Picture of "Dead" Battery Lamp
When batteries don't give enough juice to gadgets, you think that they are completely dead. But, all of them still have plenty of volts, and with a simple circuit you can unlock all of that power. This instructable makes an LED lamp which will suck all of the juice out of those batteries. If i had rechargeable batteries, such as sanyo's eneloop, I would never need to do this.

This is whats called a "joule thief" and it is an adaptation of those.

Step 1: Parts

Picture of Parts
You will need:
1 3904 transistor
Some 3 volt Super-bright LED's
1 1000 ohm Resistor
1 Ferrite Torroid
2 Different Colors Of Wire
1 AA Battery Holder
Shrink Wrap Tubing
8 in. of Heavy gauge wire
Altoids Tin
Cheap Wire
Soldering Iron & Solder
Wire Strippers and Cutters
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HamenChips4 years ago
I wish I could something like this.
starwing1235 years ago
Can this be used for commercial purposes?
What if i use NOT dead batteries? And please explain me how it works Thanks
It would give too much volts for your LED and the LED might go broken.
wizzywoo5 years ago
can someone please tell me the dimensions of the toroid as im trying to get one fom maplins?
Jodex wizzywoo5 years ago
Well pretty much any size will work. About one-two centimeters is good. From a old computer motherboard you will get couple that works fine.
raykholo6 years ago
can u give me an idea of the specs for the toroid when its made (meaning after the wiring...) i wanna build a smaller version of this so im just gonna get an already built one of these
Derin raykholo6 years ago
10 windings of each wire
raykholo Derin6 years ago
sounds about right joule thief uses 8 thanks
bobtrial6 years ago
Add the length of the wires IS "Take 2 same lengths of wire " Recommend "Take 2, 10(??} inch lengths of wire" Bob
That depends on the size of your toroid, just take enough to get 10 winds...
RPisces6 years ago
This is a good instructable. I see you saw the 'Joule Thief' HOW TO in MAKE Magazine. One thing to note is that you should include a schematic. All these written steps are good, but they can get a little confusing. I had to link to THIS site to build mine properly.
imakethings6 years ago
will i get the ferrite toroid in a white bulb?
Zem6 years ago
What size is the toroid?
Where does the resistor go. thanks great ible
zjharva (author)  Superninjacamper9416 years ago
one end to the middle transistor and the other to the non twisted toroid wire.
Cool thanks i figured it out
dyeniper6 years ago
whats the purpose of the toroid in the circuit???pls help
yondaime6 years ago
can i use speaker magnet as a toroid?
zjharva (author)  yondaime6 years ago
i don't think.
Padlock6 years ago
Nice Project. Just a question though; would there be any difference if you used a small one, and did, say only a few wraps, then if you used a huge one and wound it very, very tight? Anyway, again, nice project. I used the design to light a green LED in my "mini" light saber. It's made out of a car cigarette adapter and a mini hot glue stick. I had only room for one AAA.
Padlock Padlock6 years ago
Oh, in case you didn't figure it out, the first question is about the Ferrite Torroid. I forgot to mention that.
zjharva (author)  Padlock6 years ago
There prob. wouldn't be any difference, as long as its the same basic idea.
Juanarama6 years ago
what if I wanted a slow flash, like a lighthouse (I know a lighthouse does not flash but has that effect because of rotating source)
you can buy flashing leds or you could make a simple flasher circuit with a couple of transistors.
You might use the cylon eye circuit for a light house. It could use more power than is available here. Just divide the lights up around the cardinal points and away you go.
zjharva (author)  Juanarama6 years ago
i don't know, you'd probably need a 555 timer circuit
joinaqd6 years ago
how long can the thing stay on for?
zjharva (author)  joinaqd6 years ago
on a dead battery with half a charge, probably 2 days before it gets very dim.
lolwut226 years ago
zjharva (author)  lolwut226 years ago
but he is.....
JellyWoo6 years ago
great ible! is the Heavy gauge wire required? also, where can you get a Ferrite Torroid? thanks.
zjharva (author)  JellyWoo6 years ago
the heavy gauge wire is not required, its only for the neck. You can find toroids at radioshack, or on their website if you type in "toroid"
can't you make a super charged Ferrite Torrid if you drilled a hole on a rare earth magnet ???
nope, doesn't work that way. I'm not certain, but I think you would just end up with a very biased core that would saturate constantly in one direction.
OK a challenge for the people in Instructables. How can I make a super charged Ferrite Torrid ??
Define "super charged Ferrite Torrid" and what you expect out of one.
OK ill give an example: make a electromagnet 5 times more powerful
that's what i mean by super charged
Nah, you might be able to increase the field strength of the magnet slightly, depending how strong it was to begin with. But no, It's not magic.
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