Brett,

Boy, I'd like to see what you have inside of those little blue boxes, 
and I bet I'm not the only one.  Do you have more information on this 
design?

Larry


On 7/31/2011 12:40 AM, Brett Nordgren wrote:
> Dave,
>
> Just for laughs, here's the other end of the specturm in regards to mass.
>
> They use an effective mass of 19 grams, and don't do badly at all.  
> Design by the 'other' Dave Nelson.
>
> http://bnordgren.org/seismo/gif_images2.htm
>
> Brett
>
>
> At 07:39 PM 7/30/2011, Dave Nelson wrote:
>> hi Chris
>>        Am really at the end of the rope here ... just total 
>> frustration...  spent all day
>> yesterday improving the period got down to 11 sec. set up a magnetic 
>> dampening system
>>  with a strip of aluminium  1.5cm wide going in between the 2 magnets.
>>   The only thing that seems to achieve is dropping my period from 11 
>> sec down to
>> ~ 7 sec.  It doesnt appear to do any actual dampening  as the unit 
>> will just go on oscillating for ages and just slowly dying down on 
>> its own  see...
>> http://www.sydneystormcity.com/screen%20dump.bmp
>>
>> for the first 3/4 of the screen you can see it oscillating all nite 
>> long.   This morning I
>> gave it a nudge and as you can see the pendulum just slowly decreased 
>> in amplitude
>> on its own.
>>
>> I was so looking forward to making this work, and at the moment 
>> almost ready to throw
>> it all out !!
>>
>> BTW  I did take your bottom pivot advice.   I have a flat steel plate 
>> on the end of the
>> boom against the ball in the vertical
>>
>> maybe you can help further ?   :)
>>
>> cheers
>> Dave
>
>
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