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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Doubl3 Helix wrote ...
I have a book on DIY radio from 1922 which assumes that nothing at all is available off the shelf. Even the variable capacitor must be made from household parts. Unsurprisingly, the first half of the book is about woodwork and metalwork.
Whichever book that is; It sounds quite lovely. I love old radios and such, and I think it would be great to build something like that. I would really appreciate it if you would do that.
The volume from which I've been sending out scans of home-made coil-winding machines is: Camm, FJ,Wireless Coils, Chokes & Transformers, and how to make them George Newnes Ltd, London, 1937. There are also chapters on making your own mains transformers, and making LF and smoothing chokes.
Some of the giant home-made tuning coils and variable capacitors featured in Pritchard J.L. & Hobbs E.W.Wireless Construction Blackie & Son Ltd, London, Glasgow and Bombay 1925 are true leviathans and labours of love of their time. Half the book is dedicated to woodwork and metalwork, since almost every component must be fashioned by the constructor from simple raw materials, though there are a few thermionic valve designs at the end of the book.
A design for a variable capacitor especially caught my eye. It consists of two concentric cylinders, with large oval slots cut away in each, and the inner cylinder rotatable on a spindle. No doubt the geometry of the cut-aways can be used to modify the linearity or otherwise of the capacitance variation, but the book is almost devoid of theory. I could imagine being able to make a very high voltage VC using this principle for much much less than vacuum variables. The metal surfaces could covered with etched PTFE, and/or the whole contraption could be immersed in silicone dielectric oil. My idea of good fun!
As the Beatles song has it: "Let's all get up and dance to a song that was a hit before your mother was born/ though she was born a long long time ago, your mother should know, your mother should know."
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Vintage DIY/homebrew Coil winding machines
