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Old 13th Apr 2021, 10:00 am   #2
radioman
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Join Date: Apr 2003
Location: Ayr, Ayrshire, UK.
Posts: 630
Default Re: Vintage Diagram Drawing Techniques?

I'd suggest it's done by careful placement of their circular drawing template.
Looks like overlapping part circles for the coil and with a slight movement of the template sideways you'd achieve the thin to thick line.
That how I'd do anyway.

Andy
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