Ferrite E cores without coil formers??? - Page 1
Forum section: electronics / projects

author: DeanA
author_rank: Regular Contributor
timestamp: February 05, 2024, 04:18:42 am
content: I was looking at some Ferrite E-cores from Ferroxcube, Epcos/TDK only to find there are no coil formers to suit. E100/60/28 and E80/38/20 ferrite cores available but no coil formers, I just don't get it, what is the use of the ferrite E cores without the coil formers. The lower size E65/32/27 and below all have coil formers and other accessories but not the E100 and E80.I emailed ferroxcube in Taiwan and the only response I got was "Sorry ,we have not these product .Thanks!" so how the hell does anyone even use these E100 and E80 ferrite cores without the coil formers, surely not 3d printing their own or something?

author: coppercone2
author_rank: Super Contributor
timestamp: February 05, 2024, 04:46:54 am
content: sounds like you encountered a business to business professional

author: PCB.Wiz
author_rank: Super Contributor
timestamp: February 05, 2024, 05:31:17 am
content: Quote from: DeanA on February 05, 2024, 04:18:42 amThey tooled for their own.Those large cores are now niche products, so do not expect big investment in tooling in 2024.

author: Andy Chee
author_rank: Super Contributor
timestamp: February 05, 2024, 05:38:48 am
content: 10 years ago I also noticed that coil formers were unavailable for the large cores. I figured that the use case for large cores would generally entail a customised former anyway, hence Ferroxcube/Epcos see no point in stocking large formers.Whilst a hobbyist would have to resort to 3D printing, a commercial product would have to allow for manufacturing of the required formers.

author: Slh
author_rank: Regular Contributor
timestamp: February 05, 2024, 07:01:24 am
content: For a one off you can use resin 3d printing. For volume, Mikes-Plattshttps://milesplatts.co.ukhave a lot of larger core bobbins (including ones that can fit two or three pairs) and can make custom bobbins which mighr make sense from 10000 off and up.

author: DeanA
author_rank: Regular Contributor
timestamp: February 05, 2024, 07:17:34 am
content: Quote from: Andy Chee on February 05, 2024, 05:38:48 amI just need to supply a prototype, then if/when approved 4 more units for evaluation. So 3D print it is I guess, unless I can get away with the E65/32/27.

author: Andy Chee
author_rank: Super Contributor
timestamp: February 05, 2024, 07:48:54 am
content: You could potentially rework your design to use several smaller cores in parallel, a technique often seen in power inverters, offering the advantage of lower leakage inductance and reduction in size in at least one physical dimension (i.e. slim form factor).But I don't know what your application is, so it may not work for you.

author: jonpaul
author_rank: Super Contributor
timestamp: February 05, 2024, 11:13:42 am
content: Bonjour been design and mfg transforemrs and SMPS since 1970s,Small sizes like SMD EER11, EER 9.5 EP13 are made in millions and easily avail.Round and square center leg large shapes are ususlly made with a simple core tube of paper or plastic.TDK, have stopped any bobbin sourceing and ONLY make the cores.Old line USA bobbin suppliers are mostly gone, like Bimco, Cosmo.Old stock may still be avail on epayChinese firms like Pinshine are bobbin specailists, wide range.http://www.pinshine.com/en/product/index2.aspxTry Siemens (EPCOS) Ferroxcube (Philips) and magnetics disty like AllMag in USA.Large EE shapes like E100/60/28 and E80/38/20 are seldom used as the round and square cetner are easier to wind.We use ETD, EER, PQ. All have bobbins avail. In 1990 we used TDK PQ70 with TDK bobbins for a 750W medical off line PSU.Suggest to review the design and choose a shape and vendor with a mor epopular shape and that had bobbins avail.Bon ChanceJon

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 05, 2024, 12:20:13 pm
content: I see them at this distributor (probably not suitable for you)It seems they have them custom madehttps://www.semic.info/lj-e10028h-0p-fr4-b-en/andhttps://www.semic.info/lj-e-8020v-0p-1s-bf-en/

author: jonpaul
author_rank: Super Contributor
timestamp: February 05, 2024, 03:23:17 pm
content: Excellent old time UK bobbin supplier:https://milesplatts.co.uk/products/amcc-coil-bobbinsCheck the spec sheets, small qty, disty and samples may be avail.Look for ChiCom Pinshine disty in your country.Bon ChanceJ

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 05, 2024, 04:27:13 pm
content: Well, if it's a matter of design, I would encourage a couple smaller ones with a phase-interleave scheme. This has knock-on benefits reducing transients in the inverters, and required capacitance.Maybe that's assuming too much, and it's not simply a DC-DC application.Maybe it's not an application where phasing is practical or meaningful (e.g. induction heating is single phase), and such alternatives are only a means of series-parallel combinations, and the monolithic unit is likely cheaper / more compact.You may have luck at Asian suppliers. They're a bit hard to search for (let alone navigate..) in the west, but the products are diverse. Offhand, I see some EE70 and 80 size bobbins, nothing beyond that. Examples:http://www.ougedianzi.com/Home.htmlhttp://en.fshgs.cn/Sourcing would probably be via Ali Express or whatever.I have seen formers made from FR-4 / G10 epoxied together. It's robust material and easily glued. You do need to cut pieces to suit, of course. Ensuring good isolation through glued joints might not be trivial, either.Might also get lucky with an old school iron-core bobbin that happens to fit the ferrite you want. Might, as those are usually "wasteless" cut, whereas ferrites are usually made with thinner sections -- providing more winding area. I don't have any suppliers for those offhand though.Tim

author: DeanA
author_rank: Regular Contributor
timestamp: February 05, 2024, 10:11:47 pm
content: Thanks everyone for your advice, got more homework to do.Application is a high power DC-DC converter based around TI UCC28951, something like thishttps://webench.ti.com/power-designer/switching-regulator/customize/3.I'm very new to this type of design with transformer, up till now I've only done lower power buck type with just inductor, so any advice on transformer selection and design is much appreciated.

author: Andy Chee
author_rank: Super Contributor
timestamp: February 05, 2024, 10:15:27 pm
content: If it's a DC-DC converter, then definitely try the multiple small transformer technique.You can get a general idea of how this works by looking inside a high powered inverter:

author: coppercone2
author_rank: Super Contributor
timestamp: February 05, 2024, 11:04:46 pm
content: i read alot of chinese companies are taking less savory jobs now because its take it or go broke. you might be able to make a smaller then usual short term deal