On Sat, 18 Oct 2003 08:29:37 GMT, Bert pixelated:

Ted Edwards wrote:

For many years I've used a carbide lamp with a somewhat oversized
reflector. 4 hours operation on a film can of carbide. Good flood at
your feet with a real reach to the spot. I've been experimenting for
years with everything from candle lanterns to an inverter operated
flourescent I built in 1960. Until the LED lights came along there just
wasn't any serious competition to the carbide lamp.

That depends on your criteria and application. I used to use a carbide
lamp for caving. In terms of the duration-to-weight ratio, it was hard
to beat, and it was the hands-down winner for coolness factor. But a

So cool it could have blown your forehead off if it plugged up.
I had some fun with carbide as a bare teen. I put some in water in
a Clorox bottle and pat a pinhole in it. After lighting it, I squeezed
until a 3' flame shot across my chemistry table in my bedroom. When my
squeezing was done and I let go, it sucked the flame back into the
bottle and exploded with the nice resounding boom that knocked me
over. My mother came running into the room, screaming after she saw
me laying on the floor. She stopped screaming when she realized that
I was laughing. After many apologies and promises to never light
carbide in my room again, she let me off the hook. Ahhh, memories...


6-volt halogen lamp put it to shame in terms of light output, as well
as maintenance and ease of operation. I haven't done any caving in a
while and haven't gotten around to trying out an LED lamp yet.

One more memory. I used to live in Southern California and we used to
crawl around the boulder caves east of I-5 north of Escondido. We were
about 80' down one day when dust came down by the bucketload. After
we scampered to the surface and climbed in the truck to leave, we
found that there had been an earthquake right then. That was the last
time we went caving in SoCal. All we had were handheld flashlights.
I now have some of the Harbor Freight headlamps, a deal at $2 per. If
I were to go caving now, I'd want an LED headlamp on my head and 2
backups in my pack. (No sense dying in a cave just because you
couldn't find your way out, eh?)


-------------------------------------------------------------
give me The Luxuries Of Life * http://www.diversify.com
i can live without the necessities * 2 Tee collections online
-------------------------------------------------------------

In article , Larry Jaques says...

That depends on your criteria and application. I used to use a carbide
lamp for caving. In terms of the duration-to-weight ratio, it was hard
to beat, and it was the hands-down winner for coolness factor. ...
(gary)

So cool it could have blown your forehead off if it plugged up.

Now this is simply not true. One has to go to extreme
lengths to 'plug up' a carbide lamp. The ceramic nozzle
is held in with a taper fit, so it won't really support
much pressure. Indeed, unless the nozzle is seated properly
I've had them pop out under normal use.

The other, most important feature though, is that the
water feed drips down from the upper water chamber
into the lower, carbide can. The moment any excess
pressure is developed (and this can happen, if water
suddenly seeps into a pocket of fresh carbide after
the lamps been running for a while) is that the pressure
in the bottom can increases, and the water feed is
stopped. If the pressure goes higher, then the
excess acetlyene is bubbled out the top vent of the
water tank. By the time this happens the flame has
already blown itself out in the reflector.

The water feed valves in the lamps I own never really
shut off *all* the way, so I doubt I could blow one
of them up by even doing something as dumb as a)
feeding a huge slug of water into a tank of b) really
fresh carbide and then c) cranking the water feed
valve down as tight as possible.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

On Thu, 16 Oct 2003 17:21:36 GMT, (Gary Coffman)
wrote:

They must. LEDs don't have the thermal lag that filament type bulbs have.
So they can pulse the LED with a reasonably low duty cycle. If they use
a 5% duty cycle, they can get average current draw down to 2.2 mA while
still producing the same peak output as running continuously at 44 mA.

Of course *average* output is also only 5%, but the eye has persistence,
and is fooled into thinking it is seeing a much brighter light. Some strange
effects would occur for rapidly moving objects, strobing, but for nearly
stationary scenes you'd see about as well as if they were actually drawing
40 mA.

This is also more efficient than using a current-limiting resistor.
They may limit current with a small inductor, and vary duty cycle as
battery voltage decreases so as to run at constant intensity until the
battery is depleted even somewhat below the usual 0.8 volt per cell
that is regarded to be "dead".

The Everready X95 D-cell is rated at 18900 mah -- yes, 18.9 amp hours.
For an average voltage of 1.2 volts, this is 22.6 watt hours per cell,
or 68 watt-hours for 3 cells. (Gunner, the C-cell has about half that
capacity.) 6 LED's running at 40 mA and 2 volts each would consume
0.48 watts, so (not counting circuit inefficiency) the batteries could
last 141 hours with the right circuitry and deliver full brightness
right to the end. Efficiencies of well over 90% are quite
possible with simple electronics. The drop in a 20 milliohm MOSFET at
240 mA would be something like .005 volts! Synchronous control chips
(using MOSFET synch rectification) are now available that will operate
on 3.3 volts and maybe as low as 1.5 volts.

Gary Coffman wrote:
On Wed, 15 Oct 2003 19:08:29 GMT, "AL A." wrote:
I am looking to build a "task" lamp (think dentist-type light) that uses
high output white LEDs for a friend who often does
work for extended periods of time in very remote places. I was looking at
the NTE electronics "lightwave" flashlights
snip
They must. LEDs don't have the thermal lag that filament type bulbs have.
So they can pulse the LED with a reasonably low duty cycle. If they use
a 5% duty cycle, they can get average current draw down to 2.2 mA while
still producing the same peak output as running continuously at 44 mA.

Of course *average* output is also only 5%, but the eye has persistence,
and is fooled into thinking it is seeing a much brighter light. Some strange
effects would occur for rapidly moving objects, strobing, but for nearly
stationary scenes you'd see about as well as if they were actually drawing
40 mA.

Vision doesn't work that way.
If it doesn't flicker, then it's strictly linear.
50ma 10% of the time looks just like 5ma.
The only exception is where the frequency is low enough to create perceptible
flicker.
Some LEDs have a small efficiency gain when run at high currents.
(most modern white or blue ones do not)

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
He had been eight years upon a project for extracting sunbeams out of cucumbers,
which were to be put in vials hermetically sealed, and let out to warm the air
in raw inclement summers. -- Jonathan Swift, "Gulliver's Travels" (1726)

Bert wrote:

flourescent I built in 1960. Until the LED lights came along there just
wasn't any serious competition to the carbide lamp.

That depends on your criteria and application. I used to use a carbide
lamp for caving. In terms of the duration-to-weight ratio, it was hard
to beat, and it was the hands-down winner for coolness factor.

Indeed! I've never done any caving and my *serious* backpacking days
are over (asthma) but my application was three days to onw week trips,
often late fall or winter, and battery life/weight was very much a
consideration. My lamps are the old Justrite ones and I've not found
any newer ones as well made. They come with a dinky little reflector
but the next size up (available as an accessory back then) makes a
**huge** difference in the quality of the spot. I got a good flood at
and near my feet to avoid tripping over things and could pick out
objects a hundred yards away in the spot.

6-volt halogen lamp put it to shame in terms of light output, as well
as maintenance and ease of operation.

Any halogen that would provide as good a spot combined with simultaneous
flood would really suck hard on those batteries! But I would expect
caving is usually a few hours thing not a few days.

while and haven't gotten around to trying out an LED lamp yet.

I think the best ones will impress you. :-)

Ted

Don Foreman wrote:

capacity.) 6 LED's running at 40 mA and 2 volts each would consume

Are we talking "white" LEDs here? I was under the impression that just
under 4 volts was what they drop.

Ted

I believe it is standard practice to wire flourescent lights in
factories off each of the 3 phases alternatively in order to counter the
strobe effect. I have seen strobing when a single phase supply is used.

Jeff Wisnia wrote:

Gary Coffman wrote:

On Wed, 15 Oct 2003 19:08:29 GMT, "AL A." wrote:

I am looking to build a "task" lamp (think dentist-type light) that uses
high output white LEDs for a friend who often does
work for extended periods of time in very remote places. I was looking at
the NTE electronics "lightwave" flashlights
http://www.nteinc.com/lightwave/ and they claim that they have circuitry
that makes it possible to run one of the 10
led lights for 24 days, continuously, on 3 D cells.

Assuming that the batteries are series connected, that's an average
current draw of 2.2 mA for standard alkaline cells.

Any idea how they accomplish that? Most of the high output LEDs I have seen
seem to want to run between 20 and 40 mA
current draw. Given the amp-hour ratings I find for D cells, I don't see how
that would work out. Do they modulate the power to the LEDs
in some way that helps extend the battery life so dramatically?

They must. LEDs don't have the thermal lag that filament type bulbs have.
So they can pulse the LED with a reasonably low duty cycle. If they use
a 5% duty cycle, they can get average current draw down to 2.2 mA while
still producing the same peak output as running continuously at 44 mA.

Of course *average* output is also only 5%, but the eye has persistence,
and is fooled into thinking it is seeing a much brighter light. Some strange
effects would occur for rapidly moving objects, strobing, but for nearly
stationary scenes you'd see about as well as if they were actually drawing
40 mA.

They pulse repetition rate would have to be higher than the persistence
duration of the eye to prevent you from noticing the strobing at ordinary
movement speeds. It probably operates in the kilohertz range.

Gary


Cool reasoning there Gary, I like it, and any "hazards" caused by strobing of
spinning stuff is not very likely, as you probably wouldn't have too much
rotating machinery around places where the only light source was your flashlight.
Except maybe under the hood of a car, where we all know enough to keep the hell
away from the general vicinity of the fan blades when the engine is running.

I remember a public school shop teacher telling me maybe 50 years ago to watch
out for strobing of spinning machinery parts under fluorescent lamps, but I can't
say I've ever noticed the effect. Maybe the phosphors used in today's lamps have
longer persistance than those in the early ones.

Jeff

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone to place
the blame on."

On 18 Oct 2003 08:47:26 -0700, jim rozen
pixelated:

In article , Larry Jaques says...

That depends on your criteria and application. I used to use a carbide
lamp for caving. In terms of the duration-to-weight ratio, it was hard
to beat, and it was the hands-down winner for coolness factor. ...
(gary)

So cool it could have blown your forehead off if it plugged up.

Now this is simply not true. One has to go to extreme
lengths to 'plug up' a carbide lamp. The ceramic nozzle

Give a man a little poetic license, will ya, Jim? I make
light of the possibilities; Murphy will do the rest.

Everything we touch/eat/drink/breathe is dangerous to us.
Most of us ignore most of the danger most of the time.
(Pass the adrenaline, please.)

Now about that gas powered kitchen blender idea...


-------------------------------------------------------
Have you read the new book "What Would Machiavelli Do?"
----------------------------
http://diversify.com Dynamic, Interactive Websites!
--------------------------------------------------------

Larry Jaques wrote:

jim rozen pixelated:

Larry Jaques says...

SNIP
So cool it could have blown your forehead off if it plugged up.

Now this is simply not true. One has to go to extreme
lengths to 'plug up' a carbide lamp. The ceramic nozzle

Give a man a little poetic license, will ya, Jim? I make
light of the possibilities; Murphy will do the rest.

Everything we touch/eat/drink/breathe is dangerous to us.
Most of us ignore most of the danger most of the time.
(Pass the adrenaline, please.)

Now about that gas powered kitchen blender idea...

Hey, I've got a 21 cc weed whacker that I currently don't use for half
the year. I wonder . . .? g

R,
Tom Q.

In article , Larry Jaques says...

Give a man a little poetic license, will ya, Jim? I make
light of the possibilities; Murphy will do the rest.

OK, its just that I really do like the smell of acetylene.

When I was a kid, I had a close friend, also mechanically
inclined. I had shown him my carbide lamp, and he was
rapidly engaged in trying to duplicate it. Until his
parents found out, and threw out the 'you'll blow yer
face off kid' argument.

It was dumb then, it's dumb now. He never got to finish
that carbide lamp, made out of the aluminum 35mm film
cans. Would have been nice.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

In article , Ted Edwards says...

... My lamps are the old Justrite ones and I've not found
any newer ones as well made. They come with a dinky little reflector
but the next size up (available as an accessory back then) makes a
**huge** difference in the quality of the spot.

The reflectors come in three sizes: 'dinky,' 'big,'
and 'oh my god' and that last one really works great.

Justrite stopped making the brass lamps, and switched
over to the gray plastic ones. I think that one
change killed the entire company.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

On Sat, 18 Oct 2003 21:00:36 GMT, Ted Edwards
wrote:

Don Foreman wrote:

capacity.) 6 LED's running at 40 mA and 2 volts each would consume

Are we talking "white" LEDs here? I was under the impression that just
under 4 volts was what they drop.

Some do, others work on less. The 4-volt LED's are probably brighter
than the lower voltage ones at the same current. Do the watt-hour
math for your LED(s) and operating current of your choice.

My point was that an efficient switching regulator could significantly
extend battery life because it uses more of the available energy from
an alkaline battery whose voltage changes significantly over its
lifetime. Others have observed that as well. It therefore makes sense
to figure the watts per LED and the watt-hours available from a given
cell or set of cells, and use those to estimate operating time.

Lithium batteries are neat, but they are very pricey.

On Sat, 18 Oct 2003 18:56:47 -0400, Tom Quackenbush
pixelated:

Larry Jaques wrote:
Now about that gas powered kitchen blender idea...

Hey, I've got a 21 cc weed whacker that I currently don't use for half
the year. I wonder . . .? g

http://www.gasblender.com/
http://www.totallygross.com/
http://www.blenderblaster.com/blenderblaster/
That last one is the picture that showed up on the Wreck a couple
years ago, spewing coffee all over monitors everywhere.


-------------------------------------------------------
Have you read the new book "What Would Machiavelli Do?"
----------------------------
http://diversify.com Dynamic, Interactive Websites!
--------------------------------------------------------

Larry Jaques wrote:

Tom Quackenbush pixelated:
SNIP
Hey, I've got a 21 cc weed whacker that I currently don't use for half
the year. I wonder . . .? g

http://www.gasblender.com/
http://www.totallygross.com/
http://www.blenderblaster.com/blenderblaster/
That last one is the picture that showed up on the Wreck a couple
years ago, spewing coffee all over monitors everywhere.

Very cool.
In the same vein (high power beverage accoutrements?):

http://www.asciimation.co.nz/beer/
(jet powered cooler)

R,
Tom Q.

In article , Don Foreman says...

Lithium batteries are neat, but they are very pricey.

But supposedly they do have a very long shelf life,
and way back in the dark ages, the question came up
about using them for disaster emergency kits IIRC.

I would put the li batteries in those.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

jim rozen wrote:

The reflectors come in three sizes: 'dinky,' 'big,'
and 'oh my god' and that last one really works great.

Got one of the last but not very practicle for hiking! :-)

Justrite stopped making the brass lamps, and switched
over to the gray plastic ones. I think that one
change killed the entire company.

Could well be. I bought one of those. I was monumentally underwhelmed.

Ted

Another approach is to buy alkaline batteries, put them in a plastic
bag and in the freezer. IIRC alkaline batteries have at least a five
year shelf life, so you do have to remember to get some more every
five years or so.

Dan



jim rozen wrote in message But supposedly they do have a very long shelf life,
and way back in the dark ages, the question came up
about using them for disaster emergency kits IIRC.

I would put the li batteries in those.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Dan Caster wrote:

Another approach is to buy alkaline batteries, put them in a plastic
bag and in the freezer. IIRC alkaline batteries have at least a five
year shelf life, so you do have to remember to get some more every
five years or so.

Dan

But, make damn sure that plastic bag is dry and sealed really tight so you don't get any moisture inside it to
condense on the battery and form a discharge path.

I used to keep my spare flashlight batteries in the freezer back in the old days when the only batteries you
could get were the zinc-carbon Leclanche cells. The current alkaline cells have much longer shelf life, so
I've given up on keeping them in the freezer, and I don't keep camera film there any more either, since
switching to digital photography.

What I *do* keep in the kitchen fridge's freezer are adhesives like JB weld and other epoxies, Gorrilla Glue,
and cynoacrylic "super glues". I've got a couple of little tubes of silver conductive epoxy (I bought them
over ten years ago, and it's not the cheapest stuff in the world.) stored there for the occasional times I
need to make an electrical repair connection on something which won't take solder or would be damaged by the
heat of soldering. I used some of it a little while ago and it was still as usable as the day I bought it.

Jeff



jim rozen wrote in message But supposedly they do have a very long shelf life,
and way back in the dark ages, the question came up
about using them for disaster emergency kits IIRC.

I would put the li batteries in those.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone to blame it on."

On Mon, 10 Nov 2003 23:23:12 -0500, No1 wrote:

On Thu, 16 Oct 2003 01:22:36 GMT, Gunner wrote:

On Wed, 15 Oct 2003 14:52:10 -0500, Bob Robinson
wrote:

AL A. wrote:
Hi all,
I know this is not strictly on topic, but this crew seems to know something
about everythig, so here goes:

I am looking to build a "task" lamp (think dentist-type light) that uses
high output white LEDs for a friend who often does
work for extended periods of time in very remote places. I was looking at
the NTE electronics "lightwave" flashlights
http://www.nteinc.com/lightwave/ and they claim that they have circuitry
that makes it possible to run one of the 10
led lights for 24 days, continuously, on 3 D cells.

Any idea how they accomplish that? Most of the high output LEDs I have seen
seem to want to run between 20 and 40 mA
current draw. Given the amp-hour ratings I find for D cells, I don't see how
that would work out. Do they modulate the power to the LEDs
in some way that helps extend the battery life so dramatically?

I looked at just modifing a lightwave flashlight for the task at hand, but
the beam is a bit too wide for what he needs. So I am hoping to
build something with maybe 3 LEDs and appropriate optics to give a fairly
narrow, even beam, mounted on a gooseneck type thing,
with a remote battery pack on a cord.

Any thoughts on the electronics involved? I can handle that part of it, if
I know what I am trying to accomplish.Of course the body
of the thing will be METAL, nicely turned, naturally. (obligatory
metalworking content...)

Thanks for any ideas you can offer.
-AL


AL,

I'm working on a similar project at the moment. Here's what my research
has yielded so far. The majority of ultra bright leds do operate in the
20-40ma range, and the forward voltage is around 1.5-1.7V. If you
arrange the 3 LEDs in series with at least enough cells to provide 4.5V
and an appropriate current-limiting resistor, your current draw will be
20-40ma. If the NTE light is using 7 LEDs with 3 D cells, they are
wiring them in parallel, so the current draw is at least 140ma and the
24 hr figure is highly suspect. If you connect yours in parallel, you
could get by with 2 1.5V cells, but your current draw would triple.

Hope this helps,

Bob

If you folks come up with decent LED flashlights, or plans..the people
over on misc.survivalism would love to have some, as this is a regular
topic of discussion.

Gunner

"You cannot invade the mainland United States. There would be a rifle
behind each blade of grass." --Japanese Admiral Isoroku Yamamoto

Gunner, have a look at mine on http://members.cox.net/ledflashlight
The little two led light work really well, I used them for 4 days during Isabel.
Those cost about $12 in parts but are pretty rugged, you can turn one on and
throw it in your back yard and just go pick it up. They run on a 9 volt battery
or 4 AAA's depending on the dropping resistor. The one shown uses 4 AAA's I get
very good time out of them(usable light)before needing to change a battery. One
nice thing is these lights will fit in the mouth between your teeth , when you
need two hands, without much discomfort and an aluminum type thratens to break
your teeth. I use those particular Led holders because they act as reflectors,
versus just mounting the Led in the raw.

The 10 led job was used, along with the 2 Led versions, during Isabel also and
had been used many many hours befor. I use that one under the truck. The ten Led
flashlight runs on 4 D cells and I have yet to change them in the couple of
months since I built it. I don't know the exact run time.

A note, you wont get blazing bright out of these things, but you get plent of
usable light. Leds are directional and don't "add". If you have ten LEd's
pointing at the same spot then you get brighter light. If the Led's are pointing
straight forward like the ten Led flashlight then you get more light, some gets
brighter because some of the Led's are close enough to add.


No1

MANY thanks, saved for closer review!!!

Gunner



"By calling attention to 'a well regulated militia', the 'security' of the
nation, and the right of each citizen 'to keep and bear arms', our founding
fathers recognized the essentially civilian nature of our economy. Although
it is extremely unlikely that the fears of governmental tyranny which gave
rise to the Second Amendment will ever be a major danger to our nation, the
Amendment still remains an important declaration of our basic
civilian-military relationships, in which every citizen must be ready to
participate in the defense of his country. For that reason, I believe the
Second Amendment will always be important."
-- Senator John F. Kennedy, (D) 1960

Stuff deleted
,;
,;Gunner, have a look at mine on http://members.cox.net/ledflashlight
,;The little two led light work really well, I used them for 4 days during Isabel.
,;Those cost about $12 in parts but are pretty rugged, you can turn one on and
,;throw it in your back yard and just go pick it up. They run on a 9 volt battery
,;or 4 AAA's depending on the dropping resistor. The one shown uses 4 AAA's I get
,;very good time out of them(usable light)before needing to change a battery. One
,;nice thing is these lights will fit in the mouth between your teeth , when you
,;need two hands, without much discomfort and an aluminum type thratens to break
,;your teeth. I use those particular Led holders because they act as reflectors,
,;versus just mounting the Led in the raw.

Nice project. A circuit diagram would be nice.
,;
,;The 10 led job was used, along with the 2 Led versions, during Isabel also and
,;had been used many many hours befor. I use that one under the truck. The ten Led
,;flashlight runs on 4 D cells and I have yet to change them in the couple of
,;months since I built it. I don't know the exact run time.
,;
,;A note, you wont get blazing bright out of these things, but you get plent of
,;usable light. Leds are directional and don't "add". If you have ten LEd's
,;pointing at the same spot then you get brighter light. If the Led's are pointing
,;straight forward like the ten Led flashlight then you get more light, some gets
,;brighter because some of the Led's are close enough to add.
,;
,;
,;No1

crossposted
In article ,
No1 wrote:

On Thu, 16 Oct 2003 01:22:36 GMT, Gunner wrote:

On Wed, 15 Oct 2003 14:52:10 -0500, Bob Robinson
wrote:

AL A. wrote:
Hi all,
I know this is not strictly on topic, but this crew seems to know
something
about everythig, so here goes:

I am looking to build a "task" lamp (think dentist-type light) that uses
high output white LEDs for a friend who often does
work for extended periods of time in very remote places. I was looking at
the NTE electronics "lightwave" flashlights
http://www.nteinc.com/lightwave/ and they claim that they have circuitry
that makes it possible to run one of the 10
led lights for 24 days, continuously, on 3 D cells.

Any idea how they accomplish that? Most of the high output LEDs I have
seen
seem to want to run between 20 and 40 mA
current draw. Given the amp-hour ratings I find for D cells, I don't see
how
that would work out. Do they modulate the power to the LEDs
in some way that helps extend the battery life so dramatically?

I looked at just modifing a lightwave flashlight for the task at hand,
but
the beam is a bit too wide for what he needs. So I am hoping to
build something with maybe 3 LEDs and appropriate optics to give a fairly
narrow, even beam, mounted on a gooseneck type thing,
with a remote battery pack on a cord.

Any thoughts on the electronics involved? I can handle that part of it,
if
I know what I am trying to accomplish.Of course the body
of the thing will be METAL, nicely turned, naturally. (obligatory
metalworking content...)

Thanks for any ideas you can offer.
-AL


AL,

I'm working on a similar project at the moment. Here's what my research
has yielded so far. The majority of ultra bright leds do operate in the
20-40ma range, and the forward voltage is around 1.5-1.7V. If you
arrange the 3 LEDs in series with at least enough cells to provide 4.5V
and an appropriate current-limiting resistor, your current draw will be
20-40ma. If the NTE light is using 7 LEDs with 3 D cells, they are
wiring them in parallel, so the current draw is at least 140ma and the
24 hr figure is highly suspect. If you connect yours in parallel, you
could get by with 2 1.5V cells, but your current draw would triple.

Hope this helps,

Bob

If you folks come up with decent LED flashlights, or plans..the people
over on misc.survivalism would love to have some, as this is a regular
topic of discussion.

Gunner

"You cannot invade the mainland United States. There would be a rifle
behind each blade of grass." --Japanese Admiral Isoroku Yamamoto

Gunner, have a look at mine on http://members.cox.net/ledflashlight
The little two led light work really well, I used them for 4 days during
Isabel.
Those cost about $12 in parts but are pretty rugged, you can turn one on and
throw it in your back yard and just go pick it up. They run on a 9 volt
battery
or 4 AAA's depending on the dropping resistor. The one shown uses 4 AAA's I
get
very good time out of them(usable light)before needing to change a battery.
One
nice thing is these lights will fit in the mouth between your teeth , when
you
need two hands, without much discomfort and an aluminum type thratens to
break
your teeth. I use those particular Led holders because they act as
reflectors,
versus just mounting the Led in the raw.

The 10 led job was used, along with the 2 Led versions, during Isabel also
and
had been used many many hours befor. I use that one under the truck. The ten
Led
flashlight runs on 4 D cells and I have yet to change them in the couple of
months since I built it. I don't know the exact run time.

A note, you wont get blazing bright out of these things, but you get plent of
usable light. Leds are directional and don't "add". If you have ten LEd's
pointing at the same spot then you get brighter light. If the Led's are
pointing
straight forward like the ten Led flashlight then you get more light, some
gets
brighter because some of the Led's are close enough to add.


No1


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In article , No1 says...


Really rough directions for construction;

Really, really rough directions:

solder the led, the dropping resistor, and a decent
toggle switch together in series with a 9V lithium
battery.

Tape the switch to the side of the battery with
electrical tape, tape over the top connections
as well. Insulate the led leads with some teflon
spagetti and leave it hanging out the top.

Done.

These are basically throw-aways, cheap and they
last for *ever*. Shelf life for the li batteries
is much longer than alkaline as well.

Color of LED to be chosen at will by the end user.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

On Wed, 12 Nov 2003 00:19:46 -0500, No1 wrote:
Nice project. A circuit diagram would be nice.

Use fixed pitch for the crappy ascii art.

minus battery ------resistor-------led-------switch------plus battery
------resistor-------led-----

All LED's are in parallel with a dropping resistor in series.
I used 100 ohm for the 6 volt lights and 330 ohm for the nine volt lights.

Rdroppin = Vsupply - Vled / Iled

Vsupply = 6 or 9 volts

Vled = 3.6 volts ( I use the lower voltage rating)

Iled = 20ma. or .02 amps

6 - 3.6 = 2.4 / .02 = 120 ohms so I am a bit low on the 6 volt dropping
resistors. In the 10 led flashlight the led's run a little bit warm, probably
because new batteries are a higher voltage.

9 - 3.6 = 5.4 / .02 = 270 ohms. I used 330 ohms because it was what I had on
hand at the time and that give .016 amps rather than .02 amps, not much
difference.

There are a couple of problems with these designs. Number one is that
the resistors are dissipating more battery power than the LEDs, in other
words, system efficiency is less than 50%. Number two is that light output
diminishes as battery terminal voltage falls. Both problems can be solved
by using an LED controller IC instead of the brute force current limiting
resistors.

An example would be the LTC3205 charge pump LED controller chip. This
chip is a switch mode constant current source with 92% efficiency. It will
maintain the programmed LED current down to an input voltage of 2.7 volts.
(Max input voltage is only 6 volts, so it is only suitable for a smaller light,
but it will double the battery life, and maintain full brilliance until the batteries
are completely exhausted.)

Other choices would be the Maxim MAX1553 or MAX1554. The latter can
drive 10 LEDs at a maximum (pulsed) current of 970 mA with an efficiency
of 82%. The former can drive 6 LEDs with a maximum current of 470 mA,
and an efficiency of 88%. Either of these would be suitable for a larger
light.

There are a number of other driver chips available. I only picked these
as representative. Do some searching of the various manufacturers'
product literature to find other devices and application circuits.

Gary

"AL A." wrote in message .. .
I am looking to build a "task" lamp (think dentist-type light) that uses
high output white LEDs for a friend who often does
work for extended periods of time in very remote places. I was looking at
the NTE electronics "lightwave" flashlights
http://www.nteinc.com/lightwave/ and they claim that they have circuitry
that makes it possible to run one of the 10
led lights for 24 days, continuously, on 3 D cells.

Given your application, you almost certainly do not want to use LED's.

A quick rundown of lamp efficiency stolen from Don Klipstein's web
page, http://members.misty.com/don/light.html:

White LED: 25 lumens/watt

Incadescent bulb: 17 lumens/watt

Compact fluorescents: mostly 45-60 lumens/watt including ballast
losses.

32 watt T8 fluorescent in "average condition": typically around 80
lumens/watt including ballast losses.

Battery-powered ballasts to fluorescents will not be as good as the
numbers quoted, but they can come close. Typically task lights will
be
built around Circline fluorescents.

Tim.

crossposted to alt.caving as interest

In article ,
No1 wrote:

On Tue, 11 Nov 2003 07:01:49 -0600, (Don
Wilkins)
wrote:



Stuff deleted
,;
,;Gunner, have a look at mine on http://members.cox.net/ledflashlight
,;The little two led light work really well, I used them for 4 days during
Isabel.
,;Those cost about $12 in parts but are pretty rugged, you can turn one on
and
,;throw it in your back yard and just go pick it up. They run on a 9 volt
battery
,;or 4 AAA's depending on the dropping resistor. The one shown uses 4 AAA's
I get
,;very good time out of them(usable light)before needing to change a
battery. One
,;nice thing is these lights will fit in the mouth between your teeth ,
when you
,;need two hands, without much discomfort and an aluminum type thratens to
break
,;your teeth. I use those particular Led holders because they act as
reflectors,
,;versus just mounting the Led in the raw.

Nice project. A circuit diagram would be nice.

Use fixed pitch for the crappy ascii art.

minus battery ------resistor-------led-------switch------plus battery
------resistor-------led-----

All LED's are in parallel with a dropping resistor in series.
I used 100 ohm for the 6 volt lights and 330 ohm for the nine volt lights.

Rdroppin = Vsupply - Vled / Iled

Vsupply = 6 or 9 volts

Vled = 3.6 volts ( I use the lower voltage rating)

Iled = 20ma. or .02 amps

6 - 3.6 = 2.4 / .02 = 120 ohms so I am a bit low on the 6 volt dropping
resistors. In the 10 led flashlight the led's run a little bit warm, probably
because new batteries are a higher voltage.

9 - 3.6 = 5.4 / .02 = 270 ohms. I used 330 ohms because it was what I had on
hand at the time and that give .016 amps rather than .02 amps, not much
difference.
You would think you could put two leds in series with the 9 volts ,it works
good
on paper but not in practice. Try it and see if it works well for you.

These led I have are rated at 3.6 - 4 volts at around 20 ma.. I went through
the
trouble of checking all the leds against each other for voltage drops and
currents. You can get groups close to each other but not exactly matching. On
one of the 9 volt lights when the battery gets low you can look directly at
one
of the leds and the other is still too bright to stare at.

I got the leds from http://www.whitelightLED.com/ These are the 5mm 20 degree
6400 mcd leds. White leds can be found elsewhere on the web. Stay away from
the
crappy expensive white leds at radio shack.

While your eyes are more sensitive to the green spectrum if you use green
leds
you will have a lot of trouble distinguishing colors, really a bad thing if
you
are working in an electrical panel or need to distinguish colors. You can get
bright yellow leds but they are rather rough on the eyes, I call it ****
vision,
those are good for illuminating a hallway or such. Blues leds are way kewl
but
the ones I have are also rough on the eyes, like those blue runway lights.

Why not just slap a bunch of leds in something and then use a lens to
collimate
the beams? Because the leds already have lenses on them and you will get
several
spotlights at all sorts of angles. One led behind a lens works pretty good. I
haven't had the time to see if I could point the leds the other way, down
into a
reflector of a flashlight and get a good or better beam than the little led
holders I am currently using. There is not a great amount of sidle splash
from
the leds to be usable, bright enough to bother you and that is why I use the
led
holders.

I just slapped the web page together one night. One thing that isn't show
very
well on my little web page is the switch you get for the 2 led flashlight has
a
plastic nut with a washer built in. You have to use a pair of diags to cut
the
washer away or the nut will not fit in the case. Once cut and tightened you
also
have to shave the top of the nut down enough to close the case. The case
cover
has a slot cut out at the switch so it can fit over the nut.
I use an 11/16 paddle bit in a drill press for the switch. You put the lid on
the box and drill in the center of the side of the box, very slightly lower
than
center towards the bottom. The switch has a locking tab on it, you can cut it
off with a razor knife but I leave it on and file a slot.
The led holders go roughly center front with enough spacing to screw the nuts
down.

Really rough directions for construction;
Drill and clean all holes. File slot for switch.
Cut washer off of switch nut.
Mount switch with locking tab forward , tighten nut so that one flat is up
and
instal led holders.
Cut slot in case top and then trim switch nut to fit flush with the case
side.
Install leds so the anodes or cathodes are on top in a : pattern.
Bend led cathodes in an L shape so they point towards each other and solder.
Solder dropping resistors to led anodes, the one furthest from the switch
needs
insulation between the resistor and the led so it doesn't short to anything
(I
use insulation from bell wire).
Solder other ends of dropping resistors to one side of the switch and then
bend
that tab towards the front of the case.
Solder the red battery wire to the switch and bend that tab towards the back
of
the case.
Solder black battery wire to the led cathodes.
Install batteries and test.
If it works then put tape on the back of the switch. Out the batteries in the
case and put foam rubber(or what ever it is called now) on top of the
batteries
to hold then in place and from rattling and shorting out the leds and then
screw
down the case cover. Place light in shirt pocket for later use.
If it doesn't work then look closely and find out where you went wrong and
fix
it.

Like I said, this is VERY rough. It is much easier to build it than it is to
talks about how to build it. If you need further explanations or details then
feel free to ask.

No1


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Gary Coffman wrote:

diminishes as battery terminal voltage falls. Both problems can be solved
by using an LED controller IC instead of the brute force current limiting
resistors.

An example would be the LTC3205 charge pump LED controller chip. This
...
Other choices would be the Maxim MAX1553 or MAX1554. The latter can

I'd like to check those out. If you have a URL handy, it would be
appreciated otherwise, I'll search.

Another one Don Foreman found is
http://www.supertex.com/ and look at the HV9903.

Ted

White LED: 25 lumens/watt


per watt of LIGHT output

Incadescent bulb: 17 lumens/watt


Per watt of ELECTRICITY input.

They use different rating systems, or so I read. For instance LEDs would be
damn near 1 watt light out for 1 watt electrical in. Lumen is color-balanced
perceived intensity, highest near 500 nm depending on brightness.

Battery-powered ballasts to fluorescents will not be as good as the
numbers quoted, but they can come close.

I use a Shack inverter with low idle and reasonable efficiency to power two
each 9W spirals in desk lamps on the handlbars of the Ultracapcitor Bike. They
can be interchanged to a whole series of colors and strengths quickly. The
whole thing is pretty efficient. I just need to wire the lamps to the outlet
box to the inverter to the motor. A few minutes with the crimper.

A brilliant 100W incandescent equivalent at less than my old 35 W tractor
headlight, the one that took my up the trail at night, powered by pedaling.

Anyway, different system, non-interconvertible results. Read Grainger they have
good article on what's it called, fixture efficiency? Plug-to-light including
for parking lots, light lost to the wrong (telescope frustrating) directions.



Yours,

Doug Goncz (at aol dot com)
Replikon Research, Seven Corners, VA

1100 original posts at:
http://groups.google.com/groups?as_e...uthors=dgoncz@

On Wed, 12 Nov 2003 19:01:33 GMT, Ted Edwards wrote:
Gary Coffman wrote:
Other choices would be the Maxim MAX1553 or MAX1554. The latter can

I'd like to check those out. If you have a URL handy, it would be
appreciated otherwise, I'll search.

http://www.maxim-ic.com/

Gary

Gary Coffman wrote:

I'd like to check those out. If you have a URL handy, it would be
appreciated otherwise, I'll search.

http://www.maxim-ic.com/

Thanks Gary. Looks like some very interesting parts.

Ted

On Mon, 17 Nov 2003 04:04:51 GMT, Ted Edwards
brought forth from the murky depths:

Gary Coffman wrote:

I'd like to check those out. If you have a URL handy, it would be
appreciated otherwise, I'll search.

http://www.maxim-ic.com/

Thanks Gary. Looks like some very interesting parts.

http://www.maxim-ic.com/appnotes.cfm...ber/1037/ln/en
A key page to their LED info.

http://www.zetex.com/3.0/pdf/ZXSC300.pdf
Here is another 95% efficient off-brand I hadn't heard
of. They're half the price of the others but have a 4
to 5x quiescent drain. Switch off Vcc to the chip, eh?

I ordered some of the LEDs from www.whitelightled.com
and he even sent some resistors and schematics with 'em.
Cool.


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