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11th Apr 2017, 9:32 am | #1 |
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Winding an output transformer for PL36 push pull
I'm putting together an amplifier using all TV valves.
Push pull output with PL36s, got loads of them. The question is, do the primary windings of the transformer get wound on the bobbin/s in the same direction relative to the core or are they wound opposite ways, if so why? I have never wound a push pull transformer hence the query. To reduce the capacitance this will be wound on 2 bobbins, half the primary and half the secondary on each bobbin with the windings cross connected in series. I assume I connect end of one to start of the other? Been reading books on how to do it but can't find answers to these questions. This is the trouble it gets you in to. |
11th Apr 2017, 10:08 am | #2 |
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Re: Winding an output transformer for PL36 push pull
It will in effect be a continuous winding tapped in the centre, so both halves will be in phase from end to end but in opposite phases when fed from the centre.
Peter |
12th Apr 2017, 6:08 am | #3 |
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Re: Winding an output transformer for PL36 push pull
Have you read this Sam - http://www.dissident-audio.com/Trans...ign_Manual.pdf ? More stuff here - http://www.turneraudio.com.au/output-trans-winding.htm and here - http://www.turneraudio.com.au/output-trans-winding.htm and here - https://ludens.cl/Electron/trafos/trafos.html and lastly some ifo regarding your question here - http://deerloverssite.org/TRANSFORMERS.html
Andy.
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Curiosity hasn't killed this cat...so far. Last edited by Diabolical Artificer; 12th Apr 2017 at 6:16 am. |
12th Apr 2017, 8:01 am | #4 |
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Re: Winding an output transformer for PL36 push pull
Thanks Andy.
I had found some of these sites but more is always better, Plenty to read, won't need a paper today! Sam. |
12th Apr 2017, 6:24 pm | #5 |
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Re: Winding an output transformer for PL36 push pull
Hey Sam, Ed (Dinning) is the transformer winding expert here, but I would have thought that the self-capacitance of an iron-cored transformer for audio frequencies is so negligible compared to its inductance as to be ignored?
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Al |
12th Apr 2017, 8:35 pm | #6 |
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Re: Winding an output transformer for PL36 push pull
Hi Al, the problem with the self capacitance becomes apparent when there is feedback applied to the amplifier, usually resulting in instability.
Ed |
12th Apr 2017, 11:11 pm | #7 | |
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Re: Winding an output transformer for PL36 push pull
Quote:
Iron-cored transformers, as used for inter-stage coupling, are quite difficult to make if you want a frequency range of more than 10 octaves (say 20Hz - 20kHz). Even 8 octaves (40Hz - 10kHz) is a challenge! |
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3rd May 2017, 7:38 pm | #8 |
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Re: Winding an output transformer for PL36 push pull
Its wound and working.
2 bobbins side by side, 1788 turns primary on each, 29 turn secondary on each. 1 inch square core laminations. Primary resistance came out at 568 Ohms overall. Ran it up on a pair of EL33s, 288 volts on the anodes, sounds fine. Very loud! I'm encouraged to try bigger! |