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Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
Hi,
I've broken about 3 cores now, and I have one left here
I have a few smps transformers, and I have salvaged the former from one (by breaking the ferrite), but now I need the two ferrite halves to make a complete transformer again. I have managed to cut the former and wire off some others, leaving just the two halves of the core stuck together with some kind of white resin. The problem is, the resin is pretty strong. I have tried boiling one for about 20 minutes, but still the ferrite breaks when I try to separate the two halves... Any ideas? Is it even possible to get this glue to soften, maybe soaking it in petrol or something?
I have a good supply of these transformers, so I can experiment. If all else fails, I'll have to just wind my transformer on one of the salvaged cores, leaving the former out... that would be a shame though.
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
Thanks for the replies
I've changed my mind about these transformers now, they are so difficult to separate I might as well just use them as they are. By modifying the way the windings come out, I should be able to use them as a GDT for a halfbridge.
Something I did want to do though was make a mains inverter, I managed to separate a larger monitor transformer by boiling it. Just for the record, it appears that the brown glue (whatever it is) melts a lot easier than the white epoxy.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
If you re-use an ATX transformer you can make yourself a nice halfbridge SMPS.
You can use small drive transformer from ATX supply as GDT if main transistors were mosfet's. You can use another small transformer for a mini flyback SMPS (I failed to get results from that, witohut regulation voltage spikes are real pain).
TV and monitor transformers tend to use flyback topology due to their low power, but I think you could run them with a fullbridge for some really fierce output.
Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
With the white epoxy, you generally need to butcher it with a screwdriver to 'crack' off all the blobs of glue around the join, then sand until the only glue left is actually between the ferrite halves. If you then boil the transformer for a bit, and use gloves (stinking hot) you should be able to lever the top out, but I've found it _essential_ that any forces are applied on the round centre axis, otherwise you of course snap the ferrite wings off.
If there are largeish (0.3mm+) spacers in there, you can also rest the ferrite such that everything but the spacer is supported, and then with a knife etc 'crack' it out sideways, but it's difficult to get enough force.
If you've done it enough, it becomes a science and whenever you see some good ferrite, you'll know what to do with it. =P
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Epoxy ''around edges'' isn't the problem. Problem is that space betweent he core and former is completely fiilled with epoxy. It is impossible to soften that amount of epoxy by boiling, or physically remove it somehow.
Some transformers are much easier to get apart, smaller ones are cooked easily but ATX are really vain.
Registered Member #87
Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191
I've had some luck with those ultra thin diamond dremel cut off disks, if you hold the core in something soft to ease the vibrations. Once the outside is done, I can usually boil and twist the cores apart. The inner rod part of the core is sanded a bit to flush everything up, and there you have it.
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