Joule Thief

[jeanna]

So Paul,
In your drawing --- please post it here for clarity later,  you show that you are not making the joule thief with a center tapped bifilar primary.
This is the essential element to all joule thieves.

Makezine has a great youtube video on it and I usually recommend 3 watchings before you even begin.
http://www.youtube.com/watch?v=gTAqGKt64WM

There is also a pdf that you can download for drawings.

After you have made a few then you can make some modifications and begin to tune one.


But first since you have made one already, make sure you have connected the end of one wire to the beginning of the other.
Make sure this pair is connected to the pos rail of the battery and the emitter is connected to the negative rail.

add a 1k resistor or pot and connect that to the base of the transistor and one free toroid and then connect the collector to the other free wire from the toroid.

Now...I am assuming you are using a breadboard type thing... add the led to the Collector and Emitter.

When it lights smile.

Then make another just exactly like the first one, but this time remove the led and make a 10 turn secondary through the toroid.

This should light 1 led safely.
If you make a longer secondary like 30 turns you should be getting enough to light 4 leds.
This is usually more pos on one wire than the other so if the leds don't light one way turn the wires around.
And smile again.

Now you can add 50 turns on the next one and see 50-100 volts.
This starts to vary a lot and this is the time you will want to begin tuning, but I will stop here.

Please do those things and report back with your success or questions.

jeanna

[PaulLowrance]

Jeanna,

I appreciate the help. I'm still studying your post, and will make the modifications to my drawing immediately after. I can post the image here, but did not want to do that until Gadget can confirm that my circuit is correct. It seemed bad to post circuits that are incorrect.

Paul

[PaulLowrance]

Jeanna,

As I understand your description, it sounds like you're using two transistors, no?  Gadget uses one transistor.

A circuit drawing is so much better!

Paul

[jadaro2600]

Ive been getting reasonable results off of two identical axial lead inductors placed parallel (and reversed ) to one another.

..8.5 volts on one and 35 volts on another setup... unfortunately this doesn't produce the spectacle that other joule thief circuits do, but it's worth noting that the configuration is similar to my 2 coil Helmholtz setup.  I"ve tried placing a tertiary, but i'm limited by proximity, size factors make the circuit cumbersome to put on a breadboard..

No OU detected, i'm lacking in the ultra-cap department, etc.

[jeanna]

Jeanna,

As I understand your description, it sounds like you're using two transistors, no?  Gadget uses one transistor.

A circuit drawing is so much better!

Paul

No I never have used more than one.
I can post another plain circuit diagram, but if you have read it wrong you will need the words.

one minute I will either edit or post a new post with a plain diagram.
jeanna

oops the second one shows where you put the led on the basic jt and the part you remove for the jt with secondary.