On Fri 26 Dec 2008 12:21:58a, Jim Beaver told us...


"Wayne Boatwright" wrote in message
5.247...
On Thu 25 Dec 2008 04:53:05p, E Z Peaces told us...

Jim Beaver wrote:

"E Z Peaces" wrote in message
.. .
Jim Beaver wrote:
I've got my Christmas tree set up in my living room. A couple of
strings of lights (not those mini-lights, but the finger-tip size
bulbs). Here's the problem:

When I turn on the lights, a loud hum arises from the timer for my
yard sprinklers. This timer is mounted on the outside wall of the
living room. Obviously it's on the same circuit, as the hum comes
and goes when the Christmas tree lights are turned on or off.

The hum is loud. Probably loud enough indoors to wake a light
sleeper from a nap if it suddenly came on. It's even louder, of
course, outdoors near the timer.

The power cords, plugs, and receptacles all seem cool. So I'm
wondering: does this sound like an overloading problem, or more
likely some sort of simple harmonic vibration? Am I in danger of
fire, if everything I can get to seems cool?

I don't know anything much about electrical testing or I'd use a
tester on it somehow. But I don't really know what to look for.

Anyone NOT doing something more interesting on Christmas Eve who
wants to advise me here?

And with that in mind, happy holidays to all here. Thanks.

Jim Beaver

I haven't been able to imagine how the lights could affect voltage
or current in the timer.

Are there valves near the timer? Sometimes a solenoid valve can hum
loudly.

I discovered this morning that the hum doesn't happen in the daytime.
Which leads me, genius that I am, to conclude that it's not the
sprinkler timer but the low-voltage outdoor lighting system timer. I
have no idea whether this affects matters much in terms of safety,
etc.

Jim Beaver

My idea light is flashing! Does an electric eye turn on the outdoor
lights? Maybe the eye is exposed to one of the outdoor lights as well
as light from your tree in the window, and together they hit it with
enough light to shut it off. That brings the light below the
threshold and it turns back on. The frequency of the hum would depend
on how long it took the outdoor filament to heat white hot.


Maybe I've missed something here, but why belabor this situation? Just
plug the lights into a socket that's on a totally different circuit.

All this effort for a temporary lighting situation seems like a huge
waste of time and effort, or do you just enjoy puzzles?

Hate puzzles. Just trying to avoid running a twenty-foot extension cord
to the nearest receptacle not on this circuit. Christmas is dangerous
enough without decking cables down and across my halls. Also, I find a
house without extension cords running across major thoroughfares to be
more elegant than one with such obstacles.

Jim Beaver



Well, I really can't disagree with that. I have no clue why this is
happening. I assume when you plug anything else other than the Christmas
tree lights into this socket that it doesn't cause the problem. If that's
true, it may be that the string(s) of light on the tree are generating some
sort of frequency that's being picked up by the transformer. Actually,
transformers usually generate a hum most of the time, even if relatively
inaudible. Consider that the transformer generates a magnetic field and
may be oscillating because of the frequency that may be generated by the
multple miniature lights. Many things are possible. I doubt seriously
that this situation is actually dangerous.

--
Wayne Boatwright
(correct the spelling of "geemail" to reply)
************************************************** **********************
Date: Friday, 12(XII)/26(XXVI)/08(MMVIII)
************************************************** **********************
Today is: Boxing Day (U.K.)
Countdown till New Year's Eve
4dys 23hrs 27mins
************************************************** **********************
Shotgun wedding: a case of wife or death.
************************************************** **********************