Skeptic_07
New member
I realize that, I'm not trying to get all of the light inside the footprint of the tank but i would like it if all the light stayed inside the top rim of the tank, if that makes any sense. If not just disregard it. :lol:
DIY LEDs - The write-up
- Thread starter JohnL
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I realize that, I'm not trying to get all of the light inside the footprint of the tank but i would like it if all the light stayed inside the top rim of the tank, if that makes any sense. If not just disregard it. :lol:
I probably should have but ordered them before I had thoroughly researched optimum spectrum for algae. I guess I could swap them out for warm whites and use the cool whites on the new 135 build. I used the double-sided tape from Luxeon so I'll have to pry them off.
Which brings another thing to mind: while reading the Cree "Thermal Management" App. Notes, I noticed that they suggest using screw or clips versus the glue or tape: "Heat-sink mountings with screws or springs are often better than regular clips. Thermoconductive glue or sticky tape should only be used in situations where mounting with clips or screws is not possible."
Thougth I would pass that on since many of us are using the thermal glue or tape.
der_wille_zur_macht
Team RC
It makes sense in theory and by the math, but in practice there needs to be a "feel" aspect to it - and while my experimentation with optics hasn't been scientific or thorough, it has confirmed that you probably don't want to go as tight as you might be thinking about.
L98-Z
New member
Do you have a supporting argument? The manufacturer is "worried" enough to suggest a cap on the input if it's more than 18". Suggesting a cap makes me think they are worried about dynamics, not a static voltage drop due to resistance in the wire.
But as I said above, I'm not an EE.
I'm an EE, but I don't play with this stuff enough. I'm an EW engineer, it's been awhile since I've played with this type of stuff.
I just doubt it'll have a major impact.
kcress
New member
Wow I turn my back and this thread spews out 3 pages. THREE PAGES! :eek2:
Capacitor in the leads to a BuckPuck: The BP has a controller inside it. It's a feedback controller. Feedback controllers live in a strange area. They have to balance incoming energy with out going energy and they only have a tiny amount of time to make switching decisions. Engineers deal with this by going to the Imaginary Plane and shifting around things called poles and zeros. Where these poles and zeros land determines if a feedback controller is stable or would rather oscillate. As you feed one of these digital controllers with longer and longer leads you cause to voltage at the input to have pulsations in it. This is because the wire has resistance which presents a voltage drop commensurate with the current. But even more vexing is the inductance of long leads that dramatically increases the resistance at the very high frequency that these controllers operate at.
As the power cable gets longer the resistance and inductance actually move the poles and zeros of the controller's stability. What this causes is the controller to go unstable. What does this mean to us? It's hard to predict with no details but this list has most the common results.
1- loss of control resulting in under current output
2- loss of control resulting in over current output
3- wild variation in output current
4- compete burn-out.
5- shortened or truncated lifetimes.
I have seen this phenomenon many times, often frightening times when working at higher powers. :}
You should follow the advice of the data sheet.
If a bunch of little caps all over are a problem, then run a hefty cord and follow it up with a tidy little terminal block and paralleling straps. Tag a single large cap across the two halves. Then feed all your BPs off of this local terminal strip.
Capacitor in the leads to a BuckPuck: The BP has a controller inside it. It's a feedback controller. Feedback controllers live in a strange area. They have to balance incoming energy with out going energy and they only have a tiny amount of time to make switching decisions. Engineers deal with this by going to the Imaginary Plane and shifting around things called poles and zeros. Where these poles and zeros land determines if a feedback controller is stable or would rather oscillate. As you feed one of these digital controllers with longer and longer leads you cause to voltage at the input to have pulsations in it. This is because the wire has resistance which presents a voltage drop commensurate with the current. But even more vexing is the inductance of long leads that dramatically increases the resistance at the very high frequency that these controllers operate at.
As the power cable gets longer the resistance and inductance actually move the poles and zeros of the controller's stability. What this causes is the controller to go unstable. What does this mean to us? It's hard to predict with no details but this list has most the common results.
1- loss of control resulting in under current output
2- loss of control resulting in over current output
3- wild variation in output current
4- compete burn-out.
5- shortened or truncated lifetimes.
I have seen this phenomenon many times, often frightening times when working at higher powers. :}
You should follow the advice of the data sheet.
If a bunch of little caps all over are a problem, then run a hefty cord and follow it up with a tidy little terminal block and paralleling straps. Tag a single large cap across the two halves. Then feed all your BPs off of this local terminal strip.
kcress
New member
Skeptic_07; I'm with you on doing everything possible to not have a single photon hit the inside glass.
Photons plus glass equals algae to be hand cleaned.. blah! This probably would take a raised LED position, optics, and a cut-off or shadow bar of some sort.
widmer; I am very happy you are still on the Optics Train. I am watching closely as your success with be fundamental to mine. If I can't run my emitters well above the tank I'll be doomed.
Various; Yes you can string together all manner of different colors and voltages of LEDs they will have the same current run thru them regardless of their individual voltages.
Also thanks to der_wille_zur_macht for his pleasant and always helpful presence on these threads. :beer:
Photons plus glass equals algae to be hand cleaned.. blah! This probably would take a raised LED position, optics, and a cut-off or shadow bar of some sort.
widmer; I am very happy you are still on the Optics Train. I am watching closely as your success with be fundamental to mine. If I can't run my emitters well above the tank I'll be doomed.
Various; Yes you can string together all manner of different colors and voltages of LEDs they will have the same current run thru them regardless of their individual voltages.
Also thanks to der_wille_zur_macht for his pleasant and always helpful presence on these threads. :beer:
der_wille_zur_macht
Team RC
My plywood 360g has a 4" (opaque!) eurobrace. Problem solved. :lol:
stugray
Premium Member
Another thing to keep in mind when trying to figure out light distribution:
Snell's law ( tyrin to be as nerdy a kcress above ).
This means lets say we are using 90 degree optics (or a bare XR-E).
Light comes out of the emitter ( essentially a point source ) in a 90 degree cone and the edges hit the water at a 45 degree angle ( the angle of incidence ).
Well, the air/water interface bends the light, so the cone UNDER the water is now a 64 degree cone.
And as far as the fish are concerned, it looks like the LEDs are farther away from the surface than they really are.
As you use tighter & tighter optics the effect lessens.
And kcress - you brought back memories of nyquist plots :hmm4:
My Brain ..... it hurts
Stu
Snell's law ( tyrin to be as nerdy a kcress above ).
This means lets say we are using 90 degree optics (or a bare XR-E).
Light comes out of the emitter ( essentially a point source ) in a 90 degree cone and the edges hit the water at a 45 degree angle ( the angle of incidence ).
Well, the air/water interface bends the light, so the cone UNDER the water is now a 64 degree cone.
And as far as the fish are concerned, it looks like the LEDs are farther away from the surface than they really are.
As you use tighter & tighter optics the effect lessens.
And kcress - you brought back memories of nyquist plots :hmm4:
My Brain ..... it hurts
Stu
Skeptic_07
New member
mine too.. and IDK what you're even talking about :lol:
mdisalvo55
New member
Hello everybody, unfortunately I am still having issues with my kit from RapidLED. It's the 6 LED kit with the Meanwell LPC-35-700 driver. A few pages back I mentioned that I blew an LED after gluing them all down. In my dismay, I forgot which one it was. So I just wired them all up like I would have anyway thinking they would all light up except the blown LED. After wiring it all up though, I am not getting any light at all. I wired it up just like in the pic below (except with 6 lights). The only thing I can think of is if some of the glue got on the LED, would it have ruined it/them?
http://reefcentral.com/gallery/data/500/213612pic_3-med.jpg
http://reefcentral.com/gallery/data/500/213612pic_3-med.jpg
mdisalvo55
New member
That worked, Thanks!!!
stealle
Premium Member
Hey guys, I can't go through ~150 pages of this thread. It looks like this all started as aguide using buckpuck drivers. It looks like it evolved into using the meanwell drivers. I am interested in being able to dim the LEDs (using the Profilux controller). Can anyone point me to a step-by-step guide that sums it all up using the meanwel drivers? Thanks
widmer
Drug Enthusiast
Excellent excellent excellent response. :beer: I'm really glad we have a resident electronics expert here. So even though the buckpuck data sheet specifies that a 50v 220 uF capacitor is called for across the poles, I assumed that was because the max voltage feed on the spec can be 48v. While I'm working with 24v of course, I thought I was lucky when I found 35v, 220 uF capacitors at radioshack. When I tried connecting it across the poles on the power supply, it near killed my supply though???? The powersupply (from mpja per Soundwave) indicator light got dim and I measured a new voltage across the terminals of ~5.5v????
Anyways, I don't want to mess with ordering a different capacitor online etc so guess what: The power supply is going up in the air 8 feet of the ground too :celeb1: lol
widmer
Drug Enthusiast
All the tinkering I've done up to this point tells me that eventually, near everyone with a rimless tank will be doing the same thing I'm doing. I should have my replacement optics arriving in the mail hopefully today (or at least by Monday) and then the fixture will be in the air. For now, here's some outtakes:
What it looked like when the dealextreme LEDs arrived: Remind you of anything?
All the ingredients in order minus the new optics:
LOL @ the largest formfactor heatsinks from heatsinkusa (GREAT COMPANY BTW). The fins are 2.5" tall, then the base is 10.05" by 1.25". They were $10 apiece shipped :beer::
With XR-E star sitting on for scale: Think it will be enough heat dissipation (lol)?
And finally, working with a variety of aluminum shapes from the hardware store. This shot kind of shows you what it's going to look like when it's up in the sky. One bar of LEDs at the front, one at the back. The fans won't be in the location they appear to be in right now, instead that's where the power supply is now going, fans will be blowing in along the back and out the sides. If you look closely you can see the brackets I cut by hand on the very ends of the heatsinks to allow me to adjust them for precisely how much they will tilt inward. The overall footprint of the whole apparatus is ~10" by 10", and it should be about 3.5" tall with lenses attached...
Will hopefully be 8 feet off the ground by the end of the day :spin2:
kcress
New member
Excellent setup I'd say.
I presume that you are going to have these two strips sort of pointing...um.. ah... cross-eyed? To keep all the light in the tank?
BTW: What happened with your supply and capacitor was probably the over-current protection. A big cap looks like a dead short on power up. Your supply decided that it was feeding a problem and tripped its protection.
I presume that you are going to have these two strips sort of pointing...um.. ah... cross-eyed? To keep all the light in the tank?
BTW: What happened with your supply and capacitor was probably the over-current protection. A big cap looks like a dead short on power up. Your supply decided that it was feeding a problem and tripped its protection.
der_wille_zur_macht
Team RC
Buckpuck vs. meanwell really just depends on requirements and personal preference. That said, the fact that you want to dim with the Profilux means you probably want the meanwell (ELN60-48-D) since it takes a 0-10v DC analog signal, which is exactly what the Profilux can provide. You could use buckpucks too, but you'd have to be careful with your programming for the dimming control since the buckpuck wants 5-0v DC.
stealle
Premium Member
Thank you so much for your response. Can you point me in the right direction for a guide for newbs. This thread starts off with a great guide using buckpucks, but I'd like to see some pics and a step-by-step using meanwells. It seems like every LED thread I encounter turns into a "hodge-podge" of posts but I'm not finding an organized guide. Thanks
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