×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

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

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

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

(OP)
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!

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

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: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

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

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...

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

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: Eng-Tips.com Forum Policies

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

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

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

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

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

Cheers

Greg Locock

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

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

(OP)
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?

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

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

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources