@dbrn32 I’m letting you know I am going to go ahead and buy 15 of those Citizen COBs with the holders and thermal sheets. Is there anything else I can get on this order from cobkits, or should I get the driver and heatsinks from RapidLED?
EDIT
Just a thought, but maybe I should get 16? This would 1) give me an extra in case of any problems, and 2) perhaps give the option to go with 4 rails of 4 cobs? Just a thought.
We just went from mild to wild pretty quick lol. Sit tight for one second and let me double check a few things.
Cobkits has heatsinks. They are just colored. I went and checked black and kind of jumped the gun. Also, the rapid heatsinks wont work with the citizen cobs. And I think one hlg-185-1050 will run five of the citi 1212. By the time you have 3 drivers and 15 holders, 15 thermal pads, and heatsinks, you’re going to be quite a bit higher than $300. Are we on the same page?
It gets kind of tricky when matching the cobs to drivers. One more or one less cob can change model of driver you need pretty quickly.
Yeah - so let’s get back to “mild.”
I’m still going to go with the one rail - now with 5 COBs instead of 4. I am just buying the COBs for the rest of the light down the road (since they only $9); not for use anytime soon. Something to “stock.” 
So I’ll need one driver and 5 heatsinks. The thermal pads and holders aren’t that expensive so I’ll just stock those up right now too.
Unless you think that’s unwise, and I should wait to buy the rest of the COBs I’ll need down the road. With the advances in tech happening so quickly perhaps that is a better option.
That’s exactly what I was going to question. How long til you decide to go ahead with the rest of it? If you feel like it will be in next month, then maybe go ahead and buy some of the other stuff. If longer, may be better to wait. If I were you, here is what I would do.
First, I would reach out horticulture lighting group and see if they will cut you a deal on the 120mm heatsinks. They are showing 24 in stock, listed at $289 for all 24. See if they will cut you a deal for 15 of them instead of paying $21 each at cobkits. At that rate it’s cheaper to buy 24 from hlg, than it is 15 from cobkits. I don’t know what the hell you would do with 24 heatsinks though lol.
Then, I would buy the one driver you need from arrow electronics. Speaking of which, we will need to pick what kind of dimming you want. I would suggest a type, dimmer is built in and will let you go from 50-100% without any additional components. But there are other options. But you’re gonna save $10 here and get it shipped for free.
Once you figure out what’s going there, then see where you’re at as far as moving forward with cobkits order. But I think getting a deal on the heatsinks would take precedence on the cobs, in my opinion. It’s obviously your money, spend it however you feel best.
Hmmm… well I think it makes sense given my current finances to stick to the original plan. So I’ll just get the 5 Citizen COBs, thermal pads and holders, and 5 heatsinks right now.
I don’t know squat about dimming features so I’ll need guidance on that. I think I would like as many features as I can get for the budget, though.
I would probably look at expanding to the three rail system after my current grow. I just hit flower this past weekend so that’s, say, 10 weeks, plus drying time (dry in the tent), so let’s round up and say 3 months.
That seems like plenty of time for technology to advance these days.
Okay, so… this is what I’ve decided:
96" Aluminum Angle (Home Depot)
5 Citizen COBs (Cobkit)
5 Thermal Pads (Cobkit)
5 Ideal Holders (Cobkit)
5 Heatsinks (Cobkit?)
1 Driver (Arrow Electronics?)
What am I missing?
You’ll need some hardware, wire, and whatever you’re planning on for electrical connections. But I think that would cover it.
That can all be sourced from amazon or locally. Although the wire you want is sometimes tough locally. 18 awg solid, just make sure it’s the 300 volt rated and not 50 volt like you would get at auto parts store. You’re driver output voltage will be 190 volts dc, so that’s important. It will commonly be referred to as hookup wire or marine grade. The input side of driver will need a cord and plug of some sort. The cheapest way is probably to get a piece of extension cord and cut the female end off. Or recycle a cord from an appliance or whatever you’re throwing out. Otherwise grabbing a length of like 16/3 so type cord and male plug will do. You can make those connections the same way you do output side.
The connections can be soldered and covered with heat shrink, terminal strips, or any number of fancy connectors. Meanwell sells cool waterproof connectors, but they’re expensive and it’s not like the rest of the stuff will be waterproof. Wago connectors are probably the most common. There are some pretty cool kits available on amazon, but menards sells them too.
Hardware is pretty subjective. You can use whatever works best for you to build frame. Nuts and bolts, rivets, weld or whatever. I believe it’s 3mm screws for mounting cob to heatsink. But you should probably double check with cobkits. He may even send them.
Probably not as pressing, but they make little peel and stick cable tie mounts that work really good for wire management. And you’ll want to wipe down the heatsinks with some rubbing alcohol before you mount cobs too. But I think that will just about cover it.
You were looking at the 3000k 90 cri cobs right?
The drivers are available with the built in 50-100% dimmer (last letter in model is A). All you do is remove rubber cover and turn with screwdriver. Or with an external dimming function (last letter in model is B). That one doesn’t dim as it comes. But you can add a pwm, 0-10 volt, or resistance dimmer. The easiest way is to install a potentiometer with resistor.
My opinion is that if you intend to use it solely for flower, you probably don’t need a dimmer at all. In which case the the a version 50-100% is more than enough. You can always raise and lower light for additional control. Hooking up the other stuff isn’t a huge deal, but it is more work and added expense. Up to you.
That’s correct - the 3000k 90 cri ones.
Mind if I trouble you for a specific driver model? I think I understand how you select a driver and how it works, but I’d hate to mess up the brains of the operation.
As far as dimming I’m not worried about that. If I ever get to the point as a grower that I understand how, when, and why to use a dimmer, then I’ll get one.
Nevermind - I smoked a bowl and I figured it out. We were still talking about the hlg-185-1050. 
You got it! Just pay particular attention to that last letter. If you’re not worried about th dimming now I would get the a version. You’ll have access to 50% without doing anything extra. And I believe it’s a couple of bucks cheaper too
That’s exactly what I got. I placed the order for the driver and all the stuff from cobkit. Once that comes in I’ll head to Home Depot for the aluminum. I’ll check for the wire locally and if I can’t find it then order it this week. Should be able to get this thing built and installed by the end of next week!
Very nice! You’re going to love it, and I’m absolutely sure that you’ll be done buying led fixtures.
I’m not sure if it will be conducive on a small order, but you may want to check with online metals for the angle. If you buy in standard length like 48” it can be really cheap. Two 48” will be enough. You’ll just take a couple inches off each piece to be your cross members, and then your light bar should fit neatly inside of a 48” in tent. I would probably look at spacing the cobs about 12” on center. You’ll have to kind of measure the overlay on heatsinks to get an exact measurement, but should be around 40”. You can make it longer to have some wiggle room to play with if you’d like.
I know you are right on that count.
If it makes you feel any different, I’ll probably be ordering some as well. Wife says she still has some gifts to buy, otherwise all 24 of those heatsinks from hlg would be headed my way lol.
I’ve been wanting to tinker with the blue and amber citi cobs anyway. Figured I would get a couple of each and for $9 I wouldn’t be able to resist grabbing at least a handful.
Quick update today. Plants look good. They both dropped PH over the past 24 hours some, still within a healthy range but at the bottom of it. I topped them off with plain water and a little silica this morning. They both drank a lot of water over the past 24 hours as well. Seems like they didn’t drink anything for the first 24 hours after the complete solution change from Sunday, and then went hog wild over the next 24 hours.
Here they are together:
I did some LST along the back of the screen and now have a top in every square on the GL. I am going to yank the cloner out of there - a couple of those clones have a flower on top, but no roots…I don’t think they will make it and I was just messing around with them anyway. The one in the pot is from the first GL topping. It’s rooted and growing, so I’ll keep it for now. It is in soil and I don’t really give it a lot of love and attention. I just give it whatever water I am giving the big plants every other day or so - whenever it looks dry.
I did string up the second screen for the GL. I haven’t put it on yet - maybe today, maybe tomorrow. Maybe never, and I’ll use it for my next grow. Please excuse the mess, we moved in 6 months ago and the basement is the one place I haven’t completely organized and set up yet. I’m still trying to dig out from all the cardboard boxes from moving. Add in all the boxes for my grow stuff, boxes for Christmas, etc. it’s a serious mountain of crap I need to get done down in that basement!
Quick update today. PH on both plants was perfect. 5.8. Ok fine, 5.79 on the SSH. ;). PPM on the GL was at 730 and 1160 on the SSH. I also added the second screen to the GL:
I might need some advice to figure out how to best use the screen. Mostly on how I should treat the stuff between the screens. Do I basically prune everything below this screen now?
Nah, you don’t really want to do that. They’re still receiving light, and too much trimming will put you in unnecessary shock. You’re 2nd net should be primarily bud, and I would look at it as such.
So really I’m just trying to keep the buds level and make sure they have support with the second screen?
