My First LED Grow Light Build

What better way to start things off than by having a look at my current LED grow light equipment and providing some general info on each piece and how it all goes together:

My first setup consisted of:

  • 4x Cree CXB-3590 COB (Chip On Board) LEDs
    • Colour temperature of all 4 is 3500K. It took me awhile to decide which temperature would be best, as there’s a lot of conflicting information out there. I plan to experiment with different colour temperatures to see if they make a difference during the vegetative and flowering phase.
    • My LEDs are graded “CD bin”, which is the best and brightest of the 3500K group. LEDs of the same type can vary a great deal in terms of colour and brightness, and are broken into different categories (bins), based on these variables. So, for example, a CXB3590 with a colour temperature of 3500K could be a “CD” bin like mine, which produces a minimum luminous flux of 12,000 at 85 degrees C, or you could get a CXB3590 from a lower bin of “CB” which produces only 11,000lm at the same temperature.
  • 4x Aluminum Heat Sinks that I Purchased Used from eBay.
    • I decided that I wanted to use passive cooling (no fans involved) since I wouldn’t have to worry about the COBs overheating in the case of a fan failure. Passive cooling requires a much bigger heat sink, but provides greater peace of mind.
  • 1x Meanwell HLG-185H-C1400B LED Driver
    • I chose a driver capable of providing each COB with 1.4A at their combined voltage. 1.4A is somewhere in the middle of what each of the COBs can handle in terms of current (they are rated for 3.6A but the more power you give the COB, the less efficient it becomes and the more heat is produced rather than light).
  • 1x Woods 50009 Heavy Duty Digital Timer
    • This timer has worked really well since day 1. I can schedule separate on/off times for each day of the week (and multiple on/off times each day).

Here are some pictures of my equipment and build process:



I was so excited when this package arrived in the mail. Here are the COBs, holders, and LED driver, featuring Darth Vader socks.


I purchased 4 used aluminum heat sinks from a guy on eBay for a good deal. Getting a heat sink custom-made is very expensive (especially when you live in Canada) so I was pretty pumped to find sinks that would work for such a good price. The existing holes were spaced JUST far enough apart to allow me to mount a COB with full surface contact. I drilled and tapped 2 new holes for each COB.


Naked COB.


Thermal paste applied.


Smoothed out and installed into the holder. The holder is then screwed into the holes that were drilled and tapped on the heat sink.


A look at the top of the heat sink.


Driver close-up.


The timer that controls the on/off schedule of the lights.


The driver, after attaching a power plug, soldering on an extension to the positive and negative leads, and soldering a potentiometer to serve as a brightness control.


Potentiometer close-up.

LED growlight

Here’s how the wire connects to the cob holder, which in turn makes contact with the COB connection pads.  When connecting multiple COBs, you usually connect them in serial configuration (parallel can work, but there’s potential for more problems this way). In this case, to wire in serial, the positive of this COB would connect to the negative of the next COB, and so on, until the last positive terminal connects back to the LED driver’s positive output.

That’s all for now – it’s past somebody’s bedtime.



1 Comment

  1. AFAIK thermal paste should be applied to fill potential gaps of contact. Best thermal conductivity is where COB directly contacts the heat sink.

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