Comments on: What is considered “electrical noise”?

By: Poor one

Poor one — Thu, 26 Feb 2009 18:44:09 +0000

Electrical noise is any electrical signal that is not supposed to be there. There will always be some but it becomes a problem when it interferes with the intended signal. It widely misunderstood but can come from many places. There are a number of ways of preventing it being an issue, starting with making the signal so big that it cannot be affected and all kinds of filters, shielding and twisting of wires.

The problem of noise is predominantly with signals not power supplies so presumably your equipment is seeing noise in the communications. Keep signal cables away from power cables and ensure everything is grounded. Be aware of ground loops, its unlikely over small distances especially if everything is carefully bonded.

By: amansscientiae

amansscientiae — Tue, 24 Feb 2009 05:18:34 +0000

It means that the designer tells you how much ripple and regulation artifacts there will be on top of your power supply voltage. Usually it’s quite a lot. For a 5V or 12V computer supply this noise will be 50-100mVpp (peak-peak). A good benchtop power supply for the test lab would be at least two orders of magnitude less noisy, i.e. the ripple and noise would be below 1mVpp. The best supplies I have seen are around 100uVpp.

There are other cases of noise in electronics. For amplifiers one would specify Johnson noise and 1/f noise (low frequency noise). A good amplifier has 1-2nV/squrt(Hz) Johnson noise and 1uV 1/f noise in the 0.1-10Hz band. Needless to say these noise numbers are orders of magnitude below those of the power supply.

By: Raymond W

Raymond W — Sat, 21 Feb 2009 09:55:58 +0000

It literally shows the words “electrical noise”?

Anyway, in an ideal world, a (say) 5VDC power supply would output a voltage of exactly 5.000000V without any variation. Similarly, a 110VAC power supply would output a perfect 60Hz sine wave.

Now, in the real world, these ideal voltages are perturbed by “noise”. The source of noise can be anything from a loose contact somewhere to someone running an electric motor (for instance, in a vacuum cleaner) off the same AC line.

Generally, your power supply is supposed to filter out this noise, but I guess in your case it cannot. Without knowing more detail, I cannot help you trace the source of your noise.