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Adventures in LED's - DIY tinkering fun


Well-Known Member
Hi all. Sort of consolidating some info gathered over the last few weeks into this post in the hope its useful to someone. Have posted bits of this in other threads over the last few weeks but have now had a good play with some COB leds I bought for testing purposes. So, long post...apologies.

Have managed to get access to a few different LEDs and compared them to the 600W HPS grow light i used for my recently harvested first grow. Not a lot of yield for the first round, but have learned a few lessons for next time. :)

Anyway, have access to a good PAR light meter, a workshop and some different LED setups :)
Various setups are below with the measurements I got.

600W HPS measurements from in my tent. 3 different cheap end commercial LED setups. 3 Different DIY COB LED setups I built out of parts sourced from eBay based on the 50W "driverless" chips available cheap from China.

Measured PAR (umoles) in the centre of the fixture @ a particular height light to benchtop, and then same height but with various lateral offsets of 0 to 50cm. Representative photos (no brand names) inserted where I can for context. Hopefully formatting of this post works.

Anyhow, results below:

Ok, just cannot get this to format properly. :( First number in the row on my little tables is the vertical distance light to PAR sensor. Work it put. :(

600W Lucagrow HPS
Ambient PAR for test 008

Lateral cm 0 20 25 30 50
Hieght cm
40 1067 828 645 600 405

Cheap "120W" LED panel off the shelf unit. "burple growlight"
Ambient PAR for test 004

Lateral cm 0 20 25 30 50
Hieght cm
30 74 55 43 34 16
50 35 28 27 24 15
100 14 11 11 10 7


Cheap "600W" "Epistar LED" off the shelf unit. "burple growlight"
Ambient PAR for test 004

Lateral cm 0 20 25 30 50
Hieght cm
30 293 179 139 104 30
50 101 80 77 61 42
100 27 26 25 23 22


"600W" "COB LED" 2 x COB chips off the shelf unit. "burple growlight"
Ambient PAR for test 004

Lateral cm 0 20 25 30 50
Hieght cm
30 835 377 230 129 30
50 322 197 144 103 47
100 98 88 80 63 44


"50W" COB 1 chip Unit Draws 86W
Ambient PAR for test 011 Stable temp 40 Degrees C

Lateral cm 0
Hieght cm
30 146



"150W" COB 3 chip Unit Draws 214W
Ambient PAR for test 011 Stable temp 35 Degrees C

Lateral cm 0 20 30 40 50
Hieght cm
30 274 176 105 62 38


"200W" COB 4 chip Unit Draws 298W
Ambient PAR for test 011 Stable temp 68 Degrees C

Lateral cm 0 20 30 40 50
Hieght cm
30 360 203 112 58 30


The COBS are wired up behind acrylic that makes no practical difference to light levels (measured with and without 96-98% transmission)) so that i don't electrocute myself. Everything earthed.


Have currently removed the 600W HPS from my tent (1.2, x 1.2m x 2m). Using two of the blue COB units at the moment to finish flowering 6 clones i had left over from last grow mucking around. Need to cut power use. Have the "epistar" style 600W LED in my "spacebox" next to the tent with some clones taken in flower coming on slowly in veg.

The DIY COB's??

Well the single chip units aren't much use i think for the effort to build. And the 4 chip unit runs too hot and draws too much. I need 2 of the those for area coverage in my tent and that would draw 600W out of the wall which keeps me at around 800W overall when fans and the "spacebox" are considered??

Using the blue cased "600W" COBS i have now am at about 400W overall i reckon.

Achievable with the DIY LEDs should be two 3 chip units which will give me a total use of about 600W all up with fans and "spacebox" and pretty much cover my tent area. Which is an improvement on where i am now by about 25% in terms of power use and less heat into the grow area. Ambient temps here now regularly daytime30 degrees C. Acceptable beach weather but not so good where the tent is. Will have to go lights on nighttime only when summer hits.

Anyhow, next "project" with this is going to rebuild the 3 chip unit with 2 fans, and, have ordered a couple of the 50W "driverless" warm white chips. Will do a 3 chip unit with 2 burple "plant growth" chips and 1 "warm white".
Will do PAR measurements, but think proof or not of that will be try and do a grow with it?

Seems to be that (and i have local, professional LED people who build programmable arrays for university research tell me this, as well as seeing references on forums..) the "green" part of the spectrum that current "plant growth" LEDS lack is actually a useful thing to have in terms of plant growth. So adding warm white could be useful i think.

Anyway, feedback advice and any opinions appreciated. Seeyahs!


Well-Known Member
300 watts for 360 par at 12 inches? Yuck all those numbers are horrible,

Why not just get the ebay cob set for $20, then put in a more expensive chip, like 3030 or something like that?

$20 gets u the light, fan, heatsink, driver, lens, reflector. then just replace the chip with something better? But i hear some of those 100watt chips arent to bad.

Im personally just getting a PerfectSun Mini, no more BS DIY crap

also, yeah, the green helps with CO2 uptake.


Well-Known Member
Thanks Phil. They really arnt that bad. considering they were cheap and Im running them in parallel. I also dont have them turned up all the way. probably around 300 watts, but Im only using 195.

I have a few seedlings that are just about 20days old, and they are 24inches tall,lol..in a 40oz container. but 3 are males of the 4.

they stretched because I had them like 30inches off the light,
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