Hi there,
I'm recording mini EPSCs and I've been having a huge noise problem for the past few months now. I'm sweeping every half second, and it's definitely coming from the perfusion system, since when I turn it off, it goes away immediately. It might be the ground wire, since fiddling with the ground wire made the issue go away, but only for a few days.
I'm really at a loss here. Regular voltage-clamp step protocols do not produce this massive noise (but then again, we aren't sweeping every half a second). The perfusion system is within the Faraday cage, I've re-chlorided the ground, wrapping foil around the peristaltic pump gets rid of the upward noise but NOT the downward noise.
Here is the equipment we're using (that I can recall off the top of my head):
Axon 1550A
Multiclamp 700B
Any suggestions? Anything would help!
Hi Momoko,
I dont know anything about your System but i have to deal with ground noise while recording audio material. If you are able to use batteries / powerbanks you often can get rid of it.
If that is not possible then you have other options. In Studio Recording Situations you use two different Power circuits, one for everything wich is plugged to record and the other curcuit for everything which is needed to be recorded. Also Laptop Power Supplies or cheap 3 - 12volt supplies are very often the reason for ground noise.
Changing the power supplies as they sometimes are faulty crafted or dont use the right Amount of MicroAmpere may solve noise.
then there are also customer friendly noise canceling devices to switch inbetween but these depend on the signal to noise ratio you are needing. i dont know if this will distort your measurements to much as you are using very tiny signals ?
i hope i could help a little with this.
Kind regards, Severin
Hi Momoko,
If fiddling with the ground wire solved the issue, even for a few days, that's probably the best place to focus your efforts. I'd replace the ground wire entirely, making sure you have well soldered connections. Of course, double check your ground configuration and make sure you don't have any ground loops.
Power sources/supplies are also common sources of noise, as Severin suggested.
The fact that you were able to get rid of the noise in one direction only suggests that there is an additional source of noise, however--it should be bidirectional. Noise from fluid level changes and pulsation artifacts are super common with peristaltic pumps. You can get rid of pulsation artifacts with an IV drip (and this also breaks any electrical connection/noise source within your solution).
Other information that would be helpful to know: what are your filter settings on your amplifier? if you stop the perfusion, but don't turn off the pump electrically, does the noise go away? what is the frequency of the noise? Finally, is this specific to your minis/half-second sweeps, or do you see it in all recordings?
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