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Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
Hi, Does anyone know where to find gapped ferrite cores with bobbins suitable for flyback smps use? I've seen countless ee cores, but never any ones that specify an air gap. I also need to be able to buy them in very low quantities. Power is 15-30 watts.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
What size do you need?
RS list some, for example
A place I used to work at used to buy them in small quantities, I think they were generally Epcos ones. I'm not sure if they were ground by Epcos, or a third party.
Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
Buy ungapped cores and shim them with stiff plastic to get the required inductance. All SMPS designers do this to get the final design right before ordering a specific gap to be ground from the makers. The shimming doesnt make any difference except for a little more radiated EMI because of the disconuity in the flux loop around the outside of the core
Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
Ash: just what I needed
I've gapped EE cores before, both by grinding and by shims. Grinding Isn't accurate unless you buy or create a specialized rig- which I won't do for a one-off. Shims tend to be able to compress and increase inductance/reduce energy storage by not so insignificant amounts.
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FB transformer cores
