60 hertz hum

[Ken Weitzel]

Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work "crikey"
until today.
How about up in Canada ?? Have you?

Hi Sofie...

Been in the UK many times as well, but not in the last 20 years...
would like to once more if I can. Never heard crikey, either, neither
there or here in Canada.

My favorite expression I heard there was from someone I was doing a
bit of a job with. I made a foolish mistake, and he accused me of
"dropping a clanger"

Ken

 

[Dave Plowman (News)]

I have traveled the world over..... been to the UK many times on
business trips, personal vacations, etc.... but I had never heard the
work "crikey" until today. How about up in Canada ?? Have you?

It's an old expression and I was trying to be polite as a visitor to a non
UK newsgroup.

Otherwise I'd have said bollocks or shite. ;-)

 

[CJT]

It's an old expression and I was trying to be polite as a visitor to a non
UK newsgroup.

Otherwise I'd have said bollocks or shite. ;-)

FWIW, I've heard crikey used in the U.S. many times (but I don't recall
hearing it in the U.K. during the year +/- I lived there). Perhaps it's
a regional thing.

 

[Mark Moulding]

I knew that would raise some rabble. Yes, of course I recognize the
potential (so to speak) problems with opening the safety ground connection.
However, a few interesting points exist in this particular situation:

- The device is a laptop, and there is no direct connection from the ground
pin through the (double-insulated) AC adapter/charger to the laptop chassis,
so it's really not much of a "safety" ground.

- There are two small value (10 nF) caps from each side of the power line to
the ground terminal inside the adapter, presumably as an RFI suppression
measure.

- All of the audio equipment involved was plugged into the *same* outlet
strip - it seems highly unlikely that there'd be much of ground loop within
the 6" or so of 16 gauge wire separating the plugs

- Finally (and this is really no excuse), my house is old enough that I'm
not convinced that all of the three prong outlets have their ground pin
connected to anything at all. It's not so old that it's knob-and-tube, but
the outlets were originally two prong, and I think that many were just
replaced with three-prong as placebos, without pulling a ground wire. At
least the garage (with the concrete floor and the power tools) is wired
correctly...
--
Mark
"I prefer heaven for climate, hell for company."

CJT:
Some years ago when I was in the pro-audio installation business for an on
the road entertainment company, us installation techs would always carried
about a dozen "u-ground" 3 wire to 2 wire ground adapters in our tool
boxes
so the ground could be temporarily "lifted" on various pieces of gear to
eliminate ground loops and the subsequent hum problems. (don't cut off
ground pins on the plugs of equipment) Usually the problem would
originate
because remote equipment was on a different circuit from the breaker box
and
was located some distance from the main head-end gear.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Something you might try (although you didn't hear it from me)

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In other words, you recognize what a bad idea this is.

is completely

disconnecting the ground pin on your computer. You didn't mention what kind
of computer you're using, but if it's a laptop, grounding isn't too
essential. (In fact, having a permanently lifted [broken off,
actually]
ground pin on mine has several times saved my laptop from almost
certain
major damage when connected to equipment with a ground fault - a common
problem in my line of work.)

In my case, I'm also using a laptop for a home music recording studio
(I
know, not the best choice, but it was sitting around...). All of the audio
I/O is via an external high-quality device, but ground loop hum was killing
me, *even though everything was plugged into the same outlet strip*.
Breaking off the computer's power supply ground pin completely solved the
problem.
--
Mark
"I prefer heaven for climate, hell for company."



I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis

 

[Ken Weitzel]

I knew that would raise some rabble. Yes, of course I recognize the
potential (so to speak) problems with opening the safety ground connection.
However, a few interesting points exist in this particular situation:

- The device is a laptop, and there is no direct connection from the ground
pin through the (double-insulated) AC adapter/charger to the laptop chassis,
so it's really not much of a "safety" ground.

- There are two small value (10 nF) caps from each side of the power line to
the ground terminal inside the adapter, presumably as an RFI suppression
measure.

- All of the audio equipment involved was plugged into the *same* outlet
strip - it seems highly unlikely that there'd be much of ground loop within
the 6" or so of 16 gauge wire separating the plugs

- Finally (and this is really no excuse), my house is old enough that I'm
not convinced that all of the three prong outlets have their ground pin
connected to anything at all. It's not so old that it's knob-and-tube, but
the outlets were originally two prong, and I think that many were just
replaced with three-prong as placebos, without pulling a ground wire. At
least the garage (with the concrete floor and the power tools) is wired
correctly...

Hi...

As a side issue, there are testers available for only a couple of
dollars that you can plug into your outlets that will (by way of three
neon lamps) easily tell you whether or not ground exists, and if
hot/neutral are reversed.

Just mentioned it wondering if it might not increase your comfort level.

Ken

 

[Alan Holmes]

Neither. The hum you hear in the UK is actually 100 Hz.

How do you work that out?

Alan

 

[Alan Holmes]

Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work
"crikey"
until today.

You obviously haven't lived!-)

Used to be an everyday exclamation

Alan

 

[Jasen Betts]

Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work "crikey"
until today.
How about up in Canada ?? Have you?

dunno about there in in Australia and New Zealand it's heard occasionally.

my (aging) Concise Oxoford dictionary dosen't specifty that it's unique to
any place.

Bye.
Jasen

 

[Karl Uppiano]

How do you work that out?

Second harmonic of 50 Hz. A lot of the hum you hear in the US is actually
120 Hz for the same reason. Most objects, including speakers, really don't
radiate that well at 50 - 60 Hz fundamental, but can and do radiate pretty
well at some of the higher harmonics.

 

[James Sweet]

Second harmonic of 50 Hz. A lot of the hum you hear in the US is actually
120 Hz for the same reason. Most objects, including speakers, really don't
radiate that well at 50 - 60 Hz fundamental, but can and do radiate pretty
well at some of the higher harmonics.

I always thought the 60Hz caused core laminations, coil windings, etc to
smack into each other at both peaks of the waveform, hence the 120Hz
sound from a 60Hz source. I could be off on the process, but I do know
that if I use a sound editor on my computer to produce a 120Hz sine wave
it sounds just like the 60Hz hum from transformers.

 

[Karl Uppiano]

I always thought the 60Hz caused core laminations, coil windings, etc to
smack into each other at both peaks of the waveform, hence the 120Hz sound
from a 60Hz source. I could be off on the process, but I do know that if I
use a sound editor on my computer to produce a 120Hz sine wave it sounds
just like the 60Hz hum from transformers.

Yeah, I think a magnet or buzzer (like in an old alarm clock) will be
attracted by both peaks of a 50 or 60 Hz input, and oscillate at the second
harmonic.