Another Question about Noise

8 posts / 0 new
Last post
ecolechio
ecolechio's picture
Another Question about Noise

I am starting in-vivo single unit recordings from rats that are being artificially ventilated to help maintain a constant anesthetic plane. The ventilator/respirator is creating noise that we can't easily see on the digital oscilloscope, but can clearly hear; the higher the respiration rate, the higher-pitched the noise, which sounds like constant whining, is. We have tried shielding the machine with a copper screen and grounding the ventilator to the headstage without success. Any ideas? 

The FFM
The FFM's picture
Just to clarify. Do you think

Just to clarify. Do you think it is all electrical noise or partially mechanical?  vibrations could be transmitted through the ventialtions tubes.

Have you tried putting the ventilator on an innertube or some other type of air table?

Can you post a picture of your setup so we can see what we're dealing with?

ecolechio
ecolechio's picture
Here's a picture of the setup

Here's a picture of the setup. The table that the stereotax is on is antivibration (though we have not been using it for electrophysiology, just for optical imaging), and then the ventilator (the blue thing) is not on an antivibration surface; it's on a board that fits just over the edges of the frame of the antivibration table. For today's experiment I'll try turning the antivibration table on during recording. I do think that the noise might be at least partially mechanical, since we cannot see it on the 'scope. I'll let you know how this goes, but I'd appreciate comments on the setup. As I said, I am just starting electrophysiology experiments using it, so it's far from being optimized, and any input/constructive criticism is welcome!

ecolechio
ecolechio's picture
Update: Turning on the

Update: Turning on the antivibration table did not help at all with the noise from the ventilator. My advisor says that he can "live with" the noise level as is, but it is very annoying!

The FFM
The FFM's picture
Long shot here

Long shot here

Have you tried putting a hum-bug device (www.autom8.com/hum_bug.html) in line with your system to see if it makes any difference?

It is generally a 50-60hz noise filter, but it does filter other frequencies too and might be worth a shot if you can lay your hands on one to try before you buy.

 

ecolechio
ecolechio's picture
Well, I can also definitely

Well, I can also definitely try to put the actual ventilator on an antivib surface; as I have had the experiment set up so far, the rat but not the ventilator was on an antivibration surface.

The FFM
The FFM's picture
sounds liks a plan  

sounds liks a plan
 

SimsTina
SimsTina's picture
Hello,

Hello,

I saw your post regarding electrical noise and was wondering if I could ask a question.  I am new to "Scientist Solutions" and am looking for help.

I have an experimentation set up using a force gauge.  When the system is at rest, there is no noise.  When a small force is applied to the gauge, noise is present on top of the force signal.  Because the forces I am working with are small (fruit fly muscle, milli-Newtons), I cannot get a good reading of the true signal through the noise. 

I have tried various grounding techniques and have a "hum bug" in line, a device with filters 50/60 Hz noise, but it does not filter this noise, when the gauge is under pressure.

Any feedback is appreciated.  Thank you, ~Mia~