Any recommendations on an effective common choke for making low frequency m easurements (~10 Hz)? I have measurement problem where I need to make meas urements in microvolt range but in an electrically noisy environment. Unfo rtunately there are not a lot of options for removing the noise without spe nding thousands of dollars which my customer can't afford. I was hoping to use some instrumentation amplifiers with extremely high CMRR and use a com mon mode choke to limit noise on the lines. Any recommendations dearly app reciated.