Harbor Freight 4 LED $7.00

[ehsjr]

Henry Kolesnik wrote:

I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to beleive
they are direct wired. Looking inside as best I can it looks like all 4 are
in parallel and connect directly to the 3 cells in series. I think LEDs are
supposed draw a lot less current if they have a dropping resistor. I'm
guessing that a dropping resistor would reduce current draw substantially,
increase led life and not reduce light output significantly. But I can see
were I could easliy install a resistor. I also know just about zero on
leds.
tnx

The Electronic Goldmine sells a 4 white LED flashlight for
$1.99. Item # G15184 Watch for the line wrap:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G15184&variation=&aitem=15&mitem=24
You didn't specify the Item # for the Harbor Freight
flashlight - I assume it is ITEM 3653-0VGA

Based on the catalog pictures, it looks like the Harbor
Freight light has a metal body, while the Goldmine's is
plastic. But I'll bet they use the same LED's. I
have the Goldmine unit - there is a bluish tint to the
light it produces. Does yours produce a bluish tint?

As Watson mentioned, overdriving LEDs does reduce their
life and their light output, so your thinking seems right
on target. But for either a $7.00 or a $1.99 4 LED flashlight,
it's probably not worth the effort to incorporate a
dropping resistor - unless experimentation, rather than
function, is the goal.

Ed

 

[Jim Yanik]

"Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in
news:8ovje.1965$wb2.1791@newssvr11.news.prodigy.com:

I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to
beleive they are direct wired. Looking inside as best I can it looks
like all 4 are in parallel and connect directly to the 3 cells in
series. I think LEDs are supposed draw a lot less current if they
have a dropping resistor. I'm guessing that a dropping resistor would
reduce current draw substantially, increase led life and not reduce
light output significantly. But I can see were I could easliy install
a resistor. I also know just about zero on leds.
tnx

127ma/4 LEDs=31.75ma per LED,that's a bit high for the Nichia white
LEDs;IIRC,they have a 25ma max limit.

Are there now other white LEDs that have a higher current rating?

--
Jim Yanik
jyanik
at
kua.net

 

[Henry Kolesnik]

The Harbor Freight number is 3653 and if there's any blue tint to the light
I can't see it.
tnx

--

73
Hank WD5JFR
"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:8CJje.5174$BF5.235@trndny06...

Henry Kolesnik wrote:
I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to
beleive they are direct wired. Looking inside as best I can it looks
like all 4 are in parallel and connect directly to the 3 cells in series.
I think LEDs are supposed draw a lot less current if they have a dropping
resistor. I'm guessing that a dropping resistor would reduce current
draw substantially, increase led life and not reduce light output
significantly. But I can see were I could easliy install a resistor. I
also know just about zero on leds.
tnx


The Electronic Goldmine sells a 4 white LED flashlight for
$1.99. Item # G15184 Watch for the line wrap:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G15184&variation=&aitem=15&mitem=24
You didn't specify the Item # for the Harbor Freight
flashlight - I assume it is ITEM 3653-0VGA

Based on the catalog pictures, it looks like the Harbor
Freight light has a metal body, while the Goldmine's is
plastic. But I'll bet they use the same LED's. I
have the Goldmine unit - there is a bluish tint to the
light it produces. Does yours produce a bluish tint?

As Watson mentioned, overdriving LEDs does reduce their
life and their light output, so your thinking seems right
on target. But for either a $7.00 or a $1.99 4 LED flashlight,
it's probably not worth the effort to incorporate a
dropping resistor - unless experimentation, rather than
function, is the goal.

Ed

 

[Henry Kolesnik]

I removed the lense cap, it's an force friction fit. I looked thru the tube
at a bright lite and I saw what looks like there is something in series with
the pcb arc and the case. I'm guessing it's a surface mount resistor, and
guess it's about 1/8 watt size. It should be possible to measure it but
that requires a long slender probe which I'd have make. If I make one I'll
report.

--

73
Hank WD5JFR
"Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in message
news:8ovje.1965$wb2.1791@newssvr11.news.prodigy.com...

I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to beleive
they are direct wired. Looking inside as best I can it looks like all 4
are in parallel and connect directly to the 3 cells in series. I think
LEDs are supposed draw a lot less current if they have a dropping resistor.
I'm guessing that a dropping resistor would reduce current draw
substantially, increase led life and not reduce light output significantly.
But I can see were I could easliy install a resistor. I also know just
about zero on leds.
tnx

--

73
Hank WD5JFR

 

[Spehro Pefhany]

On Sat, 21 May 2005 16:26:08 GMT, the renowned Fred Bloggs
<nospam@nospam.com> wrote:

If you think about it, the batteries do have an equivalent series
resistance and the LEDs are not perfect voltage clamps either. There IS a
series resistance even though there is no discrete resistor in the circuit.

Jim


Exactly. That's why they work. Maybe not as perfectly as some would
like, but good enough to sell.


There is much more to it than that- parallel LEDs are more reliable than
any other configuration and putting the full battery voltage across the
LEDs maximizes sensitivity of current to battery voltage so that when
the user notices less than satisfactory light output he/she still has
ample use remaining to change out the batteries- sort of like the low
gas level warning on the car dashboard.

Yes, that would be good way to market it. ;-) It does make the design
sensitive to battery type. I have one that does not work properly with
CR123A Lithium batteries that otherwise fit (it's a 5W Luxeon module
with no series resistor that puts out less than a 3W type unless you
use special batteries).


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Henry Kolesnik]

I just made a probe out of solid No. 12 house wire and measured the resistor
at 8 ohms on my Fluke 87. So I^2*R=0.127*0.127*8=0.129 watts. I guessed the
reisitor looked like 1/8 but I was using my recollection of what 1/8 watt
radial lead resistors look like for size. I should have done all this with
my original post and not wasted all those resources. But hind site is 20
20.

--

73
Hank WD5JFR
"Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in message
news:IzKje.2483$5Z1.1437@newssvr30.news.prodigy.com...

I removed the lense cap, it's an force friction fit. I looked thru the
tube at a bright lite and I saw what looks like there is something in
series with the pcb arc and the case. I'm guessing it's a surface mount
resistor, and guess it's about 1/8 watt size. It should be possible to
measure it but that requires a long slender probe which I'd have make. If
I make one I'll report.

--

73
Hank WD5JFR
"Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in message
news:8ovje.1965$wb2.1791@newssvr11.news.prodigy.com...
I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to
beleive they are direct wired. Looking inside as best I can it looks like
all 4 are in parallel and connect directly to the 3 cells in series. I
think LEDs are supposed draw a lot less current if they have a dropping
resistor. I'm guessing that a dropping resistor would reduce current draw
substantially, increase led life and not reduce light output
significantly. But I can see were I could easliy install a resistor. I
also know just about zero on leds.
tnx

--

73
Hank WD5JFR

 

[Spehro Pefhany]

On Sat, 21 May 2005 15:42:37 GMT, the renowned Rich Grise
<richgrise@example.net> wrote:

Heck, I'm still stuck on 'fret-saw'. )-;

Thanks,
Rich

Jeweller's saw? Sort of like a hacksaw with a thin narrow blade
(shorter than a hacksaw but with similar throat). As with files,
skilled folks can do wonderful things with them.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[mc]

White LEDs require about 4 to 4.5 volts. That is about what comes out of
the AA cells. The internal resistance of the LEDs is probably sufficient.
Newer LEDs have more internal resistance than older ones.

 

[mc]

I would assume that LEDs that are now made for flashlights have
built in pulse circuitry to get the brightest output from the
LED. They would include what is necessary to operate at the
correct voltage.

Your assumptions are wrong.

And your proof is...? ;-)

I don't know about *his* proof, but I've never seen such things on the
component market. They'd be handy if they existed. I've seen LEDs with
built-in flashers and with built-in current regulators to run from much
higher voltages.

Also, if pulsing were going on, you'd see stroboscopic effects when you
moved the flashlight quickly, wouldn't you?

 

[Winfield Hill]

Si Ballenger wrote...

I would assume that LEDs that are now made for flashlights have
built in pulse circuitry to get the brightest output from the
LED. They would include what is necessary to operate at the
correct voltage.

ROFLOL, that's a good one!


--
Thanks,
- Win

 

[Si Ballenger]

On Sat, 21 May 2005 10:17:18 -0400, "mc" <mc_no_spam@uga.edu>
wrote:

I would assume that LEDs that are now made for flashlights have
built in pulse circuitry to get the brightest output from the
LED. They would include what is necessary to operate at the
correct voltage.

Your assumptions are wrong.

And your proof is...? ;-)

I don't know about *his* proof, but I've never seen such things on the
component market. They'd be handy if they existed. I've seen LEDs with
built-in flashers and with built-in current regulators to run from much
higher voltages.

Radio shack use to sell a self flashing LED.

Also, if pulsing were going on, you'd see stroboscopic effects when you
moved the flashlight quickly, wouldn't you?

I've seen the strobing on rapidly opdating LED displays when
either they moved rapidly. I would think the flash rate would be
at a level that it wouldn't be noticed under most normal
conditions. I'm sure there must be an optimum flash rate for this
type of use.

 

[Jim Yanik]

"mc" <mc_no_spam@uga.edu> wrote in
news:428e9d03@mustang.speedfactory.net:

White LEDs require about 4 to 4.5 volts. That is about what comes out
of the AA cells. The internal resistance of the LEDs is probably
sufficient. Newer LEDs have more internal resistance than older ones.

Actually,the Nichia white LEDs have a drop of about 3.5 volts at their
rated current;25ma.
The spec sheet,IIRC,said 3.2v-3.9v.
the 10 I checked were mostly 3.4V.
--
Jim Yanik
jyanik
at
kua.net

 

[petrus bitbyter]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com>
schreef in bericht news:118ubhriv1mi152@corp.supernews.com...

"petrus bitbyter" <pieterkraltlaatditweg@enditookhccnet.nl> wrote in
message news:428f0f95$0$157$3a628fcd@reader2.nntp.hccnet.nl...

"Henry Kolesnik" <kolesnik@sbcglobal.net> schreef in bericht
news:8ovje.1965$wb2.1791@newssvr11.news.prodigy.com...
I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to
beleive
they are direct wired. Looking inside as best I can it looks like
all 4
are in parallel and connect directly to the 3 cells in series. I
think
LEDs are supposed draw a lot less current if they have a dropping
resistor.
I'm guessing that a dropping resistor would reduce current draw
substantially, increase led life and not reduce light output
significantly.
But I can see were I could easliy install a resistor. I also know
just
about zero on leds.
tnx
73
Hank WD5JFR

Hank,

Adding a resistor will not be that difficult. A thin piece of two
sided PCB
and some handiwork with a fret-saw and a fraise will do the trick. As
AA is
pretty small you may need to use two or more SMD resistors in
parallel. The
round piece of PCB should be place between a battery and its press
spring.

My dictionary says a fraise is "an obstacle of pointed stakes driven
into the ramparts of a fortification in a horizontal or inclined
position".
Which I don't think is what you had in mind. Maybe you could explain.
Thanks.

petrus bitbyter

Well,

My dictionary considers it a synonym for milling cutter. I use a small handy
tool for PCB modifications and (very) smal PCBs that I don't want to etch.
Guess we have very different dictionaries

petrus bitbyter

 

[petrus bitbyter]

"Frank Bemelman" <f.bemelmanq@xs4all.invalid.nl> schreef in bericht
news:428f57cc$0$64077$e4fe514c@dreader14.news.xs4all.nl...

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
schreef in bericht news:118ubhriv1mi152@corp.supernews.com...

"petrus bitbyter" <pieterkraltlaatditweg@enditookhccnet.nl> wrote in
message news:428f0f95$0$157$3a628fcd@reader2.nntp.hccnet.nl...


Adding a resistor will not be that difficult. A thin piece of two
sided PCB
and some handiwork with a fret-saw and a fraise will do the trick. As
AA is
pretty small you may need to use two or more SMD resistors in
parallel. The
round piece of PCB should be place between a battery and its press
spring.

My dictionary says a fraise is "an obstacle of pointed stakes driven
into the ramparts of a fortification in a horizontal or inclined
position".
Which I don't think is what you had in mind. Maybe you could explain.
Thanks.

Milling cutter. (Dutch -> Frees).

--
Thanks, Frank.
(remove 'q' and 'invalid' when replying by email)

Correct, but... I checked out the two dictionaries I own and both know the
word "fraise" as a synonym for "milling cutter". Only one of them also
mentioned it as a part of a fortification. So I was really astonished to
hear that the word was virtually unknown.

petrus bitbyter

 

[Watson A.Name - \"Watt Su]

"mc" <mc_no_spam@uga.edu> wrote in message
news:428e9d03@mustang.speedfactory.net...

White LEDs require about 4 to 4.5 volts. That is about what comes out
of
the AA cells. The internal resistance of the LEDs is probably
sufficient.
Newer LEDs have more internal resistance than older ones.

White LEDs that have that much voltage across them have too much current
going thru them. I suggest you read the specs for a common white LED
here.
www.nichia.co.jp/specification/led_lamp/NSPW500BS.pdf
or here http://www.alltronics.com/download/NSPW500BS.pdf

 

[Spehro Pefhany]

On 21 May 2005 15:46:41 -0700, the renowned "JeffM" <jeffm_@email.com>
wrote:

Heck, I'm still stuck on 'fret-saw'. )-;
Rich Grise

:Jeweller's saw? Sort of like a hacksaw with a thin narrow blade
shorter than a hacksaw but with similar throat).
: Spehro Pefhany

Wow. Just look at the throats on some of these dudes:
http://www.google.com/images?q=fret-saw

When I heard it, I thought of something like this
(photographed with an actual fretboard, no less):
http://www.google.com/images?q=fret-saw+lmii

Confusingly, at least on European website called something that looked
like that (presumably with finer teeth for metalcutting) a jeweler's
saw. Nothing to fret about, I guess.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Watson A.Name - \"Watt Su]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:8CJje.5174$BF5.235@trndny06...

Henry Kolesnik wrote:
I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to
beleive
they are direct wired. Looking inside as best I can it looks like
all 4 are
in parallel and connect directly to the 3 cells in series. I think
LEDs are
supposed draw a lot less current if they have a dropping resistor.
I'm
guessing that a dropping resistor would reduce current draw
substantially,
increase led life and not reduce light output significantly. But I
can see
were I could easliy install a resistor. I also know just about
zero on
leds.
tnx


The Electronic Goldmine sells a 4 white LED flashlight for
$1.99. Item # G15184 Watch for the line wrap:

http://www.goldmine-elec-products.com/prodinfo.asp?number=G15184&variati

on=&aitem=15&mitem=24

You didn't specify the Item # for the Harbor Freight
flashlight - I assume it is ITEM 3653-0VGA

Based on the catalog pictures, it looks like the Harbor
Freight light has a metal body, while the Goldmine's is
plastic. But I'll bet they use the same LED's. I
have the Goldmine unit - there is a bluish tint to the
light it produces. Does yours produce a bluish tint?

As Watson mentioned, overdriving LEDs does reduce their
life and their light output, so your thinking seems right
on target. But for either a $7.00 or a $1.99 4 LED flashlight,
it's probably not worth the effort to incorporate a
dropping resistor - unless experimentation, rather than
function, is the goal.

Ed

Man, for those prices, you can throw them away every time you change the
AA cells! But what I find problematic is that the length of that three
cell monster is over 7".

 

[Spehro Pefhany]

On Sat, 21 May 2005 23:14:26 GMT, the renowned
shb*NO*SPAM*@comporium.net (Si Ballenger) wrote:

On Sat, 21 May 2005 10:17:18 -0400, "mc" <mc_no_spam@uga.edu
wrote:

I would assume that LEDs that are now made for flashlights have
built in pulse circuitry to get the brightest output from the
LED. They would include what is necessary to operate at the
correct voltage.

Your assumptions are wrong.

And your proof is...? ;-)

I don't know about *his* proof, but I've never seen such things on the
component market. They'd be handy if they existed. I've seen LEDs with
built-in flashers and with built-in current regulators to run from much
higher voltages.

Radio shack use to sell a self flashing LED.

Yes, and multicolor LEDs are available these days that do patterns and
such like. But nothing at the component level with white LEDs that
I've seen. There are high power white LED modules available that run
off of (say) 12V but they are not from LED manufacturers that I've
seen, and they are probably too expensive for use in a <$50
flashlight.

Also, if pulsing were going on, you'd see stroboscopic effects when you
moved the flashlight quickly, wouldn't you?

I've seen the strobing on rapidly opdating LED displays when
either they moved rapidly. I would think the flash rate would be
at a level that it wouldn't be noticed under most normal
conditions. I'm sure there must be an optimum flash rate for this
type of use.

Zero, more than likely.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Spehro Pefhany]

On Sat, 21 May 2005 18:21:55 -0700, the renowned "Watson A.Name -
\"Watt Sun, the Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

Running the LEDs at excessive current not only makes them a lot
brighter, it makes them last much shorter, and guarantees the flashlight
maker another sale in a few years, if that long!!!

The competition is a Maglite with 10-hour bulb life (assuming you
don't subject it to shock or vibration) or some even worse no-name
incandescent, so I doubt that they can make it that bad and have it
work at all.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Watson A.Name - \"Watt Su]

"Jim Yanik" <jyanik@abuse.gov.> wrote in message
news:Xns965D846554DE2jyanikkuanet@129.250.170.83...

"Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in
news:8ovje.1965$wb2.1791@newssvr11.news.prodigy.com:

I just got a 4 white LED flashlight that uses 3 AA cells from Harbor
freight. I measured the current at 127 ma and and that leads me to
beleive they are direct wired. Looking inside as best I can it
looks
like all 4 are in parallel and connect directly to the 3 cells in
series. I think LEDs are supposed draw a lot less current if they
have a dropping resistor. I'm guessing that a dropping resistor
would
reduce current draw substantially, increase led life and not reduce
light output significantly. But I can see were I could easliy
install
a resistor. I also know just about zero on leds.
tnx

127ma/4 LEDs=31.75ma per LED,that's a bit high for the Nichia white
LEDs;IIRC,they have a 25ma max limit.

Many of the commercial flashlights run the LEDs at much higher currents,
some as high as, or even higher than 50mA when the cells are fresh.

Are there now other white LEDs that have a higher current rating?

Sure. The original Luxeon Star runs at 1W and 350mA, and the newer 3W
and 5W LSes run at even higher currents. But you can get spider LEDs
and 8mm or 10mm LEDs that run at higher currents, maybe a few to several
tens of mA. Check out these lead frame LEDs.
http://www.lumex.com/product.asp?id=1006182

--
Jim Yanik
jyanik
at
kua.net