Joule Thief

[xee2]

@ mike2550

Since so many people seem to have difficulty getting toroids, I posted some videos showing a few "no toroid" Joule thiefs.  As you have access to Radio Shack, I recommend this one >>>   http://www.youtube.com/watch?v=D7CFkRLrtss

[mike2550]

I was able to get a toroid out of a cfl. It is green(not sure what it is made of). It seems to work much better than my home made one. Again, I don't have to use the resistor in the circuit? It works with out it and the transistor does not get hot.

Keep in mind I am a total novice here and just trying to learn. I have a 2 volt led in the normal position on the circuit and I also have a 3 volt led across the two toroid outputs. Both of these will light up. I also noticed the toroid outputs are putting out an AC voltage. So, I ran with both leds still in circuit, a 120V to 9V AC transformer(wall wart) in reverse feeding it from the white led. I got about 22V AC . With a stonger battery I got less voltage(about 16V AC) out of the transformer. This got me interested so, I then ran from the transformer a 120V led night lite and had it putting out some light(although not as bright as normal). So, one very used 1.5 volt AA battery runing a 2 volt led, a 3 volt led, backwards through a step down transformer and a led night lite. Pretty cool!

Another thing I have found interesting: I have a 1.5 volt AA battery that I have drained down atleast 3 times now. I can let it sit for a few hours then put back on the JT circuit and it lights up again for many hours.

[NickZ]

   Mike:
   The small toroids that come inside the cfl are ferrite, and they do work fairly well for their size. The picture of the smallest BwJt above on my last post is also from a cfl. It has a secondary, which can light several leds off of it.
   I am surprised that you were able to light the night light bulb, but it is probably because you have not used a resistor on the base of the transistor.  This can work, but the duration or running time will be much less. The point of the resistor is to control the amount of current that the circuit can use, otherwise is will discharge the AA battery in just one day, or less.
   I would recommend using the BwJt circuits as in the my pictures, it is a simple circuit and more efficient than the normal Jt. You pretty much can see how they are wired from just looking at the pics.
   You can also use the pancake coil idea made my Lidmotor, for a very efficient very low power draw circuit that does not use the toroid. There are many ways to go on this, but the neat thing is to have it last many days or weeks on an AA battery.
   Xee's circuit is also another good example of an efficient circuit. 
   If you use the 2700 mA AA rechargeable batteries they can last twice as long as a regular non rechargeable AA, and can also be recharged as well.

[Pirate88179]

Nick:

All of the toroids I have found in cfl's (the green ones) were powdered iron and not ferrite.  I know these work too but not as efficient as ferrite.  Maybe you have different cfl's?

Bill

[NickZ]

  Thanks Bill: 
   I've never seen the green toroids, but I have used the orange, and smaller black ones found in the cfls. They seam to work ok. As well as many different yellow pc types. Yes, they all work, I guess it all depends on what anyone wants to do. But, as I have used them, I still recommend not to use the iron powder ones even though they do work to a usable degree. I had a bunch of the yellow toroids around the house, so... I could not resist.
Pictures below of are iron powder cores, regular Jtc, and they are still working two years later.  Not bad for the price... Zilch!
                                                                                  NickZ