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suggestions for higher power white LEDs to testing?

J

Jon Kirwan

Jan 1, 1970
0
I've stayed completely away from driving the higher powered
white LEDs, so far. But I'm interested in playing with some
various boost driver designs of mine made from spare parts I
make out of dead CFL lamps (it's fun to do) and I'd like to
buy an "interesting" collection of roughly-1W category white
LEDs for testing purposes. Right now, I don't have a single
LED that requires more than about 100mW to drive.

I expect to buy perhaps a couple of dozen LEDs to make up a
'representative' variety that hobbyists are actually using in
practice. But I'd like to add some interesting types, as
well. For example, some with ball lenses in front. I only
want to test with singles -- none of that 'tristar' stuff.
(Probably, the 1W range limits that, anyway.) Operating
currents in the 350mA to 500mA should be the bulk, but I also
want to buy one or two 1A LEDs, just to play with. I also
want to include a few at the extremities of color
temperature, but the bulk should be in the 5500K-6000K range,
I think. (I'm ignorant of what is going on in that area, so
advice here is also good.) I'd like to get picks from
various manufacturers, too. And based on various
technologies and phosphors. I'd like to stay with ones that
are known to last -- no point testing LEDs that rapidly age.
And I'm concerned about overly complex heat sink situations,
though I won't mind buying premade supplies for that if they
are available, so some advice on this score for some LEDs
that may be SMT and not so conducive to my jury-rigged setups
may help in making selections where the LED is an SMT type
may help me here, too.

Anyway, open to good experiences. Suppliers you've liked, as
well. My temptation is to just buy only what I can find at
Digikey and do the order, that way. But I know that may be
too limiting and so I'm pretty sure I will need to pick these
up from a variety of suppliers.

Thanks very much in advance,
Jon
 
E

Ecnerwal

Jan 1, 1970
0
Jon Kirwan said:
I've stayed completely away from driving the higher powered
white LEDs, so far. But I'm interested in playing with some
various boost driver designs of mine made from spare parts I
make out of dead CFL lamps (it's fun to do) and I'd like to
buy an "interesting" collection of roughly-1W category white
LEDs for testing purposes. Right now, I don't have a single
LED that requires more than about 100mW to drive.

Well, I haven't played with them yet, but in skimming the pond scum for
interesting parts to add to an order since I was already paying
shipping, I got a few of optek's mini-half-watt series in warm white, as
seeming not too bad on bang/buck and light/watt. I am sort of amused (or
bemused) that their data sheet does not actually connect the cut corner
of the SMD package to polarity...

Those run 180 mA continuous or 350 mA pulsed (10%).
 
J

Jon Kirwan

Jan 1, 1970
0
<snip>
my fav company www.dealextreme.com also carry a wide range of good
quality (and some more typical quality) high power leds.

My only problem with dealextreme is that they owe me $60
still for product they never shipped, after more than a year.
They told me, only about 60 days after they decided they
couldn't ship, they couldn't refund the money to paypal
(which I can't dispute, one way or another) and simply asked
me to find something else to replace. However, there is no
way to access that, anyway. No 'credit balance' I can
include in a new order. I have to go through long, drawn out
emails on the mere hope that somehow someone will maybe
connect an old debt with some later purchase, if and when I
decide to make one.

This isn't considered "okay" in my book. They could write me
a check.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
No. I used a few 1w amber LEDs for experiments into outdoor lighting -
amber and red don't seem to attract many bugs.

That's an interesting experiment to try out. Did it work out
the way you expected?
A friend bought 7000
standard amber LEDs to finish the experiments, duly delivered with no
problems.

This was 7000 of the 1W ambers? I'm trying to imagine both
powering as well as dissipating that and can't imagine this
was a hobby... unless rich, time on hands, and a quirky idea
in mind.
I've also used a few 1w red LEDs for other things. They seemed
to be a little static sensitive and sometimes the construction was not
top notch (average soldering, a lens fell off, but at least they were
correctly orientated on the heatsink)

Hmm. Not exactly stellar. Were those also from that site?

Thanks,
Jon
 
J

Jon Kirwan

Jan 1, 1970
0
I had trouble with a refund too. A product missing one of the advertised
features. I had to write it off and decided that I would deal with them
as if they offered no warranty of any kind.

Okay. That's not quite the same thing as simply not
refunding nor sending product. But I take the point.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
Yeah only a few bugs - much better than an incandescent, very much
better than a florescent. Amber is also much better than red for stuff
like barbecues (food prep) and reading outdoors etc. But red does
attract the fewest bugs.

Makes sense.
7000 standard 5 mm (high intensity with a ridiculously highly focused
beam) - I thought the 1w was the better approach. But yes he had too
much time and a quirky idea in mind - nothing came of it.

I'm imagining an airport runway lighting....
BTW do you
want to buy some LEDs - as long as your not fussy on the colour and buy
by the 1000's I know a guy ....

I'm probably interested. Obviously, it'll be about
reasonable value and I'd like to get at least _some_ whites
in the roughly 1W power I mentioned if I go that route.

But yes, my LED supply is not very large and I'm interested
in doing more, now.
Yep. Average Chinese stuff. Hobbyist grade. I should clarify the
soldering. It looked OK, I had no doubts it would work for the lifetime
of any project, but I have seen better soldering. If it looked like it
might have caused a failure or been faulty itself I would have called it
bad soldering. Perhaps serviceable or workman-like is the better
expression.

Got it.

Thanks,
Jon
 
E

Eeyore

Jan 1, 1970
0
Jon said:
I've stayed completely away from driving the higher powered
white LEDs, so far. But I'm interested in playing with some
various boost driver designs of mine made from spare parts I
make out of dead CFL lamps

Unlikely to be useful component values for the purpose. Plus components
like electrolytic caps are likely to be end-of-lifed by the time a CFL
fails. The mosfets and rectifiers might be OK but that's about it. Any
inductor / transformer will be compromised by the fact you'll have no
info on the material and value / ratios unless you measure it.

Suggest design from scratch.

Graham
 
J

Jon Kirwan

Jan 1, 1970
0
Unlikely to be useful component values for the purpose. Plus components
like electrolytic caps are likely to be end-of-lifed by the time a CFL
fails. The mosfets and rectifiers might be OK but that's about it. Any
inductor / transformer will be compromised by the fact you'll have no
info on the material and value / ratios unless you measure it.

Suggest design from scratch.

Um. I did design from scratch and I've already done all
this.

I use the larger transformer for magnet wire. That's all.
There is a tiny (usually yellow, or somewhat darker) toroid.
That gets extracted and its wire is removed, also. The
magnet wire I get from the larger transformer is then used
(only a small part is needed) to wind the toroid.

The CFLs I have here use BJTs. They work fine on those units
that are broken, with some rare exceptions. There are two of
them and so far one has always worked. Even if it didn't,
I'd grab one from another CFL. So it's not a problem.

I don't need the caps. They aren't required.

I do need a resistor. Sometimes, the ones inside are about
the right value. Sometimes, I use one from my junkbox. But
I can usually adapt the transformer design to cope with
whatever I do find, if that were terribly important.

The LED I buy. Obviously. Since I posted about that.

This is a game I play with students to show them what they
can do with junk and a little effort and knowledge.

Jon
 
E

Eeyore

Jan 1, 1970
0
Jon said:
This is a game I play with students to show them what they
can do with junk and a little effort and knowledge.

Might be more useful to show them what they can do *without* using JUNK
! They might learn some REAL design skills.

Graham
 
J

Jon Kirwan

Jan 1, 1970
0
Might be more useful to show them what they can do *without* using JUNK
! They might learn some REAL design skills.

I see you've never been a child.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
A colleague used a white LED to replace a flash lamp in a product.
Part number
LXML-PWN1-100. We are obviously just flashing it, but when he ran it
CW it hurt to look at it.

~$2.50 each in quantities of 100’s from Future Electronics.

I think we drive it with only 0.3 to 0.5 amps it claims to be able to
handle 0.7 A.

I will take a look. [Though I'm honestly not looking (yet)
to buy 100 of a single part.]

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
Might be more useful to show them what they can do *without* using JUNK
! They might learn some REAL design skills.

This coming from someone who thought I needed a capacitor,
didn't notice I needed a resistor, and wasn't sure about
mosfet vs bjt (which is a difference in complexity) for a
project that uses just three parts?

Although I wouldn't imagine to know more than you do about
audio amplifiers, Graham, I know more about this particular
project than you do.

Care to be helpful, rather than critical? Can you offer some
helpful suggestions about LEDs? Or would you prefer sharing
in a little discussion with me about the REAL design skills
involved, where it might help others to see your brilliance
in action?

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
I wasn't thrilled with them. I ordered some calipers from them.
Backordered of course. Three months later I finally get them, and in
that time Harbor Freight had them for a few dollars less.

That was _almost_ my case. My products were backordered for
some time and eventually I decided to send a message asking
what is going on and when the backorder would be released.
More time goes by (month more? that, after a previous 6
weeks of delay) and I get a message about "would you like to
get something else?" Dialog is very slow (language?) and it
took still more time to begin to understand that they
intended to keep the money no matter what and not make it
easy, either, to put it onto some other order. I still don't
know how that gets done.

And, I suppose, I've become less interested in finding out.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
I've had good results with:
http://stores.ebay.com/Shop4leds

I got some piranha style RGB leds and some "straw hat" style 100 ma
white leds - the straw hat ones are at their limit with 100 ma going
through them - one set lasted for a few months (dawn to dusk - fine in
winter dead or dying in summer. Reduced the current to 50 ma and they
are good year round.

Okay. I've often wondered about aging issues. So that's
good to know.

When high power is the primary goal of a product, often other
goals are sacrificed on its alter.

I'll take a look on Shop4leds on ebay, too, then.

thanks,
Jon
 
E

Eeyore

Jan 1, 1970
0
Jon said:
I see you've never been a child.

I see you don't realise the disadvantages of use life-expired
components. I bought new parts for the vast majority of my hobby projects.

Graham
 
E

Eeyore

Jan 1, 1970
0
Jon said:
This coming from someone who thought I needed a capacitor,
didn't notice I needed a resistor, and wasn't sure about
mosfet vs bjt (which is a difference in complexity) for a
project that uses just three parts?

WTF are you talking about ?

Graham
 
J

Jon Kirwan

Jan 1, 1970
0
I see you don't realise the disadvantages of use life-expired
components. I bought new parts for the vast majority of my hobby projects.

Besides the fact that these are kids, Graham, it is exciting
for them to do something useful and fun with parts their
parents throw away. Kind of a segue to more. And it often
impresses their parents, which may for some excite them
towards further effort. And I can always help them at that
point, if they are interested in doing more.

I am on the ground, spending _my_ time in the trenches with
kids, Graham. I am dealing with what I have to work with. If
you'd like to come on over and help out, I'm all for it. And
I'd value your opinion on this more, then, because of your
direct experience with my situation.

What are _you_ doing, Graham, to pass on your knowledge and
interests to children?

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
WTF are you talking about ?

Without the battery or LED, three parts. You didn't follow
and I guess we can leave it there, then. :)

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
---
Don't you mean: "of using"?

But, in that vein, why would an Allen-Bradley carbon comp resistor
made in 1945 not work now, and perform to spec.?

Or, for that matter, a 2N2222 made a dozen years ago?
---


---
Bullshit.

You bought what you could get, and whether they were "new" parts was
the least of your concern.

Maybe Graham is just saying he was born with a silver spoon
in his mouth. But I really think it is his failure to
actually remember what it is like as a kid looking in, from
the outside.

I didn't do much as a kid -- instead spending far more time
on optics, explosives, rocketry and the like. Some others
did and they eventually made career decisions and left me far
behind in this regard. But I've always had a kids interest
in electronics, as a hobby. Never had a single hour of
formal training in it, though.

But I remember vividly building my first radio out of galena
and molten lead, with a sewing needle, to make the diode. And
all the rest involved, too. And making a jacob's ladder from
a TV flyback supply. And calling up a bowling alley owner
for permission to scavenge what I could from his building
after it was hit by a tornado the day before, for parts. And
tearing apart phone company throw-aways I'd get out of a
dumpster behind their building. Etc.

I had no money, lived in a home without walls at the time,
and had to get by without a lot that some living in better
circumstances had access to.

It's possible that Graham has no idea about any of this and
had everything pretty much handed to him.

Jon
 
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