Need help for 4X4 DIY light build

Growroom Design
#21

Yep, you’re reading it right. But, that’s not the strip you want because that one’s made for flowering, not full spectrum veg and flowering like you want. If you’re still building a combo veg and flowering space, you want 20 of the 4ft 3500k strips found at this link:

https://www.digikey.com/products/en?keywords=BXEB-L1120Z-35E4000-C-B3

The amount of watts is variable, because their voltage is pretty fixed at around 39v, but you can give them from 0 to 1.5 or maybe even 2amps without damaging them. The problem is, they lose efficiency the harder you run them.

Because they’re so cheap per strip, the sweet spot from an efficiency and heat perspective is running them at 39ish volts and about 0.7amps, or 700ma (which is called the “nominal” current, as tested by the manufacturer). You’re right that at 700ma, the Bridgelux 4ft strips (eb2 3500k or eb3 2700k) consume around 27w of energy per 4ft strip.

Most of the builds recommended here will promote dimmers so you can adjust the current, and your choice of driver impacts that from two perspectives: drivers may have built-in dimmer pots or both internal dimming pots and lead wires for external dimming pots. Dimming is really great for your situation where you want to grow plants from seedling to harvest in one tent! With dimmers, you’ll be able to lower and raise the current of the strips so you can meet the needs of the plants. Seedlings and clones don’t need a lot of light, and veg plants only need about half the amount of light as flowering, but plants in the middle of flowering need the most light you can give them.

So, the strips linked above matched to two HLG-240H-42AB drivers would give you the ability to run them from 10% to 100% of full rated output, if you add a 100k potentiometer. Or from 50% to 100% from the internal dimming pot. This driver also runs the strips at below nominal current (max of around 550ma per strip if you wire 10 strips in parallel per driver) which is good for both lowering heat and raising efficiency.

Since you’re familiar with this stuff, here’s a spec sheet for Meanwell HLG-240H series drivers, the ones we recommend the most, and the XLG-240 series which is a lower end model rated at about the same:

hlg-240h-spec.pdf (227.0 KB)

XLG-240-SPEC-1.PDF (772.4 KB)

Hope that helps. If you have any other questions, let me know.

4 Likes
#22

If you use a 50k pot you can run both drivers from one dimmer switch.

I’ve been thinking about how to leverage the per driver dimming, if you only have the one grow area and I had an idea. If you only had one tent, you get say 10 5000k strips, and 10 3500, or even 3000k strips. When you lay out the strips, alternate them, and connect all the 5000k strips to one driver, the 3500k to the other, put a dimmer on each driver, and you could vary the blue/red balance depending on what growth phase you were in.

Boost the blue a little more for veg, turn it back down, and boost the red during flower, maybe bump the blue a little during the last 2 weeks of flower. I’ve heard that can promote tighter buds and increased resin production.

On it’s face it seems like it would make your light more versatile, and effective, but I have no first-hand knowledge if that’s so or not. What do you think?
:vulcan_salute:
:guitar:

5 Likes
#23

Thank you so very much for your time and putting this together. This is of great help for me, going to do some more reading and then put a list together to make an order.

2 Likes
#24

I think it’s cool if you’re into mixing spectrum, but for me personally it’s added cost and complexity for no proven benefit. In my experience, modern white LEDs grow extremely dense, frosty buds no matter what. :wink:

Also, about controlling multiple drivers with one dimmer knob, I have seen it work and I think you’ve got it right with the 50K pot to do 2 drivers, but I’ve also seen it not work right. A buddy had a retail Timber fixture with two drivers on one dimmer pot that was bad out of the box - for some reason, it screwed up the draw of the fixture so it only drew 1/2 the wattage it was supposed to. They ended up replacing the whole thing under warranty with two separate dimmers on the new one. I guess the moral of the story is in theory it should work, but in practice there may be issues with it that require testing.

No worries! Don’t hesitate to ask if you have any further questions. And re-read the LEDGardener build link mentioned before, since that’ll give you a good idea how to build it.

4 Likes
#26

Good guides here too.

#27

I had to dig but I found an old post of mine from when I built an HLG550 clone. There might be some useful stuff in there lol