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multi-layer secondaries




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From:  Mike Harrison [SMTP:wwl-at-netcomuk.co.uk]
Sent:  Saturday, February 21, 1998 5:02 PM
To:  tesla-at-pupman-dot-com
Subject:  Re. multi-layer secondaries

On Sat, 21 Feb 1998 17:35:59 GMT, you wrote:

>>From:  Edward V. Phillips [SMTP:ed-at-alumni.caltech.edu]
>>Sent:  Friday, February 20, 1998 11:34 AM
>>To:  tesla-at-pupman-dot-com
>>Subject:  Re:  Multi-layered Secondary HELP!!
>>
>>"Another thought - it is possible to imagine a multi-layer coil layered
>>the 'other way', effectively a stack of concentric spirals going
>>alternately in and out, e.g. for 3 layers,the turn numbers being
>>something like :
>>
>>   | |
>>987| |789
>>456| |654
>>321|_|123
>>
>>It would however require a lot of ingenuity to figure out how to
>>actually wind such a beast - any takers?
>>Keeping the spirals going the same way on each layer (i.e. always
>>outward) would be easier to wind, but less neat due to the 'flyback'
>>of the wire back towards the centre on each spiral, reducing the
>>number of total turns possible."
>>
>>Mike:
>>	How do you wind the second layer, starting at the outside and
>>winding in????????????  

As I said, you can picture the finished item, but not the method of
making it! The only way I can think of would be to have an outer
sleeve with an ID the same as the OD of the finished coil (former OD +
2N * wire thickness, where N is the number of layers), which is slid
along the coil as it is wound, so the 'inwards' winding layers start
by resting on the inner wall of the outer tube. Each layer would
probably need gluing down as it is wound. Placing the wire spool
concentrically at the end of the former would help as it would
preserve the curvature of the wire, so it would naturally lay down
neatly in the winding cavity. Still *extremely* fiddly, unless the
wire was pretty thick, which would probably defeat the object of
making a high-inductance coil!  

      ____  
     /]__[ <--- wire spool
    /
    | |  |
  |45 |  | 54|
  |321|  |123|
  |---|__|---|<- endstop
  |          | 
             ^ outer sleeve moved upwards as each layer is laid
   

>By the way, "bank wound" coils were common
>in the good old days of radio.  Look up the various winding schemes
>in an old radio text.  
I assume this is what I know as 'wave-winding' One method I thought of
was to effectively have lots of seperate wave-wound sections in
series, but the number of turns in close proximity in each wavewound
section would probably be too many to avoid breakdown.

     ____                                                           ____
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