noise from other appliances

[Skeleton Man]

Hi,

I just got a new set of speakers (logitch z-340), and they seem very
sensitive to electrical noise (my old speakers weren't).
Every time the motor on my fridge cuts in or out (or someone turns a light
on or off), then I get a distorted clicking noise through the speakers. The
noise only lasts half a second, but it's annoying !

Any suggestions on fixing this ?

Regards,
Chris

 

[Chris Stolworthy]

Hi,

I just got a new set of speakers (logitch z-340), and they seem very
sensitive to electrical noise (my old speakers weren't).
Every time the motor on my fridge cuts in or out (or someone turns a light
on or off), then I get a distorted clicking noise through the speakers. The
noise only lasts half a second, but it's annoying !

Any suggestions on fixing this ?

Regards,
Chris

A battery back up for your whole system is ideal. The noise you describe is
caused by voltage avariations in the line hitting your speakers. Those same
variations are also affecting you computer components! After a while this
can lead to bigger problems than just popping noise in the speakers. A
battery back up will filter these out, or a good surge protector. A battery
back up is best tho because in times like a brownout or in suituations where
you have undercurrent or no current (black out) the pc can still be shut
down before damage is caused.

Just my 3 cents worth (2cents + 1cent tax)
-Chris

 

[Max]

Be careful not to plug in too much into a battery backup. Those speaker
systems with subwoofers can draw a lot of watts (but only if the volume is
turned up high). Also, printers should not be plugged into battery backup
for this reason.

In addition to battery backups and surge strips, you can also try different
outlets. I believe the ultimate problem is that you have too much plugged in
on one circuit (look at your circuit breakers). Normally you have your
"kitchen appliances" on a dedicated circuit and at a higher voltage (220v
?), while your normal outlets are 110v or 115v (in the US anyway. Also,
older appliances tend to use twice as much juice as newer energy efficient
ones. Not really anything you can do about it, but just thought I'd mention
why this happens.

-Max

 

[Skeleton Man]

In addition to battery backups and surge strips, you can also try different

outlets. I believe the ultimate problem is that you have too much plugged in
on one circuit (look at your circuit breakers). Normally you have your
"kitchen appliances" on a dedicated circuit and at a higher voltage (220v
?), while your normal outlets are 110v or 115v (in the US anyway. Also,
older appliances tend to use twice as much juice as newer energy efficient
ones. Not really anything you can do about it, but just thought I'd mention
why this happens.

Moving outlets wouldn't make much of a difference.. lights are a seperate
circuit to power, but flurecents still interfere when switched on or off..
(other lights have less effect)..

In Australia we have 240V for everything (appliances operate from anything
around 220V)...
The stove and oven are on a dedicated 30A circuit, with the outlets on 10A.

The kitchen + the outlet I use for my PC (and 1 or 2 others) near the
kitchen make up 1 circuit, with the laundry and lounge contibuting to
another, along with a couple for the bedrooms..

I've experienced the too much on one circuit issue before.. the kitchen,
lounge and laundry all used to be a single 10A circuit.. (with the breaker
tripping every 10 mins!)

I'm not inclinded to buy a UPS, as it's a coupla hundred bux just to keep
the PC up for a few mins to save stuff ! (plus it's a waste of energy
storing 12V, converting back to 240V, only to drop it back to 12V and 5V in
the psu.. It'd be more sensible to run a 12V psu from a car battery, with a
trickle charger attached.. (unless there's a better way?) )

Regards,
Chris

 

[Chris Stolworthy]

Moving outlets wouldn't make much of a difference.. lights are a seperate
circuit to power, but flurecents still interfere when switched on or off..
(other lights have less effect)..

In Australia we have 240V for everything (appliances operate from anything
around 220V)...
The stove and oven are on a dedicated 30A circuit, with the outlets on 10A.

The kitchen + the outlet I use for my PC (and 1 or 2 others) near the
kitchen make up 1 circuit, with the laundry and lounge contibuting to
another, along with a couple for the bedrooms..

I've experienced the too much on one circuit issue before.. the kitchen,
lounge and laundry all used to be a single 10A circuit.. (with the breaker
tripping every 10 mins!)

I'm not inclinded to buy a UPS, as it's a coupla hundred bux just to keep
the PC up for a few mins to save stuff ! (plus it's a waste of energy
storing 12V, converting back to 240V, only to drop it back to 12V and 5V in
the psu.. It'd be more sensible to run a 12V psu from a car battery, with a
trickle charger attached.. (unless there's a better way?) )

Regards,
Chris

Ummm not sure what costs are over there...but you can buy a UPS here
starting at $30. So not exactly a HUGE investment, and you don't need
60mins of shut down tme, something with 5 min is usually enough.

-Chris

 

[CBFalconer]

.... snip ...

I'm not inclinded to buy a UPS, as it's a coupla hundred bux just
to keep the PC up for a few mins to save stuff ! (plus it's a
waste of energy storing 12V, converting back to 240V, only to
drop it back to 12V and 5V in the psu.. It'd be more sensible to
run a 12V psu from a car battery, with a trickle charger attached..
(unless there's a better way?) )

Most do not use the battery until a failure occurs, which means
the cutover has glitches. The system PSU can normally handle
those.

The expense can also be much smaller. I use one that I picked up
at a closeout sale for about 30 or 40 USD several years ago. It
holds up my system for about 5 to 8 minutes, which is adequate to
get it shut down. Abrupt shut down can cause irretrievable
foulups in file systems, and I value my data.

It has only been needed once in the past few years, last spring
when a tree fell across our power lines and brought down two
poles. We had 4000 V (live) lying about in the middle of the
street for a while. Later we went and looked at the damage, and
noticed the poles were rotten through and through. Some evidence
there showed that they were at least 50 years old! I have noticed
this summer that the power company is replacing poles in the whole
area.

 

[Noozer]

Most do not use the battery until a failure occurs, which means
the cutover has glitches. The system PSU can normally handle
those.

Personally, I think that it does make sense to build the battery backup into
the PC itself, after the voltage conversion has been done. It would make
the PC a lot heavier and cost a bit more, but it should be cheaper in the
long run.

 

[kony]

Personally, I think that it does make sense to build the battery backup into
the PC itself, after the voltage conversion has been done. It would make
the PC a lot heavier and cost a bit more, but it should be cheaper in the
long run.

Could be true but how are you going to power monitor/etc, have
every device with it's own UPS inside?

 

[w_tom]

You are suffering from noise - a tiny voltage of higher
frequency carried on AC mains. Any decent power supply would
eliminate noise from AC mains. Apparently your Logitech
speaker system does not have a good power supply - permits Ac
mains noise into speakers.

One could install an AC mains filter that should have been
inside that power supply. An example:
http://www.cor.com/catalog/filters/AQ/schematic.htm
http://www.cor.com/catalog/filters/AQ/Default.htm

Another possibility is to quash the noise at the switch that
causes the transient.

Rather embarrassing is the plug-in UPS recommendation. A
typical battery backup UPS (under US$400) simply connects
output directly to AC mains when not in battery backup mode
(they do not convert to 12 volts then convert back to 240
volts when not in battery backup mode). Furthermore, many
such UPSes are extremely noisy in battery backup mode. So
noisy that they may even harm so some electric motors. But
such UPSes in battery backup mode can test the integrity of
that Logitech power supply.

The problem is with those Logitech speakers. Alternative
are to either replace those speakers with a better design,
install an inline filter such as a power entry module or
something from the above example, or modify the offending
appliance maybe with snubbers on the switch.

 

[kony]

Hi,

I just got a new set of speakers (logitch z-340), and they seem very
sensitive to electrical noise (my old speakers weren't).
Every time the motor on my fridge cuts in or out (or someone turns a light
on or off), then I get a distorted clicking noise through the speakers. The
noise only lasts half a second, but it's annoying !

Any suggestions on fixing this ?

Regards,
Chris

I suspect those have a rather basic, poorly filtered switching
power supply inside... is this correct, do they come with a power
brick or wall-wart supply or just an AC cord that plugs into the
subwoofer? It probably isn't even grounded. Granted it is
possible to have a subwoofer receiving power without it being a
switching supply inside, but it seems very uncommon, I've never
seen such done with computer speakers.

You might try any decent line filter. Open up the sub and see
how much room there is inside. If you aren't comfortable dealing
with AC power then buy a standalone "enclosure" that has a power
outlet on it (which may be the best overall solution since you
could plug other things into it as well) or you could install a
filter of maximum size possible in the subwoofer, in series with
the AC input (note that the AC jack may be surface-mounted on the
PCB so some creativity could be needed to break the circuit and
put the filter inline).

 

[Max]

I'm not sure about 240V, but a good quality $40US surge protector will
filter noise and help stop surges. This kind of protection is included in
most of the $40US battery UPS's, so it's much more cost effective to buy the
UPS.

-Max

 

[kony]

I'm not sure about 240V, but a good quality $40US surge protector will
filter noise and help stop surges. This kind of protection is included in
most of the $40US battery UPS's, so it's much more cost effective to buy the
UPS.

-Max

There is a trivial, if any, noise filtration circuit in a $40
UPS. For example I'm thinking of some from APC, 35-500VA range
should fall in a $40 range and certainly doesn't have a
sufficient filter.

 

[Skeleton Man]

I suspect those have a rather basic, poorly filtered switching

power supply inside... is this correct, do they come with a power
brick or wall-wart supply or just an AC cord that plugs into the
subwoofer? It probably isn't even grounded. Granted it is
possible to have a subwoofer receiving power without it being a
switching supply inside, but it seems very uncommon, I've never
seen such done with computer speakers.

AC cord just goes into the subwoofer, and it's not grounded no.

You might try any decent line filter. Open up the sub and see
how much room there is inside.

Would one of those EMI filters from a switch mode psu work ? (I have several
dead power supplies which I could salvage one from)

If the AC input is PCB mounted I won't bother modifying it (too much work
for a minor problem), I'll just buy some kind of inline plug-in filter..

Regards,
Chris

 

[JW Tech]

I would suggest looking into line filters, the ones you describe should be
able to be used (if you cant fit them internally, consider an external zippy
box and cutting the power cord).

As for all the US people suggesting to buy a "$30.00US" UPS, the situation
is a bit bleaker over here guys. On average for a cheap UPS we pay around
the $130.00 AUS (~$91.00US), but that has actual line filtering (I believe
it is one of the requirements over here).

Jim.

 

[kony]

AC cord just goes into the subwoofer, and it's not grounded no.


Would one of those EMI filters from a switch mode psu work ? (I have several
dead power supplies which I could salvage one from)

If the AC input is PCB mounted I won't bother modifying it (too much work
for a minor problem), I'll just buy some kind of inline plug-in filter..

EMI filter from a switching power supply may be insufficient,
analog audio circuits require much cleaner power than digital
computer circuits. In particular you may need a filter with
large chokes, which makes it physically larger. Such are
relatively expensive when found in consumer pass-though surge
strips, etc, is part of what may differentiate a $10 surge strip
from one costing $100. One cheap filter I know of is the
following, though I don't know if it is sufficient for your
particular degree of problem,
http://sales.goldmine-elec.com/prodinfo.asp?prodid=6379

 

[w_tom]

An example with spec numbers and schematic was provided
previously. You will probably need to build a separate box on
the line cord to install proper filtering:
http://www.cor.com/catalog/filters/AQ/schematic.htm
http://www.cor.com/catalog/filters/AQ/Default.htm

In the meantime, there is a trivial, if any, noise
filtration circuit in a $40 UPS. However that UPS could output
so much noise in battery backup mode to be a test bench for
filter contruction. Many UPSes actually output some of the
dirtiest, noisiest power when operating from battery. And
even that noise should not adversely affect a speaker power
supply. Borrow a UPS for testing to both learn how bad the
power supply is AND to help install sufficient noise filters.

Grounding should have nothing to do with this type of
noise. However saftey grounding the external filter box may
be required and may have some additional benefits. Three wire
AC cord to filter box. Then two wire cord to Subwoofer.

 

[Noozer]

Could be true but how are you going to power monitor/etc, have
every device with it's own UPS inside?

Anything that would need a UPS, yes... You don't need a monitor to do a
shutdown.

Not necessarily for every PC user, but something UPS makers should
consider...

How about a module that will sit in a pair of 5.25" bays. PSU plugs into
this, then cable from this goes to mainboard/drives? Would remove a lot of
the charging circuitry. Only downside is lack of UPS protection to the PSU
due to a power surge.

 

[default]

Moving outlets wouldn't make much of a difference.. lights are a seperate
circuit to power, but flurecents still interfere when switched on or off..
(other lights have less effect)..

In Australia we have 240V for everything (appliances operate from anything
around 220V)...
The stove and oven are on a dedicated 30A circuit, with the outlets on 10A.

The kitchen + the outlet I use for my PC (and 1 or 2 others) near the
kitchen make up 1 circuit, with the laundry and lounge contibuting to
another, along with a couple for the bedrooms..

I've experienced the too much on one circuit issue before.. the kitchen,
lounge and laundry all used to be a single 10A circuit.. (with the breaker
tripping every 10 mins!)

I'm not inclinded to buy a UPS, as it's a coupla hundred bux just to keep
the PC up for a few mins to save stuff ! (plus it's a waste of energy
storing 12V, converting back to 240V, only to drop it back to 12V and 5V in
the psu.. It'd be more sensible to run a 12V psu from a car battery, with a
trickle charger attached.. (unless there's a better way?) )

Regards,
Chris

I have a similar problem and it is solved . . . I'm an EE.

You need something called a "brick wall" filter on the power mains.
It is a rather simple device of inductors and capacitors. The network
is sometimes called a "pi" filter (in its simplest configuration it is
two capacitors across the mains (hot to neutral) with an inductor in
series - in the hot leg - between the caps).

It goes on the outlet directly feeding your computer (or speakers)

A good source for these is electronics surplus catalogs. (in the US)
Cost is minimal $1-$15 depending on current carrying capacity. You'd
have to jury rig the connections - and have to know enough to do it
safely.

Surge filters are worthless for most noise. They only filter spikes
over some threshold voltage and are to prevent damage.

The noise isn't necessarily causing problems in your computer -
ideally a clean power line is better than a noisy one, but most
switching supplies are able to ignore incoming noise just based on
their circuit (first thing the power sees is a rectifier and big
capacitors).

Sometimes noise can also be cured with proper grounding - assuming a
fault exists in the house wiring. I had an instance of a persistent
buzzing in an old stereo at a friend's house. I noticed there was no
ground on the incoming power / circuit breaker box. Added a ground
there (according to code) and it helped tremendously.

I checked the power pole and saw there was no ground for the
transformer (someone had stolen the copper wire). Called the power
company and they replaced it. The poles need grounding for lightning
protection anyway . . .

That finally solved the buzzing problem completely.

An ups system will usually solve the problem because they add a
transformer and additional filtering - a good ups system is more for
serious sags and surges in the power supply, a cheap ups system will
just prevent crashes from total power loss.

 

[kony]

Anything that would need a UPS, yes... You don't need a monitor to do a
shutdown.

Not necessarily for every PC user, but something UPS makers should
consider...

How about a module that will sit in a pair of 5.25" bays. PSU plugs into
this, then cable from this goes to mainboard/drives? Would remove a lot of
the charging circuitry. Only downside is lack of UPS protection to the PSU
due to a power surge.

Typical consumer-grade ups does not isolate PSU from line so
surge protection is little if any better than an average
surge-strip.

Putting ups behind PSU would remove need for big/heavy/expensive
transformer, but otherwise the differences in charging circuit
shouldn't make too much of a cost or size difference, especially
considering that a post-PSU UPS then needs multiplie rails
switched to battery when power fails, plus you'd have separate
cell packs per each voltage rail, and so some would drain faster
than others depending on specific system power rail usage, not
necessarily achieving the substantially greater runtime per
battery capacity by eliminating the AC-DC converter anymore.

The circuit board and batteries may not fit so well in a 5 1/2"
bay, unless you only wanted system to immediately shut off...
personally I do want monitor powered and at least a couple
minutes before being forced to shut off. The idea might've fared
better in past years when systems used less power.

 

[Spajky]

You need something called a "brick wall" filter on the power mains.
It is a rather simple device of inductors and capacitors. The network
is sometimes called a "pi" filter (in its simplest configuration it is
two capacitors across the mains (hot to neutral) with an inductor in
series - in the hot leg - between the caps).

It goes on the outlet directly feeding your computer (or speakers)

A good source for these is electronics surplus catalogs. (in the US)
Cost is minimal $1-$15 depending on current carrying capacity. You'd
have to jury rig the connections - and have to know enough to do it
safely.

Surge filters are worthless for most noise. They only filter spikes
over some threshold voltage and are to prevent damage.

there are also manufactured ones with built-in filter; I have one...