Tonight I wanted to see just how close most of the popular COBs are in terms of lumen output at various wattages, so I punched some numbers into the manufacturer product selection tools and compiled a list. All results are calculated at a case temperature of 55 degrees Celcius (except for the Luminus CXM-22, for which I estimated Tj to be 85 degrees in order to have a case temperature as close to 55 C as possible). A color temperature of 3500K and 80CRI was used for every COB.
I’ve been on a week-long hiatus due to being super busy with work and getting sick, but I aim to get back on track. It’s been awhile since I updated my tent and 3000K vs 5000K grows, so here are some pictures.
In this video, we’ll have a look at what happens when the sum of your COB voltage drop in a circuit is below the minimum constant current region voltage of your driver, as well as what happens when it’s above the maximum constant current region voltage of your driver.
I got my new Apogee SQ-500 quantum sensor in the mail yesterday and I found some time to play with it tonight. This thing is pretty slick. This sensor comes in a few different styles – you can get it attached to a handheld meter that gives you a digital readout (MQ-500), you can get it as just the sensor with a USB termination on the end (SQ-520), or you can get it with bare wires (SQ-500), which is what I opted for. In order to read the data from this sensor, you just hook up the wire leads to your multimeter and read the DC voltage output.
I’ve had a number of requests to put up a constant voltage version of my COB LED Driver Selection Tool so I drafted one up today. Please see the notes at the bottom of this post for some important additional info. Also, if you’d like to see any COBs added, let me know which ones and I’ll see if I can include them.
I’ve been rambling on here for about 4 months now and it’s awesome to have more and more people reaching out via email or comments. Since i’m feeling far too spent to do any useful research tonight, what I’d like to dedicate this post to is finding out what you all would like to see more of. Before I get into that though, I have to share how pumped I am about something: I just placed my order for an Apogee SQ-500 quantum sensor today (finally!), so I’m super fucking excited to get my hands on it and start doing some testing with it when it arrives in a week or two. In the meantime, I’ve been brainstorming on what I can try with this new tool and have a come up with a few things.
Hope you all had a nice weekend! We had a taste of Spring last week with +10 degree Celsius weather, but were thrown right back into the dead of Winter on Saturday with nearly a foot of fresh snow and lows in the -20C range. Not wanting to go anywhere with all the snow, I found myself with some time to spare so I modified my little DIY grow tent in order to create a bit more space for my plants.
Matching your COB to a heat sink is one of the most difficult parts of designing your own COB grow light. Unless the manufacturer of the heat sink actually specifies the wattage you can get away with running, you’re left to do the calculations yourself. Luckily, there are tons of heat sinks available now that come pre-drilled for your COB or board, and are rated, in plain English, for their power handling ability. You might see smaller pin-fins (120mm or so) that are rated for 50 watts of power, larger pin fins at 140-150mm rated for 75 watts, or even bigger sinks that are 160mm+ and rated for 100W.
That being said, you might be a glutton for punishment and have a burning desire to source your own heat sink, or figure out if the one you’ve got kicking around will work. Fortunately, like most things in the DIY LED world, we can figure this out with a little research and perseverence. Fair warning though, this is pretty dry stuff.
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