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I am looking for something similar to this coil but for the life of me I can't find it "separated" from the circuit which I want to make by myself.
enter image description here

brhans
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Andrea Bianchi
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    It's a copper pipe, moreover the example in the picture won't work because it would crate a short circuit. It would need larger gap between turns, or some epoxy paint, or a heat resistant tube. – Marko Buršič Nov 30 '20 at 16:48
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    You can get drawn copper in fairly large sizes (even a hardware store may have larger than you think) and bar stock still larger, though there you'd have to pay attention to the specific copper alloy you were buying. But many such things would use soft copper water tubing, both since the skin effect makes the outside what counts, and because for continuous duty they can run coolant through it. – Chris Stratton Nov 30 '20 at 16:49
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    Ask a car parts place or garage for copper brake pipe. (There are other alloys available so make sure you get copper) –  Nov 30 '20 at 16:57
  • This is definitely a pipe. – user253751 Nov 30 '20 at 17:04
  • +1 on copper break line and that you can’t short the turns without isolation as in the picture. Add some sleeving. – winny Dec 01 '20 at 07:51
  • My local hardware store has tons of that stuff in the plumbing section. – user1850479 Dec 01 '20 at 13:44
  • They fill the copper pipe with sand or ice, and then it can be bent without kinks. It may need to be annealed first to soften up the copper if it is the hard type of copper (read other comments/answers). – MicroservicesOnDDD May 30 '21 at 04:30

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Tubes (pipes) are used for these things.

First, you run the thing at frequencies where the current flows in a thin layer and doesn't care if the conductor is hollow (and it may as well run on the inside, halving the resistance).

Second, it may be practical (or outright required) to run coolant (usually water) inside.

The places where you can get these tubes for cheap:

  1. Air conditioning suppliers and workshops. You may even get shorter pieces (1m or less) at scrap prices or for free. 6mm, 8mm, 10mm, 12mm and their corresponding imperial sizes widely used.

  2. LPG car conversion suppliers / workshops. LPG conversion is popular here, may or may not be popular where you live. Copper tubes have fallen somewhat out of use, but are still used. Tubes come in PVC insulation (just like a cable) that may or may not be useful in your case. 6mm and 8mm outside diameters are common, scrap pieces common as well.

  3. Hydraulics and pneumatics suppliers / workshops (including, but not limited to, car and truck brakes).

Some of these places distinguish "soft" and "hard" pipes. You need the "soft" ones, "hard" are way harder to safely bend.

You can as well grab tools for aesthetically bending these tubes from the same places.

p.s. plumbers use 12mm and larger, but it is the "hard" variety (and you will rather not make an installation that big).

fraxinus
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    Hard or soft is not because of alloy. Same material. It is treated with high temperature. Can be reversed. – user263983 Dec 01 '20 at 10:48
  • @user263983 maybe. I am not sure if one can find unrefined copper these days. – fraxinus Dec 01 '20 at 10:56
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    electrotechnical copper is most pured due to demand of lowest resistance. On scrapyard guys prefer electrical wires then plumbing pipes. Solid copper that size can be fine in high power transformer, they have rectangular shape. But no idea how to get pieces. – user263983 Dec 01 '20 at 12:55
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    Most copper on the market these days is electrotechnical (refined by electrolysis). As far as I know, refining process extracts precious metals that completely offset the cost of refining. I'll remove the alloy point - you are right about the annealing. – fraxinus Dec 01 '20 at 13:37
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I knew a guy who built experimental induction heaters (under the guidance of an expert in electro-magnetics) for the semiconductor industry.

They used copper tubing.

Getting a stable resonance was tough, because the plasma conductivity interfered.

analogsystemsrf
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Copper brake line is a copper tube, easily available and cheap. Any garage might simply give you a bit of that for free as sometimes there are cut offs of a meter or more that they won't use and throw away.

Stanislaw Marczak
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