find magnetizing force of magnet

[dor baruch]

Let me rephrase the question Please

How do I calculate the magnetizing force of the pickup As a whole (permanent magnets and the wire as electromagnet without the pole pieces)

thanks

[Mike Sulzer]

Let me rephrase the question Please

How do I calculate the magnetizing force of the pickup As a whole (permanent magnets and the wire as electromagnet without the pole pieces)

thanks

Your question still confuses me, but perhaps this might help. The magnetization contributed by the current flowing in the wire from the vibrating strings is very small. It is not an issue. With very strong magnets, it might be possible to saturate a steel pole piece very close to the magnet, but not further away because the flux does not remain confined to the short open pole pieces. There are two important issues:

1. The strength of the magnetic field at the string. This determines how much it is magnetized, and so how strong the signal is and how much string pull there is.

2. The magnetic properties of the pole pieces. Their permeability is close to the value with no magnetic field. The permeability influences how much of the flux from the vibrating string is directed through the coil. (Although the open geometry of the pole pieces means that a very high degree of flux enhancement cannot be obtained even with very high permeability) The conductivity is also important because of eddy currents.

[J M Fahey]

Yes, I think we have a slight language/communication problem here.
Anyway, the idea of this Forum is to help each other to the best of our possibilities, so let's keep at it
As of Dor's question, I think he should post a drawing of the pickup he wants to make.
As I understand it, he seems to be asking about a simple pickup: "magnet+wire only, no pole pieces"
The coil , although physically possible (i.e. connected to a battery), is not used as an electromagnet.
And the small flux variation caused by string movement , as noted by Mike Sulzer, is many degrees of magnitude below what's needed to affect the magnet.
Thanks God, otherwise pickups would "wear" while playing !!

[CRU JONES]

This may or may not be OT but...

Coercive force = Amp * Turns. the coercive force developed because of a string is really small, but it still moves on the loadline.

1)Imagine a closed magnetic circuit. 2) This magnetic circuit is saturated. 3) Now remove enough permeable mass from that circuit to allow leakage fluxes to couple to a vibrating string. 4) This leakage flux magnetizes the string. 6) The coercive force of the string pushes the magnetic circuit in and out of magnetic saturation!

Yeah! put that in your pipe and smoke it!

cheers,
Ethan