I've been reading quite a bit on the site and have gotten excited about giving indoor gardening a try. I'm looking to start small in 1-2 square foot area (1'x1' to 2'x1'). I'm mostly interested in growing herbs (mint, basil, thyme, etc) and maybe moving on to leafy greens (lettuce, kale, arugula) at some point in the future. I was originally thinking of throwing together something using a bunch of 5mm LEDs, but this site has gotten me thinking about using COBs or strip lights instead.
Since I won't have very high power demands, I was hoping I could get away with a power supply I have lying around. I have an old 65W power brick from an old laptop rated for 18.5V and 3.5A http://www.primelec.com/hp-compaq-65w-1 ... BRrattKiM8. That sounds like it would give me enough power based on what I've read (30-40W per square foot), but I wanted to double check. I also wanted to check if this would act as a constant voltage driver and how that would influence which LEDs to use and their wiring.
If the power supply can give me enough power, I was hoping someone could give me a recommendation for some cheap COBs or led strips that I could buy in Canada. I was thinking of getting some EB2 strips and wiring them in parallel. However, their forward voltage seems to be 19.5v and I'm not sure my 18.5V charger would be enough. Any ideas?
low budget build using laptop charger
For my first LED project I also went with a laptop charger because it seemed simpler and safer not having to deal with AC. After completing it I think this was a design error, because you lose efficiency converting voltage twice and there is more soldering involved plus cable peeling, and converter modules seem pretty hacky. In the end, a proper CC LED driver seems more straight-forward and isn't that expensive.
That said, you would probably need some DC-DC step down circuit for 12V or a booster ("buck-boost", step up etc) for most COBs. You can find them on eBay for instance. They allow you to adjust the voltage with a screw driver.
You could also go to digikey and use filters to find a COB that matches your charger output exactly. I would expect it to act as a CV driver, but I'm not someone who should be answering that kind of question.
Update: Also with a LED driver you get dimming which is neat.
That said, you would probably need some DC-DC step down circuit for 12V or a booster ("buck-boost", step up etc) for most COBs. You can find them on eBay for instance. They allow you to adjust the voltage with a screw driver.
You could also go to digikey and use filters to find a COB that matches your charger output exactly. I would expect it to act as a CV driver, but I'm not someone who should be answering that kind of question.
Update: Also with a LED driver you get dimming which is neat.
The EB2 strips might work - the spec sheet says that the minimum voltage is 18.5v which what you have. I found my EB2 strips for $4 each so probably worth it to try it out if you can find them that cheap. That said, see if you can find a 19.5v laptop charger - my is from Dell but they seem to be fairly common (I got another from our office supply cabinet - lots of old electronic junk in there). Anyways it works very well with the EB2 - i have the 280mm version. It pulls ~.5A each... more than enough for me. Check out the "Repurposing Laptop/Electronics power supplies" thread for more info.