Hi Chris,  What you described below, I think, was one of the =
illustration,  Let me describe it this way...........
Lets say a 36" horz rod.............from the balance point 18" connect a =
short 2" x 4"  (L) shape rod, the 2" leg is welded to the balance point =
of the horz rod.
Now the 4" leg is inserted into some sort of bearing, and the whole =
thing swings back and forth from this 4" axle.   You have two equal =
masses, one on the left and one on the right of the 36" horz. rod.   NOW =
CAN  one extend the period of the device by relocating one or other of =
the masses?

Thanks, Ted
  ----- Original Message -----=20
  From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Saturday, October 27, 2007 3:44 PM
  Subject: Re: Different types of Pendulums


  In a message dated 27/10/2007 22:23:56 GMT Daylight Time, =
tchannel1@............ writes:
    Hi Folks, Sometime in the past I saw a web site describing different =
types of pendulums used in sensors.  I don't remember their names, but

    1.  one was a long vertical rod, with a center pivot, it contained a =
mass at the top of the rod and a mass at the bottom of the rod.

    My question has to do with 1.  I thought this pendulum (positioned =
like an airplane propeller) was able to adjust it's period by moving the =
top and or bottom mass, up or down the rod?
    I made a simply mock up of this illustration, but was not successful =
in any way. Can one adjust this arrangement to result in an extended =
period? Does anyone know of this web site or one similar?
  Hi Ted,

      There are several possible systems, but you need to suspend the =
pendulum near the middle, a small height above the centre of gravity. =
This gives a high moment of inertia due to the masses at the ends and =
the small restoring force due to 2x mass operating just below the =
suspension axis. It should work fine. You can also vary the position of =
one of the masses.=20

      Regards,








Hi Chris,  What you described below, I think, was one of the=20
illustration,  Let me describe it this way...........
Lets say a 36" horz rod.............from the balance point 18" =
connect a=20
short 2" x 4"  (L) shape rod, the 2" leg is welded to the balance =
point of=20
the horz rod.
Now the 4" leg is inserted into some sort of bearing, and the whole =
thing=20
swings back and forth from this 4" axle.   You have two equal =
masses,=20
one on the left and one on the right of the 36" horz. rod.   =
NOW=20
CAN  one extend the period of the device by relocating one or other =
of the=20
masses?
 
Thanks, Ted

  
----- Original Message ----- 
  From:=20
  ChrisAtUpw@....... 
  
To: psn-l@.............. 
  
Sent: Saturday, October 27, =
2007 3:44=20
  PM
  
Subject: Re: Different types of =

  Pendulums
  


  

  
In a message dated 27/10/2007 22:23:56 GMT Daylight Time, tchannel1@............ =
writes:
  
    
Hi Folks, Sometime in the past I =
saw a web site=20
    describing different types of pendulums used in sensors.  I =
don't=20
    remember their names, but
    
 
    
1.  one was a long =
vertical rod, with=20
    a center pivot, it contained a mass at the top of the rod and a mass =
at the=20
    bottom of the rod.
    
 
    
My question has to do with 1.  =
I thought=20
    this pendulum (positioned like an airplane propeller) was able to =
adjust=20
    it's period by moving the top and or bottom mass, up or down the=20
    rod?
    
I made a simply mock up of this =
illustration,=20
    but was not successful in any way. Can one=20
    adjust this arrangement to result in an extended period? Does anyone =
know of=20
    this web site or one similar?
  

  
Hi Ted,
  
 
  
    There are several possible systems, but =
you need=20
  to suspend the pendulum near the middle, a small height above the =
centre=20
  of gravity. This gives a high moment of inertia due to the =
masses at=20
  the ends and the small restoring force due to 2x mass operating just =
below the=20
  suspension axis. It should work fine. You can also vary the =
position of=20
  one of the masses. 
  
 
  
    Regards,
  
 
  
    Chris=20
Chapman