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| Thread ID: 57702 | 2005-05-10 06:48:00 | How to get these evil things apart | george12 (7) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 353828 | 2005-05-10 06:48:00 | Double-E style ferrite-core transformers. HOW do you open them up (separate the two E's)? The two halves are secured by some kind of evil glue. I've tried melting it (250 degree soldering iron -> nothing) but no luck. All I need to do is separate the two halves. What do you guys recommend? Thanks in advance |
george12 (7) | ||
| 353829 | 2005-05-10 06:57:00 | Often it is an epoxy resin. One time use only. It can bond to the ferrite core, which is also epoxy based I think. They were often permanently bonded to prevent high frequency squealing. |
godfather (25) | ||
| 353830 | 2005-05-10 07:34:00 | Crap. Know where I can buy a ferrite core? Either double-E or toroid is OK. |
george12 (7) | ||
| 353831 | 2005-05-10 07:54:00 | What are you doing? Building a transformer or using the parts for something else? Like a robot vacuum cleaner? I'd buy one. (at the right price :) ) |
mark c (247) | ||
| 353832 | 2005-05-10 07:55:00 | JayCar have toroids. LO1238 for instance Research what you want though, an RF one is different to an Audio type, different characteristics. |
godfather (25) | ||
| 353833 | 2005-05-10 08:34:00 | Is that one ferrite core godfather? It's a bit small though, and there aren't any bigger ones I can see. It's for a switching power supply. I found an old AT one that had the transformer just taped together, but it's a bit too small as well. I am making a 300-400w switching ATX computer power supply, with 12v (7-20v) input. It's going great so far :). |
george12 (7) | ||
| 353834 | 2005-05-10 08:48:00 | 12v (7-20v) input. Shouldn't that be 'output'? :eek: |
mark c (247) | ||
| 353835 | 2005-05-10 08:57:00 | Nope. Input. 7-20v in -> computer power out. Designed for in a car etc. |
george12 (7) | ||
| 353836 | 2005-05-10 09:12:00 | Oh I get it. Well good luck, be interesting to see how it turns out. Sounds pretty inventive. | mark c (247) | ||
| 353837 | 2005-05-10 22:14:00 | Double-E style ferrite-core transformers. HOW do you open them up (separate the two E's)? Presuming you have already removed the old windings, baking in an oven usually works, the epoxy bond should weaken but you have to part them while hot. You can heat them with a hot air gun too, but the ferrite sometimes cracks due to unequal heating stresses. To separate, when good and hot (above boiling point of water) insert two stiff pieces of wood or similar and spread the ends. Metal levers are OK but needs some solid padding to prevent localised pressure fractures of the ferrite. Not all epoxy glues soften with heat so your smileage may vary. Cheers Billy 8-{) P.S. What are you using as switching devices for the primary? 7-20 volts input will require 15 to 43 amps of primary current, not allowing for conversion losses. At a nominal 12.5 volt input you will still need 24+ amps. I doubt that you will need the full 300-400 watts though, so if you haven't done so already perhaps you should find out the true output power required and design backwards from there. It might make winding the transformer and heatsinking the switching devices a whole lot easier |
Billy T (70) | ||
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