supercharged lemon

build a lemon-powered flashlight!

normally it takes 3 lemons to get an LED slightly glowing...

with this design you can make a single-lemon-powered flashlight that will run for weeks!!!

credits:

it was developed during the exhibition "Cooking and Constructing" at Platform21

joule thief design

Step 1 Prepare the components

to make this lemon light up you'll need the following tools and components...

tools:
- multimeter
- soldering iron
- steel scissors
- pliers
- sanding paper
- AA battery (for testing)
- knife
- pen

components
- lemon
- 1 kOhm resistor
- NPN transistor
- ferrite bead
- copper wire
- sheets zinc & copper
- white / blue LED

Comments

[blackghost]

Awesome instructable

Could this be powered by salt water ? or even urine?

[s8]

Thanks, blackghost. I'm pretty sure it will run on salt water and urine. Please post here the results if you get to try it

[Tinker 1]

A small wiring diagram to support the good pics would help experimenters and educate a little!

Thanks,
Pipper Tinker

[Rosierap]

Please help!
Following your instructable, my first joule thief didn't work. It does light the led with a 3 volt battery, just not a 1.5. It is a 3 volt led.

Some questions, what kind of 1kohm resistor? The one I bought is 1/4 watt since that's all radio shack had. The transistor was a "general purpose" one. The toroid was large, but uncoated. The wire was 9 feet of 20 gauge.

Does this look right?

Rosie

[Rosierap]

The FAIL

[-max-]

have you tryed to put the battery in the other way? if it still doesn't work, make sure the toroid was wound right. when i was building one, that was always the case. make sure the transistor is connected correctly.

[virtualshogun]

alright rosie, first thing that i noticed is that you have the resistor on the middle lead that is where your positive input goes (+) which goes to the center leg of your transistor, if im not mistaken its the Base its really early atm but thats what im seeing, the center (two wires on your toroid go to the positive, check your legs either by useing a digital meter and putting it on continuity or run some power through it put the positive of a battery in the middle two legs then test it to make sure it has 1.5v's on the right side if its a 1.5v battery then check the other side and make sure again its 1.5v for the example once you know that both legs are hot (they have power) then you are in bussiness, the base goes to the resistor then to one leg on the outside, not the center. hopefully that helps.

[Theadamjacob]

The resistor is supposed to go on the center leg of the transistor.

[emenke]

Try testing it out with the LED ends switched out... when i first tried mine, it didn't work because the LED ends were soldered backwards.  When I tried again with  the anode and cathode ends switched around, and tested it out, the LED finally lit up!  Try using a battery that is 1.5 Volts too, then use one that has progressively lower voltage.  Also, is it possible that you got the ends of the wires wound around your bead mixed up?  Try changing that around too, and perhaps the right combination would make your Joule Thief work.  Good LUCK!

[Rosierap]

After some research, a friend of mine got one working with 7 windings of insulated wire on a breadboard! I removed that wire and added the 60 windings of  bare copper wire (this time I used 30 gague so it would be easier ... and it didn't work.

I'm thinking that the bare wire is to blame, so I ordered 26 gauge enamel coated wire (30 seemed really puny). You mentioned you used bare wire but you had to sand off the coating before soldering so I think you are using coated wire?

Now Im racing the clock before the science fair...

Rosie

[-max-]

ya, youl neefdto sand the ends, you can also scrach it off with a sharp peice of medel, of burn it off with a match (then clean off the char, of coarse!). the center tabed lead goes to to + side of battery and the two ends go to the transistor. make sure your transister is a 2n2222 or 2n4011, (2n3904 is a bad choice, their are better ones out there)

the - side of the battery goes to the emitter
the + side goes to the center tab
the led goes to the emiter and colecter (check polarity)
the center tab of the transister goes to the resistor which goes to tone end of the coil

and the other end of the coil goes to the colector on the transistor

[s8]

yep, the wire has to be enameled. could be with normal plastic insulation as well as long as you manage to fit enough windings through your coil.

as far as i remember now - it was quite tricky to get the transformer winding right. particular ring material would work slightly different with particular wire.

i suggest you to try to approach your particular coil as systematic as you can. make first 10 windings, then 20, then 30 and so on - this will be time-consuming but the most certain way to get it running.

good luck!!!

[ARJOON]

can i use ferrite electrode

[rayfalcon]

so if i have a pre- wrapped torrid from an old computer monitor that has the plastic coating on it then i have to remove the coating before the joule thief or the transformer will do anything???

[Theadamjacob]

Maybe add a switch to your circuit so you can turn it off when you don't want it to be lit.

[eranglr]

I tried to built it and has a problem: When I'm connecting the joule thief to the lemon, the led lights up for about half a second (even less) and then stop working.. when I disconnect it and reconnect it, the same result appear... How do I manage to keep the led light up? Thanks Eran

[Theadamjacob]

First of all, your transistor may be the wrong kind, It can also be wired backwards. Maybe it is your transformer. Try to make another one and make sure to follow the diagram. The best transistors to use are... A 3904, A 2222, and a 4401. The 4401 puts out the most voltage in this circuit.

[s8]

the tricky thing here is the transformer from 5 different rings i've tried, only 2 worked. I suggest you to try another ring and perhaps a thicker wire to improve conductivity. Good Luck!!!

[Theadamjacob]

Try to use toroids without paint on them. Normal toroids are a grayish color.

[geeklord]

im pretty sure its not a transformer, it two diferent inductors, it might even be called a choke(look it up on wikipedia).

[s8]

it is a 1:1 transformer.

[geeklord]

you sure?, i thought i heard that these work by storing very small amounts of charge in the toroid part of it and then releasing it; all of this happening thousands of times per second, of course.

[Theadamjacob]

It is a toroidal transformer. And yes, the coil stores energy and releases it when the time is right.

[ARJOON]

hey i tried mine directly on a lemon tree it was good but they all fell off after a few days. any idea???

[rottenmeat]

doesn't the coil just short because you stripped off the insulation?

[louwhopley]

Looks great! What are the effects on the lemon? Does it get rotten or something?

[alex_jines]

transistor serves as amplification stage, it amplify the current generated from lemon

[s8]

not really - transistor here acts as a very fast switch.

[uberdum05]

The transistor acts as a switch and the 'transformer' is just like a really small flyback transformer found it modern CRT TV's

[virtualshogun]

from what ive herd now this is just something that i saw on one video they said it was something like 90,000 pulses per minuet most dvds are 60 frames to 120 frames / second so 90,000 pulses per minuet you couldnt catch it on a camera its just too fast :D

[cnegrea]

not true , ifi you catch 100 pulses for 1 frame it will be visible

[s8]

also remember to always check it on a battery. if it doesn't work there - it won't work on the lemon. polarity of the transistor and led are crucial.

[Kiteman]

Nice idea. But does wasting food count as "green"? Would it work as well if you used sea water, or water full of potentially current-carrying pollutants (then you could call it a lamp run on pollution!).

[knektek]

plug it into the sea!

[greenbean]

A lemon can turn into soil and another lemon can grow from it. Pollutants can't, and neither can a battery. This isn't the next oil, as it is not efficient, but it is an interesting and feel good way to run a small clock for a month.

[Justinger]

Just a thought about "green". Using something that reproduces like a plant in the process of acquiring energy sounds very "green". No footprint, yada yada. For this contest in general I would imagine that all reoccurring fruit usage is very fair game considering that plants continues to produce while the fruit decays. The only downside I would see is the good one could do with food for the needy, although I don't imagine starving people would prefer a box of lemons.

[Kiteman]

Something to add to the thought, though, is the energy required to process the lemon - pick, pack, transport. If it came from your own grove, I'm sure it would be C-neutral, but all UK lemons come from overseas.

[knektek]

use the seeds in the lemon to plant. now that would complete the life cycle.

[Logan M.]

I grow my own lemons (wow that sounded weird lol)

[Redgerr]

it really did lol