Choosing led / led strip for specific project

[Jaunedeau]

Hi,

I have a project, which is a desktop lamp using many small leds. The lam pdoes not need to be very bright, it will be used for ambiance or to watch TV in a not completely-dark room. I *guess* that something around 300-600 lumen would be fine (similar to a 40-50W incandescent bulb). Cold white or warm white would be nice. Pure white would be to hospital-like

The lamp was originally designed to use flexible-pcb SMD led strip. but after some calculation, the given flux is certainly over rated. If we can get 30 lumen per watt from them, 10.5V and 20mA per 3-leds would give 126 lumen per meter, which means less than 200 lumen for the lamp (1400mm of led strip, 60 leds per meter on standard 5meter rolls).

Of course there are other options, like 90 leds per meter strip, or 5050 leds instead of 3528, which would give twice the luminosity. So I searched the forum for information, and came across the "5mm LED fade testing continued" which makes me wonder if the chinese $25 5 meter led reels are good solutions.

Another option would be to include copper wire in the designe of the lamp, and directly soler solder SMD leds on the copper wire instead of user led strips. So the problem would be to find leds which are :
-About 5 lumen each
-Slightly warm white or slightly blue, not pure white
-Long lasting
-Not to hard to source
-Wide angle

Looking at Osram website, I found LW E6SG (3.5 lumen), and LUW E6SG (4.9 lumen), but at $1 + shipping on digikey, it is not in my budget.

Does someone have an idea so I can finish the lamp before christmas ?

Thanks you,
jaune.

 

[Jaunedeau]

mmm,

So, nobody is aware of a cheap source for SMD led that match their spec and can run for 10.000 hours ?

It seems that the trend is mode to those 3W star leds nowadays

Jaune.

 

[AnAppleSnail]

mmm,

So, nobody is aware of a cheap source for SMD led that match their spec and can run for 10.000 hours ?

It seems that the trend is mode to those 3W star leds nowadays

Jaune.

Generally you can only get quality 5mm LEDs from Cree and Nichia by the roll. Grab 3 XR-Es for about $14 all together, Arctic Alumina epoxy them about hand-length apart to an aluminum rail, and put a decent diffuser on it. Power's a bit trickier when you can't get Vf to add up to house voltage. But then 120v isn't very handy for DIY anyway...

 

[Jaunedeau]

mmm, ok, but my design requieres smd led. I'll try to contact nichia directly to see if I can order 500 leds from them for a decent price !

 

[Optical Inferno]

It seems that the trend is mode to those 3W star leds nowadays

Jaune.

If you are wanting to do an SMD style of design don't even look at low powered 5mm LEDs, go high powered like AppleSnail said. You can get the same desired colour, and output from less LEDs like the XR-E he suggested. You can even try to get some of the newer Cree MX-6S LEDs with a higher forward voltage to make you driver design a little easier. I think you can get them through Digikey or Mouser.

 

[Jaunedeau]

>You can get the same desired colour, and output from less LEDs

I understand that, and already have made lampe with 360mA leds, but for THIS lamp I am making, what I need is 150 leds with about 7 lumen each. Of course I can adapt this, but the design by itself requires a large number of small leds pointing in different direction (100 to 200 leds, with a total output of 500 to 1000 lumen).

this is only for esthetic reasons. I understand that high power led are better to make lamp, but THIS lampe would just not good with 4 cree Q5.

5mm led because they would not look good either, I as going for 3528 or 5050 leds. The problem is to find a reliable source (for led which stand their specifications and do not have a fast derating over time) at a decent price.

Leds strips seems to be good, but it is very hard to find (and trust ^^) the datasheet.

Another possibility is to make change to the design, so I can cope with 20 CREE Q2. Total cost would be about $80, which is a bit over the budget but possible.

Chinese vendors can sell the smd leds for $0.10 including shipping (if you order 1000 pieces), and IF I trusted their 70l/W claimed efficiency, I'd say that I can do 7 lamps with about 600 lumen each, for $15 or led in each. That would be perfect. But if the lamp only give 300 lumen and start fading after 5 hours, I would just have lost $100 and plenty of time

I hope we can trust data from osram, but $500 with shipping for 1000 piece (or $150 for the 150 pieces I need) is over budget (digikey's price)

So, any other idea to get many reliable smd white led with about 5 lumen per led for a low price ?

thanks,
Jaune.

 

[CKOD]

Try digikey and mouser, they have other brand LED's but I'd still put any brand on there well above ebay specials. Digikey's search is fantastic, and mouser's is improving compared to what it used to be.