i’m not talking about getting led strips or cobs and making your own fixtures, i’m talking about getting the leds and soldering them together to make the strips. i got started reading this thread and then looked at prices for leds. i found some for $0.13 each but that was for 100, about half of what you need for a decent light, so i ordered them along with some others to make up the spectrum i thought i needed.
as you can see, i accidentally ordered 100 of the wrong kind, since the blue (left) almost matches a significant portion of the white (center). the red (right) helps make up the spectrum, minus some green. i recall reading that plants that are green reflect green light and don’t use it so i decided to save my efforts and money on wasting light.
the bad thing i did was not finding all of them from the same manufacturer. now i have 100 that are different. not that much in size since they are all so small i can’t see them without my glasses anyway, but in voltage requirements, which is a pretty big thing. that problem actually solved itself when i figured out how to solder them up.
it’s really hard to tell in the picture but there is a solder pad missing on this one. let the heat stay for a half a second too long and it’s fried. the only way to solder these is as a group. and do not try to adjust one, it’s a one shot deal. miss one and you have a three stack now. and there is no way to leave them lying around, you need to make some sort of a jig. and you need to fabricate some sort of holder for them. i have a 3d printer sitting right next to where i’m working but have been a carpenter for 15 years so guess what i used for the jig.
some of the worst soldering of my life, almost the smallest but 30 years ago when i learned how to solder circuit boards i could see small things. anyway, nothing a little liquid tape won’t hide.
i’m not done by any stretch. that would have wasted all that money. man, these things are bright as hell though. i just got through the baseline test and it read 30k lux at an inch away, 1381 at 6", 561 at 12", and 186 at 24". that’s just 4 leds on 2.9v. as soon as i rig up a way to hold the light straight and power on at the same time i’m gonna start the comparisons. not that this can’t be done, i just wouldn’t recommend it to anyone unless they just want a challenge or bragging rights. i probably won’t do it again, but i will always know how and be able to. it is cool just to be able to say i can do it.
i was going to ask you some questions if you don’t mind on my math. i’m having trouble figuring out the resistor value to bring my 3v down to 2v. from what i can tell the voltage drop on my 23awg wire is negligible for these distances, since i was going to just use that to drop a volt but it would have taken 2000ft of wire. the data sheets say 0.65a and i assume that it only draws what it needs, which is 0.65a. that gave me almost 31k ohms but i’m not certain.
after taking 3 hours to get the first 4 bar done it only took 5 minutes to blow it out. the next 4 bar took 10 minutes to put together. i may have enough to grow with by the time i need them.
have you seen worse soldering though? i can’t see it without a magnifying glass but i can make it work. i have a great tip and a light touch.
test results on the strips show the convex to be slightly better than flat, contrary to what i thought. concave had ~3250 at 6, ~1048 at 12, and ~310 at 24. convex had ~3600 at 6, ~1080 at 12, and ~290 at 24. flat had ~3548 at 6, ~1080 at 12, and ~260 at 24. i need to check my baseline again with the new battery setup i have though.
all measurements in lux with a free android meter.
current is dictated by the temp of the led and what voltage it is running at plus each chip characteristics.
also consider if your taking your example of 3v and cutting to 2v your literally gonna be wasting 33% of your energy to straight heat with resistors thus why people and companies use parallel series arrays and use adjustable voltage or floating voltage constant current drivers
yeah but i’m working with what i’ve got and i’ve got a lot of power supplies. i can get 3v, 5v, and 12v and up to 19a depending on what pinout i use. since i’m building strips and not fixtures i’m not worried about heat to resistors either, open tops with a fan blowing across them. if i were to put them in series i’d have to be pretty damned quick on that iron. my thought is to get them into groups of 4 with the white and 3 with the red and put 4 groups per strip. if i recall correctly the voltage stays the same and amperage adds up in a parallel connection and the opposite in series. if that’s the case, i think it’s right that a 31k ohm resistor will bring the 3v to 2v. if i can find one of those or a combination of them i’ll find out tomorrow.
I’m genuinely curious, how do you have no more money for a light or the correct parts to build one but are going to power a grow setup and don’t care about wasted electricity? Electricity is one of my most major costs and I’m having a hard time wrapping my head around your logic here. It seems like you’d be better off selling that pile of scrap and buying a light, am I missing something? I could go canning or scrapping and get the money for a 100w LED faster and easier than this build is going to be.
I say that because I’m also broke and have lots of spare time, this is the kind of project I had to learn to stop doing when I got medicated for ADHD- unplanned, unfocused, not fully thought through.
I don’t get the sense that you have a lot of experience or knowledge with this, and as much as I love to encourage a DIY, this is a pretty asinine project at this point, you’re more likely to set your house on fire or electrocute yourself based on what I’ve seen so far of the planning. Maybe don’t do that? Especially if other people live in or depend on the building you might burn down?
I understand the desire to do something yourself to say it can be done, but not everything needs to be done, and I see you barreling along not heeding a lot of advice based on professional experience or education in electrical engineering. So far you’ve ordered old, low-efficiency LEDs not pre-soldered onto stars or strips, got the wrong ones, didn’t return them for the right ones, and have blown quite a few in mistakes that were easily preventable.Those PVC Venetian blinds are likely to start sagging once the emitters heat up, or those resistors, creating a further fire hazard from that.
This is painful to watch, honestly. The best analogy I can think of is as a sober alcoholic watching someone just keep drinking. I think you’re lost in the sense of possibility here and not thinking about what makes actual sense or is safe to do.
Fuck around and find out! Life is short, do some fun stuff and laugh about it later. I believe in you, no matter how silly this project is, I want you to succeed.
i’ll second Dirt_Wizard’s. at the bare minimum you should be using some kind of Cree/Luxeon star. the leds you purchased are meant to be reflow soldered by a machine. at least with a star led of some kind you only have to worry about mounting the star into the heatsink with thermal paste, attaching a lens if you choose, and soldering them into your driver.
your life is far too important to burn out on leds. be safe! @sfzombie13
I also want to add that green light is used by plants and are a required wavelength to reach maximum efficiency. There is a reason why full spectrum led are so much better then selective spectrum, like blurple.
I really like the idea of doing something like this and sharing with us, it’s going to be exciting to see how the finished product work out.
why on earth do you think i put it all on the internet here? to get points on mistakes so i don’t make too many on my own. like the blinds sagging. i never thought about that, but now that i have, i cam put a length of coat hanger along both sides for stability.
as for being broke, i have a lot of money coming in, but none to put on this project right now. i can spare a few bucks here and a few there like for the electricity. as for burning the house down, it’s an outbuilding on a farm that nobody live at. nearest building is a barn 10 feet away and the thing has asbestos siding so it most likely won’t spread there.
as for the experience not being there, i have it but it’s 30 years old. things got a lot smaller since then and it’s gotten a lot harder to see them. other than that, dc is still dc, ac is still ac, and resistors still resist. just the fact that i can take these insanely small things and figure out how to solder them together and make them work should have been your first sign that it is not above my ability or skill level.
@crunkyeah for the record they are cree leds. see the paragraph above for the part about safety, and as a general rule i always use - safety third.
to all the rest thanx for believing in me. now that i’ve figured out how to get these series-parallel lights hooked up i wish i didn’t have to work today so i can play with them.
@LonelyOC thanx for the tip on the green lights. i may spend another $20 and get 100 green ones to put in there with the others. do you know if they’ll do ok without as much green? the white covers some of the green but that’s the low point. i can’t find any leds with a spectrum that fills the gap exactly where the green is missing.
You should check out this video, I think it would be of much help for your project! He can tell you the ins and outs of crop physiology better then I can.
I think you can do it. I taught myself to build led lights. You can teach yourself too. The above video of Bruce Bugbee is something very important. Three pionts. 1- you need the correct voltage. 2- keep the current below 80 % of maximum for longest life. Make sure the voltage is moving in the right direction across each led. Otherwise, Just play with it. I believe you said you are a farmer and that means you work with dangerous things every day. This is just a toy. Have fun
lol my grandpa was a farmer and he was missing bits of fingers on both hands, not a great argument! Existing danger doesn’t make adding new risk a good idea, it just means you’re desensitized to risk and its consequences.
safety third. i jump out of planes for fun too. risk mitigation is my priority. these leds use low voltage dc. no danger there at all at this amperage.
I am going to give a tip.
Use double sided tape and low temp tin solder. And depending how are the terminals pretinned, a little solder paste.
The double sided tape helps holding the led in place. I stick it to a small aluminium rectangle, so also helps with some dissipation when soldering.
, sometimes one just needs to figure out the hard way, hey you made an effort to try and that’s most the battle.
Have fun