Daylight viewable LEDs in small package?

[ejaf]

Hi...

Just trying to find a daylight viewable LED, that's in a package smaller than the usual 3/5mm housing.

Not sure exactly what MCD to get in order to see it in daylight, but looking around, there's a big difference between the standard LEDS (that can put out >10000 MCD on 70mA), and SMD LEDs (can't think of a package size between smd and the through hole).

Question 1: What's the lowest MCD that can be seen in daylight (not direct sunlight).
Question 2: What other package options do I have between smd and the standard 3/5mm (there are lots, but they are for specialized apps, usually). Anyone have experience with different sizes? I would love an SMD, but can't seem to find one with high MCD rating.

I'm going to be able to pulse them, so I will be able to use the max MCD ratings, rather than the typical.

Any experience/feedback helpful.

TIA...Eric

[wdutcher]

I do vehicle testing and often use the red/green bicolor LED's with clear lens. They are easly seen on the dash even in direct sun light drawing 10 to 20ma because of the color change.

[ejaf]

Right...but those are the standard 5mm LED package, correct?

[kit]

http://www.goldmine-elec-products.com/products.asp?dept=1089

[ejaf]

kit...

Thanks for the link, but I've already ordered from them before...see my orginal question, please.

I've actually just ordered 1206 LEDs that are pumping out about 500 MCD typical, I'll see if they are strong enough to see in daylight. I also ordered from the same store 7.62mm High Flux in red and green, which put out shed loads higher mcd ratings on 20ma current, and have a wide angle, but afraid that they may be too big for my application.

Guess there's nothing better than experience, huh?

Eric

[Smokin' Beaver]

Not LED's but the globes from mini Maglites are visible in daylight.
power consumption may be a problem though.
also these have a 180 degree spectrum where LED's don't which makes them useful for wing tip & fuselage lights.
you can get them in 1.5v or 2.5v versions too

[ejaf]

interesting idea...thanks.

Will google, to see if I can find specs on how many amps they draw.

Eric

[ALtitudeap]

try these from digikey. LTST-C930KAKT
they are surface mount and will blind you even in daylight.

[AleG]

I have some red, greenn white and blue 403 LEDs that are plainly visible in broad daylight, pretty amazing things; I`m going to use them on a voltage monitor.
I couldn`t tell you the manufacturer though, I just bought them at a small electronics store here in Bangkok.

[ejaf]

The ones in Digikey are 1050 MCD and they blind you? Awesome...the ones I just got off of fleabay are even higher...should work well, then.

Eric

[z-matrix]

Hi...

Just trying to find a daylight viewable LED, that's in a package smaller than the usual 3/5mm housing.

Not sure exactly what MCD to get in order to see it in daylight, but looking around, there's a big difference between the standard LEDS (that can put out >10000 MCD on 70mA), and SMD LEDs (can't think of a package size between smd and the through hole).

Question 1: What's the lowest MCD that can be seen in daylight (not direct sunlight).
Question 2: What other package options do I have between smd and the standard 3/5mm (there are lots, but they are for specialized apps, usually). Anyone have experience with different sizes? I would love an SMD, but can't seem to find one with high MCD rating.

I'm going to be able to pulse them, so I will be able to use the max MCD ratings, rather than the typical.

Any experience/feedback helpful.

TIA...Eric

the best i can suggest is to use Cree (www.cree.com) XL4550 leds,
these have very high optical outputs. viewing angle is 100 degrees, maximum current is 125 mA @ Vf_typ of 2.2V
color luminous/radiant flux
red 12 lumen
amber 8.4 lumen
green 18 lumen
blue 4.5 lumen
royal blue 65mW

it's a pain looking at them when powered 125mA
since this led is smd, you have to use proper reflow soldering or performance will degrade.
this is smaller than an 5mm led, if you want smaller, order led chips and try wire bonding them with aluminium/gold wires.

btw, mCd tells the relative amount of light radiated by the led compared to a candle
basically it is "milli Candels", so 1000mCd equals 1 candle's light.
also, you can sand paper the standard 5mm led package to be somewhat smaller, there are 15000mCd types in red at 20mA
note that led light output efficiency decreases with increasing drive current, unless you need a strobe light, there will be no advantage of driving a led with pulses.

Z

[ejaf]

try wire bonding them with aluminium/gold wires.
Could you elaborate on this idea?

Thanks for the cree info, but 125ma is a little too much draw. Actually want to strobe them to save power: thought that doing this at the LEDs max settings would give out more light.

Eric

[Brandano]

Considering that an LED emits hardly any heat, most of the current that goes into it is directly related to their output. Higher brightness = higher current, there's little to do about it. Most white LED's are visible in daylight, though other colors might be more apparent. I'd use a 5mm hyperbright red LED with the casing filed to diffuse the light more broadly than the usual 90 degrees angle and reduce the weight. Also the LED's from christmas tree decorations should work, and their casing is already arranged to increase the visible angle

[z-matrix]

Could you elaborate on this idea?

Thanks for the cree info, but 125ma is a little too much draw. Actually want to strobe them to save power: thought that doing this at the LEDs max settings would give out more light.

Eric

that is for led chips without package, if you want the least size, though i doubt you would like to get equipment for wire bonding led chips at home.

ps.: this led will give you higher brightness than any other leds at same current, let's say 20mA