DaveC said:
I presume because I've only wound one or two in my lifetime, that I'm not
familiar enough with these topics to understand your statement.
I always thought of winding a toroid much like threading a needle several
hundred times over. To my mind, you must measure out the length of wire
required and thread it through once; pull the entire length of wire through
and tight to the toriod; thread again; pull entire length through... etc.
Unless the wire spool from which you're taking this from is *tiny*, or there
is a gap of some kind in the core, you've got to "thread the needle".
Is there an easier way to wind a toroid? To my inexperienced hands, it really
sounds like a bobbin in a pot core is going to be much easier. What am I
missing, here?
I think you've got it. When you only have a few turns to wind,
just stretch the wire out to its full length, and repetitively
"thread the needle". If you have a lot of turns, you use
a shuttle. I think you understand that, too, but if not
this example might help: Imagine winding 100 feet of rope
through a car tire that is not mounted on a rim. You could
stretch out the rope and continually "thread the needle"
until the tire was wrapped, pulling the full length through
each time. Or, you could coil the rope into a loop and
just keep passing the loop through, paying rope off the
loop as you go. With a toroid, instead of making a loop
of the wire, you wrap it around a shuttle - something that
is , small enough to pass through the center hole of the
toroid, but big enough to hold the length of wire needed.
See the "drawing" below:
_________________________
\ /
/_______________________\
The wire is first wrapped lengthwise around the shuttle -
you can make the shuttle from cardboard or plastic. You pass
the shuttle through the toroid, back around the outside, and
through again, paying out wire as you go. For smaller toroids,
I've made shuttles (I think bobbins is the correct term in this
case) from two pieces of brass tube. The smaller tube is inside
the larger diameter tube, and is longer. The wire is first
wrapped around the larger tube, then the whole thing is passed
through the toroid in the same way as already described.
The smaller diameter tube acts as an axle around which the
larger, wire bearing tube can spin, paying out the wire.