuse laminations, bobbins and even copper wire.
You say you have a lathe,-which is good.
Some winding machines have a mechanism that moves the wire along the bobbin as you wind, but I've seen workshops do this by hand.
If you use the correct tension and you guide the wire so that it nearly tries to place itself on top of the previous winding, the winding will sort of fall into place by itself.
The distance from the feeding-spool to the bobbin must be as great as you can get it. This makes guiding the wire easier.
As for output transformer quality, this depends on mainly two factors (if you disregard the core for now):
- Stray inductance and stray capacitance.
These two must be kept as low as possible in order to obtain a wide frequency response.
Imagine you have one winding on the primary and one winding on the secondary.
You get the least stray inductance if one winding sits on top of the other. Unfortunately this arrangement causes a large capacitance between the two windings.
The trick is to wind such that stray inductance and stray capacitance are balanced as well as practically possible.
What they do is to split the windings into sections which are interleaved to minimize both the stray inductance and the stray capacitance.
You can read more about this as soon as you've found articles on the web.
Transformer winding involves some practicing, so go ahead and reuse laminations, bobbins and even copper wire.
You say you have a lathe,-which is good.
Some winding machines have a mechanism that moves the wire along the bobbin as you wind, but I've seen workshops do this by hand.
If you use the correct tension and you guide the wire so that it nearly tries to place itself on top of the previous winding, the winding will sort of fall into place by itself.
The distance from the feeding-spool to the bobbin must be as great as you can get it. This makes guiding the wire easier.
As for output transformer quality, this depends on mainly two factors (if you disregard the core for now):
- Stray inductance and stray capacitance.
These two must be kept as low as possible in order to obtain a wide frequency response.
Imagine you have one winding on the primary and one winding on the secondary.
You get the least stray inductance if one winding sits on top of the other. Unfortunately this arrangement causes a large capacitance between the two windings.
The trick is to wind such that stray inductance and stray capacitance are balanced as well as practically possible.
What they do is to split the windings into sections which are interleaved to minimize both the stray inductance and the stray capacitance.
You can read more about this as soon as you've found articles on the web.
BudP, cerrem, YvesM are the experts and are members here, you can touch bases with them..
this is my go to place.....output-trans-theory
nomex paper are the choice material to use in between coil insulation papers...
this is my go to place.....output-trans-theory
nomex paper are the choice material to use in between coil insulation papers...
Invest a bit more and get yourself some c-cores.
When winding a transformer only once it does not make too much of a difference, but when you wish to play with airgapping and want to disassemble-assemble in case of trying different coils, c-cores are much more practical.
Besides, when you use their properties to your advantage, they make better transformers than EI.
(Based on over 15 years experience).
Kevin pointed you to a potential and good supplyer.
When winding a transformer only once it does not make too much of a difference, but when you wish to play with airgapping and want to disassemble-assemble in case of trying different coils, c-cores are much more practical.
Besides, when you use their properties to your advantage, they make better transformers than EI.
(Based on over 15 years experience).
Kevin pointed you to a potential and good supplyer.
a good source of practical information.....http://www.dissident-audio.com/Transfos/Papers/Wolpert_Audio_Xfmr_Design_Manual.pdf
VintageWindings Audio Transformer Design Coil Winding Collection V1 .pdf DVD Page
Here's probably all you need to know about transformer winding. Quite a few pdf-files, free download.
Also Google "crowhurst transformers". This may result in you finding articles not covered in the above mentioned link.
Here's probably all you need to know about transformer winding. Quite a few pdf-files, free download.
Also Google "crowhurst transformers". This may result in you finding articles not covered in the above mentioned link.
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Hong Kong / Taiwan is not far from where you are.
I am sure that after some searching you should be able to get good quality c-core material at reasonable cost.
In the past I bought c-cores from the Chinese plant of Nicore (Japanese company); excellent quality, actually better than what is available in Europe nowadays.
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