magnetic field

[Geoff Miller]

Get yourself a three- or four-cell Maglite, and keep it in the
passenger compartment with you, not in the trunk. Not only are
maglites damned good flashlights, but they can be used (or
threatened to be used) as bludgeons in the event of roadside
confrontations. And unlike other weapons, they aren't illegal
to have in the car with you.



Geoff

--
"You know, 'elitist' has an actual meaning. Using it as a generic
pejorative only betrays your political leanings _and_ makes you
look like a moron, to boot." -- John S. Novak

 

[Mike T.]

"Geoff Miller" <geoffm@u1.netgate.net> wrote in message
news:dpealc$l3q@u1.netgate.net...

Get yourself a three- or four-cell Maglite, and keep it in the
passenger compartment with you, not in the trunk. Not only are
maglites damned good flashlights, but they can be used (or
threatened to be used) as bludgeons in the event of roadside
confrontations. And unlike other weapons, they aren't illegal
to have in the car with you.



Geoff

Better yet, get a LED flashlight. The batteries last a lot longer in an LED
flashlight, and the LED flashlight is brighter anyway. LED would be best
for emergency use, unless you use a crank-charged flashlight or one that
plugs into the cigarette socket in the car. Any mag-lite would be
practically guaranteed to have dead batteries when you NEED it. (AFAIK,
mag-lite hasn't produced an LED flashlight YET) But the LED flashlights
will continue to produce useful light even when the batteries are almost
dead, as they require very low voltage and low current to produce light.
One example follows. -Dave

http://mvp.com/product/index.jsp?productId=1960262

 

[Steve]

Mike T. wrote:

Better yet, get a LED flashlight. The batteries last a lot longer in an LED
flashlight, and the LED flashlight is brighter anyway.

I disagree with the last statement. LED flashlights aren't nearly as
bright as a Mag-Lite. Nowhere close (and I own both kinds). They are
beginning to get close to having the same light intensity in the "hot
spot," but what they lack is anything like the amount of fill-light
around the hot-spot that a Mag-Lite has. Plus Mag-lites can be focused
for a tight hot-spot, or nothing BUT fill light.

LED would be best

for emergency use, unless you use a crank-charged flashlight or one that
plugs into the cigarette socket in the car. Any mag-lite would be
practically guaranteed to have dead batteries when you NEED it.

Like I said the other day- I've got a 2-year data point with a stored
Mag-Lite with Duracells.

 

[St. John Smythe]

Steve wrote:

Like I said the other day- I've got a 2-year data point with a stored
Mag-Lite with Duracells.

I can't count the number of times over the past 30 years I've had to
pound dead D cells out of the Mag-Lites in the three family cars (yeah,
they should have been checked on schedule, but in real life...). For
that reason, we're trying out lithium-battery LED lights for those
"stored indefinitely, gotta be there when you need it" applications
(vehicles, bug-out-bags). The 1-watt Luxeon LED lights sold in the
two-pack at Costco are the current candidates, with the alkaline AAs
replaced with lithiums.

A less bright light that works when finally needed is infinitely
preferable to a bright light that's gone dead.

--
St. John
It has been said that man is a rational animal. All my life I have
been searching for evidence which could support this.
-Bertrand Russell

 

[phatty mo]

dave madden wrote:

"DK" == Don Klipstein <don@manx.misty.com> writes:


DK> I got a few such flashlights fitting the description so far,
DK> and bought them for $1.99 at a dollar store.
DK> But after that - mine appear to be even worse than described
DK> by Don Bruder!
DK> In the ones I bought, the coil leads were shorted together,
DK> the magnet clearly existed but as a clearly fake magnet that
DK> was clearly a non-magnet, and the flashlight had CR2016
DK> batteries, which I believe is a non-rechargeable type.

That's bizarre -- you'd think that the added cost of all that
non-functional crap, _plus_ the batteries and light, would exceed the
cost of really doing it. Hrmph. China. Go figure.

d.

Hold on a minute,it gets better..
A guy on a forum bought 200 of the things..
They were powered off of the lithium coin cells inside..
They had the coil,but the leads didn't connect to anything,and the
"magnets" were just a slug of non-magnetic pot-metal type stuff..
No PCB,diodes,or anything.

He noticed cause the one he was using went dead,and shaking it didn't do
anything.He took apart 4-5 of them,and they were all the same!

 

[Jasen Betts]

["Followup-To:" header set to sci.electronics.misc.]
On 2006-01-10, dances_with_barkadas@yahoo.com <dances_with_barkadas@yahoo.com> wrote:

seek recommendations. for voice intelligibility enhancement on a
orderwire copper-pair.

ordinary copper wire pair?

check that the devices at each end are operating correctly
and have the correct power supply etc..

maybe you need a better microphone?
possiblly one with background noise rejection.

amplify the signal before putting it into the wire
then the noise will be less significant

bandpass filter 300-3000Hz

encode the audio digitally (probably major overkill)

professional marine application. sturdiness is more important than
bleeding-edge performance.

keep the wires dry and waterproof all junctions...
i'd look at liquid electrical tape unless you have a superior product.

keep them away from power runs or rune them in a separate conduit from
the power

Bye.
Jasen

 

[Charles Schuler]

Best source of trojans, worms, viruses, spybots, snoops, trackers,
auto-click agents, bird flu ..............................

 

[Someone]

On Tue, 10 Jan 2006 18:11:53 -0500, "Charles Schuler" <@comcast.net>
used recycled pixels to say:

Best source of trojans, worms, viruses, spybots, snoops, trackers,
auto-click agents, bird flu ..............................

and don't forget root kits!

 

[Jayseebee]

Actually we (retired and Ex ATT,Bell,SBC and now ATT again) used to do a
frequency run test with an audio signal generator and a receive
measuring device at the far end. If needed we would put in a equalizing
unit (Wescom, Teltrend, etc) that we could adjust the 300-to 3khz slope
(sometimes up to 8khz for audio program loops for radio broadcast) with
to make all frequencies as flat as possible or boost the level of the
freqs as needed. You can get even more technical in the time delay at
different frequencies on the same copper path traveling from one end to
the other. Lets see what this stirs up.

JCB


dances_with_barkadas@yahoo.com wrote:

seek recommendations. for voice intelligibility enhancement on a
orderwire copper-pair.

professional marine application. sturdiness is more important than
bleeding-edge performance.

 

[Robert Kubichek]

Digitizing it, then running it on a network would give you the best
voice quality, and the network can be used for other data
( environmental, remote control, alarms, ect) plus it would be relatively
simple to set up..

dances_with_barkadas@yahoo.com wrote:

seek recommendations. for voice intelligibility enhancement on a
orderwire copper-pair.

professional marine application. sturdiness is more important than
bleeding-edge performance.

--
Bob N9LVU

 

[Don Klipstein]

In article <43bac2bc$0$19566$892e7fe2@authen.yellow.readfreenews.net>,
Mike T. wrote:

"Geoff Miller" <geoffm@u1.netgate.net> wrote in message
news:dpealc$l3q@u1.netgate.net...


Get yourself a three- or four-cell Maglite, and keep it in the
passenger compartment with you, not in the trunk. Not only are
maglites damned good flashlights, but they can be used (or
threatened to be used) as bludgeons in the event of roadside
confrontations. And unlike other weapons, they aren't illegal
to have in the car with you.

Better yet, get a LED flashlight. The batteries last a lot longer in an
LED flashlight,

Largely true, and mostly from LEDs not losing energy efficiency the way
incandescents do when underpowered.

and the LED flashlight is brighter anyway.

Usually not true. Make sure yours will give you enough light, although
that is probably not much of an obstacle.

LED would be best for emergency use, unless you use a crank-charged
flashlight or one that plugs into the cigarette socket in the car.

There are LED flashlights that have generators in them activated by
shaking them. They have capacitors to store this energy. Better ones,
after half a minute of shaking, can give 20 minutes of light. Since they
have only one 5-mm traditional-style LED, they will not be as bright as
most non-LED flashlights, but the latest versions have the LED efficient
enough to be fairly useful.

Beware of dollar store versions. I have seen two $2 versions where the
magnet is fake, the coil is a decoy, and the only item storing energy is a
bvank of batteries of a non-rechargeable type.

I did see an especially good "shake flashlight" at Target today for $40.
It will not be as bright as a Mag Light with good batteries, but it should
be twice as bright as the $10-$15 shake flashlights, and the $10-$15 shake
flashlights are not outright useless (although some don't run long when
you stop shaking).

Caution with shake flashlights in general, and especially the $40 one at
Target: These have "rare earth" magnets that can scramble tapes, discs,
credit cards and ATM cards, etc., maybe even 2-3 inches away. And the $40
one at Target has two magnets besides the movable one to improve shaking
ergonomics.

Any mag-lite would be practically guaranteed to have dead batteries when
you NEED it.

All too often true!

Most Dorcy LED models and most Lightwave models and probably a majority
of other LED flashlights will work usefully when the batteries are so weak
as to make an incandescent flashlight bulb only 1/4 as bright as an idling
cigarette.
In this area, I especially like an older Dorcy model which is a short
and stubby thing that looks like it should take 1 D-cel, but actually
takes 4 AA cells. This thing will work somewhat if one of the AA cells
has completely lost all voltage as long as such a cell that bad has not
lost all conductivity. Best to use AA cells with impressive dates for
"good until".

(AFAIK, mag-lite hasn't produced an LED flashlight YET)

Turns out, Mag is not in the LED business, but appears to do well by
sitting pretty while others sell LED retrofits for their flashlights.

Check out (as well as for tone of other stuff, but a good half being LED
flashlights): http://ledmuseum.home.att.net/ledleft.htm
(That URL does lack a www. - this is not a typo.)

But the LED flashlights will continue to produce useful light even when
the batteries are almost dead, as they require very low voltage and low
current to produce light.

There is some voltage requirement, but LEDs make enough light to form a
slightly, sometimes somewhat useful beam at less than 1/20 the current
necessary to get most incandescent flashlight bulbs glowing so brightly as
1 percent of the brightness of an average idling cigarette.

One example follows. -Dave

http://mvp.com/product/index.jsp?productId=1960262

Good work!

Also check out:

Target - they sell a fair number of LED flashlights now.

http://ledmuseum.home.att.net/ledleft.htm (mentioned above)

http://www.theledlight.com/LEDFlashlights.html

Lightwave products - specifically their 2000, 2100, 3000 and 4000. I know
these as examples that are good at "conserving energy" as their batteries
weaken. Although the 2000, 2100, 3000 and 4000 are 3-cell products and
will be very dim at most if once cell has complete loss of voltage (which
is not common when complete loss of voltage from one cell causes a
complete loss of current flow).

Pelican LED models - higher brightness with many having regulation
circuitry, although that takes away much (but not all) of the battery life
advantage.

- Don Klipstein (don@misty.com)

 

[Fake ID]

In article <slrndsom08.agl.don@manx.misty.com>,
Don Klipstein <don@manx.misty.com> wrote:

Turns out, Mag is not in the LED business, but appears to do well by
sitting pretty while others sell LED retrofits for their flashlights.

I got some spam from them recently indicating they're about to make a
move into LEDs. One of my 3D Mags has a 32 LED replacement head. Once
accidentally left it on overnight. Seemed just a bright.

"Best" LED flashlight I've found for emergency use is a 10 LED 3AAA
offered as a "free" gift on my credit card bill response envelope.
I hate to encourage that sort of business. I figured it's just cheap
China crap so someone else probably sells the same thing, but I looked
around for awhile and never found anyone.

At $8 final cost the illumination and ergonomics were good enough to
justify stowing away several. Unfortunately, they went to $10 before I
could stock up and might be even higher now.

m

 

[Mike T.]

"Best" LED flashlight I've found for emergency use is a 10 LED 3AAA
offered as a "free" gift on my credit card bill response envelope.
I hate to encourage that sort of business. I figured it's just cheap
China crap so someone else probably sells the same thing, but I looked
around for awhile and never found anyone.

I bought a few of those off of ebay. it is cheap China crap, but it still
works pretty good. You just have to be careful changing the batteries, or a
little spring will fall out. No big deal, easy to fix . . . unless you lose
the spring. -Dave

 

[Fake ID]

In article <43cd0309$0$65772$892e7fe2@authen.yellow.readfreenews.net>,
Mike T. <hello@howyadoin.now> wrote:

"Best" LED flashlight I've found for emergency use is a 10 LED 3AAA
offered as a "free" gift on my credit card bill response envelope.
I hate to encourage that sort of business. I figured it's just cheap
China crap so someone else probably sells the same thing, but I looked
around for awhile and never found anyone.

I bought a few of those off of ebay. it is cheap China crap, but it still
works pretty good. You just have to be careful changing the batteries, or a
little spring will fall out. No big deal, easy to fix . . . unless you lose
the spring. -Dave

You wouldn't happen to have an item number that's still in their system?
I searched again and still can't find the same thing.

FWIW, I typoed before--3AA, not 3AAA.

m

 

[Nehmo Sergheyev]

canadian_woodworker

Is there a simple way to figure out which is the first recepticle on a
circuit? I have an older house - the two upstairs rooms are on the
same
circuit and are not grouned. Id like to add a GFCI plug on the first
recepticle on that circuit, so every recepticle downstream is
protected.

The brute force method would be to guess which recepticle is the
first,
remove the outgoing wires, and test every other outlet for power -
rinse (hook back up the wires), repeat, until ive found the recepticle
that has power and all the others that dont. However this will take
awhile - most arent easily accessible - behind furnitire, beds etc.

I have at my disposal the standard home repair tools - volt meter,
etc.

Nehmo -
I don't know exactly how to do it in practice, but in theory…

1.
Unplug everything on the circuit.

At the circuit breaker box, with the breaker off, connect what would
have been the hot wire of the circuit to the neutral. Leave the neutral
connected normally.

Measure between one slot and the other at each receptacle.

At each receptacle, the measurement of the resistance and inductance
will be different. They will be lowest at the first, and highest at the
last.

14 gauge wire only has a resistance of 2.6 ohms per 1,000 feet, so the
difference in resistance will be difficult to measure. But the
inductance should be substantially different at each receptacle. At
higher frequencies, the measurement should be easy.

Or

2.
Get something that detects AC _current_ in a wire without electrically
connecting to the wire. Perhaps a pick-up coil attached to an amplifier
or perhaps a large coil simply connected to an earphone. I'm not used to
the commercial non-contact detectors, but one of them would work. You
want something that makes a different indication for a current flowing
wire and just a hot wire. After you have your detection tool, experiment
with it. Learn to detect a current-carrying wire.

With the circuit breaker on, plug-in a high-wattage lamp in what you
suspect to be the first receptacle. You should not be able to detect
current moving through the wires at any other receptacle. If you detect
current at a receptacle, it's at a position before the lamp receptacle.

Unplug the lamp and plug it in what you suspect to be the last
receptacle. You should be able to detect current at every receptacle.

Note I'm making a distinction between a receptacle with current going
through the wires connected to it and a receptacle that's just hot. All
of them should be hot. The electromagnetic field will be much stronger
around a current carrying wire.

Or

3.
Get a really high-wattage load, perhaps a big electric heater, something
with a high enough wattage to heat its supply wires detectably - but not
dangerously. Use the same system as the current detector. Plug in the
load at the (believed) last receptacle. Check the earlier receptacles
for warm wires. You get the idea.

4.
Fire the circuit up with DC (use a rectifier by the circuit breaker
box). Put a low-resistance load on the circuit at some receptacle. With
a sensitive voltmeter, measure between a hot slot of one receptacle and
the hot slot of another. The existence and the polarity of this tiny
voltage drop will show the relative position of the receptacles. If you
draw a diagram, you'll understand.

You could do this with the regular AC too, but you wouldn't get the
polarity info. You still could figure out which receptacle is first.
You're testing for a voltage drop across a load, which in this case is
just a piece of wire between receptacles. The voltage drop will not be
much.

[I crossposted]
--
(||) Nehmo (||)

 

from google on GFCI circuit breaker

For broad protection, GFCI circuit breakers may be added in many panels
of older homes to replace ordinary circuit breaker. For homes protected
by fuses, ...

http://doityourself.com/electric/gfci.htm

 

Yea, ive read that page before.

afaik, those breakers are pretty expensive. But ill check today and
possibly pick one up.

Thanks for the comments all. Nehmo - your post alluded to a method I
had considered, but im not skilled enough to know exactly what to do
What you say makes sense, but I think ill either go with a breaker, or
the method I talked abut.

Thanks all for comments.

 

[John Larkin]

On Sun, 12 Feb 2006 09:43:39 GMT, "Nehmo Sergheyev"
<nehmo54@hotmail.com> wrote:

canadian_woodworker
Is there a simple way to figure out which is the first recepticle on a
circuit? I have an older house - the two upstairs rooms are on the
same
circuit and are not grouned. Id like to add a GFCI plug on the first
recepticle on that circuit, so every recepticle downstream is
protected.

The brute force method would be to guess which recepticle is the
first,
remove the outgoing wires, and test every other outlet for power -
rinse (hook back up the wires), repeat, until ive found the recepticle
that has power and all the others that dont. However this will take
awhile - most arent easily accessible - behind furnitire, beds etc.

I have at my disposal the standard home repair tools - volt meter,
etc.


Nehmo -
I don't know exactly how to do it in practice, but in theory…

1.
Unplug everything on the circuit.

At the circuit breaker box, with the breaker off, connect what would
have been the hot wire of the circuit to the neutral. Leave the neutral
connected normally.

Measure between one slot and the other at each receptacle.

At each receptacle, the measurement of the resistance and inductance
will be different. They will be lowest at the first, and highest at the
last.

14 gauge wire only has a resistance of 2.6 ohms per 1,000 feet, so the
difference in resistance will be difficult to measure. But the
inductance should be substantially different at each receptacle. At
higher frequencies, the measurement should be easy.

Or

2.
Get something that detects AC _current_ in a wire without electrically
connecting to the wire. Perhaps a pick-up coil attached to an amplifier
or perhaps a large coil simply connected to an earphone. I'm not used to
the commercial non-contact detectors, but one of them would work. You
want something that makes a different indication for a current flowing
wire and just a hot wire. After you have your detection tool, experiment
with it. Learn to detect a current-carrying wire.

With the circuit breaker on, plug-in a high-wattage lamp in what you
suspect to be the first receptacle. You should not be able to detect
current moving through the wires at any other receptacle. If you detect
current at a receptacle, it's at a position before the lamp receptacle.

Unplug the lamp and plug it in what you suspect to be the last
receptacle. You should be able to detect current at every receptacle.

Note I'm making a distinction between a receptacle with current going
through the wires connected to it and a receptacle that's just hot. All
of them should be hot. The electromagnetic field will be much stronger
around a current carrying wire.

Or

3.
Get a really high-wattage load, perhaps a big electric heater, something
with a high enough wattage to heat its supply wires detectably - but not
dangerously. Use the same system as the current detector. Plug in the
load at the (believed) last receptacle. Check the earlier receptacles
for warm wires. You get the idea.

4.
Fire the circuit up with DC (use a rectifier by the circuit breaker
box). Put a low-resistance load on the circuit at some receptacle. With
a sensitive voltmeter, measure between a hot slot of one receptacle and
the hot slot of another. The existence and the polarity of this tiny
voltage drop will show the relative position of the receptacles. If you
draw a diagram, you'll understand.

You could do this with the regular AC too, but you wouldn't get the
polarity info. You still could figure out which receptacle is first.
You're testing for a voltage drop across a load, which in this case is
just a piece of wire between receptacles. The voltage drop will not be
much.

[I crossposted]

If you go to RatShack and buy one of their little amplified speaker
boxes (looks like an old transistor radio) and a telephone pickup
coil, that combo can ge used to hear 60 Hz magnetic fields near wires.

So connect some load gadget to the various outlets one at a time.
Something that has nasty current harmonics, like a PC or a tv set, is
best... makes the current distinct and more audible. Now you can trace
the wires in the walls and figure where the current is going. You may
wish to kill other breakers in the house, or have somebody cycle your
test load, if things get confusing.

John

 

[Fred Bloggs]

canadian_woodworker

Is there a simple way to figure out which is the first recepticle on a
circuit? I have an older house - the two upstairs rooms are on the

same

circuit and are not grouned. Id like to add a GFCI plug on the first
recepticle on that circuit, so every recepticle downstream is
protected.

Dudnt work that way- it is qwite posble there is no furst recept-icle.
Put in a brak-er.

 

[Rich Grise]

[crossposted, s.e.d dropped from followups]
On Sun, 12 Feb 2006 07:38:58 -0800, canadian_woodworker wrote:

Yea, ive read that page before.

afaik, those breakers are pretty expensive. But ill check today and
possibly pick one up.

Thanks for the comments all. Nehmo - your post alluded to a method I had
considered, but im not skilled enough to know exactly what to do What
you say makes sense, but I think ill either go with a breaker, or the
method I talked abut.

Thanks all for comments.

Well, as long as I have your attention, it makes absolutely no difference
whatsoever which outlet on a main line has a GFCI - each one only protects
itself and what's plugged into it, and couldn't care less what's happening
downstream:

[view in fixed font, with wrap off]
..
.. Mains Hot -------+-------------+-------------+
.. Mains Neut. -----|--+----------|--+----------|--+
.. | | | | | |
.. ------ ------ ------
.. | GFCI | | GFCI | | GFCI |
.. ------ ------ ------
.. P.C P.C P.C

Where "P.C" means "Protected Circuit".

What has been suggested, (sorry, don't remember by whom - jalegris?) is to
use a GFCI circuit breaker, which goes on the left:
..
.. -------
.. Mains Hot --| GFCI |----+-------------+-------------+
.. Mains Neut.--| C.B. |----|--+----------|--+----------|--+
.. ------- | | | | | |
.. Ordinary Ordinary Ordinary
.. Outlet Outlet Outlet

That's "on the left" in my attempt at a diagram - in real life, it goes in
the breaker panel.

Or, of course, you could upgrade your wiring - it will increase the resale
value of the house considerably!

Good Luck!
Rich