Quote:
Originally Posted by Pamphonica
I always wondered how they achieved the contact area. The wire on my variacs looks as if it has been flattened a bit after stripping, presumably to avoid any possibility of snagging the rotating contact. Very delicate work!
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Mine is also definitely flattened along the conract area and I also wondered about that. The exposed copper seems to be coated/plated with some other metal silver in appearance. I was informed by someone on here that this was probably to improve resistance to wear. I imagine it would have to be applied with some kind of plating process after the insulation was stripped and the surface prepared. The brush is made from two separate pieces of graphite material. The unit is rated for 2000W 8A though.
Taking on the task of re-winding a variac does not seem like a job for the faint-hearted so I hope your efforts pay off and likewise look forward to the result!