Are there any ways to reduce electrical noise coming from outside the circuit by changing the environment the circuit is in?

If so, would these changes be significant enough to qualitatively improve mV-scale readings on oscilloscope hooked to a circuit on a 5in x 8in breadboard with 50kOhm equivalent impedance? (With this example I am just trying to come up with a fairly general use case.)

  • \$\begingroup\$ Do oscilloscopes measure mA? \$\endgroup\$
    – Andy aka
    Oct 17, 2013 at 7:14
  • 1
    \$\begingroup\$ What kind of noise are you picking up? Maybe you should spend a few more words about what do you refer to with "environment", "breadboard", and "measured". \$\endgroup\$
    – clabacchio
    Oct 17, 2013 at 9:47
  • \$\begingroup\$ Faraday cage, and/or Common Mode Rejection techniques, (negative feedback of the common mode to the scope). \$\endgroup\$ Oct 17, 2013 at 13:23
  • \$\begingroup\$ Conduct all your experiments inside a copper box? As @clabacchio says, you need to give more info. \$\endgroup\$
    – John U
    Oct 17, 2013 at 15:07
  • \$\begingroup\$ Do you want to shield the whole PCB or only a portion of the PCB, like a pre-amp or filter circuit? For a relatively small portion, you could try using a RF shield that mounts over the sub-circuit you want to isolate. \$\endgroup\$
    – Shabab
    Oct 17, 2013 at 17:03

2 Answers 2


In electrophysiology labs, if all else fails, the whole setup is enclosed in a Faraday cage. Often,there are things you can do short of this that will help a great deal, like using differential amplifiers, shielded twisted pairs, shielded twisted pairs with a guard driven to common mode, finding and killing all ground loops, ...

!File:Home-made_Faraday_cage.jpg1 from wikimedia commons enter image description here


Yes, there are ways to reduce noise picked up by a circuit from outside. Yes, some of these methods could be significant to mV-scale readings, depending on the magnitude of the picked-up noise.

For example, microphones produce mV-scale voltages. Unless care is taken, the 50 or 60 Hz signal from nearby power wiring can easily be picked up. This is one source of the common "power line hum" heard in bad audio circuits.


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