Re: [ATM] Subject: light weight mirrors--mylar!

[George Anderson <tillerman1@videotron.ca>]

Instead of attaching magnets to the aluminzed mylar (which probably 
doesn't have a smooth enough surface) why not use mylar that is 
aluminized on both sides. On the back side draw a series of coils in the 
required patterns and then bring the contacts out to the edge. Then 
place permanent magnets underneath.
A variation on this concept has been used by Magnepan for their flat 
panel speakers and ribbon tweeters for years, and they work quite well.

George Anderson
Owner of a pair of Maggie MG-IIAs

Clear skies and good health

Christopher Todd wrote:
> Actually, I was thinking that part of the cleverness of the electromagnet
> approach would be that precise placement of the magnets would not be
> necessary, as you could simply adjust the current if you were a little too
> far away or too close to the mirror/film surface.  Then again, I'm not an
> engineer, so maybe that's just silly. 
>
> Also, I'm assuming you would have an array of small magnets under the film,
> like maybe one every inch or two, and probably arranged in concentric rings.
>
> I still think the tricky bit is finding the right film, since I don't think
> mylar or aluminum foil are magnetic, or would react to a magnetic field.
> Does anyone know of a metal that reacts to magnetic fields that can be
> formed into thin films (or, at least, sheets so thin they could be deformed
> by magnets)?
>
> Chris
>
>   
>> -----Original Message-----
>> From: atm-bounces@atmlist.net 
>> [mailto:atm-bounces@atmlist.net] On Behalf Of Mitchell R
>> Sent: Sunday, November 11, 2007 8:54 PM
>> To: atm@atmlist.net
>> Subject: Re: [ATM] Subject: light weight mirrors--mylar!
>>
>>
>>
>> -----Original Message-----
>> From: atm-bounces@atmlist.net 
>> [mailto:atm-bounces@atmlist.net] On Behalf Of Christopher Todd
>> Sent: Sunday, November 11, 2007 7:20 PM
>> To: 'ATMLIST'
>> Subject: Re: [ATM] Subject: light weight mirrors--mylar!
>>
>> Has anyone ever considered using some kind of metal film and 
>> deforming it with electromagnets?  You can imagine the 
>> possibilities, being able to vary the strength of the 
>> magnetic field by varying current, and using many relatively 
>> small electromagnets, would give you lots of flexibility.  
>> The key, obviously, would be to find the right material for 
>> the film.  Alas, I am not a metallurgist or engineer, so I 
>> won't be the one to try this.  I'm sure someone else must 
>> have thought of this before, so I'm curious if anything ever 
>> came of it.
>>
>> Chris
>>
>> I had thought of something crazy like that but figured the 
>> magnets would have to be placed as accurately as the surface 
>> of the mirror you wanted. Or you could just do a rim of them 
>> o something of that sort. A ring would sort of pull evenly 
>> and let is sag in the middle?
>>
>> Mitch
>>
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