DIY LED lights

[ALToronto]

Thanks lpm. So if I have a total of 11 white LEDs consisting of 7 warm and 4 cool, 5W each, should I add maybe four 690 nm diodes, 1W each? I'd probably have to run them on a different driver, or else the configuration would be too complicated.

I appreciate the advice.

---------- Post added at 11:14 PM ---------- Previous post was at 11:11 PM ----------

I have severe vertical space constraints, so halogen bulbs are out of the question. This light fixture has to fit inside a 3 cm vertical space. The horizontal dimensions are about 80 x 50 cm.

[DavidCampen]

Originally Posted by lepetitmartien

690 on the other side is very beneficial David, it's still in the chlorophyl A red peak.

I did not say otherwise. My point, which I should have explained, is that an LED with a specified emission at 690nm is not emitting at exactly 690 nm; it may be emitting at, say, 720 nm; which would be out of the chlorophyll absorption region.

Looking briefly, I couldn't even find a datasheet for a 690 nm LED. Who makes these?

[ALToronto]

Not the place I'm getting mine from. They stop at 665.

[naoki]

Originally Posted by DavidCampen

I did not say otherwise. My point, which I should have explained, is that an LED with a specified emission at 690nm is not emitting at exactly 690 nm; it may be emitting at, say, 720 nm; which would be out of the chlorophyll absorption region.

Looking briefly, I couldn't even find a datasheet for a 690 nm LED. Who makes these?

Shenzhen Fedy claims to have one in 680-690nm range:
Epistar 3w 660nm led, View Epistar 3w 660nm led, FEDY Product Details from Shenzhen Fedy Technology Co., Limited on Alibaba.com

But most of deep red diodes seem to be around 660nm.

Alla, I don't know what current you are going to drive 5W diodes, but that seems to be pretty weak for the area you want to cover. Most commercial ones seem to be driving 5W diodes at 2-3W.

[ALToronto]

The current issue is one i'm trying to sort out with the manufacturer. If I'm going to be using up to fifteen 5w LEDs in a fixture, I should need a 75+ W driver, correct? And if each LED is drawing 15-17.5 v, and they're in series, this adds up to arc welder voltage and very little current, correct? I'm just trying to remember what I learned in 2nd year, in the mandatory Electrical Machines course that all mechanical engineering students had to take. That was in 1982, so my recollection is a little fuzzy.

[Nexogen]

I'm completely in fog. I think is better if you buy already assembled from factory.
You need data book and there is the current and voltage per LED.

[ALToronto]

Originally Posted by Nexogen

I'm completely in fog. I think is better if you buy already assembled from factory.
You need data book and there is the current and voltage per LED.

Your idea would be great if a suitable fixture existed. But it doesn't. In fact, the biggest appeal of LEDs is their versatility and customizability. Otherwise, I would just use fluorescents.

This is just like putting together a computer from components - only the first one is a challenge.

[Nexogen]

without data sheet you can't control led
It's an led or led module? Give me the name and producer, I can help you.
For exemple CREE XLamp XB-D LED

Forward voltage (@ 350 mA, 85(?) °C) - white (2.9 - 3.5)Volt
Forward voltage (@ 350 mA, 25 °C) - royal blue, blue (3.1 - 3.7)Volt
Forward voltage (@ 350 mA, 25 °C) - green (3.3 - 3.9)Volt
Forward voltage (@ 350 mA, 25 °C) - amber, red-orange, red (2.25 - 2.6)Volt

[DavidCampen]

Originally Posted by ALToronto

The current issue is one i'm trying to sort out with the manufacturer. If I'm going to be using up to fifteen 5w LEDs in a fixture, I should need a 75+ W driver, correct? And if each LED is drawing 15-17.5 v, and they're in series, this adds up to arc welder voltage and very little current, correct? ...

If you have 15 LED modules that have a forward voltage of 15 volts per module when driven at a current of 1000 ma and you put these 15 modules in series then you will need a forward voltage of 225 volts to drive the string at 1000 ma.

[DavidCampen]

Here is my latest LED housing design. The copper cup is a 1.5" copper pipe end cap, the other piece of copper is a 1.5" to 1.25" copper pipe reducing adapter that has had the length cut down on both ends. The LED module is a LEDEngin LZ4, 10 watt 660 nm LED module purchased mounted on a star Metal Clad Printed Circuit Board.