I am currently building a second light using 20 gen 2 and a hlg320 24a , the only problem with this set up seems to be that to use 21 v the strips need to draw the higher end of there current specs and might need heatsinks of some sort rather than just bare strips.
I am considering adding an extra far red led to each branch of the circuit to make the driver match a bit better but am a bit daunted by all the soldering . Incidentally if anyone in the UK is thinking of building one of these that require a 24v driver, I have a number of brand new hlg320 24a available to trade or swap @£50 +pp,
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Please keep in mind that these drivers are constant current drivers and not constant voltage!
The voltage will change up or down while trying to keep the current constant.
The 24V is actually the maximum voltage for your driver.
The specified output current of 13.34A results into 667mA per strip when you have 20 strips in parallel.
With a current below the nominal 700mA you should be fine I think.
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Does anyone here solder their own 301 diodes ? or it that big factory stuff only ?
They should go through a re-flow oven (or hot air rework station) to be soldered correctly.
Cheers
G
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At 0.7amps the strips use 19v which is below the 24a drivers minimum output . Am I thinking of it wrong? , would the light only use 19 of the 21v from the driver?.
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Yes the driver will lower the voltage to 19V. The voltage range is 12-24V.
The driver will lower the voltage until the current is 13.34A.
If leds heat up then the resistance will go down resulting in an increasing current.
The driver will react by lowering the voltage even more until it reaches the desired current again.
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That is mana to my ears, I was thinking the voltage was fixed between 21v and 26v
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Seems like Arrow is clearing out these double row led strips for less than $3 each.
https://www.arrow.com/en/products/sl-b8r7n90l1ww/samsung-electronics 5000k
https://www.arrow.com/en/products/sl-b8t7n90l1ww/samsung-electronics 4000k
https://www.arrow.com/en/products/sl-b8u7n90l1ww/samsung-electronics 3500k
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Yeah bit older strips with efficiency in the 120-140 lm/w range, but for the price and what you get light amount wise, definitely usable and if you happen to have some older 48-52v cob drivers kicking around would make it easy to build an extra light.
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3500k is only 141 lm/W
Heck my Vero 18 COBs are only like 120ishLM/watt but they grow some good frosty plants.
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Last Gen is 180 and current Gen is breaking 200. At 120 you’re barely above traditional bulbs. A 315 CMH is 110.
On a cheap strip build the most expensive part is the power supply anyway not the strips. Personal opinion but a guy is better off shopping for a good deal on a power supply and buying strips to match not the other way round. No point shelling out $200 to power $20 in strips. I would rather $200 in strips on a $20 power supply.
On the flip side if a guy already had a power supply it might be cool to buy some just to play around with different colours and their effect
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Any specifics you would recommend?
Not sure if anyone has asked or mentioned this, but would there be any benefit in mixing kelvin strips in a diy build? Like maybe some 3000k and some 5000k or something?
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@Yawningtears, Yes people mix spectrums for sure. Use a nice warm spectrum for flower and throw in a few really cool strips to give it that nice blue spike for veg. I have not looked into it lately but I think those two spectrums you mentioned are a good mix. I would use 2 of the 3000k for every 1 of the 5000k. Would make a good all rounder.
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For all I’ve said there are only three real choices to hit 180+. Bridgelux Eb Gen 2 or 3 or get Samsung strips with lm301b LEDs. Samsungs are generally twice the price (unless on sale) for maybe 5% difference but ultimately what you want if you find a good deal. The strips on sale above are probably (guessing) four to five generations old.
In regards to spectrum red will give you stretch and concequently higher yield because of it while blue will keep them short and obviously lose yield. One grow report I read used 4k and although yield was lower quality was up which seemed to me a good middle of the road for my scenario. I’m not growing for resale so I’ll take quality over yield any day.
So I think mixing is good but it comes down to the environment and strains, with some trial and luck to figure out what’s best for each scenario. This is why I mentioned the strips above that are on sale wouldn’t be bad for spectrum testing if someone were running all one CCT to play around with effect.
Over the Christmas break I’m going to build a 3 power supply light. 1st will be all 4k which will be the backbone, second will be 2:1 red & blue and 3rd 2:1 blue & red. My hope is I can stretch and stunt on demand by turning on or off the appropriate secondary. Or blast all 3 in the last few weeks of flower if they will take it. Time will tell if it buffs out. I haven’t bought the blues and reds yet. Still not entirely set on my ratios to get the quantities to order. Might go 3:1.
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I forgot to mention the samsung lm561c I beleive (if I got the right part number) are the Gen prior to the lm301b and are comparable to the Eb Gen 2. And lm301h are the same led as the b’s but with green tax.
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Consider all of the strips regardless of color temp will have a blue spike which will be more than enough for our purposes, reason being all white LEDs are just blue LEDs with a phosphor coating and also why LEDs are more efficient on the bluer side of the color temperature spectrum as less energy is lost in shifting of the wavelength.
So saying that you don’t really need to mix and why most just stick to one general temp choice aka 3000k-4000k
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@Mr.Sparkle. I recently read about an led for seedlings/clones running at 9000k. In your opinion, helpful or gimmick?
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probably quite gimmicky to a point as at that side your more or less just giving a lot of blue light and not much else, so would it work sure but bet cost of this “special” light vs what you get in the end is probably quite a bit.
I’m more of the opinion at least for myself that all these exotic, far red initiators, uv augmentors, or say your example high color temp specific growth stage lighting isn’t needed, like sure if they can say provide a 10+% higher yield in the end in comparison to not using them and cost the same energy and money wise then there is benefit though most all don’t compare the use of those things vs providing more light in general when you consider energy use at the end of it.
As a general example sure say someone is using 200w of white led light and then adds 30w of far red and says they get _% greater yield then everyone thinks thats conclusive proof regardless of other grow factors, so yeah they added 30 extra watts of far red on top of the base line of course its gonna produce more but rarely do you see anyone using that energy going towards all these “special” lights toward more light in general such as 230w white led vs 200w+30w of white and far red leds if you get my point.
Little side tracked there and im not saying they don’t have there benefit or there are spectrum’s or color ratios that are more conducive to certain types of growing just the cost energy, time, or money for our application doesn’t really warrant it.
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Probably, no definitely, overkill in my setup. I have the majority of my lights in 2700K (720 watts) with the remainder in 5000K (360 watts) Red (30 watts) Far Red (30 watts) UV (30 watts) and IR (30 watts). All of them are individually dimmable. That being said, I count those watts when considering intensify and yield.
Have you heard of the Emerson effect? Emerson grew some plants with red light and got X amount of yield. He then grew a plant with far red and got Y amount of yield. But when he grew them in a mix of red and far red he got > X + Y yield. 
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