Homebuilt Pickups

[dsrb]

Hello!

More headache for you guys.. sorry! ;D
So, I need to build a complete guitar from a scratch for school. Now, I'm on the pickups. The guitar is supposed to be HH with a 3-way switch. I've a few questions:

Do I need pole pieces? I mean, can't I just use 12 screws for the pickup?

I don't see magnets for sale anywhere in my zone.. Can I use anything for this project? Or it must be a dedicated/specialized magnet?

I already saw a lot of humbuckers designs, but I can't figure out one thing. Think of two "covers" or single-coils skeletons. Can I just put them together and wire it clockwise (in both) with two magnets (one positive and one negative) ? Or will I need to wire them separately and only then put it together? In that case, must one be clockwise and the other the opposite?

Thanks a lot

[ranchtooth]

Humbuckers are supposed to be wired seperately with one coil in reverse of the other. Thats how the "buck" the hum. One coil being 180 degrees out of phase with the other makes the 60 cycle hum cancel out.
Putting the two skeletons together and wiring them clockwise would work, but it would be more like one bigass single coil. Theres nothing wrong with this, and some might even argue it gives a better sound than a traditional single coil. (Think P90s)
I think screws would work for the pole pieces as long as they are magnetic, which most are.

As for what magnets to use... I haven't a clue. I'd assume any old magnet should work as long as the dimensions are right and the field is strong enough. Theres pickups with alnico magnets and ceramic magnets, so that alone shows some variety is possible.

Out of curiosity, what are you using to wind the pickups?

[sumgai]

ranchy,

Putting the two skeletons together and wiring them clockwise would work, but it would be more like one bigass single coil. Theres nothing wrong with this, .........

You wanna re-think that one there, bunky?

One coil bucks hum? And this just after you said that two coils are out of phase by 180° to each other in order to buck hum? (Which of course is correct.)

More to the point, depending on the magnetic alignment (or polarity) of the two bobbins (what's been referred to as a skeleton), you'll have one of two possible outcomes: the two aligned in the same direction (both North facing the strings) will be a large unfocused magnetic mass, and probably a highly undesirable tone (talk about muddy!); or the other way (one North, one South facing the strings) will yield a self-cancelling magnetic induction of currents within the coil itself. IOW, there won't be anything coming out of that there hank o' wire.

Bad juju, that.



sumgai

[sumgai]

dsrb,

Use whatever magnets you have on hand, or can get easily, locally and cheaply. Experiment with your own materials before you start buying stuff from innerweb stores.

And no, the magnets found in a pickup are not special, nor purpose-built, but they are of high quality, which is why they're more expensive when compared to hobbyist stuff from Edmunds Scientific.

Screws and/or slugs should be steel, and not zinc, brass or other materials.

Good luck with your project! ;D

HTH



sumgai

[ranchtooth]

I think I must have misunderstood what was meant by skeleton haha. I was in no way saying a single coil can reduce hum. I just figured a skeleton would be a shell around which one winds the pickup...

[spud1950]

Here's a pretty good explanation of humbucker construction theory.Pay careful attention to what it says as to how the magnets have to be polarized along the edges and the winding directions of the coils and how you hook them up to each other.
www.1728.com/guitar1a.htm

Here's a source for pickup parts,wire,etc., including kits.You might want to consider just getting a kit.That way you'll know your getting all the right parts. Click on "Electronics,Pickups"

www.stewmac.com/cgi-bin/hazel.cgi?action=HOME


The two most common types of magnets used for pickups are Alnico and ceramic. Some pickups use rare earth magnets,but the other two are much more common. Iron and steel magnets are not used because their charge holding property is far inferior to the other materials.

****CHECK OUT THIS WEBSITE****
I forgot I had this site bookmarked. This guy makes a home made humbucker from scratch. The directions are extremely detailed with lots of pictures and drawings for making the parts. I think this is exactly what you're looking for. Although his design uses screw pole pieces in one coil and steel slugs in the other, there's no reason why you can't use screws in both if you want to. There's even a sound sample of the finished pickups!

galileo.spaceports.com/~fishbake/buck/humbuck.htm

[ChrisK]

Can I just put them together and wire it clockwise (in both) with two magnets (one positive and one negative) ? Or will I need to wire them separately and only then put it together? In that case, must one be clockwise and the other the opposite?

A. If you want a humbucking pickup, the (effective) winding direction of the coils must out of phase with each other. This means that one must be wound clockwise and the other must be wound counter-clockwise.

Well, actually, they just must sense common mode interference out of phase with each other. Wind them any direction that you want and just reverse the leads from one to effect hum cancellation if necessary. If you wind them the same way and reverse the leads from one, the common (mode) interference subtracts (or averages to zero if in parallel).

B. Now, since the coils are effectively reversed in their sensing phase, having the magnet polarity opposite in one as compared to the other effects a summed differential (mode) output signal.


In essence, the common mode interference subtracts towards zero and the differential mode sensed string signal adds towards twice the output of a single coil.


This is why only the magnetic polarity between two coils matters in effecting a humbucking combination. The effective winding direction is most easy to reverse.

[spud1950]

Well, actually, they just must sense common mode interference out of phase with each other. Wind them any direction that you want and just reverse the leads from one to effect hum cancellation if necessary. If you wind them the same way and reverse the leads from one, the common (mode) interference subtracts (or averages to zero if in parallel).

This is an excellent point. Instead of using the phrase "Reverse wind/ Reverse polarity" when speaking about hum canceling, "Reverse Phase/Reverse polarity" is a much more accurate term as reversing the leads of a coil acheives the same effect as if it were wound in the opposite direction.