Cheap and Cheerful DIY using Citizen cobs

[CobKits]

1 - I want to use 5x 1212 running at 50W. Which driver should I use?

id have to check voltage but hlg240h-c-1400 should do it

2 - CRI 80 or 90, since there's a lot of theory behind CRI let's put it this way, which yield more gram per watt wise?

not a simple question. lets just say differences are subtle. personally if just flowering and cantake some stretch i think 90 has some advantages

3 - Can I save some money on the cob holders and screw it directly on the aluminium? Ok ok, I won't save on the thermal grease.
I understand holders are good to unsure maximium contact with the heat sink, worth every cent? Hope not...

sure if youre decent at soldering

4 - Heat sink. The heat sinks I see people recommending for "small" COBs like the 1212 seems to me a bit overkill. When I open my pc case and look inside, the CPU (90w consumption) and graphic card produce considerable ammounts of heat, still, manufacturers installed much smaller heat sinks.
What would justify using massive heat sinks on COBs and saving on tiny CPU heat sinks that easily pulls the same as the 1212 or even 1818.

you can cool 100W with a noisy $5 cpu cooller which is also using power. people like the massive heatsinks because passive is quieter and more efficient, more reliable, and less wiring

 

[Metacanna]

Thanks for your input.

Now that you say it I feel kinda dumb, I forgot about the fan on the top of the small CPU heat sinks.
What would happen if the heat sink is undersized for the COB? Less efficiency, plus risk of damaging the COB?

Maybe thermal adhesive would be enough to hold the COB, I'm not comfortable drilling aluminium.

In the meanwhile I found this in another thread:

i think that where the 1212s shine is if you wanted to glue up a bunch to a big ass heat sink and solder them.

arguably the best price/performance by a long shot for people with time on their hands

Actually, soldering wouldn't be too bad, at least it would be fast for me, and you'd only be dissipating like 4.5W each, so yeah, no problem with thermal adhesive. That'd be fun, and definitely take less time than a frame/individual heatsink solution. And no holes to drill.

I vote for that. It would be a thing of beauty.

 

[Moflow]

I want to build my COB lights, there's too much information around, it's hard work to put all pieces together.

1 - I want to use 5x 1212 running at 50W. Which driver should I use?

2 - CRI 80 or 90, since there's a lot of theory behind CRI let's put it this way, which yield more gram per watt wise?

3 - Can I save some money on the cob holders and screw it directly on the aluminium? Ok ok, I won't save on the thermal grease.
I understand holders are good to unsure maximium contact with the heat sink, worth every cent? Hope not...

4 - Heat sink. The heat sinks I see people recommending for "small" COBs like the 1212 seems to me a bit overkill. When I open my pc case and look inside, the CPU (90w consumption) and graphic card produce considerable ammounts of heat, still, manufacturers installed much smaller heat sinks.
What would justify using massive heat sinks on COBs and saving on tiny CPU heat sinks that easily pulls the same as the 1212 or even 1818.
I know nothing, I'm just trying to get grasp on this.
What really bothers me is price of those heat sinks, otherwise I would just buy them and save time.

I'm sure the bigger the heat sink, better. Would this work and keep some efficiency on the 1212?

View attachment 3893631

It's thick aluminium, 25mm x 100mm x 70mm. I wonder if one these per COB running at 50w would be enough.

Cheap as chips?
You could use Kapton tape to stick the cobs to the Aluminum....

 

[thetr33man]

drilling aluminum isnt much harder than drilling wood. Just add a little oil to the spot you wanna drill, vegetable oil works fine.

 

[frica]

Thanks for your input.

Now that you say it I feel kinda dumb, I forgot about the fan on the top of the small CPU heat sinks.
What would happen if the heat sink is undersized for the COB? Less efficiency, plus risk of damaging the COB?

Maybe thermal adhesive would be enough to hold the COB, I'm not comfortable drilling aluminium.

In the meanwhile I found this in another thread:

Thermal adhesive works.
It's epoxy so it won't get loose.

Citizen cobs take a high temp very well, but they just fail if the temp is too high.

 

[GreenMotion]

4 - Heat sink. The heat sinks I see people recommending for "small" COBs like the 1212 seems to me a bit overkill. When I open my pc case and look inside, the CPU (90w consumption) and graphic card produce considerable ammounts of heat, still, manufacturers installed much smaller heat sinks.
What would justify using massive heat sinks on COBs and saving on tiny CPU heat sinks that easily pulls the same as the 1212 or even 1818.
I know nothing, I'm just trying to get grasp on this.
What really bothers me is price of those heat sinks, otherwise I would just buy them and save time.

Having cooler cobs will increase efficiency.

 

[Metacanna]

id have to check voltage but hlg240h-c-1400 should do it

From the graph it seems the 1212 loads 37V when working with 1400mA. So, for my set up with 5x 1212 it would sum 185V. The driver you suggest works between 89V - 179V. I would need to scale to HLG 320, I guess?

 

[Baura]

If you are using holders/adapters check the holder max voltage specs. Some 150v and some are 300v I guess.

Cheers

 

[The Dawg]

View attachment 3894055

From the graph it seems the 1212 loads 37V when working with 1400mA. So, for my set up with 5x 1212 it would sum 185V. The driver you suggest works between 89V - 179V. I would need to scale to HLG 320, I guess?

The 1212 Operates at 36.5 v On A 1400mA Driver Which In Turns Powers the 1212 Cob To 47.5 Watts. So Your 240 Watt Driver Will Run 5 1212's @47.5 Watts Each So That Would Be 237.5 Watts Give Or Take A Few Watts

 

[Metacanna]

One thing I don't get. 36.5V x 5 units of 1212 equals 182.5V. If the driver has a maximum output of 179V, what happens then? Voltage drop on the COBs?

 

[thetr33man]

HLGs are underrated I think typically...

 

[CobKits]

pretty sure as long as your cob voltage is less than open circuit voltage on the driver it will light up. the driver may trim a few mA but in general, these are all underrated as stated

 

[Metacanna]

Ok thanks.

1 - If I have only one 1212 driven by an HLG-240H-36C (constant current), 1400ma, what would happen? The driver will pull 50W to feed the COB and that's all?

2 - if I have only one 1212 driven by a standard HLG-240H (fixed current and voltage) what would happen? The driver would deliver full power and melt the COB?

Let's put it another way:

3 - If I had 24 1212 driven by an HLG-240H-36C, 1400ma, what would happen? The driver would be asked to deliver 1200W and explode?

4 - if I had 24 1212 driven by a standard HLG-240H (fixed current and voltage) what would happen? The driver would deliver 10W to each COB, everything would work smoothly, and that's all?


Sorry for my extensive array of questions, please enlighten me

 

[Baura]

pretty sure as long as your cob voltage is less than open circuit voltage on the driver it will light up. the driver may trim a few mA but in general, these are all underrated as stated

Maybe then the lpc60-1050 will run a 1812? Just wondering...

For a micro grow, 1 plant with a grow area of 50x50 or a 300liter tonel, a 1812@50w is too much?

Cheers

 

[CobKits]

50w sounds on the low side for a 50x50, 100W better

 

[Baura]

50w sounds on the low side for a 50x50, 100W better

1812@75w=43%eff=150ppf
150ppf is 600 ppfd for a 50x50cm(2.7sqft).

Veg with @45w=47%eff=100ppf
100ppf is 400ppfd for a 50x50.

Any suggestions on dimmable 700-1400ma and 55v drivers?

 

[The Dawg]

I Would Jump Up To The 1818 More Wattage For Your Buck. However The 1812's Are Fine Also I Own 2 Of Them. I Run 4 1812's On A 240-1050 And I'm Pushing 60 Watts Per Cob

 

[rocho]

The 1212 Operates at 36.5 v On A 1400mA Driver Which In Turns Powers the 1212 Cob To 47.5 Watts.

36.5V at 1.4A gives 51.1W

 

[The Dawg]

36.5V at 1.4A gives 51.1W

Brother rocho Have You Ran Any Test On The On The 1212?? Well I Have And Below Is The Results On A 4 Cob 1212 Ran On An HLG-185-1400. Below Is Pics Well Shit The Bed Fred. The Pics I Was Going To Post Shows the 1212 Running At 190 Watts At 1.56mA

 

[TheChemist77]

just wanted to update,, bought 2 100 watt go green citizen cob's.. i run them along side 2 315 watt ceramics over a 4ftx6ft table... huge difference than running the 315's alone... im impressed on the penetration of these little cob's,,its only been 1 run using them but so far,,,,im very happy