Sometimes, sitting in a windowless office can drive you crazy. Adding a little bit of life and color can really help. [Gripen40k] did this by building a biosphere. He didn’t have any windows though, so he made an LED light on a PIC based timer. What is interesting is what he did with a thermistor. The Cree LED bulb that he salvaged was going to be submerged in the water, so he had to do some workarounds to keep from over heating the biosphere. Read the project log for more details.
This is a fun project that can be applied on a larger scale even for some cool plant displays at home.
No where near enough light for the plants. he needs to quadruple the number of LED’s and add some read and blue ones to actually get light that the plants would want in there.
P.S. a biosphere in sunlight = cooked biosphere I had an executive buy one of those high dollar ones that had a live shrimp in it and was all hand blown glass cook it by putting it in the sun. Internal temps got high enough to bust the glass sphere from air and water vapor pressure.
I used LED lighting for the potted herbs during the winter. The problem is that white LEDs emit a very narrow spectrum of light. The result was that my plants grew very thinly and became mildly sickly. To the point where they were unable to deter pests and became a breeding ground for some fruit-fly/knat like bug.
I’d love to see a project like this using a full spectrum CFL ($7-10 at your local home repair store.
Alastair: The white LEDs don’t exactly emit a narrow spectrum of light. What they produce is a sharp peak in blue and then a wider peak in yellow frequencies. [<a href="http://ledmuseum.candlepower.us/twelfth/nspwf50d.gif"LED-Museum-linl]
The problem is that this is not the distribution of frequencies which plants use. If you had added in some red LEDs, the plants would probably have grown normally.
The fruitfly/knat like bugs were probably fungus gnats due to overwatering. If the soil doesn’t have the chance to dry out between waterings, fungus will grow and attract/feed fungus gnats.
ehh, link fail. sorry.
I got the inspiration for this project from lifehacker here:
http://lifehacker.com/5508166/make-a-biosphere-for-a-low-maintenance-cubicle-companion
However, I did also get some help from a few local aquarium stores. White LEDs are used in a number of low-light aquariums and the particular plants I got are well suited for this kind of LED lit environment. The one aquarium store I went to had a similar (but professional) setup involving LED lighting and the plants in it were very healthy.
See a link for an update on the project.
Isn’t that huge pic chip a bit overkill for an LED on/off timer? Does it do PWM dimming? The ‘writeup’ was a little lacking. Cool idea though.
Yep, the chip is a bit overkill, but it was free (in my parts bin) and it’s always better to have more IOs than less :)