suggestions for higher power white LEDs to testing?

On Thu, 26 Aug 2010 22:15:51 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:
On Thu, 26 Aug 2010 16:51:06 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:
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.
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 ?

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

Besides the fact that these are kids, Graham

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?

I bought new parts for the vast majority of my hobby projects.

---
Bullshit.

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

I've often wondered about aging issues.

On Thu, 26 Aug 2010 14:46:14 -0700, Jon Kirwan <jonk_at_infinitefactors.org> wrote:

On Thu, 26 Aug 2010 22:14:20 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:
On Thu, 26 Aug 2010 16:51:06 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:
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.

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.

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

What makes you think kids read Usenet, let alone even know of its
existence ?

Jon Kirwan wrote:

I've often wondered about aging issues.

Most higher power LED manufacturers quote lifetime at 70% of initial
luminosity.

Jon Kirwan wrote:
On Thu, 26 Aug 2010 22:15:51 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:
On Thu, 26 Aug 2010 16:51:06 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:
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.
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 ?

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

You didn't answer my question.

snip
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 ....
snip

On Thu, 26 Aug 2010 09:24:05 -0700 (PDT), George Herold

ggher...@gmail.com> wrote:
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

On Aug 26, 2:43 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
On Thu, 26 Aug 2010 09:24:05 -0700 (PDT), George Herold

ggher...@gmail.com> wrote:
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

Oh, If these might work for you, I could slip you a few in an
envelope. I've got some other white LED's kicking around from a
previous project, but mostly through hole, lower current ones.

There's a slush fund here where I put money for the parts/ supplies
that I steal from work, so I can add a few bucks to help out the
education effort.

I just sent $50 to the OSA for a Galileoscope project. Students get
to make their own telescope. The $50 covers parts, one is sent to a
school and I got one for myself (and my kids)

On Fri, 27 Aug 2010 07:44:33 -0700 (PDT), George Herold





ggher...@gmail.com> wrote:
On Aug 26, 2:43 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
On Thu, 26 Aug 2010 09:24:05 -0700 (PDT), George Herold

ggher...@gmail.com> wrote:
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

Oh, If these might work for you, I could slip you a few in an
envelope.  I've got some other white LED's kicking around from a
previous project, but mostly through hole, lower current ones.

Well, if you feel that is okay.  I had no problem at $2.50
ea, just the "100's" part of it.  If you are willing to sell
a few of them, I'm fine with that.

There's a slush fund here where I put money for the parts/ supplies
that I steal from work, so I can add a few bucks to help out the
education effort.

Or I can send it.

I just sent $50 to the OSA for a Galileoscope project.  Students get
to make their own telescope.  The $50 covers parts, one is sent to a
school and I got one for myself (and my kids)

Hehe.  Is this something akin to the "one laptop per child"
thing, where you buy two and get one?

Jon- Hide quoted text -

- Show quoted text -

On Fri, 27 Aug 2010 02:47:48 +0100, Eeyore
rabbitsfriendsandrelations_at_removethishotmail.com> wrote:

Jon Kirwan wrote:

I've often wondered about aging issues.

Most higher power LED manufacturers quote lifetime at 70% of initial
luminosity.

Which provides a definition for one point. It doesn't say
much about the different causes and the general picture or
what one might expect in some specific situation.

Which provides a definition for one point. It doesn't say
much about the different causes and the general picture or
what one might expect in some specific situation.

Which provides a definition for one point. It doesn't say
much about the different causes and the general picture or
what one might expect in some specific situation.

Well, as to specific causes, cooking is a big one. Pay a lot of
attention to cooling, and/or don't run at peak power. While it's nice to
get everything it's got to give, getting the heat out is a big issue
with the high power LEDs, and not getting the heat out is a major cause
of degradation at higher than expected rates.

Which provides a definition for one point. It doesn't say
much about the different causes and the general picture or
what one might expect in some specific situation.

Well, as to specific causes, cooking is a big one.

Pay a lot of
attention to cooling, and/or don't run at peak power. While it's nice to
get everything it's got to give, getting the heat out is a big issue
with the high power LEDs, and not getting the heat out is a major cause
of degradation at higher than expected rates.