Power amplifier for B&K Mini-Shaker 4810 that can handle DC-offset

[arnoldw]

I would to perform some vibration tests using the Brüel & Kjær Mini-Shaker Type 4810. My test setup is a little odd because I want the shaker to be slightly displaced from its default position when performing the tests. This means the signal I send to the shaker must have a DC-bias. I have an Arbitrary Waveform Generator so generating a signal with a DC-bias is no problem. However, the Arbitrary Waveform Generator can't deliver as much power as the shaker needs. So, I need a power amplifier that can deliver about 1 Watt and that can amplify a the DC-component as well. Does anybody know where I can find such an amplifier or which companies might make these? If not, does anybody know of an alternate solution which doesn't require too much electronics design skills (I'm a software engineer)? Thanks in advance!

 

[GregLocock]

Well you basically need a DC coupled current amp, with sufficient capacity for your load. Any DC coupled shaker driver will do, Ling, Environmental Engineering, or B&K will almost certainly make a suitable unit. It's basically an FET power amp, child's play to design (says me). There may even be a DC strap in your existing amp.

BUT

The problem is more likely to be that the constant DC will fry the voice coils in the shaker. Can you not use an independently sprung suspension to provide the necessary displacement?



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[btrueblood]

You need a fixed offset (displacement) of the shaker...any reason you can't just, say, move it? Build a fixture, add a shim, cut a hole...

 

[IRstuff]

I'm not even sure there's much displacement to be had. From what I tell, the 4810 is a tiny shaker. Any offset is probably going to kill its dynamic range performance.

You'd be way better off shimming to get the offset

TTFN

FAQ731-376

 

[IRstuff]

I finally found the number. The maximum pk-pk displacement for the 4810 is only 0.236 inches.

TTFN

FAQ731-376

 

[GregLocock]

I used to have a couple. Far too fragile for automotive use!

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[arnoldw]

Thanks for all your comments and advice. I work in the bone-conductive microphone industry and I need to displace the shaker about 0.125 millimeters and I will only offset it for two seconds every ten seconds so I think it should be fine.

Greg Locock: You mentioned a manufacturer called "Environmental Engineering", would you happen to know their web site address?

 

[GregLocock]

No, sorry.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[arnoldw]

I found some amplifiers which can amplify both DC and AC-signals. Labworks, inc makes them.