Joule Thief

[Mk1]

Primary made up of:
7 turn at top and at bottom (3 over 4 back) connected in joule thief way.

Ok that is where i think you could try to ad some turns to get a better response from the toroid and more voltage.

@pirate

Good video for getting the word around, Thanks

@light

Nice work , welcome.

[jeanna]

@mk1,

OK I will do that tomorrow. There is maybe enough wire on it to make one or 2 more, so it would end up with 8 or 9 turns. It will show what kind of change to expect, even if it is not enough change.

thank you,

jeanna

[Pirate88179]

Thanks Mark!

Bill

[AbbaRue]

@jeanna
Thanks for doing the test I mentioned.  With only 10 in series you are getting the right results.
My point was made.  The more LED's you connect in series the higher the voltage across the array.
For some reason the measurements must be made at the second and second last LED.
Also if someone replaces the LED's with those cheap switching diodes from Radioshack you get similar results.
Somehow the diodes step up the voltage when connected in series.
I believe it may be the other way around, each diode acts as a voltage regulator,
so the more you have in series the higher the voltage of the regulator.
So if each LED regulates at 1.2 Volts then connecting 100 LED's will regulate 120 Volts.
This is why those LED lights Pirate is using have 100 LED's in them.
But once the breakdown voltage of the diode is reached diodes will start to burn out.
This information may come in handy down the road as we dig deeper into this phenomenon. 

NOW to a different point; if the Joule Thief follows standard transformer principles:
If you have twice as many windings on the secondary as you have on the primary then you will double the voltage.
So the less windings you put on the primary the higher the voltage output will be across the secondary.
The only reason for having more windings on the primary is to handle higher input voltage.
Because the less windings on the primary the more current it will drain from the battery and the more strain on the transistor.
Now if you have to many windings on the primary you loose energy in the form of heat in the coils due to higher resistance in the coil.
Less windings more heat in transistor, less heat in windings.
More windings less heat in transistor, more heat in windings.
So the art is to find the happy medium. 

So in this case Jeanna if you want more voltage output you must either;
decrease the windings of the primary or increase the windings of the secondary.
If you have 7 windings on the primary and 56 windings on the secondary
you should get 8 times as much voltage out as what you put in.
But the JT uses feedback oscillation of the output back into the input.
So 1 volt is boosted to 8 volts and then that is fed back so 8 volts is boosted to 64 volts, etc. 
Something like that anyway, so you can get hundreds of volts out of it.

I think I've got it right anyway.

[Pirate88179]

@ Abbarue:

Thank you for your post.  I just learned a lot more.  This is great thanks.

Bill