Magnets & Copper Wire: A Pickup Building Thread

[Bruce Johnson]

I can't say I've done experiments on the effect of 'scatter' winding. As a coil winder of years ago I could comment that neat, side by side winding increases the self-capacitance of the winding. This might cause strange resonances at high frequencies. Scatter, or 'Pie' winding reduces capacitance, hence you will see it in old radios for high frequency work. unfortunately it also causes wires to cross each other with the potential of shorting each other out. You can reduce this by dipping the coil in wax. This stops vibration of wires and the resulting erosion of insulation. Of course it also reduces the number of wires you can get in a given coil size so output might go down. Would love to hear how you get on.

Yes, winding coils neat and tight may increase the self-capacitance, as compared to loose scatter winding. But I haven't seen that that has any noticeable effect on the sound of my pickups. Not in our frequency ranges. The main reason why I like winding my coils neat and tight is to increase the definition and clarity. Pack all the wire tightly into the densest area of the magnetic field. That makes the coil more powerful, so it responds to the tiniest bits of string movement. That's also why I like using very large size magnets, to get the field more fully saturating the coil.

We all "pot" our pickup coils to prevent microphonic vibration. Most folks use wax, like Leo Fender did , but I use CPES, a very thin epoxy.

 

[Beej]

View attachment 3709545

Wound with 42AWG, 8500 rounds each. Cover, keeper and magnets were grounded after this pic. They sound very nice, I’m trying to upload a clip later tonight.

And here's a clip. Bridge/both/neck pickup.

Maihinnousu - Lataa - MPU - Vmedley

Really nice work - I have to ask, have you ever made them in a 5 string variety?

 

[Bruce Johnson]

This touches on something I’ve been curious about for a while: what would happen if a coil was wound with Litz wire? Fewer winds, but each wind would have multiple strands.

I'd guess that it would be just like using larger gauge wire, fewer turns. The strands would be connected in parallel, so their voltage gains when the field wiggled wouldn't add together; they would be equal. One turn of a multi-strand Litz wire would have the same voltage spike as one turn of a single larger gauge wire, right? The same size coil would have fewer turns, lower resistance, lower impedance, and lower output level. What would the advantage be?

 

[Will_White]

Something wholly impractical but could be interesting is wiring each strand of the Litz wire so it's in series.

 

[ardgedee]

One turn of a multi-strand Litz wire would have the same voltage spike as one turn of a single larger gauge wire, right?

That makes sense. I was having difficulty picturing what was wrong with the idea.

Something wholly impractical but could be interesting is wiring each strand of the Litz wire so it's in series.

Speaking from personal experience, soldering individual 42awg strands in a Litz bundle is the sort of thing that's fun to try exactly once.

 

[Will_White]

Speaking from personal experience, soldering individual 42awg strands in a Litz bundle is the sort of thing that's fun to try exactly once.

Yeah that's what I'd expect. Thinking more it probably wouldn't work because it's being wound alternating clockwise/counterclockwise so it would be out of phase.

 

[MPU]

Really nice work - I have to ask, have you ever made them in a 5 string variety?

I don't think so. At least I don't remember making one.

 

[Freekmagnet]

The last week or two I’ve basically just been making pickup prototypes. I’ve got a few parts coming in the mail this next week. When they arrive, I can get to finalizing some of these.

From L-R: The first pickup I ever made. I pull it out every once in a while to compare it to my newer pickups; a single coil with one A5 bar magnet - my next project will be to make make a single coil with either a solid bar or P90-style with the magnets underneath; a bridge and neck version of a mini-humbucker - these are pretty much done, and I’ll be building a few of these soon; a pair of C8 humbuckers - I made one to go in the bass I’m building. It’ll be a bridge pickup with a preamp. The other I’m making for a client - it’ll be a passive pickup in the P position. I’m actually really loving this pickup.

I’ve been on a pickup-designing frenzy, which is good because now I have the foundation already built for my next two bass builds. The only trouble is that now I have to design two more bass builds!

 

[slowburnaz]

Been playing around with more ideas lately... wanted to make a bass P-90 kinda thing, but one that could also allow for different cores, solid or laminated... or no core, too.

I wanna expand this to a humbucker as well, using the same bobbins. I currently have it loaded with Alnico 2 bar magnets. Never tried those before, but I'm liking how they sound.

A couple of my friends said it looks like a harmonica. Lol.

 

[MPU]

Looks nice!

 

[Bruce Johnson]

Been playing around with more ideas lately... wanted to make a bass P-90 kinda thing, but one that could also allow for different cores, solid or laminated... or no core, too.

I wanna expand this to a humbucker as well, using the same bobbins. I currently have it loaded with Alnico 2 bar magnets. Never tried those before, but I'm liking how they sound.

A couple of my friends said it looks like a harmonica. Lol.

View attachment 4023642 View attachment 4023643

A nice combination of design features! And it looks cool too! Which is important in the pickup business.

It does look like a harmonica. Maybe use that as the brand/model name?

 

[Matt Liebenau]

Been playing around with more ideas lately... wanted to make a bass P-90 kinda thing, but one that could also allow for different cores, solid or laminated... or no core, too.

I wanna expand this to a humbucker as well, using the same bobbins. I currently have it loaded with Alnico 2 bar magnets. Never tried those before, but I'm liking how they sound.

A couple of my friends said it looks like a harmonica. Lol.

View attachment 4023642 View attachment 4023643

Looks pretty cool. If you were in production I’d at least want to know the price and you wouldn’t have to work too hard to keep my interest after that.

 

[Novarocker]

Looks pretty cool. If you were in production I’d at least want to know the price and you wouldn’t have to work too hard to keep my interest after that.

Same here, a linear humbucker in a p90 size or similar is something that I've been looking for. Especially with looks that good.

 

[byacey]

I can't say I've done experiments on the effect of 'scatter' winding. As a coil winder of years ago I could comment that neat, side by side winding increases the self-capacitance of the winding. This might cause strange resonances at high frequencies. Scatter, or 'Pie' winding reduces capacitance, hence you will see it in old radios for high frequency work. unfortunately it also causes wires to cross each other with the potential of shorting each other out. You can reduce this by dipping the coil in wax. This stops vibration of wires and the resulting erosion of insulation. Of course it also reduces the number of wires you can get in a given coil size so output might go down. Would love to hear how you get on.

The whole point of scatter winding RF / IF coils was to increase the Q of the coil at RF frequencies by reducing inter-winding capacitance. At our frequencies of interest, the Q isn't a significant factor.

 

[Freekmagnet]

Been playing around with more ideas lately... wanted to make a bass P-90 kinda thing, but one that could also allow for different cores, solid or laminated... or no core, too.

I wanna expand this to a humbucker as well, using the same bobbins. I currently have it loaded with Alnico 2 bar magnets. Never tried those before, but I'm liking how they sound.

A couple of my friends said it looks like a harmonica. Lol.

View attachment 4023642 View attachment 4023643

As always, @slowburnaz, that’s some really beautiful work you’ve done there!

 

[slowburnaz]

I went ahead and made a humbucker version... basically a double P-90 pickup.

I need to find a good way to easily polish the stainless and brass. I'm thinking a vibratory cleaner that's typically used for cleaning spent brass cartridges for reloading might work.

 

[MPU]

That looks very professional made. Dremel felt polishing pad with some polishing compound would make that surround shine in a very little time.

 

[slowburnaz]

That looks very professional made. Dremel felt polishing pad with some polishing compound would make that surround shine in a very little time.

Thanks, man!

I've been doing that on the stainless, with mixed results... I probably just need to be more patient . Definitely am gonna try the vibratory thing, too, to see how it does.

 

[T_Bone_TL]

Vibratory will do well at deburring, might be a bit sad for final polish - they do poorly (unevenly) on flat things in general, but are great at round things or taking off edges, and can generally get things "ready for final polishing" better than they final polish them - IMHO.

Something a bit bigger than a Dremel helps with speed/throughput/blending for hand-polishing / final polishing / polishing of flat things. Several big buffs each dedicated to one grade of polishing compound is also helpful / efficient.

 

[Bruce Johnson]

Do you actually want a shiny polish, or just an even satin finish?

Like T Bone said, a vibratory machine is better at deburring the edges and putting on a satin finish. Not so good on polishing flat plates. By the time you got it shiny with soft abrasive, it would really round off all the edges.

If a satin finish is okay, you could use sandblasting in one of those little benchtop cabinet machines. There are many grades of abrasives available. That would be fast and easy to do.

If you want them full-polished, use buffing wheels with common Tripoli compound. Because these parts are flat with all the holes and cutouts, you'll have to come up with some way of holding them while you buff. You have to apply some pressure to buff out brass, and they will get hot. Make up some kind of a handle/holder. Another approach would be to screw a group of them down to wood board, clamp it down, and go over them with a 6" buffing wheel in an electric drill. You'd want to use a fairly stiff buffing wheel, maybe a felt wheel.