My DIY 4xQB120 Flowering Light

Okay, as promised in the main QB thread, I am posting my 4xQB120 build. This is my first true DIY light (kits don't count, in my opinion), so it's a little rough around the edges, but it worked out great. As it says in the title, this is a flowering light (though it will surely see some veg action too); I know most people are putting the 120s to work as veg lights, but I couldn't resist the $/watt value presented by these boards. So I'm replacing a single QB288 running at 150w with four QB120s running up to 250w. I honestly have no clue if this was really a good idea or not, but what the hell, it's worth a shot...

Parts and prices:
Four QB120 boards at 3000k - $130 (after shipping)
Meanwell HLG-240C-2100A - $60
One 8-foot length of 1"x1" L-channel - $10
One 8-foot length of 1"x2"x1" U-channel - Free (already had it)
Various nuts, bolts, screws, etc. - $20
18 gauge solid-core - $5

If I'd had to pay for the U-channel, around $225 or so? The build is a little rough - not my skill-set - but it turns on and lights up, so I'm content!

This is a 2.5'x2.5'x6' tent. I'm currently running four plants, in flower.

Before:

After:

Cranked all the way up:


It turns down to 83'ish watts. I'm running it at 200w to begin with - don't want to shock the plants with too much more than they're accustomed to. I'll turn it up little by little and we'll see how they respond. I'm excited about the light spread I'm getting with this compared to the single QB288. I'm sure the light directly beneath the 288 was more intense than any spot under the 120s, but between the coverage and the overall extra power, I'm pretty sure this thing will prove worth the investment!

I think that's it? I'll close by saying that HLG rocks!

What are the dimensions of a qb120? Looks like better spread

tidy!

Very nice Humple

Powerful

ingenious.

Rocket Soul said:

What are the dimensions of a qb120? Looks like better spread

Click to expand...

About 9.5"x11". The dimensions of the fixture are 21"x26".

Yupp, it rock's for sure!
Subbed!
250w seems perfect for a 2,5 x 2,5 and the better spread allow you to run them even closer to the tipps.

Congrats to you 1st DIY!

Thanks, everyone! I just read back through my post and realized that I missed a couple of pics. Wanted to get some feedback on the overall design of the frame, because I just sort of threw it together (I figure there's probably a better way to do it). Have to wait till I can hop on my PC because that's where the photos are, but I'll post them up a little later.

Nice job. I hope you keep updating with plant pics showing the progress.

Okay, here's a closer shot of the frame. I was originally thinking of using only L-channel, as many do, but when I started to think about how I'd attach the driver, I gave up on that. I needed to keep the overall size within the limits of my tent, but the QBs are taking up all but two inches of the center rails; there's no way to bolt the driver down when the boards are just beneath it (if using L-channel). So I pondered and looked around the basement for a solution and found that old length of U-channel. Putting it on its side gave me two full lengths of surface for attaching both the boards and the driver. But I can't help but think there could have been a better way to do this? Cutting that U-channel with a hacksaw was a real pain in the ass, and one of the main reasons the damn thing isn't square. I'd like to plan something easier for the next one of these I build (assuming this first one performs the way I think it will!).

Here's an in-progress, top-down shot. I ended up using zip-ties to attach the driver, simply because I couldn't find a small wrench in the right size to get in between the legs of the U! Kind of silly. I'll probably correct that little oversight before long though...

And here is a pic of how I attached the boards. This pic shows how off-square it is. Not pretty, but I'm not entering it in any pageants! I'm thinking there's room for improvement on this design though. Any thoughts?

It works you saved money you are happy. The rest is relative. Congrats on your hand work. Best way get intimate with the parts

Humple said:

View attachment 4019933 And here is a pic of how I attached the boards. This pic shows how off-square it is. Not pretty, but I'm not entering it in any pageants! I'm thinking there's room for improvement on this design though. Any thoughts?

Click to expand...

It looks great and I'm sure it will grow the shit out of some plants- and that's the most important thing, right?

We all cannot be Growmau5 building a Ferrari looking light. Your light looks great. Crank it up!

Thanks, guys! You're a great bunch of people, you really are.

Turned it up to max (250w) last night. About 12" from the tops. Temps at the canopy are 74°F. The boards are warm, but I could leave my hand on them all day long. The driver is a bit warmer, but still not what I'd call hot. So far, so great! Wish I had one of those HydroFarm meters so I could get the numbers on this thing!

Humple said:

Turned it up to max (250w) last night. About 12" from the tops. Temps at the canopy are 74°F. The boards are warm, but I could leave my hand on them all day long. The driver is a bit warmer, but still not what I'd call hot. So far, so great! Wish I had one of those HydroFarm meters so I could get the numbers on this thing!

Click to expand...

Hi again!
You could order a cheap 10-15$ lux-meter from e3ay/amazon instead and multiply the redings with 0,0145 to get an idea of your ppfd. The screenie below is from Sylvania/Osram and there is also an old thread here in the LED section about converions from lux to μMol/s. There are also lots of lux-meter apps available but they are inaccurate and need to be calibrated.

Randomblame said:

Hi again!
You could order a cheap 10-15$ lux-meter from e3ay/amazon instead and multiply the redings with 0,0145 to get an idea of your ppfd. The screenie below is from Sylvania/Osram and there is also an old thread here in the LED section about converions from lux to μMol/s. There are also lots of lux-meter apps available but they are inaccurate and need to be calibrated.

Click to expand...

Hey, thanks, man! That sounds doable. Any idea on the accuracy difference between a genuine PAR meter and this calculation using the lux meter?