Re: solderig enamelled wire, problems.

<albert@spenarnc.xs4all.nl> wrote:

In article <1redwas.10sf9o41u2k5q8N%liz@poppyrecords.invalid.invalid>,
Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
>

Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:

<albert@spenarnc.xs4all.nl> wrote:
>

I remember soldering coil/transformer wire was simple in the 70's.
The trick was putting the wire an aspirin tablet and 0.1 mm was no
sweat.
>
Now for the 1v-5v step up converter I followed the advice, and remove
the winding of a 5x5 mm ferrite coil and replaced it with a bifilar
wire with the same number of turns. This was surprisingly easy.
.35 mm wire with 2*.25 wire. (The wire was stolen from a broken
ventilator.)
>
Now I get stuck. I can't solder the wire! The aspirine trick doesn't
work. Burning the insulation turn it into a black coating that
is equally tenacious. Making the copper redhot to burn the coal,
only make the copper to melt.
>
Groetjes Albert

>
>
Put some methylated spirits or ethanol in a small open metal container
such as the lid of a bottle .  Set fire to it and hold the end of the
wire in the flame until it is red hot.  Plunge it downwards into the
liquid and slide it out sideways so it doesn't get heated a second time.
>
There will be a chemical reaction between the oxide on the red hot
copper and the ethanol, which removes the oxide and leaves the wire
bright and clean.
>
Have a piece of metal ready to put over the container to extinguish the
flame and plan in advance how you will deal with the rapidly-spreading
fire if you upset the container.  Put the bottle of ethanol some
distance away.
>
>

>
Fun. I’ll try it outdoors sometime, but not at my bench!

>
When I worke at Eddystone Radio, that was the standard method of dealing
with Litz wire.  The meths pot was like an old fashoined whale-oil lamp
with a spout and it was mounted in an asbestos-lined steel box with a
hinged lid that could be flipped down in emergency.
>
The chief engineer also used it to light his cigarettes.

 
This doesn't appreciate the fact that better and better plastics
are used. E.g. a bag of nuts can't be opened by hand, you
really need a knife for that.
The inner surface of a soda can is coated. I tried to burn it
off, then polish it. Forget it! The soda can is destroyed before
the coating gets it.
Mechanical removing of the coating is always possible, but it is
increasingly difficult if the wire gets thinner, 0.25 mm.

Some wires now have a 'self-fluxing' coating, which breaks down at
soldering temperature and allows the wire to be easily tinned, but your
description of the problems you were having suggested that this wire
wasn't the self-fluxing type.

I'll try the Liz method. This resemble what I have already tried,
but my wire melted. It is also clear that I have to have tinned
the wire before winding the coil.

You may find that the lower temperature of an ethanol flame doesn't melt
the wire (assuming the wire is copper, not aluminium).  The base of the
flame will be cooler than the top, so you may be able to find a suitable
temperature zone which produces just enough heat to remove the oxide
when you quench it.  The wire should then be easily tinned with ordinary
flux-cored solder.


--
~ Liz Tuddenham ~
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www.poppyrecords.co.uk