Fast, efficient IR LEDs?

Phil Hobbs a écrit :

Shh. Don't feed the Jiant Troll :-)

Maybe use a visible part? They seem to get the most development effort lately. I'll measure the capacitance on some of the right-angle surface-mount Osram parts we use. They are blindingly bright, clearly on at 1 uA in normal office lighting.

The red response of a silicon detector isn't much below the IR peak.

And now, back to politics...

John

I looked, but I haven't found any with speed and capacitance specs. If you can find any that are quick and have an output of above 0.5 W/A, that would be perfect. (Because each photon has more energy, you need more photons for a given photocurrent, and it's a photocurrent that's the desired output--it's sort of a special-purpose dorked optocoupler. Smaller would be good too.

The IR ones have been really bright for awhile--the 15-year-old DN401s (corrected P/N) are very nearly as efficient as the newest ones, and only a factor of 2 slower. The IRDA application is why they need speed specs, and nobody does IRDA in the visible.

Cheers

Phil Hobbs

This one is too big, too much capacitance, but they have smaller plastic versions, maybe give them a ring?

That can change in milliseconds :-)

I measured a red one of these at 9 pF, orange at 13.5. I have no idea what the optical power output may be, or the ctr you can get into a silicon detector. We consider 5 mA to be "bright" on the red and green, 10 mA for the orange and blues. "Dim" is 1/10th that.

These are really nice led's. The colors are bright and pure, the orange being especially nice looking. And they are dual-shot moulded, so they don't melt when you solder them.

John

pF typ

cs

=A0no C spec

I have no part numbers to recommend. (Sorry) But I wonder why IR LED=92s are so much more efficient than visible. (I calculate about 33% efficiency for the 850nm at 0.5W/A.) (O.5 W/A =3D 0.5 eV/electron and each photon is about 1.5 eV)

George H.

pF typ

cs

=A0no C spec

Isn't low current and high speed mutually exclusive, like intelligence and Republicans?

Hmm, interesting. The red ones specify about 7 lumens/W at 635 nm. The photopic response there is about 22% of the peak value, or 138 lumens/W, which makes these ones about 0.05 mW/mA, which is a bit on the low side. I definitely like the capacitance though!

Cheers

Phil Hobbs

Ah, politics!

I wonder why lefties always assume that conservatives are stupid. That's the "what's wrong with Kansas?" dilemma, the lament that the working class won't toe the party line and follow the lead of their betters.

Conservatives generally assume that lefties are both stupid and evil.

John

Yeah, I guess 635 isn't red enough.

John

How retro. ;) I'll do that, thanks.

Cheers

Phil Hobbs

Nice try, Soup. ;) I enjoy talking electronics too much though.

Cheers

Phil Hobbs

His "email address" always makes me crave miso soup and sushi. So, we just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have sushi in the evenings, I can't really work after that, it's so good that I tend to eat too much of it.

...lefties are both stupid and evil _and_ pathological liars. ...Jim Thompson

gizmo.

Other

=A070 pF typ

specs

l, =A0no C spec

Sushi doesn't make for an evening meal. Just too light, even when supplemented with miso soup. It's better for lunch.

Getting back to electronics., this is really an i=3Dc*dv/dt issue. It seems to me all you can do is reduce C if current is limited.

"Jim Thompson" schrieb im Newsbeitrag news: snipped-for-privacy@4ax.com...

To me it seems both leftist and rightists are apparently mainly bored and they appear boring to others as well. Nobody here is interested in political drivel of any colour and it is a pity this group has turned into 90% crap. ciao Ban

Design any cool electronics lately?

John

Yes!! Bash them Russkies AKA REDs!

Hmmm...try the Rohm SMT LED, 755-SML-P12YTT86 is the Mouser P/N. Seems rather bright at 50uA (it is yellow; there was a red one almost as good but do not remember the part number).