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Audio transformer for small tube projects?

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#41
@JMFahey
The only reason I can come up with, is structural integrity.
Doing the way they did it, makes it a lot stronger.

The mounting plate of the Conrad (Ela) transformer is welded directly on to it.
While most other transformers have a sperate mounting piece that's folded around it (see photo above).

I will have a look how those are made as well.

Or just a legacy way of doing things to avoid infringing some kind of patent.
Probably the patent is long gone but their machines just work this way.
 
#44
I just had a look at the Visaton TR 10.16 and the T7010 (70V).

Laminates are stacked the same way as the Conrad one.
 

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#45
Maybe there is One BIG Factory In The Sky making all of them or this type of cheap construction became an unwritten "standard" ($$$$$).
Neither option would surprise me 😉

There is a video about EÜPA, "the largest factory in the World" which apparently makes all the coffee makers, pressing irons and electric grills under all kinds of brands do after that, nothing surprises me.
Worst thing?
Video Is about 10 years old.
In the meantime China became "too expensive" 😲 so it was uprooted 😱 and moved to Vietnam.
 
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#46
Tubelab_com said:
No, but it does ensure an additional eddy current load from all the tiny short circuits they create. Welding the lams is a cheap, quick and dirty shortcut usually reserved for mass produced low margin parts like microwave oven transformers.
Click to expand...
So that style of manufacturing contributes to "global warming" by loading the AC mains additionally, every time I run my microwave. I wonder if that's in all the transformer based wall-warts as well? Thinking stuff plugged 24 / 7 -
 
#47
 
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#48
The EWC part has 302 pF from primary to primary. 276 pF from primary to secondary (worst case ), 280 pF from sec. to sec.
The Signal part has 181 pF from primary to primary. 248 pF from primary to secondary (worst case ), 252 pF from sec. to sec.

The Signal parts I've seen are typically more like $20 each. I see one Signal dual 8V DPC-16-1500 from the UK for GBP 40

I would suggest using the Crowhurst Twin topology with any of these, to double the primary voltage without increasing effective primary capacitance.
(ie., minimize voltage difference between the primary halves)
Any number of them could be series connected (primaries) in Circlotron mode.

Don't bother trying to dis-assemble these for SE, thoroughly epoxied together.
 
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#49
jjasniew said:
So that style of manufacturing contributes to "global warming" by loading the AC mains additionally, every time I run my microwave. I wonder if that's in all the transformer based wall-warts as well? Thinking stuff plugged 24 / 7 -
Click to expand...
I doubt that the Eddy Current losses amount to much of an efficiency loss at 50 / 60 Hz, but they will act differently and possibly unpredictably so across the audio frequency range. Unless every weld is exactly the same as every other weld there could be some part to part variation in HF response.
 
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