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1970s Design Indulgence

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 07 Dec 2021 at 9:16am
Anyone reading this topic might think it's lumbering on like some massive old vegetarian dinosaur. It does look like I am having serious trouble, doesn't it?

J R Hartley was far more successful in obtaining his rare copy of "Fly Fishing," but, then again, that was last century too!

We've done a great job of wrecking our country, and the fear of Covid19 looks to have sunk the last nail in the coffin.

Our transformer manufacturers are far too busy chasing Don Quixote knight-errantry, to give two hoots about a transformer they could so easily make!

I refuse to lay down and be steam rolled by China, or any amount of greenwashing, but it may be too late, as it seems like everybody else has.

It took more than a year to get the ultra-simple case made. I designed it to use off the shelf aluminium sections that can be easily machined by just about any engineering firm, and also geared to CNC turret heads, which once programmed, can whip the pieces out in seconds.

Perhaps the firms I've known about all these years are just a façade, behind which nothing exists?

We managed to prove that the case could be manufactured (see the 5V 3A PSU), albeit at a premium cost, with the work spread across four different firms. The one that used to be Farnell Instruments declined to help, but they do make the sort of thing I want, but for an arch enemy, perhaps that's why?

With the exception of the transformer, it's all systems go (I kid myself, really), and recent work on the transformer has seen my graveyard of iron and copper double in size (must be careful not to let certain travelling people know).

The spirit buried in the anals of the '70s timewarp manifested itself, found discarded in a Welsh set of drawers. It surfaced like some curiosity, but then the drawer was shut again. From time to time, it manifests itself again, is seen as a fleeting glimpse, but nobody knows why. God help them if out of some whim, it disappears.

The subject of somebody's Ph.D.., it's there at 1 minute 23 seconds in the Rotel transformer video. It was there in 1997, looking me straight in the face, although nobody knew why, and probably took it for granted so nothing was ever said, and I remained ignorant until just the other day.

An English company is going through the motions of rediscovering it, whether they know it or not. It is Imag. It is about controlling the noise at that Imag. It is what EI laminated transformers did so well, but that looks to be a secret too - possibly hidden in some RS Components filing cabinet, if not, somewhere in Poland.

The great problem is you cannot ask the dead! You can only talk to the living in the hope that they'll know. Sadly, they either don't, or won't.

All I can do is ask just two people, amongst the living, to humour me. We are making progress, but as another global shutdown beckons - Christmas - it causes this designer to go into thumb twiddling mode. And that's something I really hate.


Edited by Graham Slee - 07 Dec 2021 at 9:17am
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 07 Dec 2021 at 10:21am
The transformer men of la mancha

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2021 at 8:46am
Please no! I don't want to be the transformer manufacturer as well.

I've worked out the size of available parts to make an E-I transformer that will fit the space available:

Lamination size: EI96
Stack height: 32mm - dictated by the bobbin size which fits

ASCO Components in Birmingham (UK) have all the parts.

I've read about magnetostriction, and it would seem that non orientated grain electrical steel (NOSS) isn't as noisy as the orientated type (GOSS) for the magnetising current required for the sound quality of the amp.

(I hope I've got that last bit right!)

ASCO offered me a lamination grade called M400-50 in 0.5mm thickness (requiring a 64 lamination stack).

From the graph data sent, I found that 1.43 teslas would give me roughly the magnetising current ballpark required.

From then on in, I hadn't a clue, but found https://ludens.cl/Electron/trafos/trafos.html
https://ludens.cl/Electron/Magnet.html
and then the downloadable spreadsheet entitled
Transformer calculation sheet, by Manfred Mornhinweg

From the ASCO data I could fill in the Watts/kg at 50Hz, and the rest was based on the advice on the page https://ludens.cl/Electron/trafos/trafos.html.

It gives me 738 turns of 0.5mm dia. copper wire for the primary, and 178 turns of 1mm dia for the secondary.

Will it work? Well, it will transform, but whether or not it achieves the correct secondary voltage, or the wanted magnetising current, is unknown. You'd think it would, but having zero experience, you end up with "the fear of the unknown."

And if it did do exactly as computed, would it buzz? OK, it will need varnish dipping (for hours) and oven drying (SWMBO would not be impressed).

I would much prefer a transformer manufacturer to make it, but they're all too busy it would seem.Cry
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Post Options Post Options   Thanks (1) Thanks(1)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2021 at 3:04pm
It may take as long to make a transformer yourself as wait for an experienced manufacturer to make one. And then, it might not meet one or more of your design requirements.
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2021 at 8:42pm
Having hand wound a few inductors and guitar pickups I see this as being on another level.
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ICL1P Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2021 at 10:34pm
Has this project reached the end of the road?
Ifor
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2021 at 11:16pm
Originally posted by ICL1P ICL1P wrote:

Has this project reached the end of the road?

Hopefully WinkWinkWink
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