I wanted to share with you all my DIY COB light I built. The light is based on four CXB3590s. These diodes are 3000K and run at 36 volts. The 3500Ks are more efficient, but I wanted more red in my spectrum. These are attached to a 30 inch piece of 5.886 inch extruded aluminum heatsink from heatsinkusa. Active cooling is provided by four Noctua 140mm fans. Finally, the COBs will be powered by a HLG 240H C1750B Meanwell driver. This driver is dimmable and will run the COBs up to 1750 milliamps. With four COBs at 1750 mA, that’s about 250 watts. I took a bunch of pictures of the build. Enjoy!
First layout the COB holders. And punch the centers for easier drilling.
Next mark holes for wiring and hanging. I’m short a D-ring, so I’ll have to pick one up.
Next I drilled the holes for hanging and the COB holders. Tappping these is turning out to be a bitch. I broke two taps before getting the hang of it.
I sanded the heatsink where the COBS will go and whipped it down real well with alcohol.
Next step is to mount the COBS. Take the COB holder and flip it over. The chip clicks in place, make sure the positive signs match up. Add a thin layer of thermal compound, then attach the holders firmly to the heatsink.
Next I wired them up in series, so negative from the previous COB goes to positive of the next COB and so on. I put a power cord on the driver and hooked up the positive and negative wires to the COBS.
A quick bench test confirms that the lights are wired correctly. I’m still seeing spots.
Next I hooked up the fans and ran the wires for the remote driver. The fans are simply connected by shoving the rubber feet between the heatsink fins. They may be overkill, but they sure are silent!
Finally I mounted the driver in the electronics section. That little box on top is the 12v power supply for the fans.
Here is the light all complete with plants ready to transplant.
