Introduction: "Dead" Battery Lamp

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

Step 2: Wiring the Toroid

Picture of Wiring the Toroid

Take 2 same lengths of wire and fold them over together to find a center point. Put the wire through the toroid and start winding equally until you have a whole layer surrounded by the wire which should be around 10 winds. Now take 2 of the different colored wires, and cut them shorter so they're not so long. Strip them, twist them together and solder them.

Step 3: Solder It

Picture of Solder It

First, strip and twist 2 of the opposite colored wires together. Slip some shrink wrap onto the positive battery holder wire, and then twist the positive wire onto the other 2 wires. Solder those wires, and then shrink wrap them. Take another wire (the green wire for me) and strip it. Solder the wire onto the resistor, and shrink wrap it. Then, fold the transistor wire back, and solder the resistor to it. Take the last unsoldered wire from the coil (my red wire, not from the battery holder) and solder it to the right pin of the transistor. You should bend the pin out a bit so it doesn't short out. For the last pin, solder the ground wire (black) from the battery holder to the left pin. For the 2nd to last soldering step, measure 2 wires approx. 3 in. longer than your heavy gauge wire. Strip the ends of both, and solder 1 to the left transistor pin (the one with my black ground wire from my battery holder) and the other one to the right transistor pin (the one with my red coil wire). My red wire is + for the LED's and the black wire is ground for the LED's.

Step 4: Constructing the Lamp

Picture of Constructing the Lamp

Take the altoids tin, and mark out where you want the "stem" to be. Then poke some slits to allow for the heavy gauge wire and 2 wires to go through. Place the circuit in the tin and make sure it fits. Put the heavy gauge wire through the whole, along with the other 2 wires form the circuit. My heavy gauge wire had 3 internal strands, so i bent them out so its stable. Once you have your circuit placed correctly, hot glue it down, and cover the whole transistor, soldered part as strain relief and to prevent shorting. Then, pull a bit of wire back out of the hole in the lid so when you open the lid, it doesn't pull the wires. Push down the "flaps" from the hole around the wire to secure it, and then hot glue it. Now, close the lid and glue the "base" of the wires on the outside of the lid. Take your 2 thin wires, and hot glue them approx. every 1 in. along the heavy gauge wire (man it is getting old writing heavy gauge wire every time!) until you're at the top. The last soldering part is to twist your 2 LED's together, and trim and strip your 2 wires at the top of the heavy gauge wire. Solder the positive LED lead to the wire that was connected to the right side of the transistor (my red wire). Sloder the ground LED lead to the wire that was connected to the left side of the transistor, and the battery ground (my black wire). Then, wrap some electrical tape or heat shrink tubing around each lead and around the whole top part there, leaving the LED's exposed.

Step 5: Wrap the Flexi "Neck"

Picture of Wrap the Flexi "Neck"

Take 2 colors of your cheap wire and take a long length of it. Glue the 2 wires at the base where the heavy gauge wire or flexi neck goes in. Wrap around with equal spacing until you get to the bottom of the black tape. Glue it there, and then take 1 wire color and glue at the bottom of the tape. Wrap with no spacing until you hit the LED's, and then glue it. You could get some inspiration for designs from bleep labs thingamagoop's Ledacle.

Step 6: You're Done!

Picture of You're Done!

It's done! You can use it for anything you need to light. I lit my fish tank at night with it for a neat affect. It is very bright, and lasts very long (as of writing i am on 2 days and counting with no decrease in brightness!). Any suggestions are welcome, and if you make one, please post pictures! If anyone wants to know how it works, simply ask in the comments and I'll put up another slide explaining it.


HamenChips (author)2011-05-19

I wish I could something like this.

starwing123 (author)2009-12-09
Can this be used for commercial purposes?
aliyevzaur1989 (author)2009-05-02

What if i use NOT dead batteries? And please explain me how it works Thanks

Jodex (author)aliyevzaur19892009-12-06

It would give too much volts for your LED and the LED might go broken.

wizzywoo (author)2009-12-06

can someone please tell me the dimensions of the toroid as im trying to get one fom maplins?

Jodex (author)wizzywoo2009-12-06

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.

raykholo (author)2008-12-27

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 (author)raykholo2009-07-13

10 windings of each wire

raykholo (author)Derin2009-07-13

sounds about right joule thief uses 8 thanks

bobtrial (author)2008-11-28

Add the length of the wires IS "Take 2 same lengths of wire " Recommend "Take 2, 10(??} inch lengths of wire" Bob

boullie (author)bobtrial2009-06-14

That depends on the size of your toroid, just take enough to get 10 winds...

RPisces (author)2009-03-26

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.

imakethings (author)2009-02-13

will i get the ferrite toroid in a white bulb?

Zem (author)2009-02-03

What size is the toroid?

Superninjacamper941 (author)2009-01-09

Where does the resistor go. thanks great ible

one end to the middle transistor and the other to the non twisted toroid wire.

Cool thanks i figured it out

dyeniper (author)2009-01-29

whats the purpose of the toroid in the circuit???pls help

yondaime (author)2009-01-24

can i use speaker magnet as a toroid?

zjharva (author)yondaime2009-01-27

i don't think.

Padlock (author)2009-01-03

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 (author)Padlock2009-01-03

Oh, in case you didn't figure it out, the first question is about the Ferrite Torroid. I forgot to mention that.

zjharva (author)Padlock2009-01-27

There prob. wouldn't be any difference, as long as its the same basic idea.

Juanarama (author)2008-12-10

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)

rocketman221 (author)Juanarama2008-12-24

you can buy flashing leds or you could make a simple flasher circuit with a couple of transistors.

strmrnnr (author)Juanarama2008-12-18

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)Juanarama2008-12-14

i don't know, you'd probably need a 555 timer circuit

joinaqd (author)2008-12-23

how long can the thing stay on for?

zjharva (author)joinaqd2008-12-24

on a dead battery with half a charge, probably 2 days before it gets very dim.

lolwut22 (author)2008-12-20


zjharva (author)lolwut222008-12-20

but he is.....

JellyWoo (author)2008-12-09

great ible! is the Heavy gauge wire required? also, where can you get a Ferrite Torroid? thanks.

zjharva (author)JellyWoo2008-12-14

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"

looking4ideas (author)2008-11-27

can't you make a super charged Ferrite Torrid if you drilled a hole on a rare earth magnet ???

Arx (author)looking4ideas2008-11-27

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.

looking4ideas (author)Arx2008-11-28

OK a challenge for the people in Instructables. How can I make a super charged Ferrite Torrid ??

static (author)looking4ideas2008-11-29

Define "super charged Ferrite Torrid" and what you expect out of one.

looking4ideas (author)static2008-12-01

OK ill give an example: make a electromagnet 5 times more powerful

that's what i mean by super charged

Arx (author)looking4ideas2008-12-01

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.

looking4ideas (author)Arx2008-12-02

so if I get a more powerful magnet to make a one I can get higher voltage from the torrid

Arx (author)looking4ideas2008-12-02

No. All using a magnet does is starts you with I biased core. Not really helpful. I guess a better question would be "What are you trying to do?" The voltage output from this type of circuit is pretty decent already. There's ways to get more, but they're generally going to involve more electronics, not just changing your core material.

looking4ideas (author)Arx2008-12-02

OK a noob question what is biased ( define in the electrical terms plz.)

Arx (author)looking4ideas2008-12-02

It just means that the core is already magnetized in one direction. I don't think it'll help in any way. It may allow slightly more energy storage than you would get otherwise, however, since a magnet probably isn't the best core material to start with. I don't want to sound negative or anything. But you really should try and learn the basics first, before you worry about creating some revolutionary new super-toroid. If it were that easy, it would have been done already. Start by learning DC stuff, voltage/current/resistance. Ohms law, etc. Then learn some AC stuff, Inductance, Capacitance, etc. Once you understand all that, then you can start looking at the details of how an inductor works magnetically. It's not the simplest concept out there, and without a grounding in the basics, you're not going to get anywhere with it.

static (author)Arx2008-12-09

I would think a magnetized core would choke the windings, decreasing the power output. As a rule transformers use an iron core alloy that doesn't magnetize and, stay magnetized.

Arx (author)static2008-12-09

I'm just thinking out loud here since I'm no expert on magnetism, but if you used a "permanent" magnet, it should return to its original state in the end (no extra hysteresis losses?). I think it might saturate much more easily in one direction though. That said, it's not going to give the coil any superpowers. In general it's going to make things worse.

looking4ideas (author)Arx2008-12-03

i have studied the stuff you mention above but i just had no idea how a torrid works. that's the reason why i was asking.

Arx (author)looking4ideas2008-12-03

Okay, well, A toroid is just like any other inductor. They use them because the field is pretty much fully contained so they cause less EMI.

looking4ideas (author)Arx2008-12-05

Thanks for your help

the_mad_man (author)Arx2008-12-02

couldn't you just wire in 2 diodes going into 2 different bits of wire wound in different directions? i mean have the diodes arranged so AC can pass. would that work?

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