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[justDIY]

new project for January; 9 watt RGB stars

[g7mjv]

Very nice, what are your plans for them ?

[jlforester]

Niiiice...can't wait to see what's next!

Did you have to solder the rebel to the PCB or can you get the stars pre-made?

[justDIY]

I had to solder them by hand.  The star pcbs are compliments of GK Technik, Germany.  Pictured is the 30mm star specifically designed to work with the Polymer Optics RGB collaminating optics (the white lens thing).

The rgb collaminator contains at least six mirrors and a bunch of lenses to redirect the light from each rebel and project it straight forward, leading to very uniform color mixing

[minster9]

  Can't find a heat sink to cover the whole mounting area of the star? This is just a quick mock-up,right? The 2 emitters along the one edge of the sink are gonna be hotter than the one on the opposite edge.  You need 3 equidistant mounting holes in the sink,I wonder how much that star is gonna heave up into the air when it gets hot being held down by 2 fasteners on opposite edges? Or are you using thermal epoxy? Drilling & threading 4-40 holes ain't hard,drill your holes .003-.005" over what the the threading chart says & thread your holes 3/8"-1/2" deep. I hold the tapwrench pointed upwards w/one hand & start my threads holding the heatsink w/the other hand and start turning the sink onto the tap. Turn your tapwrench 1/4 every so often to ensure your starting your threads straight into your sink. I always drill all holes to be threaded all the way through so I can squirt wd40 in from above to wash out cuttings. Take your time;you should be able to get a turn or 2 before you feel it bind up a bit,then back out until it feels free.  Always use a new tap;chances are you can get one for nothing from anyone who has a 1/2" tap&die set. Nobody wants to monkey around with threads that small,make sure it ain't rusty . If I can solder rebels onto ends of 8 gauge wire,you can thread some little holes,JustDYI? And,of course,the sink pictured will require a fan. Are the individual emitters good for 150C?  Any idea about price,availibility,lms,etc? I'm staying away from stars;I prefer to solder emitters onto threaded copper posts & screw them into large heatsinks that don't need active cooling.  Keeps the parts count down.

[justDIY]

this is just a test run ... the little guys are hooked to a 250ma const-cur driver right now - even without heat sink, the star barely gets warm.  I have some 1a buck-pucks on order, the adjustable kind, which can be dialed in from 400ma to 1000ma

the hold downs are definitely temporary, since they are not compatible with the optics.  I'm not sure if I'll go with screws or a thermal epoxy - I have some ampules of Arctic Alumina epoxy designed for gluing heat sinks to $500 cpus, so it might work for leds?

i tried tapping holes once, using a 'massive' (by comparison) 1/4" thread cutter, and still managed to bust it.  I think I'll pass on tapping #4 holes - do they make #4 screws in a self tapping flavor?

I need to find five matching (more or less) heat sinks, with smooth bottoms and quiet fans.

this star is not premade - I bought the rebels from the top bins at future ... however, they're the 350/700 rebels, not the ones binned for 1a, most of those aren't even offered for sale.

I have no idea on pricing for the pcbs; mine are free engineering samples.  When I get a little further along I'll be contacting the manufacturer to see if I can setup a small quantity purchase.

[minster9]

 :yeah:Jeez o peetz! Ya scared me !Haha! The 95% spheroid silver-silicon paste seems 2 work ok for me. UH,huh,huh,if your heat sink feels WARM,you're killing your led(s). All one has to do successfully is thread the 1st tiny hole. I busted a coupla #4 taps before common sense kicked in. "what u lose in thread depth is gained in length of thread". And be deliberate when cutting threads,a turn or 2 or more,& stop when doesn't cut but instead binds. Back out 3-4 turns,let the tap cool,burn one,piss,or whatever. Squirt some wd in there. I've given thought to star-mounted emitters,but found that I could do better. And have

[justDIY]

the holes in this star are for a #2 sized screw, the #4 is much too big!

I could ream them out a little bigger but not much, there are electrical traces to worry about.

I'm not concerned about these leds lasting 50000 hrs.  If they last 5000 hrs I'm happy.

[cadstarsucks]

this star is not premade - I bought the rebels from the top bins at future ... however, they're the 350/700 rebels, not the ones binned for 1a, most of those aren't even offered for sale.

I have no idea on pricing for the pcbs; mine are free engineering samples.  When I get a little further along I'll be contacting the manufacturer to see if I can setup a small quantity purchase.

You can get them premade.  They run $16 each, but the rebels are not the best.  You can probably double it's intensity and make it more even by putting the highest bin red and blue with the lowest bin green (just guessing from memory).  The 18/30/50 bin combination truly makes no sense.

Dan

[justDIY]

without green, you'll wind up with a very cool blue.  you need the intense green to warm things up.  even with the top bin green, the red + blue are still too much and the color temp is a bit cool.  cutting back on their output via software yields more desirable results.

i have no means to measure or quantify any of this, just basing the observations on personal preference.

these are not the same as premade rgb rebel stars - the ones from ledsupply and elsewhere have an arbitrary layout which is not compatible with any (known) off the shelf optical package.  without optics, you have a huge viewing angle, resulting in tremendous glare and loss of intensity, not to mention poor color mixing.

Dan, if you have a source for pre-populated stars which fit any known mixing optics package (several of the big names have them), let me know - these stars aren't exactly easy to get a hold of atm