suggestions for higher power white LEDs to testing?

Wed Aug 25, 2010 7:40 pm   

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

Wed Aug 25, 2010 8:47 pm   

In article <ovna7651f35uq5j3k9dmcdtlih9ckgt11a_at_4ax.com>,
Jon Kirwan <jonk_at_infinitefactors.org> wrote:


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%).

--
Cats, coffee, chocolate...vices to live by

Thu Aug 26, 2010 12:44 am   

On 26/08/2010 5:47 AM, Ecnerwal wrote:

lots of Chinese stuff - so just the thing hobbyists are playing with

http://ledz.com/

Thu Aug 26, 2010 12:46 am   

On 26/08/2010 5:47 AM, Ecnerwal wrote:

quality (and some more typical quality) high power leds.

Thu Aug 26, 2010 4:38 am   

On Thu, 26 Aug 2010 09:44:13 +1000, David Eather
<eather_at_tpg.com.au> wrote:


Any experiences with specific LEDs from there in the watt
area I'm looking for?

Thanks,
Jon

Thu Aug 26, 2010 4:42 am   

On Thu, 26 Aug 2010 09:46:34 +1000, David Eather
<eather_at_tpg.com.au> wrote:


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

Thu Aug 26, 2010 5:00 am   

On 26/08/2010 1:42 PM, Jon Kirwan wrote:

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.

Thu Aug 26, 2010 5:05 am   

On 26/08/2010 1:38 PM, Jon Kirwan wrote:

No. I used a few 1w amber LEDs for experiments into outdoor lighting -
amber and red don't seem to attract many bugs. A friend bought 7000
standard amber LEDs to finish the experiments, duly delivered with no
problems. 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)

Thu Aug 26, 2010 10:53 am   

On Thu, 26 Aug 2010 14:05:56 +1000, David Eather
<eather_at_tpg.com.au> wrote:


That's an interesting experiment to try out. Did it work out
the way you expected?


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.


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

Thanks,
Jon

Thu Aug 26, 2010 10:56 am   

On Thu, 26 Aug 2010 14:00:49 +1000, David Eather
<eather_at_tpg.com.au> wrote:


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

Jon

Thu Aug 26, 2010 11:26 am   

On 26/08/2010 7:53 PM, Jon Kirwan wrote:

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.


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. 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 ....


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.

Thu Aug 26, 2010 12:23 pm   

On Thu, 26 Aug 2010 20:26:35 +1000, David Eather
<eather_at_tpg.com.au> wrote:


Makes sense.


I'm imagining an airport runway lighting....


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.


Got it.

Thanks,
Jon

Thu Aug 26, 2010 12:34 pm   

Jon Kirwan wrote:

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

Thu Aug 26, 2010 1:00 pm   

On Thu, 26 Aug 2010 12:34:25 +0100, Eeyore
<rabbitsfriendsandrelations_at_removethishotmail.com> wrote:


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

Thu Aug 26, 2010 4:51 pm   

Jon Kirwan wrote:

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

Graham