Noise in LabView using NI BNC-2120

[pagurus]

Hi!

I do have a problem with the NI BNC-2120. I am performing two-electrode voltage-clamp experiments with oocytes and record the membrane potential as well as the transmembrane current.

I record these signals both on a chart recorder (which works very well) and with LabView using the BNC-2120. Now, the membrane potential is recorded without any problems, however, the channel which records the current (output is also voltage) shows quite a strong sinus noise. This does not come from the amplifyer and seems to be routed in either the BNC-2120 or the PC. Does anyone have some advice on how I could get rid of that?

This would be greatly apprecitated!

Thanks, Mike

[Bob_Schor]

Does "sinus noise" mean 60- (or 50-)Hz waves riding on the signal?  I suspect an "electronics" problem, such as an unshielded cable, a Ground Loop, or something similar.  Does the (forgive the expression) Current Voltage have a reasonable range, i.e. volts as opposed to milli- or micro-volts?

Bob Schor

[pagurus]

Dear Bob,

thanks! Yes, it is a wave riding my signal. There is a difference in "Current voltage" but even if I increase the output signal the noise remains. Today it also occurred in the other channel, so I think it is an electronics problem at the BNC-2120 or Computer. Do you have any advice on the best way to ground a PC?

Mike

[pagurus]

I found the source of the noise - it was one of the power cords! Anyway, thanks for the rapid reply and input!