Meredith, I can confirm that these plastic forms hold their shape. I used
these for both of my Lehmans and a couple of other seismographs over the
years. I also found that a cow magnets work very well with this form and if
you fill it with #54 magnet wire you end up with a coil in the 16K range.
The forms seem withstand the elements well. One other point, if you wind
extremely fine magnet wire onto these forms, be sure and sand the edges
smooth using an fine paper.

Regards, Steve Hammond  PSN Aptos, California

----- Original Message -----
From: meredith lamb 
To: 
Sent: Tuesday, November 09, 1999 8:26 PM
Subject: Radio Shack fine coil examples


> Radio Shack has an example of generally fine wound wire on
> coil forms.  Its their #278-13458, which is an assortment of 3
> enamel coated magnet wire.  The package I have uses this
> side-by-side wire wound method, but its really machine wound.
>
> One coil uses 40 ft (12.2m) of 22 gauge wire (~.7 ohms).
> One coil uses 75 ft (22.8m) of 26 gauge wire (~3.3 ohms).
> One coil uses 200 ft (60.9m) of 30 gauge wire (~22.6 ohms).
>
> The coil forms are some form of white plastic, about .088"
> to .1" thick; which don't seem to deform or vary on the inside
> diameter very much ~ .803 to .807".  The thought of using a
> 3/4" (.750") magnet or pole inside has occurred, as a possible
> copper damping means, especially with the larger gauge wire.
>
> The end flanges are obviously larger in diameter than any of
> the wire sizes wound on them, at, 1.975".  This plastic appears
> to be tough to cut, and probably tin shears might work somewhat.
> They are molded plastic, and have the halfs junction with slight
> extrusions of plastic, which seems to be fairly easy to smooth
> off.  The plastic coil spindles seem to be the toughest I've seen
> over the years.
>
> They are interesting in themselves, and possible seismic uses
> are varied.  They have been around for some time, but I
> think they could be interesting to see for some, in conjunction
> with the Sean-Thomas Morrissey recent messages on coils.
>
> Meredith Lamb
>
>
>
>
>
>
>
>
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