Let's talk DIY lights

Which board did you get, and what color temp?

Already have a driver picked out?

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I just bought 8 COBs and a bunch of dollar or two parts from Digikey to drive them. I talked it over with my analog designer guy and I’m going to try running pairs of the 68 volt COBs in series with a DIY MOSFET buck switcher circuit. Bridge rectified 120 VAC will give me about 170 VDC across a big cap. Then a big P-channel MOSFET driven by a comparator and a little N-channel MOSFET level shifter as the gate driver should keep the output at 1.0 amp. I’m trying to do it without inductors to keep the losses down. One cap charging another cap with an inductor will have some ripple, but I don’t really care. The comparator gives me dimming for the price of a potentiometer.

The cool thing, is I can experiment with 120 watts of incandescent first and check it all out with my scope before I have to risk a COB. Hopefully, I have designed out all the bits that lower switcher efficiency. We’ll see.

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Sounds pretty cool. What would you expect from an efficiency standpoint? And what kind of cost will you be at as far as the power supplies go? I always use a pot for dimming, cheap and fairly reliable.

I think you’ll like that set up a lot more than what you were originally looking at. Your electrical efficiency (par watts vs heat watts) will be much better, and the boost in led efficiency is pretty good too.

I really don’t know how efficient it will be. I went out of my way to optimize it, accepting some ripple in the output. But that ripple should be at about 50 MHz, so it doesn’t matter. I’m using a linear comparator instead of a microprocessor as the control element, and it responds at about that speed. It is good because the capacitors can be small, but it might be bad because it uses a lot of current to switch the big p-channel MOSFET gate so much. I’ll see in my prototype. I may have to do some stuff to slow down the comparator.

Cost is at $28.56 so far, not counting the COBs. That is for driving 8 COBs, so the cost is about $3.57 per COB. I still need to get a few more parts at Fry’s like power cords, perf board, little wall wart to power the comparators, etc. The stunning thing is a 5.2 amp 200 volt p-channel MOSFET is only $1.01 now!

Mosfet gate similar to igbt? To be honest, I’m vaguely familiar.

You’d be much higher than that buying a driver for sure. I was just wanting to compare efficiency vs cost. I’m sure I could find the components and diagrams and make it happen, but I doubt I’ll ever get that ambitious.

I sure am getting a lot of ads for grow lights from Amazon. They’ve really gone in for all the adult entertainment items now: Porn CDs, sex toys, and now grow lights and nutes! Big Brother really is watching, and he wants to sell you stuff.

The thing I notice about all these grow lights is they are very casual in calling them “1000 watt” when they consume only 300 watts, and so forth. Like they have some sort of standard of incandescent floods and use that to calculate equivalence. Got news for you guys: Nobody has used incandescent floods for years and years. 1000 watts should mean 1000 watts. And when you put a resistor on every LED, that resistor turns current into heat, not light. That’s not a feature, that’s a design flaw.

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Yes, MOSFETs and IGBTs are similar. Just different technologies. Both have isolated gates so they make great switches. The MOSFETs are CMOS and IGBT stands for Isolated Gate Bipolar Transistor.

If my drivers work out I’ll put the schematic and BOM on this thread. I’m not trying to make money at this. But it will take a few weeks to get everything and experiment with the prototype. Or maybe I’ve screwed up and overlooked something. I’m really more of a programmer than a designer.

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I know the feeling!

I’m familiar with how and and what an igbt does, and capacitors. But I do more automation and control type stuff, so it’s more using the components that use those components. Never really been into the electronics end of things. I don’t really have the patience or steady hand to be soldering tiny components, so it pretty much ends there for me lol.

I ALWAYS specify “through hole” for the mounting option on the parts suppliers websites. I can’t see well enough to solder surface mount chips anymore.

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First @dbrn32 opened to me up to DIY lighting, and now you’re really expanding it @1BigFella! What are you guys talking about when you say MOSFET and IGBT? What does it mean, and what does it refer to when it comes to the lighting? I’m so curious now lol

:v::evergreen_tree::evergreen_tree:

@1BigFella is talking about building his own power supplies. It’s a little beyond the scope of what I do, but still pretty neat.

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These are the parts that go inside a driver module. Unless you have some experience assembling electronics, you should just stick to buying lights, or buying driver modules and the LED COBs (chip-on-board) we were talking about earlier. This is 120 VAC line powered stuff and if you don’t know exactly what you are doing you could blow up a lot of expensive parts or even kill yourself.

If you do have such experience, drivers only put out about 38 volts for the low-voltage high-current COBs. I would vastly prefer it if you fiddled with 38 volt drivers. And please, please, please plug your lights or driver modules into a ground fault protected outlet. We are fooling around with electricity in a bathroom or basement here. If a chassis is hot and you touch it and a good ground like a water fixture or drain, you could die without a GFI.

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@ktreez420 was wandering hlg page, and I looked at these 3 different times thinking of your future project. I’m not sure which way you were leaning, but 4 of them and driver would run about $180 for little over 200 watts. You may have to keep them a little lower to have intensity, but I’d say they would probably do half your tent.

They don’t have heatsinks for them, but I bet a piece of 1/8 " aluminum plate would keep them cool at only 50 watts a board.

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I’m still confused on what these quantum boards are exactly! Not that I’m opposed to using them, I’m just curious why they’re the new rave? @dbrn32 I know you’ve tried to explain it before lol, but could you try again for a high guy like me please?

:v::evergreen_tree::evergreen_tree:

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@ktreez420 They are essentially just boards of several Samsung diodes configured into a usable voltage and current. The thing with the Samsung diodes is that they are uber efficient, like almost 3 ųmols per joule when driven soft. Compared to most cobs that around 2 ųmols per joule, or even the de gaits at like 1.5-1.7 ųmol per joule. Plus they will have a little less of a hot spot than a cob or hid when boards are spaced well.

They have some flaws, but are very negligible. When looking for high efficiency and low heat, they’re one of the best options currently available. And on diy level, cost per watt is pretty reasonable.

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And they grow huge buds
@ktreez420 @dbrn32

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@MAXHeadRoom you’re last grow was only ran under the qb’s for the last few weeks right? Did you calculate gpw on your harvest?

Thelma and Louise had the QB for the whole flower period. GPW estimate would be around 0.75 but should be higher if grown 100% under boards

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Not to shabby at all! How long have you been growing for and what strain were they?

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I bought Gold leaf from ILGM when they where on sale. This was my first grow. For my second grow I have 12 clones ready to go into the 2 aeroponic systems that I grow in and I am growing 4 clones in 5 gallon buckets with foggers. I have 1000 watts of Quantum Boards for this grow so I should be able to bump up my GPW to 1 or hopefully 1.5 for this grow

All the clones are from Louise the Monster that yielded 1170 grams wet weight

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