A
Andrew VK3BFA
- Jan 1, 1970
- 0
I am trying to recycle old computer power supplies, so need to rewind
them - and thanks to the people who responded with suggestions for
getting the ferrite core apart - mixed success, will file a report
when a batch of Toluene and MEK gets picked up tomorrow.
Started unwinding them, and got perplexed. And not being able to post
a diagram, bear with me.
The main primary winding seems to be centre tapped, but the centre tap
is not connected to any external components. On top of this are the
secondary windings, not a problem except for nutty turns ratios, vis
the 5v winding is 3 turns each side of Centre tape, the 12v winding is
4 turns each side of centre tap - doesnt make sense!
Another layer of tape, then a single turn of copper foil, one end
connected to primary winding. Another layer of tape, and then a 20
turn single layer (covers the bobbin area) of enamelled wire, one end
connected to the same end of the prinary as the copper foil, the other
end connected to the centre tap.
I can guess the copper foil is a shield to stop it radiating RFI, but
what does the top layer do? - and more to the point, if I rewind this
transformer in a conventional manner without it, will it affect
operation?
Any comments appreciated.
Andrew VK3BFA
them - and thanks to the people who responded with suggestions for
getting the ferrite core apart - mixed success, will file a report
when a batch of Toluene and MEK gets picked up tomorrow.
Started unwinding them, and got perplexed. And not being able to post
a diagram, bear with me.
The main primary winding seems to be centre tapped, but the centre tap
is not connected to any external components. On top of this are the
secondary windings, not a problem except for nutty turns ratios, vis
the 5v winding is 3 turns each side of Centre tape, the 12v winding is
4 turns each side of centre tap - doesnt make sense!
Another layer of tape, then a single turn of copper foil, one end
connected to primary winding. Another layer of tape, and then a 20
turn single layer (covers the bobbin area) of enamelled wire, one end
connected to the same end of the prinary as the copper foil, the other
end connected to the centre tap.
I can guess the copper foil is a shield to stop it radiating RFI, but
what does the top layer do? - and more to the point, if I rewind this
transformer in a conventional manner without it, will it affect
operation?
Any comments appreciated.
Andrew VK3BFA