Digitally Controlled Vibration Device

Something like this comes to mind.

Just Google cell phone vibrators and take your pick.

Hey there REDGRNR.

Well, I think you have a pretty good suggestion. When I googlized the words "cell phone vibrator", I sort of figured I would get a number of places that sell parts to repair phones... Nope!

There are a number of conversions available to convert the vibrate function of the typical cellular phone to another, more personal function! YOU HAVE GOT TO BE KIDDIN' ME! (In retrospect, perhaps I can use some of this information in my ongoing Quixotic quest to convert my 1988 Econoline into a 'Chick Magnet'... maybe if I ... Hmmnmm.. better think this through.)

Well, if the OP can get past the more personal applications, he may be able to use your suggestion. I think it has some merit. GA.

The best is to use a "voice coil linear motor" with a stroke controller or with an acceleration control loop as you wish. Google for the supplyer since there are several and I do not know which one will offer the best solution for your demand. One of them is BEI.

The suggestion to use an eccentric has a VERY important draw back: the amplitude and the frequency are directly related since the force is proportional to the eccentric mass the radius and the rotation speed squared.

This means that at low frequency you get a very low vibration and at high frequency a strong one. If you have the intention to test a component you MUST be in the position to run different amplitudes at different frequencies which means that frequency and amplitude MUST be disconnected from each other and independently programmable.

In general the response of swinging systems is exactly the contrary: big amplitudes at low frequency and small amplitudes at high ones. With an eccentric you will NEVER obtain it.

A very valid and cogent point. I admit, though, I am not certain of the OP intent.

He tells us "I am in need of an oscillation plate or vibration device that can have the vibration frequency controlled accurately from 10 to 500hz." This sounds like some sort of testbed device. I agree that I read into this comment that amplitude should also be controlled, even though not stated. I also read into it that he is not looking for a wind-up device, even though not stated. He really isn't telling us much.

Then he says "Ideally, the device will weight under 10 grams and have a vibration surface about 3 * 3 cm." This is the element of confusion for me. If a testbed, why the small weight constraint? And 3cm X 3cm? Is that an upper or lower limit? That information I do not know what to do with at all.

With all of this ambiguity, and the fact that cell phone vibrators can be had for free for experimentation, I believe RDGRNR had a pretty good idea. I further believe your approach is more exact, more complete, but not really what OP is after. We will have to wait for our original poster to return, and see if my beliefs are misplaced.

Did you consider a loudspeaker + tonefrequency generator + potmeter? Will be much bigger and heavier than you require, but amplitude and frequency will be independantly programmable.

A small shaker with sine controller is the best solution. The guys at MB Dynamics are helpful and very knowledgable:

http://www.mbdynamics.com/Vibration-Solutions.php