Heavy pendulum excitation

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petrakis_nomikos 16 years ago

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MouseFet, It took a while for me to picture your 2 magnets solution, which is brilliant in its simplicity. That would allow me to apply a knife edge suspension, since both magnets will prevent the knife from 'walking' out of its bed. My only concern is if the swing amplitude will be stable enough without an amplitude control. Note that this is important for accurate prediction of the crack growth.

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Ross Herbert 16 years ago

:I am in the process of designing a metal fatigue demo setup. :For this purpose I need a heavy pendulum, swinging at quite large :angles (say 30 degrees to either side). :In order to keep the pendulum swinging permanently some excitation :circuit will be needed to compensate for bearing/aerodynamic drag. : :Being a mechanical engineer I have only faint ideas how to do this :electronically. My simple idea is to use a coil with a soft iron :segment attached to the pendulum. To see what I mean watch at: : :

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: :The excitation could be accomplished by adjusting the current strength :(or current pulse length) through the coil, controlled by the length :of the light pulse on the light sensitive element. :My question is: does this 'simple-mind' excitation mechanism make :sense? If so, how could I accomplish it electronically? If not, what :would be a sensible alternative?

A good example of pendulum drive is shown in the old pulse clocks used in step-by-step telephone exchanges. A typical clock is the BPO type 36 shown here (with circuit)

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The part you are interested in is the magnet drive pulse contact operated by the Hipp toggle pendant. No electronics are required at all.

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Ross Herbert 16 years ago

:On Thu, 13 Aug 2009 05:44:30 -0700 (PDT), petrakis_nomikos : wrote: : ::I am in the process of designing a metal fatigue demo setup. ::For this purpose I need a heavy pendulum, swinging at quite large ::angles (say 30 degrees to either side). ::In order to keep the pendulum swinging permanently some excitation ::circuit will be needed to compensate for bearing/aerodynamic drag. :: ::Being a mechanical engineer I have only faint ideas how to do this ::electronically. My simple idea is to use a coil with a soft iron ::segment attached to the pendulum. To see what I mean watch at: :: ::

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:: ::The excitation could be accomplished by adjusting the current strength ::(or current pulse length) through the coil, controlled by the length ::of the light pulse on the light sensitive element. ::My question is: does this 'simple-mind' excitation mechanism make ::sense? If so, how could I accomplish it electronically? If not, what ::would be a sensible alternative? : :A good example of pendulum drive is shown in the old pulse clocks used in :step-by-step telephone exchanges. A typical clock is the BPO type 36 shown here :(with circuit)

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: :The part you are interested in is the magnet drive pulse contact operated by the :Hipp toggle pendant. No electronics are required at all.

Apologies to Terry Casey... I only read your post re Hipp toggle drive after I posted answer.

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Terry Casey 16 years ago

Thanks Ross! I thought for a moment my post must have got lost somewhere!

Terry

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JosephKK 16 years ago

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monostable

The two of you are using terminology in different ways. Get through that first, and you will communicate better.

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Heavy pendulum excitation

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