Joule Thief

[xee2]

@ timmy1729

This is how to hook up the transistors for a Darlington Joule Thief. Note that the base resistor will have to be larger since the Darlington pair has a larger gain than a single transistor. I do not know what value will work, I have just put 10K to show it needs to be greater than 1K (it may need to be as high as 100K). Also the circuit will stop working at a higher battery voltage (about 1 volt instead of 1/2 volt) because the voltage needs to be high enough to turn on two transistors junctions.

EDIT: I do not think there is any performance advantage produced by using a Darlington transistor. But, maybe your experiments will prove otherwise.

[innovation_station]

Here is a video of a small joule thief with a secondary coil winding.
The second coil puts out about 8 volts and can fill a large 4400 mfd capacitor to over 75v in about 10 minutes.

It will allso charge 10AA rechargable all at once just on the second coil.

This is running off a rechargable 1.2v AA battery that has 1.28v in it.
It took about 10 minutes to recharge 10 AA batterys from 8.9v to 13v.

http://www.youtube.com/watch?v=p1Z2wUSu5Aw

well i had 1 more yoke but now used...

i built something similar to your coil...  slayer007

yes already ...  i used a 2 part yoke 1st part jt 45 turns 22ga   second half 22ga single wire 200 turns .... 

gonna hook it up to see what it will do ... 

ist!

[timmy1729]

@All

http://www.airgas.com/browse/product.aspx?Msg=RecID&recIds=379618

This is the carbon rod that Bill has and that I am getting.

[nievesoliveras]

@ nievesolive

Can you put the EBC letters on the transistor in jenna's circuit diagram, for those who do not understand the symbol? And maybe put a plus sign on the battery?

@ jenna

The collector usually goes to the positive end of the battery and the emitter to the negative for NPN transistors. Are you sure you have the emitter going to the positive end of battery?

I included the EBC letters and your graphic too.
I have recieved PMs stating that the flipped transistor does not work.
I have used it flipped on other circuits and it have worked. But I never have used it on a joule thief.
It just pass a voltage through it when it is triggered, it does not know what polarity is letting pass through.

Jesus

Edit:

My apologies to everyone,

I appear to be hopelessly confused about the transistor symbols. I don't know if I will ever be able to clear it up.

Anyway, Jesus, your first drawing was correct.

The emitter goes to the neg of the battery, and the symbol is as you had it. Of course, you were right.

(In a little explanation, which none of you need, of course, it all started after the second lesson 5 years ago. I was fine with following electrons around a circuit, but, all of a sudden when the explanation started with transistors, the current was changed to conventional current and I was now supposed to follow the protons going around the circuit and the symbols and their wonderful arrow pointing the way had to be reversed  and Oh my goodness.... )

So, again I apologize.

The Emitter goes to the negative!! whatever that looks like!

jeanna

Yes, jesus, you may delete the wrong drawing.

The lady that made the experiments asks to delete the wrong drawing. But I will leave it here just in case somebody can get something out of it. If for any reason something fails on your experiment, You have been warned that she wanted it deleted.

Jesus

[flathunter]

Great to see everyone is busy busy busy!

Heres a picture of my joule thief lighting ten LEDs.  I've used an old AA battery, and instead of a toroid there was an iron bead or cylinder which i found in the back of an old monitor (3cm long).  its the standard evilmadscientist version (no secondary coil.)  The primary is 9 turns of bifilar wire (from a mobile phone charger).  The transistor is everyones favourite, the 2N 3904.
The 10 LEDs are wired in parallel to the emitter and collector (i think ))))....don't know how many more its capable of yet - need to get some more LEDs and wire.

My multimetre reads 0.89 on the last LED, and 1.29 on the AA battery.  I'm assuming this is in Milliamps??!!??  Forgive my ignorance!   The voltage is about 1.3 V throught the circuit.

Now, I want big lights like I saw pirate playing with.....   
Time for some tinkering...

Cheers for the ideas everyone! 

PS I'm a wally with computers - how do i get my photos into a smaller file?