Re: Current transformer Wire wrapping

In article <asKdnUIIqakO_YreRVn-uA@xxxxxxxxxx>, Bordon wrote:

> If all else fails I may try this, as AC/DC adaptors are cheap.

espeically the unemployed ones :)

> I may get
> back to you on this. I have have one actually open on my desk right now.
> Its .25 A and 16.5v. However if you look at my diagram I think I will need
> to un solder the botom of the lamenated metal Pieces to get at the Primary.
> May be other tranformers dont have this problem. (I think its from an old
> modem or something)

sometimes if you remove the aluminium (or steel) bracket the I sections are
all together and come off easily allowing access to the windings.

sometimes they are interleaved and that doesn't happen.


>
>
> .----------.
> ,´--------- /|
> ,´-----------/ |
> /------------/ |
> +-------------+ |
> | | o-------o Lamenated Metal Pieces
> | +---------+ | |
> | |========o------------o Secondary (16.5v)
> | |=========| | |
> | |XXXXXXXXX| | |
> | |========o------------o Primary (120V)
> | |=========| | |
> |#+---------+#----------o Solder
> | | ' I guess where they put the
> +-------------+´ bottom part of Transformer
> in after they have put in
> winding asembly.

possibly welded, I jabe a microwave transformer that's welded. it's probably
not worth the bother trying to undo the welds (or solder joins) all that
Iron is going to require a large soldering iron to unsolder.


much easier is to (carefully) cut the secondary using a sharp knife or chisel
as pull it out

> I can get from my local Electronic store the a "Toroid" Dounut. They don't
> seem to have anything else eg Current transformers. Nearby anyway.

that would work, if you get a pre-wound toroid you could just
make a few turns of mains wire through the centre, use the high voltage
winding for output and ignore the low voltage winding.

> Can I wrap one of these up. And would I get better response with this ? If
> So how many wraps would I use. The dounut is probably a 3/4 inch hole and
> about 1 3/4" across.

Toroids are typically more efficient than ***-metal transformers.
use as many turns as you can.

Bye.
Jasen
.

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