I want to build a transformer with the same characteristics as the hammond 125a, since I cannot buy it and it is very expensive to import it, what calculations do I need to do from the values that the data sheet gives me to be able to have everything to be able to build it?
And if it can't be done, where can I get information on the design of push pull output transformers, since I couldn't find much on the internet
I leave the link of the data sheet
https://www.hammfg.com/electronics/transformers/audio/125a-125e.pdf
And if it can't be done, where can I get information on the design of push pull output transformers, since I couldn't find much on the internet
I leave the link of the data sheet
https://www.hammfg.com/electronics/transformers/audio/125a-125e.pdf
The late Patrick Turner had a lot of information about winding transformers on his website.
Google leads me to this URL for a copy of his site:
http://search.digicom.bg/output-trans-winding.html
Google leads me to this URL for a copy of his site:
http://search.digicom.bg/output-trans-winding.html
Certainly there are other resources, but a Classic is:
Radiotron Designer's Handbook, 4th Edition
Radiotron Designer's Handbook, 4th Edition
what Country are you in?
it´s important information and will influence answers.
If you wish to learn designing your own output transformers, you should start with the following books and papers: Patrick Turner, Crowhurst and RDH4.
Its a $45 part. Buying all the raw materials and trying to make an exact copy is going to cost significantly more. Plus the characteristics are going to be off unless you get the same core material. Sounds like Brazil if they still have the ridiculous import taxes on electronics.
Before I spent $45 (or significantly more) on a three watt output transformer I’d take a step back and figure out exactly what is needed and be looking for alternatives.
Patrick Turner/Radiotron Handbook/etc. is the long way towards the goal.
You'll have the transformer finished in 10 years from now . . . good luck.
A shortcut would be using spreadsheets from https://www.delatsch.com/
Delatsch also has the needed materials.
When you have the spreadsheets and materials, you need a winding machine.
Forget winding an output transformer by hand unless you used to work as a winder in the 1950's.
A winding machine project can be found here:
https://curiousscientist.tech/
Scroll down and look for his old posts. Here you'll find the winding machine project pages.
You'll have the transformer finished in 10 years from now . . . good luck.
A shortcut would be using spreadsheets from https://www.delatsch.com/
Delatsch also has the needed materials.
When you have the spreadsheets and materials, you need a winding machine.
Forget winding an output transformer by hand unless you used to work as a winder in the 1950's.
A winding machine project can be found here:
https://curiousscientist.tech/
Scroll down and look for his old posts. Here you'll find the winding machine project pages.
The only great feature of the 125A is the semi-universal impedance tappings. Do you actually need that??
A power transformer wound one coil over the other will give similar performance. 240V:12V suits 3K:8r. 12VA (so 12V 1A) will handle 3 audio Watts well. 240V:6V makes 13k:8r. A 120+120:6+6V part will cover many small amplifiers.
A power transformer wound one coil over the other will give similar performance. 240V:12V suits 3K:8r. 12VA (so 12V 1A) will handle 3 audio Watts well. 240V:6V makes 13k:8r. A 120+120:6+6V part will cover many small amplifiers.
Agree ;
A couple of these might be useful to be in stock for a Tech dealing with such stuff. just as a "better than nothing" solution.
Performance is usually **** poor: notice 150Hz lower limit and 3W power handling; they are not really "universal" but a sort of desperate measure, primary inductance is not enough to match the wide variety of reflected impedances, from 1200 to 25000 ohm 😱
And I guess it will be used at one impedance setting anyway, I guess carloszulca will be better served by straight searching for a transformer meeting that specific need, period.
Which to boot will work better, because it will be designed for that impedance.
"Universal" transformers are not really that.
If anything , transformers made out of multi separate primaries and a few secondaries such as those made by Mr Patrick Turner will do a way better job, but switching only secondaries is bad engineering.
is a feature useful only in very limited cases: when an off the shelf OT is not available, and limited budget (say you are repairing an old radio or gramophone) for which it is not worth or practical sourcing the proper one.
A couple of these might be useful to be in stock for a Tech dealing with such stuff. just as a "better than nothing" solution.
Performance is usually **** poor: notice 150Hz lower limit and 3W power handling; they are not really "universal" but a sort of desperate measure, primary inductance is not enough to match the wide variety of reflected impedances, from 1200 to 25000 ohm 😱
And I guess it will be used at one impedance setting anyway, I guess carloszulca will be better served by straight searching for a transformer meeting that specific need, period.
Which to boot will work better, because it will be designed for that impedance.
"Universal" transformers are not really that.
If anything , transformers made out of multi separate primaries and a few secondaries such as those made by Mr Patrick Turner will do a way better job, but switching only secondaries is bad engineering.
Wow - that information is practically a work of art. Always inspiring to witness a craftsman in action. I get the same sort of sense from the woodworking resources of Paul Sellers.
Yes I confirm the big banana Brazil still have the highest Customs duties on this Planet ranging 100 to 110%, please see others countries here Post #2.
https://www.audiocircle.com/index.php?topic=176690.0
opss
Italian site for the design of TU ... with excellent program.
https://digilander.libero.it/giunchifabrizio/
Italian site for the design of TU ... with excellent program.
https://digilander.libero.it/giunchifabrizio/
The "ridiculous" import tax as you call it, makes Brazilian Industry possible, keeps Brazilian jobs inside Brazil, and in general make Brazil grow every day.
Exact opposite of what US does, with well known results.
Works fine, as long as the country is actually making what you need. It sort of like what would happen in the US if they put a 5000% tariff on everything from China and then go trying to buy a washing machine. Until one is actually made at home you wouldn’t find one for less than a new car.
Plenty of speakers being made in Brazil these days. PRV, Selenium may not beat the best Italian brands, but eat most Eminence for breakfast (Eminence was late to the party in terms of the super capacity touring PA drivers). Tube output transformer? What’s that, and why would anyone want one? Then you have to pay the piper, or just go without. I suppose you could get a local motor rewind shop to make one out of a donor core, but the quality might not be there and paying shop rates is usually more expensive than paying duties. When a little bitty transformer that by all rights should cost $20 ends up being over $100 landed, you just re-think the project.
Plenty of speakers being made in Brazil these days. PRV, Selenium may not beat the best Italian brands, but eat most Eminence for breakfast (Eminence was late to the party in terms of the super capacity touring PA drivers). Tube output transformer? What’s that, and why would anyone want one? Then you have to pay the piper, or just go without. I suppose you could get a local motor rewind shop to make one out of a donor core, but the quality might not be there and paying shop rates is usually more expensive than paying duties. When a little bitty transformer that by all rights should cost $20 ends up being over $100 landed, you just re-think the project.
Agree when you have one person needing one transformer.
But if Tube transformers become regularly needed, rest assured that some local entrepreneur will set up a Factory and then supply as many as you wish, and for a reasonable price.
Now if imported product is made at abusive low salaries, long overwork hours, disregard of Health and Nature keeping conditions, no possibility of strikes or even complaints, backed by a HUGE sales and shipping Company such as Alibaba or Aliexpress, then NOBODY can invest a cent because he will never get his money back.
Not sure how old are you. US was making all that and 1 million more things, had the largest Industry in the World, by far , high quality and reasonable price, and lost most of it.
Won´t get Political, I am simply quoting History and Fact.
I was born in 1952, best fridges and washing machines were US made, of course, Westinghouse and Kelvinator come to mind, TVs were RCA, Dumont, etc. , cars were most envied in the World, planes were Boeing, Lockheed, Convair, etc. , amplifiers and Guitars were Fender, Gibson, Ampeg, Acoustic, Peavey, organs were Hammond or Baldwin, tubes were Silvania, RCA, Western Electric, semiconductors were TI, NS, Fairchild, GE, all US made, and so on and on and on.
No need for 5000% tariff (and even IF, who cares, just buy US made) , there´s many different ways to protect own Industry, yet allowing some foreign product in, at least to keep local producers "motivated" under some pressure so they don´t get lazy or greedy.
But that´s very different from allowing full destruction of locals.
If you don't want top quality I use reversed mains transformers.
Clearly you need to work back from 8 ohm output to primary impedance you require but thats just square of turns ratio times 8 ohms equals primary impedance.