Instructables

Electric Bottle Garden (LED grow lights Mk 1.5)

Picture of Electric Bottle Garden (LED grow lights Mk 1.5)
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As a kid, me, my brother and my mum used to make bottle gardens, the idea was to plant a load of plants in a bottle only through the neck (think of those ships in a bottle).
Anyway i was thinking of building an update to this: http://www.instructables.com/id/Growing-Plants-With-LED-Lights/ when i got bored and thought i'd put together an electric bottle garden in old water bottle i had lying around.

Although this is kinda similar to my other instructable i figure its different enough to be worth posting. Its also not really an entirely sensible project, loads of light leaks out the sides (but it looks pretty) so its more of an LED assisted bottle garden, and it would of been a hell of a load easier to just cut up the bottle, but i liked the idea of doing it just through the neck.
 
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Step 1: Building the lighting rig

Picture of building the lighting rig
I wanted to fit everything through the neck of the bottle, and i also wanted the LED's to cover as much of the soil as possible. So i figured some kind of expandable lighting rig that would fit through the neck of the bottle was the way to go.

To do this you'll need:
12 red LED's
1 blue LED
a square bit of plastic
thick copper wire
13 220ohm resistors
wire

you should also have a fair bit of experience soldering and making electrical circuits.

Firstly solder 3 LED's along a piece of copper wire at about one inch intervals, making sure they are all soldered the same way around.
Sweet! The only thing is, you really don't need 13 resistors, only one. Put one resistor in series with the power supply, and then keep your LEDs in parallel. Using 13 of them in parallel is actually dropping your resistance quite a bit. Way further than you would expect it to.
Well... it is actually better for the LEDs to have a resistor in series with each one, rather than putting all the LEDs in parallel.

The cut-in voltage can vary from LED to LED, and the current above the cut-in voltage rises very rapidly, so whichever LED turns on at the lowest voltage may carry a lot more current than the others - that's the whole reason you need a current limiting resistor!

On the other hand, LEDs in series are much better behaved. If you're feeding these LEDs off 5V or more, you're better off to put as many LEDs in series as possible. So you may only need to solder 7 resistors instead of 13. Check out The Guru at ledcalc.com for the optimal design for the LEDs you're using.
webgiant Patrik5 months ago

Do remember that good old Ohm pointed out that each Vd (an LED in this case) in series uses a portion of the voltage (Vt = V1 + V2 + V3), possibly making the LED at the end not receive enough voltage to light up because V1 and V2 have used up most of the power, or reducing the lifespan of the first LED since each LED is the current limiting "resistor" for the next LED in series.

This is why LEDs are usually wired in parallel, because in parallel the Vd for each LED is equal to the voltage provided by the power supply (Vt = V1 = V2 = V3). Makes it much easier to do the math, and certainly requires a much smaller power supply than for LEDs in series.

}{itch (author)  Patrik6 years ago
yeah, I noticed quite a big difference in brightness in the LED's when I only used one resistor to limit the current for quite a few in the first instuctable i did (there's a link somewhere). I figured it might of been possible to use fewer resistors, but from a structural standpoint it was easier to solder a resistor to the leg of each LED (isn't it odd to think about electronics structurally?) Anyways, thanks for the link, that calculator looks hella useful.
arnookie3 years ago
If you are thinking of building a diy grow light please take note of this.
Each and every led needs to be atleast 1watt each. Anything below that will be useless so don't use old leds out of toys or old boards, they simply will have too little Total lumens versus lumens per watt. You need atleast 10mm LEDs with 1watt per LED to supply enough light to the plant anything lower will not work. A good combination is a pannel made from 75% 1watt red high brightness leds, 20% 1watt blue high brightness leds and 5% 1watt amber high brightness leds. somewhere in the region of 660nm for red and 460nm for blue
There is also no effective difference in penetrative power for horticultural purposes between a 1W LED and a 3W LED. So anything over 1watt is just wasted. This means brightness has very little to do with the benefit you will get once you use 1wat leds. Don't confuse this with a pannel made from say 20 LEDs rated a 10watt as to one with 10 LEDs rated at 10watt. As the 20 watt pannel will use the useless 0.5watt leds verses the 10watt pannel that uses 10x10watt 1watt LEDs that are ideal. This has been tested and proven that 1watt single LEDs have great benefit to plants and anything less is just a waste of time and has no benefit at all to plants. The same applies with going brighter than 1watt has no benefit either.
Hope that may help some of you. Especially if you are growing indoors.
Also LEDs are more efficient than any other form of grow lighting available.
The commercially available LED growlights outperform all other growlamps from HID lamps to including high pressure sodium (HPS) and metal halide (MH) lamps.
So prepare to see other grow lamps become obsolete as LED growlight take over.
Just to clear a point up. If you make a 100watt pannel with 100x1watt leds you will benefit. But if you use 200 0.5watt leds to make a 100watt pannel it will not benefit the plant at all. The same applies if you use say for eg 10x10watt leds to make a 100watt pannel then you are only really getting 10watts overall because the extra 9watt per LED is just wasted as the plant will not benefit. SO using 100x1watt LEDs will benefit the plants by 100watts. 10x10watt LEDs would not because 9Watt of each led is just wasted giving the plant just 10watt of usefull light. Sorry but thats just the way plants absorb light.
downgrade4 years ago
Any updates on how the plants came out? I'm waiting for my LEDs in the mail for a similar but bigger project
tcase6 years ago
why not just put the led's in the lid instead of hanging down, and put aluminum foil in the lid aslo to shine the light toward the plant.... not sure on the room, and how many led's, but the theory sounds tood... i think...lol
drj1136 years ago
Clean and simple - well done Might be a scout project in the making :-)
xtank56 years ago
This is awesome!! I need to get me some LEDs!!! Arrgh I'm so mad at myself for not ordering some off of ebay.
gamer xtank56 years ago
get some online from an electronics store like abra electronics, or addison electronics -gamer
LinuxH4x0r6 years ago
Great Job! Did they turn different colors (plants only need 630 and one other freq. that I forgot)?
}{itch (author)  LinuxH4x0r6 years ago
its about 470nm (blue) They grow pretty much the same colour, the leaves turn a bit darker if anything (this is based on the couple of little sprouts I've got growing in it, should be interesting to see how/if they change as they get more mature, i'll post some updates as they get a bit bigger)
Can't wait to see them!
AMAZING job! ALL your stuff is awesome, and I mean ALL OF IT! +1 rating! (added to favorites)