Anyone know of any individual LED group buys?

[number1gsxxr]

I'm going to be purchasing the following parts. These are the best prices I have found so far. Does anyone know of of any group buys going on, or want to jump in on the ones I am buying to save on price/shipping?

Luxeon Rebel SMT Emitter High Power LED Cool White Lambertian 350 mA 100 Lumens

Rebel SMT Emitter High Power LED Royal Blue Lambertian 350mA 425mW Lumens Min

Future Electronics:

LXML-PWC1-0100 (Cool White Rebel)
52 @ $3.72 = 193.44

LXML-PR01-0425 (Royal Blue Rebel)
52 @ $4.40 = $228.80

REBEL STAR (Mounting star for Rebel)
104 @ $0.57 = $59.28

 

[DoctaQ]

http://www.dealextreme.com/details.dx/sku.2134

if you get the 52 to replace the whites you will spend a hair over 3 dollars each and they are already mounted to stars, only 80 lumens though
or
http://www.dealextreme.com/details.dx/sku.2394

for a little more than yours but slightly higher effeciency, but at the high drive currents 700+ma, the cree is king.

 

[focus]

Do you have a reflow oven to mount the leds? Or some other means of doing this properly? It is pretty difficult to do and you won't save anything if you cook the leds. I would suggest buying them already mounted on the stars.

I'm going to be purchasing the following parts. These are the best prices I have found so far. Does anyone know of of any group buys going on, or want to jump in on the ones I am buying to save on price/shipping?

Luxeon Rebel SMT Emitter High Power LED Cool White Lambertian 350 mA 100 Lumens

Rebel SMT Emitter High Power LED Royal Blue Lambertian 350mA 425mW Lumens Min

Future Electronics:

LXML-PWC1-0100 (Cool White Rebel)
52 @ $3.72 = 193.44

LXML-PR01-0425 (Royal Blue Rebel)
52 @ $4.40 = $228.80

REBEL STAR (Mounting star for Rebel)
104 @ $0.57 = $59.28

 

[focus]

Oh they have some private sellers over here letting the leds go cheap. Usually they have GB also but i didn't see a current one.

http://www.nano-reef.com/

 

[number1gsxxr]

I have a friend who is an electrical engineer who is helping me with my DIY. Hopefully I assume he has all the necessary tools to solder it the right way.

 

[DoctaQ]

you should ask him if he can reflow smt because you cant solder an led to a star with a soldering iron, either a reflow oven or a heat gun.

on a side note, i used a candle warmer, the kinds used to melt candles to release the smell instead of burning it, to desolder an led from a star, with some flux and high quality soldering paste it could be possible and i am interested in the solution you come up with here as well, keep me posted.

the temp was about 130c

 

[Royalty]

I have a friend who is an electrical engineer who is helping me with my DIY. Hopefully I assume he has all the necessary tools to solder it the right way.

let me know how it works out for cause im planing the samething i really want some leds but the cost of a led light fixture is way more then what i feel like spending.

 

[phalanx]

you should ask him if he can reflow smt because you cant solder an led to a star with a soldering iron, either a reflow oven or a heat gun.

on a side note, i used a candle warmer, the kinds used to melt candles to release the smell instead of burning it, to desolder an led from a star, with some flux and high quality soldering paste it could be possible and i am interested in the solution you come up with here as well, keep me posted.

the temp was about 130c

I'm the "him" that everyone is refering to. I have a few ways to reflow rebel stars that have worked in the past. If the stars come in a multi-unit panel, the fastest way is to use a hot plate or toaster oven to reflow them. If they are individual stars, I use a mapp gas torch turned down very low and hold the stars over the flame with needle nose pliers.

I like the cheap prices on the DX Cree stars but what sent me back to the Rebels was the very high price of XP-E royal blue Cree's. The top of the line royal blue rebel is considerably cheaper than the equivalent Cree. By keeping the whites in the Rebel line, I can get a better volume discount on 50 degree optics which puts them in the $0.93 a lens range which is also a fair amount better than what I could find for cree optics.

Ultimately the goal was to save money while still having a substantial array to cover the entire 75g tank. 100 LEDs will be in the array (the additional 4 are for testing purposes) and they will be driven by 4 custom controllers based on the Supertex HV9961 controller IC running off 120VAC. This will eliminate the need for upwards of 14 buckpucks and the associated 300-400W powersupply to go along with it. The drivers will have an isolated PWM dimming interface for easy intensity control. It will take some experimenting when the parts come in to see if my concept will work but the design will have a selectable high and low current range for the array (outside of the PWM dimming) that will hopefully allow me to use the royal blues as moonlighting if I can get the current low enough to them.

 

[sciknen]

I'm trying to get a group buy together on here.. from LED supply.. I'm going with Cree though i think

 

[DoctaQ]

I'm the "him" that everyone is refering to. I have a few ways to reflow rebel stars that have worked in the past. If the stars come in a multi-unit panel, the fastest way is to use a hot plate or toaster oven to reflow them. If they are individual stars, I use a mapp gas torch turned down very low and hold the stars over the flame with needle nose pliers.

I like the cheap prices on the DX Cree stars but what sent me back to the Rebels was the very high price of XP-E royal blue Cree's. The top of the line royal blue rebel is considerably cheaper than the equivalent Cree. By keeping the whites in the Rebel line, I can get a better volume discount on 50 degree optics which puts them in the $0.93 a lens range which is also a fair amount better than what I could find for cree optics.

Ultimately the goal was to save money while still having a substantial array to cover the entire 75g tank. 100 LEDs will be in the array (the additional 4 are for testing purposes) and they will be driven by 4 custom controllers based on the Supertex HV9961 controller IC running off 120VAC. This will eliminate the need for upwards of 14 buckpucks and the associated 300-400W powersupply to go along with it. The drivers will have an isolated PWM dimming interface for easy intensity control. It will take some experimenting when the parts come in to see if my concept will work but the design will have a selectable high and low current range for the array (outside of the PWM dimming) that will hopefully allow me to use the royal blues as moonlighting if I can get the current low enough to them.

maybe kinda silly but i bought http://www.nanotuners.com/product_info.php?cPath=71&products_id=513, just to see what its like, obviously i could have just asked but the whole reflow thing is pretty interesting, plus i really wanted to see how the vias were set up to transfer heat.

what happens after the rectifier? i know your plan was to convert ac to dc with a rectifier, just curious as to what to do to clean up the noise.

i would be in for a few rebels just to play with if you guys decide to go that route

 

[phalanx]

...obviously i could have just asked but the whole reflow thing is pretty interesting...

what happens after the rectifier? i know your plan was to convert ac to dc with a rectifier, just curious as to what to do to clean up the noise.

If you are interested in a few reflowing techniques for the hobbyist, have a look at this tutorial: http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=59 . It is focused around hot plate soldering but they have other tutorials that show other SMD techniques.

You are right about the rectifier. AC from the wall will be full wave rectified and filtered by electrolytic capacitors. The nominal voltage of a 25 LED string combined with some of the characteristics of the driver IC (loses current accuracy with duty cycles over 75%) allowed me to have a ripple voltage of 50V on the filter caps. My math says I would need 125uF for proper operation. Trying to find an electrolytic capacitor that could handle the ripple at this working voltage was difficult so I ended up using 2 100uF caps in parallel to get the filtering I need. Extra capacitance will reduce the voltage ripple and put less stress on the caps hopefully leading to a longer life span.

Since the current has to flow through an inductor before going to the LEDs, the rise times on the current waveform won't be too sharp which should keep the unit from acting as a transmitter.

My friend has started ordering parts so it looks like we will be following through on this build. I just recently got my prototyping parts in so I can spin the first attempt at the controller.

 

[DoctaQ]

i built a few drivers based on a diodes(company name) IC, zotd something or other i have all the names at home, they handle up to 30v although i got another few that can handle up to 60v, my experience with them thus far, and could totally be me since i am by no means an engineer is that somehow the maximum current without a reference voltage is only 700ma whereas it should have been 1000, i only remembered recently that i had a ton of small caps but never tested tieing the reference down to the ground with it which is what was suggested in the datasheet.
i sent them out to an internet friend of mine to look at but he hasnt gotten back to me yet, i never even got around to creating the reference voltage with an LDO

the whole pwm side of control is like a foreign language to me, duty cycles and waveforms and soft starts and that jazz.

 

[DoctaQ]

for the driver i built i might use a little candle warmer i got but for leds i might want to go with one of those fancy rework guns, they look very fancy (and expensive). maybe a silly thought but would it blow tiny parts around? like tiny smt resistors or some of the smaller ICs

 

[phalanx]

i built a few drivers based on a diodes(company name) IC, zotd something or other...

Sounds like Zetex to me which was bought out by Diodes Inc recently. Their 30V 1A part is the ZXLD1360 and the 60V 1A part is the ZXLD1362. I've used Zetex driver ICs in a few projects (not aquarium related) and they are rather easy to get working. If you want, I wouldn't mind taking a look at them for you if you're still interested in getting them running.

 

[phalanx]

for the driver i built i might use a little candle warmer i got but for leds i might want to go with one of those fancy rework guns, they look very fancy (and expensive). maybe a silly thought but would it blow tiny parts around? like tiny smt resistors or some of the smaller ICs

All of the hot air rework stations I've used have user controllable air flow so you wouldn't have to worry about blowing small components around. High end models can be very very expensive but the same site I linked to for tutorials also sells a good rework station for about $175. http://www.sparkfun.com/commerce/product_info.php?products_id=76

The hot air gun is very handy if you have a real need for it but for most hobby work, you can get by with a quality iron. With a little practice, almost any SMD package that has exposed leads can be soldered with a regular soldering iron. The rework station really becomes an asset when you need to repair boards with lots of SMD components.

 

[DoctaQ]

the zetex is exactly what i used, but i only used the 30v max model but still have the components to put a 50v max one together, limited by the diode i beleive.
after all the words associated with it, to 220 packaging and bulk and ammo haha, its all a bit much for me.
where are you located?
the main usage for an air gun for me is to surface mount led emitters, not trying to use a star or anything silly like that. ill look into the rework station when i get home, thanks a bunch

 

[phalanx]

I'm up in Candia NH, just outside of Manchester and I work in the Newburyport MA area. Perhaps I should update my profile!

Are you trying to solder your LEDs to the square FR4 boards you linked to before? If so, you can probably solder them from the rear using a regular quality iron, ie. not a Radio Shack carpet burner.

 

[DoctaQ]

im actually hoping to have a pcb made out for me for a cree xr-e, any suggestions?

 

[phalanx]

I have a few board houses that I use depending on the quantity of boards, their size, and the urgency of the project.

For small boards and small quantities where time is not an issue:
http://batchpcb.com (a division of Sparkfun Electronics)

For any board where I need it yesterday:
http://www.4pcb.com/

For rapid prototypes where soldermask and silk screens aren't necessary:
https://www.barebonespcb.com/ (a division of Advanced circuits)

For any larger quantities or board sizes with normal turn times:
http://www.goldphoenixpcb.biz/ (the service used by BatchPCB)
and
http://www.pcbcart.com/


I do all my board layouts using Eagle: http://www.cadsoftusa.com/

 

[DoctaQ]

aw man, sounds expensive, id already looked into phoenix before.

how about heat transfer through the board to a heatsink on the back?
from the little rebel square i looked at it seems like i should encompass some kind of solid copper block right on the back of the led and vias all around it