Bicentennial Firebird Pickup -- Magnet

[Zhangliqun]

I'm still reading and learning but so far "most sidewinders are weak and anemic" certainly describes the 'prototype' I made. The weird part is though it's weak and though it's ceramic, the tone -- if it could be made louder -- is actually pretty freaking good.

I've got some Ceramic 8's on order, will try that. If that fails, I'll try to convince him that a more conventional design will be better, like the ceramic below and steel bars in the bobbins sitting upright the way the Good Lord meant them to...

[rjb]

Well, I thought I was done...

I've got some Ceramic 8's on order, will try that.

Is there a particular reason you are using ceramic magnets?
David Schwab's '76 Thunderbird pickup used an alnico magnet.
The bar magnets that Mojotone lists for Firebird pickups (although not necessarily Bicentennial design) are Alnico5.
Theoretically, an alnico magnet's permeability would help guide flux from the string through the steel cores
(versus ceramic magnets, which have about the same permeability as air).

If that fails, I'll try to convince him that a more conventional design will be better,

Man, what a spoil-sport!
But seriously, if you've gotten this far, why not try a (miniature) copy of David's pickup- one steel blade through both coils, with a narrow alnico magnet sitting on the blade between the bobbins?

David's Post

like the ceramic below and steel bars in the bobbins sitting upright the way the Good Lord meant them to...

In the Book of PAF, the Good Lord Seth blessed us with two sidewinder designs (neither of which was very marketable, AFAIK).
https://docs.google.com/viewer?url=p.../US2896491.pdf

[mr fab]

I make a sidewinder pickup with central alnico 5 magnet and with two coils positioned in the centre magnet blade
and have been selling these for a few years now.

my first protos were wound to around 4500 winds per bobbin which made them exceptionally thin and bright
so I increased the number of turns until I reached a point where I liked the tone,

these pickups sound very much like single coils and are extremely quiet. in fact quieter than most normal humbuckers

the output is equivalent to a strat like pickup, albeit with much more wire.

they sound fantastic and have a very authentic single coil like tone without the hum

I hope this helps

[big_teee]

"I make a sidewinder pickup with central alnico 5 magnet and with two coils positioned in the centre magnet blade
and have been selling these for a few years now."

Can you clear that up please, and a picture would help?
T

[mr fab]

sorry terry

I make one similar to the bicentennial

it has an alnico bar magnet positioned vertically with two bobbins positioned with the tops of the bobbins in contact the sides of the magnet

I use mild steel blades inside each of the coils

looks a lot like the pic in post #8, however I use different bobbins and magnets, but the principle is the same

[Steve A.]

Just to reiterate: The permanent magnetic field has nothing to do with cancelling hum.
Physical orientation in the same plane (or parallel planes) and reversal of end-to-end coil winding direction cancels hum.
(I hope I said that clearly enough. My native language is New Jersey patois.)

True enough, but the magnetic orientation of the two reverse-wound coils must be reversed for them to be in phase.

Steve Ahola

[rjb]

True enough, but the magnetic orientation of the two reverse-wound coils must be reversed for them to be in phase.

Yup. I"m not sure if we're talking in circles or not.
Mike explained how the magnetic field orientation works out in a sidewinder, although he assumed a different configuration.
In the sidewinder configuration I'm "advocating", the varying field from the strings is guided "down" by the alnico magnet, then splits "left and right" through the steel cores.

In a side winder, one would expect to have screws from the center up to the strings to guide the field up to magnetize the strings, and the varying field from the strings back down. Then there should be a piece of steel going through both coils (with magnets at the other ends of the coils) to turn this flux sideways so it goes into the coils pointing in opposite directions, and so the coils must be electrically out of phase for the signal to add. ....

In any case, a ceramic magnet between the coils is absurd. Ceramic magnets have low permeability and do not guide the field well.

[rjb]

Can some one (Mike?) offer an explanation why both sidewinder versions of Seth Lover's humbucking pickup used two offset coils rather than two full-length coils?
Here is the patent.
https://docs.google.com/viewer?url=p.../US2896491.pdf
It states that the coils are offset "to reduce pickup or inductance between the two coils", but I don't understand what that means in practical terms.
Does this have anything to do with efficiency, i.e. number of turns required to get a reasonable output?
I learned from this thread that the mutual inductance in a sidewinder is series opposing, but so what?
http://music-electronics-forum.com/t24481/