Lighting My DIY COB Setup (in the making)...

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I think you will be just fine with what you have hanging. 8 cobs will do much better than 4 with twice the wattage.

Yea i would like to pack the tent out with 7 autos really...even if they are small just run a SOG kinda style in there just to see if it will work with the new light, im hoping that because of the layout ive gone for the spread around the tent will be nice and even allowing for them to all get even light...which I think was an issue running one HID in there, it just didnt get to all the little bits around each plant properly, especially being a 250W....i might even get 4 x citizens 1212's and some cheap drivers off ebay which would probably cost another 75 pounds with heat sinks which would give an extra 15,580 Lumens and would add another 326 PPFD to the 750...but i think thats overkill in some respects! I have another Meanwell HLG-185-C700A driver at home that i ordered by mistake so I could just run another 8 and have the sun in my tent

Im just trying to get my head around those figures and that graph and Im going to try to convert it to an actual % figure...only as the PPFD figure from the calculator would be based upon your area of space entered, where as that PPFD on there graph could be based upon any size or area....on the COB calculator citizens are down at around 51% where as my CREE's are at 64%...i know its only a slight difference but I definitely think it will be noticeable in the long run...I might even make a cheap Citizen setup on the spare driver ive got, even if its for a VEG tent or for side lighting...

 

[BigSm0]

Sounds great. 7 autos will be some work so hopefully you have a scrog handy. I agree with you on the 10% efficiency being a big deal. I do believe the 1212 is just short of the Cree 3590 but the 1812 is very close if not even and the 1818 beats it. Personally I use the 1812's since they are said to be a very close replacement. 1212's for veg since it's a short term and the price. I was actually going to do some par mapping today with the 1812's I have at 55w vs the 3590's. I don't have a sphere so a par meter will have to do.

 

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yep i have just found all the autos ive grown a bit 'small' so 4 dont really fill the tent up enough in my opinion, i think an arrangement of 2-3-2 i could get 7 in there if they stay to a similar size...but im hoping the mephisto seeds ive got they might outgrow the ones ive done so far...

yea the 1212's are what I can get cheap off ebay, 5 for 40 pounds...im very very tempted to buy some now as some additional COB's for my light for when its proper packed out...youve got my thinking and i revisited some of my calcs...lumens is less than a 400W light but the PPFD is at 750 which people say is good...would you happen to know at what point the PPFD becomes wasted light or too much without other beneficials such as CO2?

If i didnt add the extra COB's I could always run a 1050ma driver to up them and only drop a few % in efficiency...i would even try to to implement a quick switch over device to change the drivers out if i required the extra lumens...one thing you might be able to help me grasp is the following....I understand sizing of drivers etc but 8 cobs @ 36V is 288V total...so if a Meanwell HLG-320H-C1050 has an output of 152-305V will it self regulate down to the 288V and not blow the COB's? As it fits into that bracket but I just wonder as 305V divided up to the 8 COB's would give them 38.125V each which I assume would damage then?

 

[Druid]

The 1212s can handle a max of 37,5vf

 

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thanks^^...i just wonder as the hlg-320h-c1050 driver would still be providing a voltage which is too high for 8 COB's..which makes me think that the driver must limit its output down which I know would effect the efficiency slightly...

I have decided to order one though and I am going to run my COB's at 1050mA rather than 700mA...for the 3/4% i will lose in efficiency i believe the extra lumens output will be worth it...goes up to 54,650 Lumens and will be a PPFD of 1103.67 in my tent...it might be overkill but im intending on having quite a busy tent with this light and I believe ive read 1100 is the highest you want to go without supplementing with co2...but this will mean I have an extra 2 drivers now so Might make 2 cheaper lights out of Citizens for a VEG or something...

 

[BigSm0]

You can run 1 cob off of that driver of you wanted to. I never understood max voltage when the cobs only use what they need. Max amperage is another thing.

It's like seeing a 40w max light bulb plugged into a 120v 15a outlet. This is rated for 1800w and the little bulb is rated for 40w max.

 

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thats the thing i dont understand and im glad im not the only one!

it says its output is 152 ~ 305V so I assume the driver can modulate its voltage whilst keeping the current through the circuit constant...similar to a piped water circuit...the current is the flowrate and the voltage is the pushing power (pressure)...so say a few compnents are removed, there would be less resistance in the pipework (same as removing COB's from the circuit)...so less pressure is required to force the same flowrate around a circuit...makes sense in my head anyway, i always have to compare electrical circuits to water or air circuits as im a mechanical engineer...

 

[BigSm0]

Makes sense to me too. All I know is it works and works safely. Smart chunks of metal I suppose. I think growmau speaks about it in one of his videos but I have no clue which one. What did you think of the chart I posted? It's not my work and the brains behind it has more I can add if your interested. Basically for the cost of the 1212's you can drive them softer and be more efficient with better spread for the same price. 1812's are very close in efficiency and the rest out perform Cree especially at higher wattages. I'm sticking with my few hundred citizen cobs till something else much better comes along.

 

[BigSm0]

I am planning a 30 cob light to be built very soon. 10w citizen 1212's should be very close to 70% efficiency. May just use some flat aluminum and screw in 1/4x1/4 u channel to make my own heatsinks. To many projects

 

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this is where my calculator must either be fucked or its just wrong...when i do a calculation for citizen 1212 or 1812's etc their efficiencies are only like 45% on the Citi calculator then on the DIY COB CALC its around 52% as i can only use 500mA....wish i could calculate or work it backwards from the graph/chart you uploaded as it would really entice me to use some citizens with the spare drivers ive got...especially as I have the drivers the COB's and other parts are so cheap to create another light for a second tent or room...