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Old 8th February 2011, 10:36 PM   #21
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I have been doing quite a bit of reading today. It seems that the success or failure of the output transformer design has much to do with balancing low frequency and high frequency characteristics. There is a great deal of mathematical formula available for designing output transformers which is extensive and cumbersome.
Does anyone know of a website or source which will break this down to core stack volume and copper area.
Very large radio frequency transformers have been around for several decades and they work flawlessly. I only need a transformer design for several hundred watts at audio frequency. Why is this information so hard to find? I am not an engineer just a casual tinkerer and have found this subject extremely hard to research.
I need a transformer capable of delivering 300 plus watts at audio frequency with an 813 tube.
Does any of our more experienced members know of such a design.

Tad
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Old 8th February 2011, 11:09 PM   #22
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Why not shoot this guy an email, see what he reckons--

Champ 1000 Watt Tube Amp
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Old 9th February 2011, 01:12 AM   #23
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Other than what's on the WWW, these books have design info:

"Electronic Transformers and Circuits" by Reuben Lee, 2nd or 3rd edit.

"Transformers for Electronic Circuits" by Nathan Grossner, 2nd edit.

"Audio Transformer Design Manual" by Robert Wolpert (try internet, download)

RDH4

H. A. Hartley's book "Audio Design Handbook" gives an interesting comment on the "ultimate" lab wideband transformer for audio output, using single wire wide (seems to me like two wire wide would be mandatory, not one) vertical wound sections which are stacked up on the core with thin insulating discs between them all. Pri and Sec interleaves stacked along the core length. (must be a night-mare of interconnections though) Then mentions the more practical extension of interleaved Pi windings. But no design data at all. A very general type book.
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Last edited by smoking-amp; 9th February 2011 at 01:41 AM.
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Old 9th February 2011, 02:18 AM   #24
Matt BH is offline Matt BH  United Kingdom
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OK here is Patrick Turners run down of the RDH4 method:

education+diy

Scroll down to the bit you need, if you dont get sidetracked reading the rest. Its all good.

Champs site is pretty bloody good, I have never had a reply to an email from him.

Patrick will always respond, just give him some time. He has not been too well of late(read the rest of his site)

Cheers Matt.
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Old 9th February 2011, 11:49 AM   #25
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Bereskin describes performance and transformer layout in a rather high powered amp back in 1956, which uses insulated wire to allow a bifilar primary winding to minimise the leakage inductance, with the technique to regularly transpose that filar winding to minimise primary interwinding capacitance.

http://dalmura.com.au/projects/A%203...0Amplifier.pdf

Ciao, Tim
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Old 8th March 2011, 02:36 PM   #26
Unimog is offline Unimog  United States
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So if one wanted to wind an MI350 transformer, how would one go about accomplishing 5 wires beside each other? I can find bifilar wire and even trifilar wire online, but not pentafilar.
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Old 8th March 2011, 07:27 PM   #27
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Unimog - one method to implement multifilar is to start with say 5 separate wires, and lay them as flat turns, and then connect the ends of the winding to suit you final configuration - it gets a but ugly at the start and end of each layer, so you end up with some dead margin room at the layer edges.
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Old 20th March 2012, 11:24 AM   #28
Tyimo is offline Tyimo  Hungary
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Hi!
A bit off topic question, but still bifilar:
Do I need put insulation between the layers of a bifilar winded 1:1 transformer?
(Operated around 100V.)

Quote:
the technique to regularly transpose that filar winding to minimise primary interwinding capacitance.
What is that " transposed filar winding" technique?
Tyimo

Last edited by Tyimo; 20th March 2012 at 11:28 AM.
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Old 20th March 2012, 09:17 PM   #29
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I'm a bit naive wrt the way McIntosh handles bifilar, but it seems to be just the winding wire enamel coatings that provide the insulation between separate 'windings'. Nowadays I reckon one could look at a tefzel type wire with supplementary insulation (ie. not triple insulated) - as I recall the insulation is very thin and the effective capacitance between filar windings may not be too different.

As I understand it - transposing the winding is a technique that winds two wires A & B, such that they are in a configuration ABBAABBAABB rather than the normal ABABABABAB when looking at the turns of one layer. This effectively halves the turn-to-turn capacitance between A and B, but requires the wires to be 'transposed' each turn (which would be a laboriuous job and require some extra room - but maybe worth the effort if hand laying a very large transformer).

Ciao, Tim
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Old 21st March 2012, 07:19 AM   #30
Tyimo is offline Tyimo  Hungary
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Thanks a lot Tim!
Greets:
Tyimo
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