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Natural Science Forum / Physics / General Physics / July 2008Help building a magnetic membran pickup
I want help to build something much like an microphone but instead of picking up airwaves, i want it to pickup oscillation (in the field?) from a moving magnet. Could i use an ordinary microphone and replace the membran with something? >I want help to build something much like an microphone but instead of > picking up airwaves, i want it to pickup oscillation (in the field?) > from a moving magnet. > > Could i use an ordinary microphone and replace the membran with > something? Telephone pickup coil: http://www.techlib.com/electronics/induction.html http://www.exo.net/~pauld/activities/magnetism/magneticfeedback.html > <jonas.thornv...@hotmail.com> wrote in message > [quoted text clipped - 10 lines] > > http://www.techlib.com/electronics/induction.htmlhttp://www.exo.net/~pauld/activ ities/magnetism/magneticfeedback.html But this will pickup electro magnetic fields as well as magnetic? I want to build something that will pickup an oscillating permanent magnet in the range 10-96 000 khz I plan to use a ordinar speaker that work in the range 40-15 000 khz, and replace the cone with glued neodynium magnets. Could you give an idea how to build a receiver for this *crude* permanent magnetic oscillation. > > <jonas.thornv...@hotmail.com> wrote in message > [quoted text clipped - 20 lines] > Could you give an idea how to build a receiver for this *crude* > permanent magnetic oscillation. I guess i have to place the speaker in a vaccum chamber to keep it quiet ;) > > <jonas.thornv...@hotmail.com> wrote in message > > [quoted text clipped - 10 lines] > > > > http://www.techlib.com/electronics/induction.htmlhttp://www.exo.net/~pauld/activ ities/magnetism/magneticfeedback.html > But this will pickup electro magnetic fields as well as magnetic? Yes; enclose it in a non ferrous shield. > I want to build something that will pickup an oscillating permanent > magnet in the range 10-96 000 khz > I plan to use a ordinar speaker that work in the range 40-15 000 khz, > and replace the cone with glued neodynium magnets. Good luck on that. You do realize the mass of a speaker cone is squat? > Could you give an idea how to build a receiver for this *crude* > permanent magnetic oscillation. Amplifiers: http://en.wikipedia.org/wiki/Operational_amplifier_applications  SignatureJim Pennino Remove .spam.sux to reply. > jonas.thornv...@hotmail.com wrote: > > > <jonas.thornv...@hotmail.com> wrote in message [quoted text clipped - 23 lines] > > You do realize the mass of a speaker cone is squat? Hardly squat, you really beleive there would be a problem glueing neodyniums around an eight inch speaker. No problem what so ever, the problem is to get it quiet..... You know it is quite alot of air to be moved at 120 db 30 hz, so if you actually remove the cone you will find that the coil is a lot stronger than you thought. > > Could you give an idea how to build a receiver for this *crude* > > permanent magnetic oscillation. [quoted text clipped - 7 lines] > > - Visa citerad text - > > jonas.thornv...@hotmail.com wrote: > > > > <jonas.thornv...@hotmail.com> wrote in message [quoted text clipped - 23 lines] > > > > You do realize the mass of a speaker cone is squat? > Hardly squat, you really beleive there would be a problem glueing > neodyniums around an eight inch speaker. No problem what so ever, the > problem is to get it quiet..... No, the problem is moving the mass. > You know it is quite alot of air to be moved at 120 db 30 hz, so if > you actually remove the cone you will find that the coil is a lot > stronger than you thought. And what holds the coil in place if you remove the cone? SignatureJim Pennino Remove .spam.sux to reply. > jonas.thornv...@hotmail.com wrote: > > > jonas.thornv...@hotmail.com wrote: [quoted text clipped - 42 lines] > > - Visa citerad text - Well the idea is to make it move.... I guess you could glue the magnets directly on the dome or on the wired coil and constrain it with a lowresistance spring instead of the cone. What i wonder about is the ideal surface area should it be like an coil/antenna or cover as much area as possible. > > jonas.thornv...@hotmail.com wrote: > > > > jonas.thornv...@hotmail.com wrote: [quoted text clipped - 42 lines] > > > > - Visa citerad text - > Well the idea is to make it move.... Yeah, and F=ma. Compare the mass of the cone to the mass of the magnets you want to glue on. > I guess you could glue the magnets directly on the dome or on the > wired coil and constrain it with a lowresistance spring instead of the > cone. A minimum of 3 low resistance, low mass, non magnetic springs. Have you every taken a speaker apart to see how they are constructed? SignatureJim Pennino Remove .spam.sux to reply. > I want help to build something much like an microphone but instead of > picking up airwaves, i want it to pickup oscillation (in the field?) > from a moving magnet. > > Could i use an ordinary microphone and replace the membran with > something? Make a loop of wire with a voltmeter attached. > > I want help to build something much like an microphone but instead of > > picking up airwaves, i want it to pickup oscillation (in the field?) [quoted text clipped - 4 lines] > > Make a loop of wire with a voltmeter attached. Good idea Dimensions of the wiring, does it matter? But can't i place the wired loop direct on a high sensity mic, or will it be to low current flowing the loop? Would be nice with at least 1-2 meter between sender and receiver. > > > I want help to build something much like an microphone but instead of > > > picking up airwaves, i want it to pickup oscillation (in the field?) [quoted text clipped - 7 lines] > Good idea > Dimensions of the wiring, does it matter? Magnetic flux is int(B.dA), induced EMF is the negative time rate of change in ..wait... instead of having me teach you basic E&M, why not buy a textbook and learn this sh.t yourself? > But can't i place the wired loop direct on a high sensity mic, or will > it be to low current flowing the loop? Use an amplifier? > Would be nice with at least 1-2 meter between sender and receiver. A pony would be nice, too. Or a cube a meter on a side made of pure gold. Or a sensual massage from one of the women with nice tits who lives around here. Or all of the above! Tell you what, you worry about your latest inane fixation and I'll worry about my attractive neighbors. > Magnetic flux is int(B.dA), induced EMF is the negative time rate of > change in ..wait... instead of having me teach you basic E&M, why not > buy a textbook and learn this sh.t yourself? Hmmm.... Nothing about *time* in this article. http://en.wikipedia.org/wiki/Double_integral#Some_practical_applications If you ever decide to sue your school for fraud remember my offer to give tesimony on your behalf. :o) Sue... > > Magnetic flux is int(B.dA), induced EMF is the negative time rate of > > change in ..wait... instead of having me teach you basic E&M, why not [quoted text clipped - 3 lines] > > http://en.wikipedia.org/wiki/Double_integral#Some_practical_applications That's because it is IRRELEVANT, stupid. > If you ever decide to sue your school for fraud remember my > offer to give tesimony on your behalf. :o) > > Sue... “ a sensual massage from one of the women with nice tits who lives around here ”, you say, and: “ I'll worry about my attractive neighbors ”. Thanks for the warning. Now, when I hear you screeming in pain on Sci.Physics, I'll know exactly what the true cause was. > I want help to build something much like an microphone but instead of > picking up airwaves, i want it to pickup oscillation (in the field?) > from a moving magnet. > > Could i use an ordinary microphone and replace the membran with > something? Hall effect sensor; piezoelectric fiber with a low-mass high field magnet at its free end; fiberoptic and Faraday rotation; a coil. SignatureUncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 > jonas.thornv...@hotmail.com wrote: > [quoted text clipped - 11 lines] > Uncle Alhttp://www.mazepath.com/uncleal/ > (Toxic URL! Unsafe for children and most mammals)http://www.mazepath.com/uncleal/lajos.htm#a2 The question needs to be restated. What kind of EM are you measuring ? [1] Frequency, and [2] intensity please. But you know something.....you just gave me an idea how to build a nanoscale motor. Who cares...probably already been done. > But you know something.....you just gave me an idea how to build a > nanoscale motor. > > Who cares...probably already been done. It has. gears, motors and all sorts of stuff that small already has been created. But, if you can find a way to create them "cheaply" then you have something worth thinking more about. :) SignatureJames M Driscoll Jr Spaceman > > jonas.thornv...@hotmail.com wrote: > > [quoted text clipped - 19 lines] > > Who cares...probably already been done. Flagella. SignatureUncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 > > > jonas.thornv...@hotmail.com wrote: > [quoted text clipped - 25 lines] > Uncle Alhttp://www.mazepath.com/uncleal/ > (Toxic URL! Unsafe for children and most mammals)http://www.mazepath.com/uncleal/lajos.htm#a2 SQUID > I want help to build something much like an microphone but instead of > picking up airwaves, i want it to pickup oscillation (in the field?) > from a moving magnet. http://www.qsl.net/mnqrp/Loop/Pickup%20Loop.gif http://www.qsl.net/mnqrp/Loop/Mag_Loops.htm http://www.scott-inc.com/html/nrsc.htm http://images.google.com/images?gbv=2&hl=en&q=faraday+loop+antenna&btnG=Search+Images Sue... > Could i use an ordinary microphone and replace the membran with > something? |
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