rickcr42
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Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on May 15, 2006 2:11:37 GMT
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Post by hower on May 15, 2006 3:50:24 GMT
Good article, its a new insight for me indeed.
But where do we find such a good hi-end EI Transformer??? I believe it is much much more easier to find a good Torodial Transformer instead.
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on May 15, 2006 5:35:03 GMT
before answering that first a curve ball www.bryston.ca/pdfs/news/85.pdfamazing how you can get two total polar opposites on any audio related topic and have both make perfect sense ! That is why all the confusion is out there and why trying to make good decisions such a bitch. The long and the short is for high current designs a toroid is the best choice and low current designs a split bobbin. I personally hate toroids and that because I have had problems with them buzzing like a hornets nest from DC on the AC line,have had to add in more RFI protection to the power supply because these pupies suck at filtering,have had problems with rectifiers needing added protection from the first stage capacitors charging up at turn on because these babies turn on lightenng fast and feel they add complexity to a power supply if you want to have it right. At the same time if you want a transformer in a limited space with the audio circuits the toroid is really the only way to go unless you shield the transformer by either/both grounding the end bells if present and/or an actual physical ground-shield barrier plate or as I do more often than not taking the whole deal right out of the "box" for total isolation.Having the AC section totally isolated adds to cost (two boxes cost more than one as does the added connection) but for me personally well worth it in the returns vs. added cost area.
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FritzS
Been here a while!
Sound of Blue Danube
Sound of Blue Danube
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Post by FritzS on May 28, 2006 12:10:16 GMT
I am unsteady now - I will make a new PSU for my headphone amp and need a 20 VA till 30 VA transformer with sec. 2x 18V AC some transformers I found from Farnell 15VA toroid - regulation 16% 30VA toroid - regulation 12% 30VA EI - regulation 81%
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FritzS
Been here a while!
Sound of Blue Danube
Sound of Blue Danube
Posts: 1,364
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Post by FritzS on Jun 28, 2006 8:37:39 GMT
Rick, some likes toroids, some EI, but all forget's the C-core The only drawback, pricey and hardly to get them .... Only Lundahl make then, but not for PSU www.lundahl.se/catframe.html
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Jun 28, 2006 14:56:45 GMT
Iron in general is pricey and for me the major cost of any project so why my first stop is usually one of the surplus electronics joints (check links section ) For standard power supply work I mostly use the Hammond split bobbins which are readily available from many sources and priced reasonably ofr even a cheap so and so like myself
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Jun 28, 2006 18:16:43 GMT
The Hammond split bobbins look like this : I like the added layer of RFI filtering the split bobbin adds but with the downside of it radiates a lot of self noise so unlike a toroid needs physical space along with proper orientation if you want to avoid hum.This means forget about using one in a tight chassis (where toroids rule) unless you are prepared to make an effective shield for the AC section that or do as I do and keep ALL transformers "out of the box" which is an absolute on induced noise or hum but increases both complexity and cost plus means you need to figure out just where to put the "box" without it looking goofy
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