Minimalistic multichip DIY LED build

^^What he said

Perhaps the localized hot spots caused warping despite adequate sinking when looking at it as a whole? It seems most densely packed designs have opted for CPU cooling style devices. I'm assuming it is because these devices perform well dissipating heat from small localized spots quickly.

After the junction to solder point resistance(9ºC/W) and the FR4 resistance(~5ºC/W) your only left with 2ºC/W to spare. Those are rough calculations obviously.

Bean here is the article I got the above information from.

Optimizing PCB Performance

May I ask why you used thermal tape as opposed to grease? From what I understand the grease performs much better despite the ratings of some of the tapes.
 
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Pretty sure that is the document I referenced when I was working on this a few months ago. I got kinda sidetracked with my control panel project and have not got back to the LED project. This thread has me almost ready to start over (again, my first design was linear instead of clusters).
 
dc said:
There are also censored sites, that should be easy to figure out.

The posts removed in this thread were commercial, plain and simple. Those are never allowed.
Click to expand...

I guess I'm too new to know what you mean about "censored sites".
Of course those who want a group buy for these new 5 channel multichip pannels will just google to find it elsewhere, there is no shutting this kind of thing down.

I was enjoying the original conversation and learning quite a lot. But now the thread seems to have changed topic somewhat towards reflowing chips and other more technical issues which I am afraid is a bit above my pay grade.

Respectfully, and I dont want to hurt anyones feelings, believe me, -- can it be suggested that a new thread be started for those wanting to learn and discuss design and engineer their own discrete elements into their own led/pcb panel of some sort. It's not really minimalistic is it!



So that I can learn some more about the 1 watt multichips if Lassef is still here? I thought your picture comparisons of sunlight and your multichip on carpet was useful. I'm not really sure why some other posters dismissed them so out of hand. Since to me any kind of really really bright light source is white
I am wondering if you can post a few pictures of your sun spot and the multichip spot with the same camera but manually reduce light intensity by 2 fold per frame (1 f-stop). Alternatively shoot one frame with both spots at a few f-stops. I'm reliably assured that your sun is my sun.
 
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I thought the 5 channel multichip design had gone a bit beyond minimalist too but I understand your point. Really the only commonality at this point is the multichip packaging aspect of it. Perhaps this discussion is worthy of another thread.
 
Keep in mind 5 channel multichips require a lot of wires and expensive drivers. The cost per watt to drive 3 channels is much lower than that of 5 channels. 8 wire DIN cables work well with 3 channel chips, but with 5 channels you need two DIN cables which gets messy. On top of this, you need to build a driver box that houses five drivers per light fixture and run wire to the dimming control.

In my opinion, the reds, whites and blues should each have their own channels but there is little value in dimming within each colour group. This doesn't limit the colour variations as you can still have up to 10 colours without additional cost.
 
Not sure if anyone else here noticed this, but there's a recent build thread with a 100w multichip, and a nice comparison to a 14k radium, includeing a side-by-side. IMO the radium gets it's balls kicked in the color dept.

http://www.reefcentral.com/forums/showthread.php?t=2199428&highlight=multichip

mr wilson: +1 on the wiring issues! Especially since by the time you get to a 4 pair or 6 pair cable, it's going to be THICK. Now try to find a 6 pair cable that's flexible, and you're going to be talking $4/ft or something. The 9 conductor / 18ga wire I used on a friend's build was $1/ft but just over 1/2" diameter.
 
Ah, ok perhaps this is my inexperience showing but cannot they all be tied to the same ground? And or several channels tied together blues/whites)
In any event 2 cables to a single chip or pair of chips sounds a little more minimalistic than all the spagetti I was dredding with the star chips

Would anyone more electrically savvy ( than i) supply some option diagrams?

Would 22-24 ga wire be ok? I need ~10 feet.
 
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Screener said:
Ah, ok perhaps this is my inexperience showing but cannot they all be tied to the same ground? And or several channels tied together blues/whites)
In any event 2 cables to a single chip or pair of chips sounds a little more minimalistic than all the spagetti I was dredding with the star chips

Would anyone more electrically savvy ( than i) supply some option diagrams?

Would 22-24 ga wire be ok? I need ~10 feet.
Click to expand...

Each channels needs to have it's own driver for independent colour control (dimming). Each driver has two wires (+ & -) and you must use these. You cannot simply share a common ground.

The tiny tabs on the sides are very brittle and break off easily if you bend them too many times during installation. They also need to be insulated from the CPU cooler or chip holder. I prefer to use multichips that have terminals right on the frame/block.

I use 3 channel multichips, so that means 6 wires to the chip and two wires to the cooling fan. An 8 pin DIN cable is perfect for this purpose, as you only need one cable to run the whole light. A single channel multichip uses only two wires so they are usually wired with a 3 pin DIN cable, but it's nice to be able to bundle the fan wire in with it, so you are back up to 4 wires (you don't use a grounding wire for LEDs).

8 Pin DIN cable...
8_pin_connectors.jpg


3 Pin DIN cable suitable for single channel multichip...
t_left4ringxlr.jpg
 
Molex automotive type connectors are an alternative and they come in weatherproof styles. I used multiple sizes when I did custom car stereo and security systems with extral bells and whistles. Shoot you could use the atx plugs off a power supply and old motherboard to accomodate the wiring.

100 posts!!!
 
I use "ATX" style plugs on my lights, they are cost effective, can handle 9A and readily available. A bit of a PITA to put on wires without the special crimping tool, though, you have to solder them to have any kind of hold on the wire. The product series is called" VAL-U-LOK. Popular electronics distributers should carry them. The 4 position plug is $.20 each, pins are about $.02 each.

I looked at waterproof/weatherproof connectors and the price is prohibitive to say the least, and they are usually very particular about the size of wire in order to seal around it. I spent a lot of time looking and the best price I could find would have been like $6 each!

Those 8 pin waterproof DIN connectors are HUGE, btw.
 
Well, for hanging on the back of a light fixture it's pretty big, I guess. It all depends on how you want to wire the light and the size / type of light.

By the picture there it looks like the female side of the plug is about 45-50mm in diameter, that's in the ballpark of a hospital type cord plug (round style). Pretty big for the job it would be doing, I suppose.

The val-u-lok connectors I use are about 1x.5" for the 8 pin version, though they are not waterproof, you can gain some protection using dielectric grease in the connections.
 
mr.wilson said:
The tiny tabs on the sides are very brittle and break off easily if you bend them too many times during installation. They also need to be insulated from the CPU cooler or chip holder. I prefer to use multichips that have terminals right on the frame/block.
Click to expand...

This is good info. I just got done soldering three of the 60W combos about thirty minutes ago. I contemplated soldering to the pads on the frame block but I was not sure how to apply enough heat there. (I'm not a pro) :)

Maybe I should give it a try.

LED%20Solder%20Pads.JPG
 
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Didn't work out too good. What kind of sealant/goo can I put on there to insulate those tabs? I think silicone is a no no because of the acetic acid.
 
tomservo said:
Well, for hanging on the back of a light fixture it's pretty big, I guess. It all depends on how you want to wire the light and the size / type of light.

By the picture there it looks like the female side of the plug is about 45-50mm in diameter, that's in the ballpark of a hospital type cord plug (round style). Pretty big for the job it would be doing, I suppose.

The val-u-lok connectors I use are about 1x.5" for the 8 pin version, though they are not waterproof, you can gain some protection using dielectric grease in the connections.
Click to expand...

The male side is 13.2mm and the female isn't much bigger. It's about the same size as an RCA or coax cable.
 
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