- #1
markmal
- 21
- 0
Hi here,
I am trying to make an efficient ribbon microphone motor.
My target is to get a highest possible output voltage so it can be plugged into a regular mic pre-amp.
It should have possibly flat output on frequences 20Hz to 20KHz.
I know that electric output depends on magnetic field B and velocity of a wire in it. (and velocity is proportional to frequency and amplitude.)
So target is to achieve highest possible B in air gap where ribbon oscillates.
I've made a model of motor using Gmsh and GetDP. It shows more than 1 Tesla in the gap, and as high as 2.5 T in core tip. I plan to use cobalt-iron core because of its high saturation capabilities. But I also read that it is not very good for high frequences like 20KHz because of Eddie currents.
My question is, should I consider to suppress Eddie currents that should appear in the core as a reaction on movind a wire in B field?
Is my understanding correct that Eddie currents should appear in this case?
Will be Eddie currents significant enough at high frequences (5KHz-20KHz) that I should take precausitions to suppress them?
I have this concern because all microphone/speaker motors I saw were made of just solid soft steel, not of electrical steel laminates like transformers are.
Is my concern about Eddie curents valid?
I am not sure how to calculate Eddie curents/losses in core for my case where a wire moves in mag field.
What portion of it will produce a voltage in the wire and what portion will impact mag field B so it will create Eddie currents in core? If such proportion exists, what it depends on? Does it depend on frequency?
Could you please advise?
Thanks,
Mark
I am trying to make an efficient ribbon microphone motor.
My target is to get a highest possible output voltage so it can be plugged into a regular mic pre-amp.
It should have possibly flat output on frequences 20Hz to 20KHz.
I know that electric output depends on magnetic field B and velocity of a wire in it. (and velocity is proportional to frequency and amplitude.)
So target is to achieve highest possible B in air gap where ribbon oscillates.
I've made a model of motor using Gmsh and GetDP. It shows more than 1 Tesla in the gap, and as high as 2.5 T in core tip. I plan to use cobalt-iron core because of its high saturation capabilities. But I also read that it is not very good for high frequences like 20KHz because of Eddie currents.
My question is, should I consider to suppress Eddie currents that should appear in the core as a reaction on movind a wire in B field?
Is my understanding correct that Eddie currents should appear in this case?
Will be Eddie currents significant enough at high frequences (5KHz-20KHz) that I should take precausitions to suppress them?
I have this concern because all microphone/speaker motors I saw were made of just solid soft steel, not of electrical steel laminates like transformers are.
Is my concern about Eddie curents valid?
I am not sure how to calculate Eddie curents/losses in core for my case where a wire moves in mag field.
What portion of it will produce a voltage in the wire and what portion will impact mag field B so it will create Eddie currents in core? If such proportion exists, what it depends on? Does it depend on frequency?
Could you please advise?
Thanks,
Mark