Hi Brian,
Could this be helpful for you?
http://www.lenco-elect.com/r_core_transformers.htm
Does anyone know if an R-Core transformer will show the same kind of attenuation of HF as an Ei-core trafo?
Karsten
I'm wondering about this, too. I would guess, from the claim that stray fields are arranged to cancel, there should be 1/2 pri and 1/2 sec on each leg, hopefully well seperated (split bobbins for low coupling capacitance). To be a perfect tranny there would also be a need for a electrostatic screen layer encapsulating the primary to reduce capacitive coupling. I suspect R-cores to be very sensitive to DC, which is a disadvantage.
For the german speaking folks, here is a reseller in switzerland who seems to have some types available:
http://www.hifituning.ch/transfor.htm
- Klaus
For the german speaking folks, here is a reseller in switzerland who seems to have some types available:
http://www.hifituning.ch/transfor.htm
- Klaus
Karsten, not exactly helpful. While they have a few words on the left side of the screen, there is no other information. I believe that someone checked with this Lenco outfit and found that they can't supply transformers.
JPS, just because UL and CSA have offices in China is no indication that any Chinese transformer you purchase is UL certified. I repeat my comment. I have found no web vendor from whom I can actually purchase an R-core transformer that indicates that their transformer is UL (or CSA, etc.) certified. Just because some Chinese or Indian factory makes "good" transformers for some customers does not mean that the ones that make it out to hobbyists is the same thing. Ask Mattel what happened to the quality lead-free paint that they shipped to their Chinese contract manufacturer.
I will check out this Lenco company and see if they really make their own USA-made transformers and what their certifications are.
Just for reference, even some of the respected toroid vendors have models that are not UL listed as I found when attempting to source one for a product I was designing.
JPS, just because UL and CSA have offices in China is no indication that any Chinese transformer you purchase is UL certified. I repeat my comment. I have found no web vendor from whom I can actually purchase an R-core transformer that indicates that their transformer is UL (or CSA, etc.) certified. Just because some Chinese or Indian factory makes "good" transformers for some customers does not mean that the ones that make it out to hobbyists is the same thing. Ask Mattel what happened to the quality lead-free paint that they shipped to their Chinese contract manufacturer.
I will check out this Lenco company and see if they really make their own USA-made transformers and what their certifications are.
Just for reference, even some of the respected toroid vendors have models that are not UL listed as I found when attempting to source one for a product I was designing.
This is normal practice, because it depends on the region of market which certificate(s) a product will have/need. No need for north-american standards (as per UL) for a xformer with only 230V primaries. So IF a transformer has at least any certificate (and be it CCC, for the chinese market) it's certainly safe enough, as those standards don't differ dramatically. UL isn't the only one for your region, it just happens to be the most respected.BrianL said:
WRT transformes, I know of many european manufacturers which have full approvals for local and specific target markets, but not UL (and North-America isn't a target, therefore). Although this can be usually had as an option, at extra cost, and is normally combined with a power derating for the transformer (which might indicate that the UL approval is more strict in thermal issues).
- Klaus
Hi again BrianL - and others!
BrianL
Sorry if I made a little mistake. However, I have found a chinese producer of (high quality?) R-Core transformers. This company states (under "Construction and safety"):
http://www.rn-core.com/english/products/sort285.asp
Hope that this helps and that I didn´t make another little mistake ;-)
Kind regards
Karsten
BrianL
Sorry if I made a little mistake. However, I have found a chinese producer of (high quality?) R-Core transformers. This company states (under "Construction and safety"):
http://www.rn-core.com/english/products/sort285.asp
Hope that this helps and that I didn´t make another little mistake ;-)
Kind regards
Karsten
side note:
THLAudio in Thailand listed a few dozen dual 42V secondary 280VA R-core transformers they removed from Proton amps, for $15 each.
With added P&H costs, pretty interesting for the Ozyania blokes.
Unfortunately, Dutch customs would fry my heiney if i ordered a couple.
(for the weak of mind: Proton is a Thai audio gear manufacturer, the (NAD designed) D-1200 from 1987 was pretty much the numero-1 power amp with R-core transformers inside.)
Edit-to :Link
PS : James, TY for the Nikko info, no doubt Mr Tsunemoto would agree that i should be flogged in public by a bunch of leather motorcycle dykes for my ignorance. (if only)
THLAudio in Thailand listed a few dozen dual 42V secondary 280VA R-core transformers they removed from Proton amps, for $15 each.
With added P&H costs, pretty interesting for the Ozyania blokes.
Unfortunately, Dutch customs would fry my heiney if i ordered a couple.
(for the weak of mind: Proton is a Thai audio gear manufacturer, the (NAD designed) D-1200 from 1987 was pretty much the numero-1 power amp with R-core transformers inside.)
Edit-to :Link
PS : James, TY for the Nikko info, no doubt Mr Tsunemoto would agree that i should be flogged in public by a bunch of leather motorcycle dykes for my ignorance. (if only)
BrianL
Hi Brian,
Don´t be afraid to drop the company an email or give them a phone call (email-addresses and phone numbers are shown).
Modern chinese companys have employees who speak very good english. If you are strictly looking for shops where to buy R-Core trafos locally I might, unfortunately, not be able to help you.
I do not know about the prices from the chinese factory, but maybe a group buy could be interesting???
The primary reason for me to show the link was due to the question about different international approvals. At least in the picure their R-Core trafos are good looking
Kind regards
Karsten
Hi Brian,
Don´t be afraid to drop the company an email or give them a phone call (email-addresses and phone numbers are shown).
Modern chinese companys have employees who speak very good english. If you are strictly looking for shops where to buy R-Core trafos locally I might, unfortunately, not be able to help you.
I do not know about the prices from the chinese factory, but maybe a group buy could be interesting???
The primary reason for me to show the link was due to the question about different international approvals. At least in the picure their R-Core trafos are good looking
Kind regards
Karsten
http://www.diyaudio.com/forums/showthread.php?s=&threadid=64208&perpage=25&highlight=&pagenumber=3
I had made one which was tested by my Kevin and he had suggested improvement. the application was headphone amplifier, but we lost contact. (post 57).
The core size is RC20.
I had made one which was tested by my Kevin and he had suggested improvement. the application was headphone amplifier, but we lost contact. (post 57).
The core size is RC20.
An externally hosted image should be here but it was not working when we last tested it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.