Aerospace Eng in Foreign Electromag Land, gulp.

[bigwilliejoe]

Hello Gents,

My son has a little project (science) that has us looking to build a mechanism similiar to a shaker (axial vibration)that works at ~10hz, force amplitude of 1-3lbs, constant duty cycle (okay, i think that is it). Part of the task is to find resources for information. Therefore....

It has to be somewhat home-made except for the windings,etc. I purposed a heavy coil winding on a hinged system with stoppers (reversing poles). Our problem is what size and type of coil ($$?). Also, questions such as, what is the limiting cycle time? (i.e. can it cycle at 10hz), what else don't we know?

He came to me...I came to you.

Thank you ahead,
B.J. Williams
Aero Eng.
NCD, inc.
Laguna Niguel, Ca.
ncdi@cox.net

 

[BrianG]

Hi there. You are going to need some strong magnets! The prposed hinge system sounds a little dubious to me. If you are familiar with the vibration tables in environmental testing labs these generally use a "moving coil" exciter on each axis. These are effectively just like the innards of your hi-fi loudspeaker, but on a giant scale and without the speaker cone. You should be able to make some quite resonable smaller scale ones if you use the cardboard tube from the centre of a toilet roll.

You don't say what kind of motion you are expecting from the shaker, i.e. sinusiodally, or what? If you just want it to flip-flop back and forth then you can make quite a simple driver circuit, but if want it to follow a waveform you will need quite a large power amplifier.

Hope that helps.....

 

[bigwilliejoe]

Thanks Brian,

I appologize it's sinusoidal. If I recall my speaker classes then we are talking about a coil and perm mag config? what do we use for a signal driver?

Heck maybe a motor and piston set up would be more effective. Although, it would increase the complexity of the item.

B

 

[Comcokid]

For 10 Hz, I might try a mechanical cam/motor. Maybe an old sewing machine? Otherwise, for a electro-dynamic type, try a old powered subwoofer, or one of those power amps used for car speakers - like used in the annoying cars that you find at a traffic light with all the body panels rattling! For either, check a local thrift shop or pawn shop. For the magnetic drive element - can't think of anything that might be adapted easily other than an old sub woofer speaker.

 

[bigwilliejoe]

That's why I luv you guys...you got great ideas! Thanks Comcokid and BrianG.

B

 

[nbucska]

Simply an universal motor ( e.g. sewing machine motor, as mentioned) with an excentric mass and speed control.


<nbucska@pcperipherals.com>