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Replacement LED?

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  Replacement LED? DaveC <not@home.cow> - 2016-03-21 10:30 -0700
    Re: Replacement LED? Bob Engelhardt <BobEngelhardt@comcast.net> - 2016-03-21 17:00 -0400
    Re: Replacement LED? John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-21 20:05 -0700
    Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-21 20:51 -0700
      Re: Replacement LED? DaveC <not@home.cow> - 2016-03-21 22:56 -0700
        Re: Replacement LED? N_Cook <diverse@tcp.co.uk> - 2016-03-22 15:42 +0000
        Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-22 16:42 -0700
          Re: Replacement LED? DaveC <not@home.cow> - 2016-03-22 16:56 -0700
            Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-22 18:16 -0700
              Re: Replacement LED? DaveC <not@home.cow> - 2016-03-22 18:56 -0700
                Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-23 11:11 -0700
                  Re: Replacement LED? DaveC <not@home.cow> - 2016-03-23 21:50 -0700
                    Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-23 22:49 -0700
                      Re: Replacement LED? DaveC <not@home.cow> - 2016-03-24 14:02 -0700
          Re: Replacement LED? not@telling.you.invalid (Computer Nerd Kev) - 2016-03-24 21:44 +0000
      Re: Replacement LED? Syd Rumpo <usenet@nononono.co.uk> - 2016-03-22 09:10 +0000
        Re: Replacement LED? DaveC <not@home.cow> - 2016-03-22 13:41 -0700
          Re: Replacement LED? rickman <gnuarm@gmail.com> - 2016-03-22 21:46 -0400
            Re: Replacement LED? DaveC <not@home.cow> - 2016-03-22 19:00 -0700
              Re: Replacement LED? rickman <gnuarm@gmail.com> - 2016-03-23 00:19 -0400
                Re: Replacement LED? DaveC <not@home.cow> - 2016-03-22 22:23 -0700
                  Re: Replacement LED? DaveC <not@home.cow> - 2016-03-23 11:52 -0700
                Re: Replacement LED? "Ralph Mowery" <rmowery28146@earthlink.net> - 2016-03-23 10:31 -0400
      Re: Replacement LED? Andre Majorel <cheney@halliburton.com> - 2016-03-26 19:56 +0000
        Re: Replacement LED? John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-27 10:20 -0700
        Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-28 19:21 -0700
          Re: Replacement LED? "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-03-31 04:20 -0400
            Re: Replacement LED? Jeff Liebermann <jeffl@cruzio.com> - 2016-03-31 08:34 -0700
            Re: Replacement LED? krw <krw@nowhere.com> - 2016-03-31 20:10 -0400
              Re: Replacement LED? "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-04-01 17:21 -0400
                Re: Replacement LED? krw <krw@nowhere.com> - 2016-04-01 19:14 -0400
                  Re: Replacement LED? "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-04-01 19:43 -0400
          Re: Replacement LED? Andre Majorel <cheney@halliburton.com> - 2016-03-31 10:40 +0000

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#5920 — Replacement LED?

The LED in my flashlight is blinking (2/sec). It’s not the support 
circuitry (constant current): the voltage across the LED is constant 4v. I 
presume it’s a failure mode of the LED. It happens immediately upon 
power-on.

http://imgur.com/a/rIRDG

The form-factor is close to a 5x5mm (h x diam). Standard through-hole leads.

But it’s a pretty high-intensity one. Don’t know what makes it so, but I 
classify anything with a yellow square visible in the center as 
“high-intensity”. Maybe not technically accurate, but there you are.

What I’ve found so far is either a standard 5mm LED but not very bright, or 
SMD types requiring heat sinks.

It’s a great little light, and I’ve not found anything as small, 
long-lasting, with single AA that I like as much. And this is a learning 
experience, so there’s that.

Any pointers to a suitable replacement LED would be appreciated.

Thanks.

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#5921

On 3/21/2016 1:30 PM, DaveC wrote:
> ... the voltage across the LED is constant 4v.
>  ... with single AA  ...

So it has a boost SMPS?

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#5922

On Mon, 21 Mar 2016 10:30:03 -0700, DaveC <not@home.cow> wrote:

>The LED in my flashlight is blinking (2/sec). It’s not the support 
>circuitry (constant current): the voltage across the LED is constant 4v. I 
>presume it’s a failure mode of the LED. It happens immediately upon 
>power-on.
>
>http://imgur.com/a/rIRDG
>
>The form-factor is close to a 5x5mm (h x diam). Standard through-hole leads.
>
>But it’s a pretty high-intensity one. Don’t know what makes it so, but I 
>classify anything with a yellow square visible in the center as 
>“high-intensity”. Maybe not technically accurate, but there you are.

That's probably a downconversion phosphor. White LEDs are really blue
LEDs with a blob of epoxy on top, loaded with yag powder that converts
some of the blue to yellow.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#5923

On Mon, 21 Mar 2016 10:30:03 -0700, DaveC <not@home.cow> wrote:

>The LED in my flashlight is blinking (2/sec). It’s not the support 
>circuitry (constant current): the voltage across the LED is constant 4v. I 
>presume it’s a failure mode of the LED. It happens immediately upon 
>power-on.

I beg to differ with your diagnosis.  Unless the LED has magically
turned into a thermostat controlled flasher, it's not going to do
that.  More likely, the LED driver circuit is doing the flashing.
Based on zero detail about the actual flashlight, my wild guess(tm)
would be the big electrolytic that usually goes across the battery.
Broken or badly soldered connections on the driver PCB are also
likely.

>http://imgur.com/a/rIRDG
>The form-factor is close to a 5x5mm (h x diam). Standard through-hole leads.
>
>But it’s a pretty high-intensity one. Don’t know what makes it so, but I 
>classify anything with a yellow square visible in the center as 
>“high-intensity”. Maybe not technically accurate, but there you are.

If it's not too much trouble, could you disclose the maker and model
number of your flashlight?  Extra credit for providing a link to the
manufactures web site or China source link.  If there are no numbers
or sources, perhaps a photo of the assembled flashlight?

>What I’ve found so far is either a standard 5mm LED but not very bright, or 
>SMD types requiring heat sinks.

Yep.  You're looking at the wrong stuff.  Maybe something by Cree:
<http://www.cree.com/LED-Components-and-Modules/Products>
Nope.  Ok, I give up.  What the photo looks like is a common dome
shaped LED (as in the Cree URL above) with a lens over it.  I did some
Googling looking for the lens and couldn't find it.

>It’s a great little light, and I’ve not found anything as small, 
>long-lasting, with single AA that I like as much. And this is a learning 
>experience, so there’s that.

I have one that meets your requirements.  L3 Illumination L10:
<http://www.candlepowerforums.com/vb/showthread.php?376058-L3-Illumination-L10-%28XP-G2-R5-or-Nichia-219-1xAA%29-Review-RUNTIMES-BEAMS-VIDEO>
Single cell, very bright, tolerably priced, small, adjustable
brightness, etc.  However, there's a catch.  It has 4 brightness
levels set by twisting the two sections of the body.  No problem
except that it makes it a two handed operation.  I would have
preferred a push button at the back end.  I've also measured the
brightness (using my highly creative and non-standard procedure) at
about 90-110 lumens (varies with temperature).

>Any pointers to a suitable replacement LED would be appreciated.

Again, I don't think it's the LED.  The driver board is a more likely
culprit.  Put it under a magnifier and see if you can find the broken
trace.  Put a light behind the PCB to make it easier to see the break.
If desperate, trace out the schematic and try to identify the LED
controller chip.  If it uses an MLCC capacitor, use a hot air gun to
reflow, not a soldering iron tip.

You might also get some help in CandlePowerForums:
<http://www.candlepowerforums.com>

Good luck.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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#5924

> I beg to differ with your diagnosis. Unless the LED has magically
> turned into a thermostat controlled flasher, it's not going to do
> that. More likely, the LED driver circuit is doing the flashing.
> Based on zero detail about the actual flashlight, my wild guess(tm)
> would be the big electrolytic that usually goes across the battery.
> Broken or badly soldered connections on the driver PCB are also
> likely.

Nebo NU15J:

https://www.nebotools.com/prod_details.php?id=31&cid=16&subid=94&subsubcid=

I like this model for its good trade-off between brightness and battery life. 
Might be “better”, but this fits my needs. (And it ft fits in my pocket 
along with my micro Swiss army knife...)

No controller chip. Looks like a boost converter (inductor, BJT, schottky 
diode, ceramic cap).

I scoped the voltage across the LED: it's constant 4v (with a very 
small--20mv?--rise and fall as it switches on and off). Haven’t yet 
measured current. Surely if there was a bad solder joint or other failure it 
would show up here.

Thanks for the referrals of other lights, but I’m not buying a replacement. 
I’m doing this for fun and to learn.

Cheers.

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#5929

On 22/03/2016 05:56, DaveC wrote:
>> I beg to differ with your diagnosis. Unless the LED has magically
>> turned into a thermostat controlled flasher, it's not going to do
>> that. More likely, the LED driver circuit is doing the flashing.
>> Based on zero detail about the actual flashlight, my wild guess(tm)
>> would be the big electrolytic that usually goes across the battery.
>> Broken or badly soldered connections on the driver PCB are also
>> likely.
>
> Nebo NU15J:
>
> https://www.nebotools.com/prod_details.php?id=31&cid=16&subid=94&subsubcid=
>
> I like this model for its good trade-off between brightness and battery life.
> Might be “better”, but this fits my needs. (And it ft fits in my pocket
> along with my micro Swiss army knife...)
>
> No controller chip. Looks like a boost converter (inductor, BJT, schottky
> diode, ceramic cap).
>
> I scoped the voltage across the LED: it's constant 4v (with a very
> small--20mv?--rise and fall as it switches on and off). Haven’t yet
> measured current. Surely if there was a bad solder joint or other failure it
> would show up here.
>
> Thanks for the referrals of other lights, but I’m not buying a replacement.
> I’m doing this for fun and to learn.
>
> Cheers.
>

Desolder the original LED, carefully , as balance of probability it will 
be fine.
Jumper in any old high power LED and see if that flashes too.

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#5932

On Mon, 21 Mar 2016 22:56:51 -0700, DaveC <not@home.cow> wrote:

>Nebo NU15J:
>https://www.nebotools.com/prod_details.php?id=31&cid=16&subid=94&subsubcid=

Looks like the flashing LED is a common problem:
<http://www.candlepowerforums.com/vb/showthread.php?417142-Replacement-LED>

>I like this model for its good trade-off between brightness and battery life. 

Some day, someone will design a flashlight with an automatic PWM light
dimmer.  Shine the light at something bright, and the flashlight runs
at full brightness.  Shine it at something in the dark, and it goes to
fairly dim.

>No controller chip. Looks like a boost converter (inductor, BJT, schottky 
>diode, ceramic cap).

Yep, that's about it.  No controller.

>I scoped the voltage across the LED: it's constant 4v (with a very 
>small--20mv?--rise and fall as it switches on and off). Haven’t yet 
>measured current. Surely if there was a bad solder joint or other failure it 
>would show up here.

Ok, I'm wrong.  The flashing is not caused by the non-existent
controller chip.

>Thanks for the referrals of other lights, but I’m not buying a replacement. 
>I’m doing this for fun and to learn.

Like I mumbled previously, see if there's a dome type LED under a
plastic lens.  You'll probably need to unsolder the LED leads to do
this.  If they really are two parts, it should be possible to find a
replacement LED.

If you can't identify the LED by the power output, try measuring the
current drain with a new battery.  Multiply the current with your
measured 4V, and you should get the power in watts.  That should tell
you if you should be looking for a 1/2, 1, or 1.5v LED.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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#5933

Jeff Liebermann sez:

> Looks like the flashing LED is a common problem:
> <http://www.candlepowerforums.com/vb/showthread.php?417142-Replacement-LED>

That’s my post on canblepowerforums.com. (c:
> Like I mumbled previously, see if there's a dome type LED under a plastic 
lens. You'll probably need to unsolder the LED leads to do this. If they 
really are two parts, it should be possible to find a replacement LED.

Will do.
> If you can't identify the LED by the power output, try measuring the
> current drain with a new battery. Multiply the current with your
> measured 4V, and you should get the power in watts. That should tell
> you if you should be looking for a 1/2, 1, or 1.5v LED.

You mean 1/2, 1, or 1.5 *watt* LED, yes?

Thanks.

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#5934

On Tue, 22 Mar 2016 16:56:48 -0700, DaveC <not@home.cow> wrote:

>Jeff Liebermann sez:
>
>> Looks like the flashing LED is a common problem:
>> <http://www.candlepowerforums.com/vb/showthread.php?417142-Replacement-LED>
>
>That’s my post on canblepowerforums.com. (c:

Oops(tm).

>> Like I mumbled previously, see if there's a dome type LED under a plastic 
>> lens. You'll probably need to unsolder the LED leads to do this. If they 
>> really are two parts, it should be possible to find a replacement LED.
>
>Will do.

>> If you can't identify the LED by the power output, try measuring the
>> current drain with a new battery. Multiply the current with your
>> measured 4V, and you should get the power in watts. That should tell
>> you if you should be looking for a 1/2, 1, or 1.5v LED.
>
>You mean 1/2, 1, or 1.5 *watt* LED, yes?

Oops 2.0(tm).  I was in a rush to get out of door.  Sorry.  Also, I
just noticed that there is no such thing as an individual 1.5w LED.
-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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#5936

> Also, I just noticed that there is no such thing as an individual 1.5w LED.

I think this is an under-used(?) 1W LED.

If I can’t find a direct replacement I’m considering flipping 
the PCB it’s soldered to and using the copper side to solder a SMD 
unit. That way can dissipate some W.

But that presents its own set of problems. Optics will need to be matched to 
the new LED.

Hmm...

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#5941

On Tue, 22 Mar 2016 18:56:51 -0700, DaveC <not@home.cow> wrote:

>> Also, I just noticed that there is no such thing as an individual 1.5w LED.
>
>I think this is an under-used(?) 1W LED.

Sounds about right.  If you can light it up, just measure the battery
current drain, and calculate or estimate the power dissipation.

>If I can’t find a direct replacement I’m considering flipping 
>the PCB it’s soldered to and using the copper side to solder a SMD 
>unit. That way can dissipate some W.
>But that presents its own set of problems. Optics will need to be matched to 
>the new LED.

If you can remove what I believe to be a lens, I think you'll find
that the actual LED is rather conventional and can be found in the
Cree catalog.  
<http://www.cree.com/LED-Components-and-Modules/Products>
If you sort the above list by power output, there are only 3ea 1w
LED's listed.  Just find the right die size and good luck soldering
the tiny chip.  You can also dig throught the current flashlight
offerings and see which 1w chips are popular.

>Hmm...

Learn by Destroying.... then buy a new flashlight.


-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#5943

> If you can remove what I believe to be a lens, I think you'll find
> that the actual LED is rather conventional and can be found in the
> Cree catalog.
> <http://www.cree.com/LED-Components-and-Modules/Products>
> If you sort the above list by power output, there are only 3ea 1w
> LED's listed. Just find the right die size and good luck soldering
> the tiny chip. You can also dig throught the current flashlight
> offerings and see which 1w chips are popular.
[Jeff Lieberman]

I found these:

https://www.led-tech.de/en/0.5W-Power-LEDs_DB-86.pdf

Looks good, no?

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#5944

On Wed, 23 Mar 2016 21:50:18 -0700, DaveC <not@home.cow> wrote:

>> If you can remove what I believe to be a lens, I think you'll find
>> that the actual LED is rather conventional and can be found in the
>> Cree catalog.
>> <http://www.cree.com/LED-Components-and-Modules/Products>
>> If you sort the above list by power output, there are only 3ea 1w
>> LED's listed. Just find the right die size and good luck soldering
>> the tiny chip. You can also dig throught the current flashlight
>> offerings and see which 1w chips are popular.
>[Jeff Lieberman]

Please deduct one point for spelling my name wrong.

>I found these:
>https://www.led-tech.de/en/0.5W-Power-LEDs_DB-86.pdf
>Looks good, no?

No.  I thought you said your flashlight was bright and possibly 1
watt.  Those are common 5mm LED's with 0.5 watts maximum.  
<https://www.google.com/search?q=5mm+white+led+0.5+watts>
These photos look very much like what I would expect to be hiding
under what I believe to be a lens of some sorts:
<https://www.google.com/search?q=5mm+white+led+0.5+watts&tbm=isch>
This looks a bit closer:
<http://www.ebay.com/itm/161246348498>

That data sheet is also slightly insane, specifying the luminous flux
as:
  Lumen typ.: 19 mcd
Lumens are measured in umm.... lumens, not millicandelas.  It is
possible to convert between lumens and mcd's using the viewing angle:
<http://www.rapidtables.com/calc/light/mcd-to-lumen-calculator.htm>
Anyway, 19 lumens is not very bright but probably good enough for a
pocket flashlight.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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#5945

> > [Jeff Lieberman]
> 
> Please deduct one point for spelling my name wrong.

And I tried so hard to get the “Lei/Lie” bit right! (c; 2 steps forward, 
1 step back...
> These photos look very much like what I would expect to be hiding
> under what I believe to be a lens of some sorts:
> <https://www.google.com/search?q=5mm+white+led+0.5+watts&tbm=isch>

One of those images (located here):

http://tinyurl.com/j4pwvuw

looks exactly like the one in my light. It’s squat, with very (relatively) 
large yellow die(?) in the center. I don’t think there’s a separate lens. 
Maybe it’s molded to focus the light (integral lens)?
Wish I could find that LED other than @ Alibaba...

Ah-HAH! From that Alibaba image page: “strawhat LED”. Search turns up 
similar-looking LEDs. Searching on the terms “strawhat” and “dimple” 
tells me that this form-factor is for radial distribution of the light, not 
throwing a beam. Which means the flashlight designer wanted the reflector to 
shape the beam, not the LED.

So I’m looking for one of these types.

Thanks.

(Why are my search skills so crap? Google keeps returning Manga images and 
cartoon faces...)

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#5946

In sci.electronics.components Jeff Liebermann <jeffl@cruzio.com> wrote:
> On Mon, 21 Mar 2016 22:56:51 -0700, DaveC <not@home.cow> wrote:
> 
>>I like this model for its good trade-off between brightness and battery life. 
> 
> Some day, someone will design a flashlight with an automatic PWM light
> dimmer.  Shine the light at something bright, and the flashlight runs
> at full brightness.  Shine it at something in the dark, and it goes to
> fairly dim.

Hmm, that sounds like a good idea to put in my planned LED torch project,
which was going to have a manual dimmer anyway. I guess an LDR would be
suitable? Maybe mount it in a small tube to make it directional?

I guess I'll have to find an LDR and wave it around with my multimeter
attached. Ahh, the dignity of research. :)

-- 
__          __
#_ < |\| |< _#

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#5928

On 22/03/2016 03:51, Jeff Liebermann wrote:

<snip>

> I beg to differ with your diagnosis.  Unless the LED has magically
> turned into a thermostat controlled flasher, it's not going to do
> that.

Thermostat controlled flasher is probably the exact description. It 
happens when LEDs are driven straight from batteries too, and is 
probably the bond wire heating and cooling making intermittent contact 
at a few Hz.

I have a cheap LED torch which uses nine parallel connected white LEDs 
running directly from 3 AAs.  After a battery replacement, one is out, 
four flash at different rates, and four are on.


Cheers
-- 
Syd

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#5931

Circuit:

http://imgur.com/YeELiHI

which is identical to the application note in the datasheet (scroll down to 
the ME2108A diagrams):

http://img.ozdisan.com/ETicaret_Dosya/431770_1622138.pdf

(easily translated via Google, but a bit more confusing...)

Measured current at the battery terminals is 275 mA (due to meter insertion 
loss it’s difficult to get an accurate current reading at the LED’s 
terminals--the LED dims). Voltage across the LED is a pretty-constant 4v. 
Estimating the efficiency of the converter at (roughly) 75 percent the LED is 
using 825 mW.

I guess I’m looking for a 1W replacement?

How’s my math?

Thanks.

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#5935

On 3/22/2016 4:41 PM, DaveC wrote:
> Circuit:
>
> http://imgur.com/YeELiHI
>
> which is identical to the application note in the datasheet (scroll down to
> the ME2108A diagrams):
>
> http://img.ozdisan.com/ETicaret_Dosya/431770_1622138.pdf
>
> (easily translated via Google, but a bit more confusing...)
>
> Measured current at the battery terminals is 275 mA (due to meter insertion
> loss it’s difficult to get an accurate current reading at the LED’s
> terminals--the LED dims). Voltage across the LED is a pretty-constant 4v.
> Estimating the efficiency of the converter at (roughly) 75 percent the LED is
> using 825 mW.
>
> I guess I’m looking for a 1W replacement?
>
> How’s my math?

Didn't you say it used a *single* 1.5 volt AA cell?  I think that would 
make it 412 milliwatts not counting the conversion efficiency, so more 
likely a 1/2 watt LED.

-- 

Rick

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#5937

On 22 Mar 2016, rickman wrote
(in article <ncssb4$c6l$1@dont-email.me>):

> Didn't you say it used a *single* 1.5 volt AA cell? I think that would
> make it 412 milliwatts not counting the conversion efficiency, so more
> likely a 1/2 watt LED.

1.5v boosted to 4v (measured) output from the converter. 275 mA (measured) at 
the battery terminals. I make that to be 1100 mW. If presume 75 percent 
efficiency, 825 mW.

No?

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#5938

On 3/22/2016 10:00 PM, DaveC wrote:
> On 22 Mar 2016, rickman wrote
> (in article <ncssb4$c6l$1@dont-email.me>):
>
>> Didn't you say it used a *single* 1.5 volt AA cell? I think that would
>> make it 412 milliwatts not counting the conversion efficiency, so more
>> likely a 1/2 watt LED.
>
> 1.5v boosted to 4v (measured) output from the converter. 275 mA (measured) at
> the battery terminals. I make that to be 1100 mW. If presume 75 percent
> efficiency, 825 mW.
>
> No?

Perhaps I am missing something.  The battery terminals will be at the 
battery voltage, no?  So why would you use 4 volts which is at the 
output?  It would be 4 volts times the LED current or the battery 
voltage times the input current.

-- 

Rick

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