Joule Thief

[NickZ]

   Guys:
   If all you want to do is to light an led with a Jtc for a couple of days, then the yellow colored Iron Powder Toroid Cores (non ferrite) that are found in the used pc power supplies or motherboards will work.
But, if you are trying to get better efficiency than that, the junk pile is not the way to go. 
  Electronic Goldmines ferrite type toroid cores I'm sure will be well worth the money.
  http://www.goldmine-elec-products.com/searchprods.asp?searchstring=1++toroids+ferrite&pagenumber=1&sort_on=&sort_by=

[wings]

i know this isn't a joule thief..
but the jt folks are more likely to use this than the desk jockeys.. out there..
if you use 9 volts and higher use a small 90v neon bulb with a diode to the battery..
if tuned right you can double your run time.. this is a ferrite core from a junk flyback coil..
i used a dual pot but it measures 2.2 k .. puts out a mod sine wave..
transistors or mosfets work.. fet have a cleaner sine wave..
the trick here is to not use the batterys voltage so use a diac , sidac , or even gas discharge tubes rated high than your battery volts.. just catch bemf back to the battery on the side that the transistor is in the off position so the volts feed back go in the battery and not the coil..

robbie

gas discharge I like sparks.... with high electrons avalanche
this concept is applicable to short muller motor coils?

http://www.youtube.com/watch?v=kvIUq9aCKIU&feature=autoplay&list=ULpQ0FyFaPqJQ&lf=mfu_in_order&playnext=2

[LeaningGreen]

@NickZ,
Many come here new and want to see it they have the ability to do this.
If they can from junk parts then they will search out better things if they read.

[NickZ]

  I just want to let the newcomers know that the advice of using junk parts will only get them meager result, as the toroids found in old Pc power supply are not "ferrite" nor will they work the same, just to save a couple of bucks.  I know, as I've built many of them. The picture below are mostly using the pc power supply toroids. Which is why I'm letting you know that they don't work as well as the real ferrite ones.
  These are Kooler style backward Jtc. or Hartley oscillators, which are generally more efficient than the regular JT.  Kooler had some of his BwJt last 7 months running non stop. That's quite a difference compared to just couple of days running when using Iron powder cores.
   Just trying to point some of the new guys in the direction of obtaining the best results.
 

[pree5]

mini Ring Core Calculator it's help to all

http://www.dl5swb.de/minirk12_install.exe