Toroid Rewind

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Hi Guys,

Im looking to rewird a toriod secondary to be a center tapped 6.3v... I just cant figure out the best way to wire it.

Should I:
a- get two lengths of wire and loop them together around the toroid
b- wind one then wind the other..

Im hoping "a" isn't an issue as will save alot of time:)

Cheers all
Craig
 
So i will wind the secondaries in this order -

6.3v ct wound together
glass isolation tape
250v single wind
glass isolation tape

I like to learn by doing:) just very carefully!! Trying to get all the information to make sure its right and this forum is great for that!:)

CT HV secondary would be nice as it would half the turns required which is in the thousands! Glutton for punishment:) Any ideas on how high you can go with Bifilar winding before voltage isolation becomes an issue?
 
I would agree substantially with DF and suggest that wire to wire insulation must never see excessive voltage difference.
<=50Vac may be a good guide, but I suspect <=100Vdc is acceptable.

But with thousands of turns could the ONE winding overlap at the beginning/end where 250Vac of difference would exist? If your 250Vac is done as two layers, then you have 125Vac between the layers. I would insulate one layer before adding the second layer.

Then repeat for other windings.

This results in:
Primary
insulation
screen
insulation
layer1 sec1
insulation
layer2 sec1
insulation
layer1 sec2
insulation
layer2 sec2
insulation.

You will need a long mandrel to get that length of 125Vac winding onto a slim through the hole bobbin.

Note if you swap the phase of a winding, you can get 250Vac difference between adjacent ends.
 
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What I often wonder is, would there be advantages in segregating the secondary windings to separate segments of the toroid, or conversely shared evenly.

No. Due to better coupling and mimimalizing magnetic leakage, all windings should be done fully circumferentially. So it is better to wind the low voltage heater winding(s) on top of the plate supply winding.

Best regards!
 
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