Replacement LED?

[rickman]

On 3/22/2016 10:00 PM, DaveC wrote:

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

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

 

[DaveC]

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

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?

 

[rickman]

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

 

[Ralph Mowery]

"rickman" <gnuarm@gmail.com> wrote in message
news:nct5ah$v2h$1@dont-email.me...

On 3/22/2016 10:00 PM, DaveC wrote:
On 22 Mar 2016, rickman wrote
(in article <ncssb4$c6l$1@dont-email.me&gt:

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.

From what small ammount of playing with the voltage converters, they are
almost like a transformer in action. If you go to a higher voltage, the low
voltage current will be a lot more than is used by the load, and if going to
a lower voltage , the current from the battery will be less than the actual
current used by the load.
That keeps the total power drawn the same minus the efficency of the
converter.

 

[Jeff Liebermann]

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

 

[DaveC]

On 22 Mar 2016, DaveC wrote
(in article<0001HW.1CA25FD300316D8E1132D13CF@news.eternal-september.org&gt:

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

Yikes! Of course you’re right.

Thanks.

Just measured working light of same model: using power supply @1.5v (measured
at flashlight battery terminals), the current from the ps is 400 mA.
Estimating 75 percent efficiency that makes about 450 mW.

So a 1/2W replacement LED might be what I’m looking for.

Thanks.

 

[Jeff Liebermann]

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

 

[DaveC]

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?

 

[Computer Nerd Kev]

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.

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

 

[DaveC]

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...)

 

[Andre Majorel]

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

--
André Majorel http://www.teaser.fr/~amajorel/
J'ai des vrais problčmes, vous avez des faux problčmes.

 

[John Larkin]

On Sat, 26 Mar 2016 19:56:12 +0000 (UTC), Andre Majorel
<cheney@halliburton.com> wrote:

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

Not a bit.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Jon Elson]

Andre Majorel wrote:

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

Really, before I got my pick and place machine, I hand-soldered about 25,000
..1uF 0805 capacitors. NEVER ONCE had a bad one. I still hand-solder a fair
number of low production boards and prototypes, and have never seen a
problem with MLCCs.

Jon

 

[Jeff Liebermann]

On Sat, 26 Mar 2016 19:56:12 +0000 (UTC), Andre Majorel
<cheney@halliburton.com> wrote:

Sorry for the delay but I missed the followups to my comment.

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

Thermal shock easily cracks MLCC caps. I learned that the hard way
while fixing several Apple Mac Mini computahs, which feature a
collection of MLCC on the bottom of the main board.
<https://web.archive.org/web/20130606062903/http://blog.helpmymac.ru/?p=3585>
The original failure mode was shorted MLCC caps caused by either
thermal shock or board flex. The bad ones were easy to find with an
ESR meter. However, when I tried to install replacements (and
guessing the part value because Apple doesn't supply service
information to non-authorized repair shops), I managed to crack and
short several known good MLCC caps with a soldering iron. Having
learned the lesson, I used some solder paste and a hot air SMT reflow
gun to do the soldering. I also pre-heated the PCB and let the caps
cool down slowly. I don't know if that was necessary, but it worked
every time. I'm told that two solding irons used as a tweezer also
works, but I haven't tried that yet.

You'll find some more details under:
<https://www.google.com/#q=mlcc+capacitor+crack>
<https://www.google.com/#q=mlcc+capacitor+soldering+iron>
Lots of articles and guidelines on handling and soldering these caps,
some of which warn about using a soldering iron. For example:

<http://www.vishay.com/docs/45034/soldrec.pdf>
6. Soldering with a Solder Iron
Attachment by soldering iron is not recommended. A
heat shock may cause a crack in the MLCC chip capacitors,
however, if solder iron is used, the following precautions
should be taken: ... (etc)

Damage Prevention When Soldering Ceramic Chip Capacitors
<http://www.eptac.com/webinars/presentations/eptac_09_17_14.pdf>
Hand Soldering
- A pencil type soldering of 30 watts
maximum and with a diameter of 3 mm
maximum should be used.
- The soldering iron tip temperature should
be less than 300C [572F] and maximum
contact time should be 5 seconds.
- The soldering iron tip should never come in
contact with the component body.
Ever try to solder a small MLCC cap without touching the body with the
soldering iron tip? Good luck.

<http://www.murata.com/en-us/support/faqs/products/capacitor/mlcc/mnt/0001>
In order to prevent damage (cracks) to the component that
can be caused by localized rapid heating and heat shock, preheat
the chip, for example, to prevent it from being subjected to
heat shock.

--
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

 

[Jon Elson]

Jeff Liebermann wrote:

The original failure mode was shorted MLCC caps caused by either
thermal shock or board flex. The bad ones were easy to find with an
ESR meter. However, when I tried to install replacements (and
guessing the part value because Apple doesn't supply service
information to non-authorized repair shops), I managed to crack and
short several known good MLCC caps with a soldering iron. Having
learned the lesson, I used some solder paste and a hot air SMT reflow
gun to do the soldering. I also pre-heated the PCB and let the caps
cool down slowly. I don't know if that was necessary, but it worked
every time. I'm told that two solding irons used as a tweezer also
works, but I haven't tried that yet.

I've heard these stories a number of times. And, yes, maybe some people use
insanely hot irons or in some other way cause this problem. And, some
really large caps are prone to this damage. But, as I say, I have hand-
soldered over 25,000 0805 MLCC caps of modest value without seeing this
problem. I use a very good Weller temperature-controlled iron, and run it
at a modest temperature. Much better to use an iron with really good
thermal conductivity at a lower temperature than one with poor conductivity
at a very high temperature.

Jon

 

[Jeff Liebermann]

On Mon, 28 Mar 2016 22:15:42 -0500, Jon Elson <elson@pico-systems.com>
wrote:

What does this suppose to mean, do, or prove?
Newsgroups: Choose,an,appropriate,group,to,redirect,replies...
If you want to black hole replies, just redirect to /dev/null

Newsgroup changed to: sci.electronics.design,sci.electronics.repair

Jeff Liebermann wrote:
The original failure mode was shorted MLCC caps caused by either
thermal shock or board flex. The bad ones were easy to find with an
ESR meter. However, when I tried to install replacements (and
guessing the part value because Apple doesn't supply service
information to non-authorized repair shops), I managed to crack and
short several known good MLCC caps with a soldering iron. Having
learned the lesson, I used some solder paste and a hot air SMT reflow
gun to do the soldering. I also pre-heated the PCB and let the caps
cool down slowly. I don't know if that was necessary, but it worked
every time. I'm told that two solding irons used as a tweezer also
works, but I haven't tried that yet.

I've heard these stories a number of times. And, yes, maybe some people use
insanely hot irons or in some other way cause this problem. And, some
really large caps are prone to this damage.

Yep. As James Arthur mentioned, it's not a problem with the
physically small caps, which come to a uniform thermal equilibrium
rather rapidly. It's only the big caps, with lots of plates, thin low
voltage ceramic dielectric, and larger thermal mass, that were a
problem for me.

But, as I say, I have hand-
soldered over 25,000 0805 MLCC caps of modest value without seeing this
problem.

One exception will break any such rule. Dig out a larger and higher
capacitance MLCC cap in a 1210 or larger package. Try soldering it
with a single soldering iron. Unless you're very good, it won't take
much to trash the cap.

<http://www.avx.com/products/ceramic-capacitors/high-voltage/high-voltage-mlc-chips/>
"Chip sizes 1210 and larger should be reflow soldered only."

I use a very good Weller temperature-controlled iron, and run it
at a modest temperature.

I use several ancient Weller WTCP TC201 and TC202 (because they were
free) soldering stations. Most of my tips are 750F with a few at
850F.

Much better to use an iron with really good
thermal conductivity at a lower temperature than one with poor conductivity
at a very high temperature.

I don't understand. All the tips are made of plated iron. There's
little difference in thermal conductivity between tips, unless you
want to throw in copper tips heated with a gas burner. What part of
the soldering iron varies in thermal conductivity?


--
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

 

[Andre Majorel]

On 2016-03-29, Jeff Liebermann <jeffl@cruzio.com> wrote:

> Sorry for the delay but I missed the followups to my comment.

Not at all. That was very interesting. Thanks Jeff and everyone.

--
André Majorel http://www.teaser.fr/~amajorel/
J'ai des vrais problčmes, vous avez des faux problčmes.

 

[Michael A. Terrell]

Jeff Liebermann wrote:

On Sat, 26 Mar 2016 19:56:12 +0000 (UTC), Andre Majorel
cheney@halliburton.com> wrote:

Sorry for the delay but I missed the followups to my comment.

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

Thermal shock easily cracks MLCC caps. I learned that the hard way
while fixing several Apple Mac Mini computahs, which feature a
collection of MLCC on the bottom of the main board.
https://web.archive.org/web/20130606062903/http://blog.helpmymac.ru/?p=3585
The original failure mode was shorted MLCC caps caused by either
thermal shock or board flex. The bad ones were easy to find with an
ESR meter. However, when I tried to install replacements (and
guessing the part value because Apple doesn't supply service
information to non-authorized repair shops), I managed to crack and
short several known good MLCC caps with a soldering iron. Having
learned the lesson, I used some solder paste and a hot air SMT reflow
gun to do the soldering. I also pre-heated the PCB and let the caps
cool down slowly. I don't know if that was necessary, but it worked
every time. I'm told that two solding irons used as a tweezer also
works, but I haven't tried that yet.

How were the new caps stored? If it is where they can adsorb
moisture, you can damage them with an iron that is too hot.

 

[Jeff Liebermann]

On Thu, 31 Mar 2016 04:20:59 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

Jeff Liebermann wrote:

On Sat, 26 Mar 2016 19:56:12 +0000 (UTC), Andre Majorel
cheney@halliburton.com> wrote:

Sorry for the delay but I missed the followups to my comment.

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

Thermal shock easily cracks MLCC caps. I learned that the hard way
while fixing several Apple Mac Mini computahs, which feature a
collection of MLCC on the bottom of the main board.
https://web.archive.org/web/20130606062903/http://blog.helpmymac.ru/?p=3585
The original failure mode was shorted MLCC caps caused by either
thermal shock or board flex. The bad ones were easy to find with an
ESR meter. However, when I tried to install replacements (and
guessing the part value because Apple doesn't supply service
information to non-authorized repair shops), I managed to crack and
short several known good MLCC caps with a soldering iron. Having
learned the lesson, I used some solder paste and a hot air SMT reflow
gun to do the soldering. I also pre-heated the PCB and let the caps
cool down slowly. I don't know if that was necessary, but it worked
every time. I'm told that two solding irons used as a tweezer also
works, but I haven't tried that yet.

How were the new caps stored? If it is where they can adsorb
moisture, you can damage them with an iron that is too hot.

Well, I must admit that I didn't take any special precautions.
Methinks that the relative humidity in my office runs between 40% and
60% but is not monitored or recorded. Occasionally, it gets low
enough to where static electricity becomes a problem, or high enough
to where I'm rather uncomfortable, but those are rare. The caps a mix
of cut tape and loose bags stored in Ziploc bags (mostly pink
anti-static) and in paper coin envelopes. Nothing in hard plastic or
metal drawers that might chip or crack them. Although I know that
these caps make tolerable hydrometers (and microphones), I don't think
they can absorb enough moisture from the air to where a steam
explosion would be a problem.

I did some digging to see if humidity might be a problem in storage
conditions. There were plenty of notes on how a cracked capacitor
might allow water to enter the dielectric. Soft (solder) termination
is the recommended fix. Some suggests pre-heating the capacitors
before soldering to drive off any moisture. One demands that the caps
be used within 12 months. I didn't see humidity as being a problem
until AFTER the capacitors had cracked. It would take some time for
the moisture to alter the capacitor characteristics. With my hand
soldering technique, I managed to instantly produce shorted
capacitors, which methinks was more likely due to uneven thermal
expansion, than to moisture incursion.

--
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

 

[krw]

On Thu, 31 Mar 2016 04:20:59 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

Jeff Liebermann wrote:

On Sat, 26 Mar 2016 19:56:12 +0000 (UTC), Andre Majorel
cheney@halliburton.com> wrote:

Sorry for the delay but I missed the followups to my comment.

On 2016-03-22, Jeff Liebermann <jeffl@cruzio.com> wrote:

If it uses an MLCC capacitor, use a hot air gun to reflow, not
a soldering iron tip.

News to me. In what way are multi-layer ceramic caps and
soldering irons incompatible ?

Thermal shock easily cracks MLCC caps. I learned that the hard way
while fixing several Apple Mac Mini computahs, which feature a
collection of MLCC on the bottom of the main board.
https://web.archive.org/web/20130606062903/http://blog.helpmymac.ru/?p=3585
The original failure mode was shorted MLCC caps caused by either
thermal shock or board flex. The bad ones were easy to find with an
ESR meter. However, when I tried to install replacements (and
guessing the part value because Apple doesn't supply service
information to non-authorized repair shops), I managed to crack and
short several known good MLCC caps with a soldering iron. Having
learned the lesson, I used some solder paste and a hot air SMT reflow
gun to do the soldering. I also pre-heated the PCB and let the caps
cool down slowly. I don't know if that was necessary, but it worked
every time. I'm told that two solding irons used as a tweezer also
works, but I haven't tried that yet.

How were the new caps stored? If it is where they can adsorb
moisture, you can damage them with an iron that is too hot.

I haven't had any problems with cracking but I used to have problems
with end caps falling off. I haven't seen the issue for some time,
though perhaps it was a problem with the manufacturer. Our purchasing
group prefers Murata, so that's what I use (GRM series).