Pickup winding/basic info needed...Newbie content!

[Rick Turner]

And if your inner lead is hot and the magnets are lacquered and grounded, you'll lose highs from the capacitive coupling between the innermost turns and the grounded magnets. Some folks put copper foil tape on the bottoms of Strat pickups and ground the tape to ground the magnets. Great if the inner start wire is grounded, not so good otherwise.

[lexluthier72]

Thanks all for the wealth of information! =) Hopefully I'll have some quiet time this weekend to get my first coil wound!

[David King]

And if your inner lead is hot and the magnets are lacquered and grounded, you'll lose highs from the capacitive coupling between the innermost turns and the grounded magnets. Some folks put copper foil tape on the bottoms of Strat pickups and ground the tape to ground the magnets. Great if the inner start wire is grounded, not so good otherwise.

Rick, that's the first time I've ever heard about that capacitative coupling with the magnets. On pedal steel pickups they leave an airgap between the coil and the polepieces to keep them from being too bright. Presumably the pedal steel pickups are start-grounded?

[Rick Turner]

I have no idea how they may be wired, but if you want to hear the effect, try wiring up a Strat pickup with inner wire as hot (assuming no dead short between inner windings and magnets), and now disconnect the hot wire, put a piece of copper foil with conductive adhesive onto the magnets and wire that to hot. Guess what! Signal! Yes, with hum, but with an open circuit coil, you'll still have signal...of a sort. Yes, another hard learned lesson...

[Peter Naglitsch]

That sort of stuff is in my book but its also been talked about here

And the best description ever is IIRC from your book; Think "path to ground" instead of "winding direction". Not a word-by-word quote, but I think thats how it's described in Jasons book and to me it makes perfect sense.

[Joe Gwinn]

most places that make buckers wind them in the same direction- probably for ease of manufacturing- but on fenders if you make them like the vintage pickups and you insulate the magnets with shellac or lacquer your inner wire will almost always eventually short out against the magnet so if its your hot lead and you touch the magnet it will buzz like crazy or if the string touches the magnet and the strings are grounded it will kill your signal.

And if your inner lead is hot and the magnets are lacquered and grounded, you'll lose highs from the capacitive coupling between the innermost turns and the grounded magnets.

The common solution is to use something fairly thick to separate the windings from the magnets, such as scotch tape or polyimide tape.

This works because:

The tape is probably ten times as thick as a shellac or lacquer film, and so the capacitance will be a tenth as much. (Unless the tape absorbs moisture.)

The tape is far more robust, and requires no drying time.


I came on an alternative solution in the trade press, mylar insulating tubing. I think I remember a similar proposal in the big thread about how to insulate magnets, but here are the details:

Precision Paper Tube Company | Supplier of Custom Dielectric Tubing.

Note that they offer both plain mylar and heat-shrink mylar. I have not tried this, but it seems to me that one could push the magnets (or slugs) into the bottom flatwork, drop cut-to-length pieces of heatshrink tubing onto the magnets, shrink the tubes with hot air, and then press the top flatwork into place.

Or, just buy kraft paper tube, cut to length and wax it, and drop the tubes over the magnets during assembly, the wax keeping the tubes on the magnets during assembly. Or, go whole hog, and use vulcanized fiber.

As for cutting tube to length, all these materials are easily cut with a steel blade, and it would be easy to build a little fixture to cut out large numbers of equal-length tubes from tube stock.

[big_teee]

The common solution is to use something fairly thick to separate the windings from the magnets, such as scotch tape or polyimide tape.

This works because:

The tape is probably ten times as thick as a shellac or lacquer film, and so the capacitance will be a tenth as much. (Unless the tape absorbs moisture.)

The tape is far more robust, and requires no drying time.


I came on an alternative solution in the trade press, mylar insulating tubing. I think I remember a similar proposal in the big thread about how to insulate magnets, but here are the details:

Precision Paper Tube Company | Supplier of Custom Dielectric Tubing.

Note that they offer both plain mylar and heat-shrink mylar. I have not tried this, but it seems to me that one could push the magnets (or slugs) into the bottom flatwork, drop cut-to-length pieces of heatshrink tubing onto the magnets, shrink the tubes with hot air, and then press the top flatwork into place.

Or, just buy kraft paper tube, cut to length and wax it, and drop the tubes over the magnets during assembly, the wax keeping the tubes on the magnets during assembly. Or, go whole hog, and use vulcanized fiber.

As for cutting tube to length, all these materials are easily cut with a steel blade, and it would be easy to build a little fixture to cut out large numbers of equal-length tubes from tube stock.

I like to use a waxed floral tape. I usually drip a little extra wax on it to help it stick.
It's waxed based, and if it loosens, all you have to do is warm the base plate and wallah, its bonded again.
Later,
Terry

[verhoevenc]

So the point of this stuff is to separate the coil from the magnets, got it. But my question is, with how thin the wire is don't you have to be REAL exacting as to the height of this stuff? Any wrong cut and a wrap of wire may get between the bobbin and your 'tape' or choice? Or are we not worried about a single wire, just the whole shebang? Also, I would have thought over-sizing this stuff to avoid this problem would also cause issues in that when you installed the top flatwork it might push this stuff out creating edges to get caught on, or an odd shaped surface to then wind upon? Or perhaps I'm over-thinking this.
Chris

[Joe Gwinn]

So the point of this stuff is to separate the coil from the magnets, got it. But my question is, with how thin the wire is don't you have to be REAL exacting as to the height of this stuff? Any wrong cut and a wrap of wire may get between the bobbin and your 'tape' or choice? Or are we not worried about a single wire, just the whole shebang? Also, I would have thought over-sizing this stuff to avoid this problem would also cause issues in that when you installed the top flatwork it might push this stuff out creating edges to get caught on, or an odd shaped surface to then wind upon? Or perhaps I'm over-thinking this.

People use tape all the time, and the fit cannot be perfect unless one compresses the tape sideways somehow.

With tubes cut to length using a fixture, one should be able to get at least as precise a fit as tape, as the theory goes.

[John Carlsen]

I usually measure the tape before i cut by laying it along the same spacer i use assemble the strat bobbin. Seems to work pretty well and i usually dont have any problems with gaps or anything since I used the same exact measurement for pickup spacer and tape width.

[David King]

Regarding tape width, you can order tape in custom widths if you are willing to buy enough of it. I put a 3" roll of clear 3M packing tape on a mandrel between centers on my lathe and sliced through the entire roll with a modified cut-off tool. My coils are .65" tall and my tape is .67" wide so I have a nice smooth fillet at the ends and NO wire can get past.

For a long time I was planning to build bobbins around flatwork and rigid tubing that were glued together. The idea was that you could slip different magnets in and out to your heart's content without disturbing the coil. I've always thought that if the tape layer was too thick you'd loose treble. The tubing was .015" wall thickness vs about .002 for the tape.

Now I'm hearing about the capacitive coupling to the magnets if the start is hot.
If you make the tail hot and then wrap a foil shield over that -won't your capacitative coupling be much worse with the foil??

[Joe Gwinn]

For a long time I was planning to build bobbins around flatwork and rigid tubing that were glued together. The idea was that you could slip different magnets in and out to your heart's content without disturbing the coil. I've always thought that if the tape layer was too thick you'd loose treble. The tubing was 0.015" wall thickness vs about 0.002 for the tape.

Now I'm hearing about the capacitive coupling to the magnets if the start is hot.
If you make the tail hot and then wrap a foil shield over that -won't your capacitive coupling be much worse with the foil??

Yes, there will be capacitance between the outer layer of turns and the foil shield wrapped around the coil. Again, if one interposes a reasonably thick layer if insulation between coil and foil, the added capacitance can be greatly reduced.

Parallel Plate Capacitor