transformer cores suppliers - Page 1
Forum section: electronics / beginners

author: tron9000
author_rank: Frequent Contributor
timestamp: April 10, 2018, 12:59:57 pm
content: I'm looking for a hobbyist/commercial supplier that sells transformer steel EI cores but am having no luck.does anybody know where I can pick some up?

author: FotatoPotato
author_rank: Regular Contributor
timestamp: April 10, 2018, 05:55:44 pm
content: Try taking a look ar coilcraft.com. Im not sure if they only sell the cores of transformers but I do know that they have a HUGE variety of inductors, transformers etc. and they make good stuff. I have baught form them before and havent been disappointed.

author: james_s
author_rank: Super Contributor
timestamp: April 10, 2018, 06:26:43 pm
content: I've bought cores from Alphacore, I don't remember if they have EI cores but I've used a number of their toroidal and cut C cores.

author: Unknown
author_rank: Unknown
timestamp: April 10, 2018, 08:05:40 pm
content: https://www.edcorusa.com/m6-steel#/pageSize=25&viewMode=grid&orderBy=0&pageNumber=1I found this site via Craig Hollabaugh's youtube channel. I'd recommend checking out his coil winding machine and software.

author: Jwillis
author_rank: Super Contributor
timestamp: April 11, 2018, 12:37:48 am
content: Quote from: steverino on April 10, 2018, 08:05:40 pmThanks Steverino ! I've been looking for exactly this sort of thing as well. I don't really want to buy a minimum of a ton from China.

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2018, 12:40:35 am
content: I remembered where I bought the Alphacore cores, it was Bridgeport Magneticshttp://www.bridgeportmagnetics.com/

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 11, 2018, 01:32:26 am
content: Oh yeah, once spec'd a custom part from Bridgeport Magnetics -- was for a medium frequency application, up to 2kHz or so. They did the design, looked reasonable (other suppliers ranged from 2-4 times larger, to no-quote!), put it in, worked fine, didn't seem to overheat or anything. 20kVA, toroidal, about 12" O.D. I think it was, $800 in small quantity. Quite reasonable.I guess I have to laugh a bit at their sheet-wound inductors, but as they're completely without data, and intended for the audio market anyway, I suppose that doesn't matter much. (The claim "free from skin effect" is easily disproved with an impedance curve, but as they don't even have that, and their primary customers apparently don't need it, it doesn't matter much.)Tim

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2018, 02:29:27 am
content: I couldn't find any date either, so I used generic data I could find for ordinary transformer iron and it worked fine. I was only making power transformers for line frequency so there was nothing too critical.

author: gregariz
author_rank: Frequent Contributor
timestamp: April 11, 2018, 03:16:48 am
content: Quote from: tron9000 on April 10, 2018, 12:59:57 pmIn the past I typically just buy a premade transformer of a given wattage, carefully tapping the laminations out of the core - after the first few they come apart fairly easily and then remove the secondary counting the turns ---> turns/volt. it's usually much cheaper than trying to source a core these days. Most consumer type silicon steel cores very roughly saturate (in the linear zone) around 1.5Tesla or 450mA/m so you can use that to work out peak current in a pinch.

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2018, 05:04:28 am
content: Cores are not expensive, and it's a lot less hassle than trying to modify an existing transformer. I've tried that a few times and mostly couldn't get the cores apart without mangling.

author: tron9000
author_rank: Frequent Contributor
timestamp: April 11, 2018, 08:10:38 am
content: Quote from: blueskull on April 11, 2018, 05:17:37 amSorry, would help.Mains, I'm wanting to build a simple 50Hz, 240V to 48V 250VA transformer for a linear power supply, I've done all the calculations subject to bobbin size, so just shopping around trying to find a core/bobbin near enough to fit my calculations.Quote from: gregariz on April 11, 2018, 03:16:48 amNow I have seen this done, considering I didn't mention that I wanted 250VA, you'd have thought a low power transformer would be ok using this method. Plus as James_s said: its looks like a bit of a hassle.Thanks to your suggestions. Since OP I tweaked my search and found that "transformer Lamination Suppliers" yielded some better results:http://www.ascocomponents.co.uk/- they're based in Birmingham here in the UK, so going to ask them for a quote. But if they have an MOQ in 100kg's then I think EDCOR looks like what I'm after.thanks guys

author: tron9000
author_rank: Frequent Contributor
timestamp: April 11, 2018, 08:36:21 am
content: I did look at these:http://uk.farnell.com/multicomp/mcta250-25/transformer-toroidal-2-x-25v-250va/dp/9530770?st=troidal%20transformerSo far my build is coming out at £27.50 (500g of 20AWG: £12.50, 500g of 13AWG: £12.50, 3D Printed bobbin (unless negligable price):£0, wax Preform: £2.50, tape/consumables: already have) just need the laminates.True toroidals are better than EI cores, but I want to build my own, its a learning thing, if it comes out too expensive then I'll just buy...or salvage... at least I know...

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2018, 04:48:04 pm
content: I don't think I'd use a 3D printed bobbin, transformers can commonly have a 70C temperature rise and even more under a fault condition. As far as I know, 3D printing materials are all thermoplastics that will melt again if they get hot. Transformer bobbins are usually made of a high temperature plastic or fiberglass. They should only cost a few dollars for most cores.

author: gregariz
author_rank: Frequent Contributor
timestamp: April 11, 2018, 05:21:11 pm
content: Quote from: james_s on April 11, 2018, 04:48:04 pmMy suggestion above is something I have used to good effect on a number of tube based transformers ie 300-0-300 that were not commonly available where I am. My trick was gently tapping them out using a lamination from a discarded transformers as the tool ie hitting all three ends of the lamination to break the lacquer.The bobbin comment also raised my eyebrows - there is actually quite a bit to designing a transformer - even a garden variety one, and that is something I have never seen taught at a practical level in colleges and universities - so its easy to make your transformer run hot simply by getting the core magnetization wrong - using the primary of an existing is one way to know that core and copper losses have been minimized and it is running a linear magnetization for a given size of core - which is actually determined experimentally to some extent unless you have very good data (which you don't often have). Good books on the practical aspects are even not that common - you will likely be referencing old texts on the topic.