Building a non-professional shaker :)

[branadic]

I'm currently working on a shaker for use on fairs to present some vibration sensor systems we develope. The shaker is based on a subwoofer that needs some metal work and additional parts to change it into a shaker:
https://www.conrad.de/de/auto-subwoofer-passiv-160-mm-200-w-sinustec-st-bs-250-4-378979.html

The amp is a cheap kit:
https://www.reichelt.de/Bausaetze/K8060/3/index.html?ACTION=3&LA=5&ARTICLE=119286&GROUPID=7836&artnr=K8060
https://www.reichelt.de/Bausaetze/K8060/3/index.html?ACTION=3;ARTICLE=141260;SEARCH=HSVM100

Power supply will follow soon. All it takes is a computer and its soundcard, to play some vibration profils of your choice. However, this is not a professional shaker, but an interesting cheap way to demonstrate vibration sensor system preformance.

- branadic -

[2N3055]

Hi Branadic,

I'm really looking forward to progress on this... 

I was entertaining a concept based on subwoofer shaker .. Never got around to try it.. But always something else must be done first...

And although not professional, it could be useful for development work, if outfitted with accelerometer and roughly calibrated...

What is most interesting is the mechanical design of shaker table...

Sinisa

[T3sl4co1l]

Beware that a sound card may not have enough low frequency response to faithfully reproduce any given waveform.  Some modifications may be called for.  (This is done, from time to time, by people using sound cards as cheap oscilloscopes, or by hi-fi audio enthusiasts.)

Tim

[MagicSmoker]

The usual way of DIYing a shaker table is to drive an eccentric weight with a variable speed motor that is bolted to the underside of a platform which is supported by springs or air cushions; if you want to get really fancy use two motors mounted at right angles. The eccentric weight can be as simple as a disc with an off-center hole (should be easy enough to do - pretty much every time I try to drill a hole in the center of something it ends up off-center...  )

I don't think a subwoofer is going to be able to move a useful amount of mass unless driven with >1kW, mainly because of the high magnetic reluctance of the voice coil. You can buy linear electromagnetic actuators (basically solenoids) which should do a better job at this task, but you aren't going to come anywhere close to the performance vs. cost of the motor-based approach.

[Seekonk]

All that amp is going to produce is smoke.

[branadic]

I know that this approach is working, because we have a prior version of such a shaker, that is working with K4001:

https://www.reichelt.de/Bausaetze/K4001/3/index.html?ACTION=3&GROUPID=7836&ARTICLE=119277

for another presentation, where much smaller amplitudes are requested and mass of the presented element is small.
However, as said this is a non-professional shaker for presentation only, not for characterization and reliablility purpose.

[LaserSteve]

Call Scannermax Inc and get an open loop "actuator". I'll have more respect for your product at a trade show if it's moved by something other then a "woofer".

Steve

[calexanian]

I have seen this done with tactile sound drivers. It does work, but everything has to be just right. Don't get discouraged if it does not work the first time you turn it on. You will have to tube the system for resonance and that may change under varying loading conditions.

[CatalinaWOW]

The pro systems I have worked with always develop trouble in the spiders (the support system for the moving part).  Seems like that would be where I would look for trouble first.  The requirements are contradictory (support lots of load, have zero friction, zero spring constant and infinite fatigue life.)  The spiders that come with the speakers suffice for a perfectly balanced and symmetrical load, but are likely to give "interesting" results with your sensors mounted since they are unlikely to be perfectly balanced with symmetrical moments.  The voice coil clearances in speakers are designed with those same symmetries in mind.  It allows higher magnetic efficiency than in a system that has to allow for more sway and tilt.

I know you have had some success before, but I suspect you also had limited life and some strange times matching your sensor response to the drive.

[b_force]

Nice idea, but what are you really looking for?
In other words, what are you are measuring, and what do you mean with the 'vibration profiles'?

Difficult to give any advice if there isn't a 'which list'.

[branadic]

After some metal work I finished the shaker for the fair today. And for all the critics out there, it works just the way it should, but as said it's a non-professional design.

[CatalinaWOW]

Very nice work.  I am sure it will meet your needs for a demonstration.  I still suspect that it will have limited life (10s or 100s of hours) if driven to significant amplitudes and that looking at the results in detail you will find some "interesting" things.  At least that has always been my experience. 

All of that is likely to be fine for your purpose.  100s of hours is an infinity in show time.  And your instrument may be totally insensitive to the "interesting" things.