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Re: Secondary coil forms
Hi Bill, Jim,
Tesla List wrote:
> Original Poster: Jim Lux <jimlux-at-jpl.nasa.gov>
>
> Tesla List wrote:
> >
> > Original Poster: Bill Fuller <wfuller-at-home-dot-com>
> >
> > So, should I bother with coating the coil form with shellac or similar
> > coating???
> >
> I find that if I spray the PVC pipe with clear acrylic just before
> winding, the slight tackiness as it dries helps keep the wires in place
> when you have to stop turning, or someone distracts you so the tension
> varies, etc.
>
> Lately, I've been winding on a lathe, which turns a bit fast and isn't
> variable speed, and, requires engaging the clutch with one hand while
> holding the wire in the other, etc. Making the form sticky made the
> difference between a nightmare and making it easy.
>
> Next time I have to wind anything, I'll probably build a winding jig
> with a variable speed foot pedal with a small motor
> --
> Jim Lux Jet Propulsion Laboratory
Just wanted to add that secondary self capacitance will change a bit with
coatings due to the dielectric between windings (air or acrylic, etc..). I
can't say if it's enough to worry about as I haven't built a non-coated coil
yet.
Also, I've partially built a winding jig using a variable dc motor. A dc
motor should work excellent for tension. Applying 5v to say a 24v motor will
begin it rotating, but slight tension will load it by slowing or stopping as
the torque is very low at this voltage. Once the coil form is mounted and
the winding spool is set, the tension and speed can be set via the voltage
to the motor. Additionally, the winding spool itself will need a variable
drag built it to final set the tension and speed. I still haven't used it as
I'm in "think mode" for the coil form attachments, but the rest is finished
and the idea should work well and allow proper tensioning.
Bart