Lately I have been having some problems with some electrical
interference. Occasionally through my computer speakers I get some
popping noises. I checked the outlets with one of those plug in wiring
fault testers. No problems there.
Anyone know what could be causing this?
popping sounds more like dirty connections than electrical interference,
which would be more likely to cause a continual hum.
how are the speaker wire connections? if they are dirty a little contact
cleaner will fix them right up.
If you wanted to go nuts you could shut off all the circuits in your house
but the one your computer is on and shut off every device on that circuit
except the computer and see if the popping still occurs. If it does that
pretty much rules out interference.
After I wrote this reply. About an hour later the popping from the
speakers happened again. I used a multimeter on one of the outlets to
monitor any fluctuation in current. And there was none.
The strange part about this is that it only started about a week ago.
I might check all the connections is the receptacle boxes and the
circuit breaker that supplies the bedroom current. This circuit
breaker only supplies this particular bedroom and no other circuits.
The existence of or a missing earth ground cannot be
measured at a wall receptacle. The only effective method of
verifying earth ground is inspection. Each incoming utility
must have a dedicated wire that connects to the earth ground
rod (or whatever is being used as the earth ground). The
earth ground wire that comes from circuit breaker box must use
same earth ground that telephone interface box connects to AND
that cable shield connects to. Code demands that each
utility earthing wire be less than 20 feet. You want each
wire to be less than ten feet.
Will this solve your problem? Maybe. Maybe not. But it is
one reason why such noise could happen AND a very common and
overlooked failure in homes.
You have described noise. Noise might be single volt
transients on a utility wire. Surge protectors ignore most
below its let-through voltage: typically 330+ volts. Are
those popping sounds from 330 volts? Most likely not, since
otherwise you now have damaged appliances, GFCI receptacles in
bathroom and kitchen, failed smoke detectors, etc.
IOW start by inspecting the most obvious. All utilities
must connect to same earth ground where all utilities enter
Popping sounds may be voltages of single or a few ten
volts. But they would also be composed of frequencies well
above 60 Hz. The multimeter is not good for observing those
higher frequencies. The common tool to see such 'pops' would
be the oscilloscope. Now a very common tool these days.
And so we should try to relate the popping to other event
such as the powering off of a refrigerator or other heavy
appliance. Or something occurring in the very few neighbors
who share your same AC utility transformer.
Noise from speakers is common because those computer
speakers generally use inferior power supplies - not very well
filtered. You could build a box containing the filter that
should have been inside the speaker power supply using
industry standard line filters such as:
Appreciate the can of worms you have decided to open. EMC is
quite difficult to solve sometimes. First you should locate
the source of that noise. Then the best place to solve that
noise is at or inside the offending device. The line filter
is not just to solve the problem but to provide more data (and
a tool) that might identify the noise source.
Meanwhile, the house utilities must be earthed per post 1990
National Electrical Code requirements. Even if that does not
solve the noise problem, it does address or avoid other
potentially future problems. Just one more suspect to
verify. A problem so obvious when it is located and solved.
But one that may take days or weeks of observations before
suddenly the "Ah-ha" breakthrough occurs. Welcome to the
world of EMC/RFI.
Bill Davis Jr wrote:
What conditions produce this sound? There are two possibilities I see.
If the sounds appear to occur randomly then its probably static
electricity generated by yourself. You need to be grounded, or you need
a grounded floor mat if there is such a thing.
Personally I have one of those plastic mats, and whenever I cross my
legs or roll my chair, I get popping in my speakers.
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