Garage1217
GET OFF MY LAWN
Any of my fellow led people recognize this led? Thinking an osram but not sure the model. It is the size of a xp-g to note but not a cree. Maybe a bit smaller.
DIY LEDs - The write-up
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kcress
New member
Fishman has it! That's exactly my point. If you use a 0.1ohm resistor then the resistor can be only a 1/2W resistor but when using the resistor for its designated purpose you have to move the decimal place one to the right to get the correct current measurement.
I suggest this because you're planing to drive over 1A which starts to really dump some power in the resistors.
Use these babies:
http://search.digikey.com/us/en/products/WHAR10FET/WHAR10FECT-ND/678941
I like those terminal blocks to support everything nicely too.
Nice build you got going there.
I suggest this because you're planing to drive over 1A which starts to really dump some power in the resistors.
Use these babies:
http://search.digikey.com/us/en/products/WHAR10FET/WHAR10FECT-ND/678941
I like those terminal blocks to support everything nicely too.
Nice build you got going there.
Consider using shunt and adjust the circuit current according if you want the strings fail safe.
Guys guys, long time no see!
I am moving next month; sold my tank already, sadly won't have a tank for a while!!
Sensing this upcoming "dry spell", I cannot seem to stop craving another project. Been wanting to get into hydroponic gardening for a while now (done some dabbling in peppers already). So I want to turn the garage of my next house into an Aeroponic grow room! (turns out my RO booster pump is the perfect misting pump also!)
First let me say that most of the gardening forums are a SAD sight when it comes to LED info, dear lord. People start a thread asking if LEDs are good... 3 posts say to get a UFO they're great (lol!!), then three more posts of people saying it can't be done and its too expensive. Then I post some real quick info and stats on a DIY LED rig that BLOWS all the commercial fixtures they are discussing out of the water... and they call me a shilll?!?! lolz!
So annnnnnnyways. I think we all here know that LEDs lighting up a small hydro growspace is really no problem at all.
The best way that I can find to do this would be to use the Meanwell 185-48B (or maybe the bigger 240, but probably not necessary).
My idea would be to run the driver at 3 amps and run 8 parellel strings of 12 LEDs (most likely XPGs, but whatever is cheap on DE when I decide to go forward).
So each LED would be running at 0.375ma, close to optimal. I want to run them low power for Eff and also because I don't want any cooling on the actual aluminum channel. I'd rather avoid potential issues where parts of the frame are cold, parts are warm, and as a result the Vf's drift much more than if you had just let the whole thing reach a nice and even temperature. I'm just guessing this would help the parallel strings based off things I've gleaned reading here. But please tell me if I'm wrong
So I am thinking of putting the 1ohm resistors for monitoring, as well as probably 0.7ma or 1a fuses. Haven't looked into these yet, but the idea would be to allow one or several strings to fail before fuses go, hopefully giving me a chance to see the problem (Thanks Kcress for this idea I read from you years ago).
How does my plan sound? Anybody have any suggestions? Tell me I'm a shill? lol
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emora
New member
Could you explain that? How would we implement a "shunt" with several LED series connected in parallel?
I am aware of the use of a shunt as an over voltage protection, but wont our power supplies/drivers (ie Mean Well LED specific gear) take care of the voltage? Am I wrong to be worried only about an excess current situation?
TheFishMan65
New member
I saw somewhere (a thread somewhere) a device put in parallel with each LEDs. The idea was that if the voltage got above X (say 3.5 volts) the device would start to conduct. The idea is that if the LED opens (no longer conducts) the device would start to conduct. This works fine for a open, but if the LED fails in a short then no protection is gained. I think this is what they are referring to.
FWIW the one failure I have had was a short.
FWIW the one failure I have had was a short.
TheFishMan65
New member
Is that for the 75? If so I assume you are doing 2. I don't think you have enought LEDs or width if only one fixture. Probably more light than you need, IMHO. Also too wide for a 75. Coverage looks OK to me.
ReefEnabler
Premium Member
Yea I'm not sure what the point of a shunt would be in a parellel setup where you are way under driving everything.
With the current's I am thinking of running (0.35-0.375), with 8 strings and a 3.9a driver, 5 of the strings could fail WITHOUT having any fuses and the XPGs would still be under their rated 1.5a. So putting a .7-1a quickblow fuse seems like a no brainer here. The odds of 5 full strings failing (which would be required to surpass 1a on the rest), are so low that it's basically not happening without bad wiring or something IMO.
maybe I'm missing something, and there IS a good reason to use a shunt? I just think this current idea is very simple and will work, why complicate it?
With the current's I am thinking of running (0.35-0.375), with 8 strings and a 3.9a driver, 5 of the strings could fail WITHOUT having any fuses and the XPGs would still be under their rated 1.5a. So putting a .7-1a quickblow fuse seems like a no brainer here. The odds of 5 full strings failing (which would be required to surpass 1a on the rest), are so low that it's basically not happening without bad wiring or something IMO.
maybe I'm missing something, and there IS a good reason to use a shunt? I just think this current idea is very simple and will work, why complicate it?
I believe the point of using the PLED's (led protectors) is so that in the event of a led failure (open short) the current will by pass the led through the pled. The pleds use a certain amount of voltage for which ever size you get. Essentially if a led fails open you won't lose the entire string, just the single led so there's no real rush to take the rig down and fix it right away.
You can check out his video of how it works if you go to post #831 on this page...http://www.reefcentral.com/forums/showthread.php?p=19112440#post19112440
This is technology that's already widely in use in many applications.
pelochas
Member
sorry i need to update my info. its for a 120g tank, 6 footer. it has a wide glass center brace which is killing me. i got a couple of issues, its a tall tank and i want to put some light in the tank's center but not corals will be there. just so that i will have enought light if needed to.
im using 4 of the triple cat4101 drivers, 2 150watt 24v mean well ps. 18 leds per triple cat4101s boards. 2 boards on each power supply.
on the coverage of the whites and blues. not sure if two whites or two blues next to each other will have a too white or too blue effect.
TheFishMan65
New member
So 2 of these over a 120. That sounds reasonable.
How high over the tank? Optics?
I think the mixing will be all right.
I wish I could go from a 75 to a 120 that fast
How high over the tank? Optics?
I think the mixing will be all right.
I wish I could go from a 75 to a 120 that fast
pelochas
Member
i think one or two feet high with 80 degree optics, will be on a height adjustable fixture.
just dont know what the light coverage will look like. i want light in the tank, not outside. Then i hope the light isnt reflecting on the center glass brace. that will not look good on the walls with light reflecting up. so im thinking lowering the unit down and spreading the light to get some light towards the center bottom of the tank just to not have it not to look dark.
i may end up getting narrow optics for the leds near the center and raise the unit higher.
just dont know what the light coverage will look like. i want light in the tank, not outside. Then i hope the light isnt reflecting on the center glass brace. that will not look good on the walls with light reflecting up. so im thinking lowering the unit down and spreading the light to get some light towards the center bottom of the tank just to not have it not to look dark.
i may end up getting narrow optics for the leds near the center and raise the unit higher.
der_wille_zur_macht
Team RC
A 6' 120g tank? What are the other two dimensions? Knowing that would help us talk about coverage, height, and optic choice.
der_wille_zur_macht
Team RC
So what you're saying is, your heatsink is the same size as your lit area in the tank? Or maybe I am misinterpreting the diagram you posted above? At any rate, it looks like your outer row(s) of LEDs will be a mere inch or two from the edges of your tank, which IME is too close, unless there are really tight optics in the mix, which you probably don't want (unless the fixture is very high off the aquarium). So I'd pull the LEDs in another inch or two or three from the edges. It's probably typical on a tank your size with a typical distribution and typical optics for the outer LEDs to be 4 - 6" from the edges of the area desired to be lit.
pelochas
Member
thanks. it is really tight area. im not using a big heatsink, going to use 4 U channels in aluminum. probably screw down the leds closer to each other in each channel, then then will test set the channels above the tank and move them in closer to each other till i find a good spot and bridge it.
thanks again.
thanks again.
der_wille_zur_macht
Team RC
That sounds like a great approach. The U channel gives good flexibility in this application.
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