Accurately Measuring Precision Resistors

Yabbut, that's a reset winding. We were talking about noninductive wirewound resistors.

Cheers! Rich

The point I was making was about *windings*, the direction they go, the fact that the inductances cancel out (verifying what you were told from my own experience with coils wound on toroids), and the fact that they are not bifilar. I didn't think it necessary to state that the thing wound on a toroid wasn't intended to be a resistor, figuring that is obvious. But perhaps not.... Ed

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I can only speak for others, not myself. er, whatever...

Here's a copy of your original post (between the >):

That's it, exactly. Someone called it "contra-wound" - but I don't know if that is the proper term. On the toroids I wind that way, the first half occupies about 40% of the diameter and the last half occupies another 40%. Ed

But earlier, this whole thread was all about cancelling inductance so I assumed that the point of doing either of these was to cancel out the inductance.

In my case, I was thinking that the first example, \\ \\ \\.. is the way they were telling me to wind the turns on the resistor with 2 conductors paralleled in each turn. Of course this is to cancel out inductance.

Then you talked about contra-wound on a toroid. I assumed this was to cancel out inductance as was being done previously. I did make a mistake about yours being bifilar. Sorry.

But to continue, I would like to see the complete circuit with the MOSFET you drew above. Might make a whole lot more sense.

No! The post you quoted (below) was from Rich, not me. My reply to it begins with the words "That's it , exactly."

You're seeing most of it. Add a 555 circuit to the gate of the mosfet and you have it. See

I can post pictures of a toroid wound that way, if it would make things clearer. Ed

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The desulfator article uses two separate inductors, I don't see how you're doing it with one.

It is one toroid, but it has two inductors wound on it, with one continuous piece of wire. Just like a center-tapped inductor, except (see diagram) L2 is wound in the opposite direction from L1.

I tried to reply to this twice before with an attached picture. I'm guessing that the attachment is the cause of the problem. I'll try to post a picture of it - look for Contra-Wound Toroid.

Ed