Using enamelled copper wire

[tonga]

Hi all,

I've been lurking around the forums for a few weeks gathering info and tips before I start my first DIY amp build....All the parts have arrived and I'm ready to rock but I have a straitforward practical nooby type question.

The project requires that I make an inductor by winding enamelled copper wire around a wire wound resistor and soldering the Cu wire to the resistor leads which is in turn soldered to the PCB. My question is do I need to strip the ends of the Cu wire before I solder it to the resistor or does the heat of making the joint burn away the insulation? If I do strip the ends of the wire is it best to burn it with a lighter or use emery paper to sand it away?

Thanks in advance and dont flame me if I'm being stupid!!

tonga- (new DIYer, wallet already in intensive care)

[Centauri]

Unless the enamel is specifically the meltable type (unlikely), it will need to be removed. I usually just scrape it off with a razor blade or hobby knife. If you burn it, it will be difficult to solder .

Cheers
Graeme

[tonga]

Thanks Graeme....very consice and all I needed to know!

Tonga

[thomas997]

It is burnable but it makes a little mess and requires a higher temperature.

If I am in a hurry I just crank the temperature on the soldering iron and tin the ends of the wire.

If I want it done "properly" I grab some sand paper and takes 20s or so to get most of it off the end.

[tubetvr]

Use the old professional method.

heat the wire end in an open flame until it is red hot.

Quickly dip the hot end in a small bowl containg ethyl alcohol.

The result is a wire end perfectly clean and without any oxides, just pure copper.

This method is a bit tricky when used with very small wire diameter but I have used it succesfully with as tiny wires as 0.15mm.

Regards Hans

And no there is practically no risk that the alcohol catch fire as there is not enough heat in the copper wire for the alcohol to reach high enough temperature, the risk is also minimised by using a small amount of alcohol, say a few cc.

[d3imlay]

I use to work at a transformer shop. Certain types of magnet wire had a varnish that would melt in a solder pot. It's been 25 years. Can't remember what it was called. I do remember that there was a bright red and bright green varnish that melted. The dark brown varnish didn't melt.

[peranders]

Originally posted by tonga
Hi all,

I've been lurking around the forums for a few weeks gathering info and tips before I start my first DIY amp build....All the parts have arrived and I'm ready to rock but I have a straitforward practical nooby type question.

The project requires that I make an inductor by winding enamelled copper wire around a wire wound resistor and soldering the Cu wire to the resistor leads which is in turn soldered to the PCB. My question is do I need to strip the ends of the Cu wire before I solder it to the resistor or does the heat of making the joint burn away the insulation? If I do strip the ends of the wire is it best to burn it with a lighter or use emery paper to sand it away?

Thanks in advance and dont flame me if I'm being stupid!!

The question is not stupid. I use a sharp knife and scratch it off.

Picture of inductor here.

[d3imlay]

The downside to the knife is that a nick in the wire will eventually result in a broken wire.

[aarsoe]

Tubetvr

Funny you should mention it, as I have been searching for such a tip for some time - however I seem to remember something about cobber loosing conductivity if overheated. Am I wrong or...?

[454Casull]

Originally posted by aarsoe
Tubetvr

Funny you should mention it, as I have been searching for such a tip for some time - however I seem to remember something about cobber loosing conductivity if overheated. Am I wrong or...?

The electrical conductivity of copper drops with increasing temperature, but the increase in resistivity is only temporary (unless the temperature stays high forever).