I made this grow light over the last few months, because i just love having plants around me. In winter, my two windows just don't give enough light, so i built this one =) There are so many cheap (and bad!) products on amazon and ebay, which i didn't want to order, and i need nothing professional either. So i figured that i would just build it myself.
The perfect lockdown project, btw!
-Can be fed from 15V-28VDC
-Made with Lumileds SunPlus20 Series of horticulture LEDs
-Adjustable R,G,B LED string currents -> adjustable output color
-75W at full power
-Three temperature controlled Fans
-Fan's rotational speeds are synchronized, to allow for even more silent operation.
-Shuts itself down if a fan is stuck, or if the temperature rises too high.
It is a work in progress and may contain mistakes, so i wont't release everything publicly. But contact me if you would like to have some advice/some schematics/some code =)
The DC-DC converters inside the light have spread spectrum modulation. This way, i expect to have less electomagnetical interference problems.
The computer fans are synchronized to within 1-2° of deviation. In the first few months, i didn't have this feature, and it was quite annoying to have the fans run at slightly different speeds. But now, it runs really silent and without any disturbing interferences between the fans
The old fans were a noisy mess right from the start, so i exchanged them for some new ones. They run much quieter, and also they are white, which makes it possible to get a really cool effect by illuminating them with a LED. Have a look! The video is not slowed down; this really is what you can see when you view it with your own eyes.
Recently, i added some protective acrylic glass in front of the LEDs. Before, i was afraid that some plants could grow into my lamp, if i don't pay enough attention - well, that's unlikely, but you never know. The glass doesn't seem to impact efficiency too much.
Acrylic glass does reflect about 8% of incident light (at 90° to surface), and almost 92% are transmitted. Of those 8% that are reflected, most will be reflected again by the white PCB, making a second attempt to pass the glass plane. This again will be 92% successful. In the end, the efficiency will most likely be reduced by 1-2%. On the plus side, the light distribution will be a bit more uniform, so shadows are not that harsh.
Also, i finally put some near UV LEDs onto the board. I don't think they will help too much in irradiating the plants, since the are really low-powered, but they're nice to have.
The old lampshade was made from cardboard and aluminium foil. Just a quick and simple solution, but it didn't look too nice. So today, i finally cut out some aluminium sheets and drilled holes in them to make a new one - and it turned out quite nicely.
I might add some corner pieces in the future, but for now, it is good enough. At the corners, there won't escape too much light anyway, since it is blocked by the lamp frame. Also, i might add one more bend to each of the shade pieces. This way, i could approxmiate a parabolic reflector a little better. Also, the shade needs a painting on the outside. Maybe black with a waterdrop effect.
First, however, i will work on the cooling system some more. I've got a really cool idea for a visual effect, which has something to do with the fans already being synchronized. But i won't tell too much, you have to be patient :P