Cheap and Cheerful DIY using Citizen cobs

Metacanna

Metacanna

Well-Known Member
klx said:
I am not sure about Europe but I am sure someone from EU on here can point you in the right direction. I just think that these days passive is so cheap it is worth the extra few dollars to remove all those fans and points of failure...but each to their own!
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In US northerngrowlights.com is selling the 120mm at 14.5$, I would buy for that price... In Europe, so far the best I found is 111mm pin fin for 25€ ~ 26$. The Alpine 11 GT (80mm) costs 7.5$ here on the local store. I will give it another day to see if there are some deals outhere I might be missing.
 
CobKits

CobKits

Well-Known Member
i posted the lm data on here a few weeks ago. like most cobs they are rated in the tens of thousands of hours

Metacanna said:
Question: I will be running Citizens 1212-048 at 1.4A, 50W each, on Arctic Alpine 11 Pro CPU coolers, rated for 100W. What happens if a fan/ PSU dies? I suppose it all depends on the time it will take until I notice the failure. But let's assume I would be away 24h, would the Cobs survive? If one failed, I suppose the chain would be interrupted and the others would survive, I hope.

The 1212-048 datasheet has the following info on the "Reliability" section

Continuous Operation Test: IF=1080mA Ta=25C (with Al-fin) ×1000hrs / IF=1080mA Tj=140C (with Al-fin) ×1000hrs

Does it mean the COB that was tested runned for 1000hrs at 140C ?? That would be great.

At 10$ per COB, I wonder if it's worth to think too much about it, it might be wiser to have one or two replacements around than to try to figure out expensives and complicated solutions. Plus, these PC fans rarely fail, the PSU might be the weaker link, maybe I should avoid cellphone chargers... a 12V MeanWell is cheap anyway.

Having this said, I don't know how the chain of happenings would be in case one Cobs died, I guess the chance of fire hazard is low, but I feel insecure about this. If anyone experienced fan failure would be cool to know the story.
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Metacanna

Metacanna

Well-Known Member
Sorry I didn't get what you are saying. What is lm data and in what aspect are the cobs rated in the tens of thousands of hours? You mean, running at 140C?
 
CobKits

CobKits

Well-Known Member
lm= lumen maintenance data. LM90= 90% of original lumen intensity

yes they tested them at 105C case temp at 4600 mA which would put Tj around 140C. after 15000 hrs their estimates were

LM90 = 36000 hrs
LM80 > 90000 hrs
LM70 > 90000 hrs

at 55C case temp (and the same ridiculously high current), LM90 was 48000 hrs (12 years of 12/12)

so it would be reasonable to expect an LM90 close to 60000-80000 hrs/15-20 years at the 1000-2000 mA most people run them at
 
CobKits

CobKits

Well-Known Member
also worth noting that due to the nature of the long test (15000 hrs so far), the ones they are currently testing are at least 2 gens old, maybe 3. they apply this data to the whole series but i gotta think the newer chips with better thermal properties would prob offer an advantage in lumen maintenance, but we wont know for another year or two (assuming they are even running tests with current chips)
 
DankaDank

DankaDank

Well-Known Member
CobKits said:
also worth noting that due to the nature of the long test (15000 hrs so far), the ones they are currently testing are at least 2 gens old, maybe 3. they apply this data to the whole series but i gotta think the newer chips with better thermal properties would prob offer an advantage in lumen maintenance, but we wont know for another year or two (assuming they are even running tests with current chips)
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I think they have been running the CLU056.
 
Redoctober

Redoctober

Well-Known Member
@CobKits Hey, just wondering if you're going to carry the new Gen 6 Citizen CLU048 - 1818 (90CRI) in 3500K?
I see both the 4000K and the 3000K versions (in both 80CRI and 90CRI) but not the 3500K?
Just curious
Thanks
 
Metacanna

Metacanna

Well-Known Member
CobKits said:
yes they tested them at 105C case temp at 4600 mA which would put Tj around 140C. after 15000 hrs their estimates were
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I thought they would fry in seconds running at 4600mA. Are you referring to the 048-1212?

So based in that information I conclude is ridiculous the amount of stress and caution people put in case of fan failure or overheat when building the lights. This things are much more reliable the I thought.

When it comes to lumen maintenance, more likely the cobs we have will be obsolete in 2 or 3 years, plus, the cost will keep going down. The 1212 is selling for 10$, 3 years ago it's equivalent was selling at 40$? My point is, we will be replacing them faster than they start degrading.
 
Dreddd

Dreddd

Well-Known Member
Guys help i've been trying to find somewhere to buy a few citizen cobs for the past week and the only place i seem to find is fucking digikey, and they are so damn expensive,

i'm looking for 3500k 90 cri cobs and they seem to be out of stock on both cobkits and northengrowlights..
 
Dreddd

Dreddd

Well-Known Member
CobKits said:
ive got 33 gen6 in stock
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Sorry should have specified, i'm looking for the 5th gen ones since the 6th gen have a different spectrum, 5th gen peak at 630nm while the 6gen peak at 620nm and look like they have more green, am i wrong about this?

Btw, anyone tried a build with their 97 CRI 4000k cob? that spectrum...
 
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KonopCh

KonopCh

Well-Known Member
Dreddd said:
Sorry should have specified, i'm looking for the 5th gen ones since the 6th gen have a different spectrum, 5th gen peak at 630nm while the 6gen peak at 620nm and look like they have more green, am i wrong about this?

Btw, anyone tried a build with their 97 CRI 4000k cob? that spectrum...
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Have you data and pictures/graph with difference between 5gen and 6gen?
 
DankaDank

DankaDank

Well-Known Member
Dreddd said:
Sorry should have specified, i'm looking for the 5th gen ones since the 6th gen have a different spectrum, 5th gen peak at 630nm while the 6gen peak at 620nm and look like they have more green, am i wrong about this?

Btw, anyone tried a build with their 97 CRI 4000k cob? that spectrum...
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You're actually correct good eye man, I didn't pick that up.
 
CobKits

CobKits

Well-Known Member
according to datasheet: gen 5: 450 nm emitter with a 630 peak

upload_2017-3-8_11-54-9.png

gen6: 455 nm emitter with a 620 nm peak:

upload_2017-3-8_11-55-25.png

i dont have my spectrometer here but will shoot gen 5 vs gen 6 to verify. in any case gen6 tested way higher on PAR in my first test

upload_2017-3-8_11-57-47.png
 
CobKits

CobKits

Well-Known Member
"in theory" it has a slightly different spectrum, per those datasheets, which should be tested and confirmed.

620 and 630nm both have 100% absorbance per mccree. spectrum is only very slightly different yet par is substantially increased in gen 6.
 
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