Joule Thief

[SkyWatcher123]

Hi folks, Hi dasimpson, thanks for sharing all your recent experiments.
On the fuji, or whichever disposable camera that is, what kind of run time are you getting with it, thanks.
I'm making a somewhat different oscillator, with ferrite beads in solenoid configuration and 1 bifilar coil in center with 2 pickup coils on either side and another pickup coil wrapped around the center bifilar, already tested one side coil and seems to work pretty well.
peace love light
tyson

[dasimpson]

one unit is Fuji and another is Kodak. I have not done a longevity test yet as I use it as a bedside light so it is not on for long. it charges up during the day from a 2 volt solar panel . I will charge a  2500mah Ni-MH battery and let you know. I wont to move away from the cfl and use a mains led light as i feel it would give off more light. as to hand winding toriods my hands hurt to much after doing them so i stoped and try to find other ways and things to use instead. i find ac line filters from dead pc psu's work very well

[SkyWatcher123]

Hi dasimpson, thanks for the reply. Yes that sounds like something I'll be doing as well, I have a few of those garden light solar panels I'm going to use and make a separate charger for placing outside with protection from rain should that occur.

I have some interesting experiment results I wish to share.
The other solenoid setup didn't work as good as I hoped, it seems the toroids are the still the winners.
Though I wrapped a 24 awg., 6 filar-non twisted, on a 1-1/8" diameter ferrite toroid and made 2 layers.

I then used 2 of the strands to make a typical joule thief oscillator, then I placed 7 white/bluish leds in series and placed strand 3 of 6 across the leds as a pickup coil and it lit the leds to maybe just over half of full brightness, this was drawing 120 milliamps with a 1.6 volt AA nickel zinc rechargeable.
Then I added the next strand in series  with 4 of 6 and it lit the 7 leds even brighter and still the same 120 milliamps input.
Then I added strand 5 of 6 in series and the leds were now blinding to look at and probably just about full brightness using the same 120 milliamps input.
And finally, I added the strand 6 of 6 in series and the 7 leds were extremely bright and still 120 milliamps input.

This is the best performing joule thief I have ever made and it is so easy to wind multistrand coils like this. I think BruceTPU was working on something along these lines.
Also, I am using a TIP31 NPN.
I think folks should give this a try as it really seems to work well. Let me know what you folks think.
Here's a couple pics of the setup.

peace love light
tyson

edit: I rechecked the input amps using a 1 ohm resistor on input leg and it was 102 milliamps at 1.63 volts on loaded AA cell, instead of 120 milliamps.

[NickZ]

   SkyW:
   Thanks for sharing your results.  I find that the TIP31 is the strongest transistor for getting the most light from the circuit, but it does so by draining the battery quite fast.  Even if adjusting the pot, I still find it it's a hog, but does a great job if light is your main interest, and you give it a couple of AAs to work with. 
   I would recommend trying Koolers bwjt, as he lit 70 led, with only 27mA.  the diagram that he used in on previous videos. For those that can or haven't figured out the wiring I place the picture of the small 5 month running replication, although I only get a few days out of it, with my set-up.   
http://www.youtube.com/watch?v=TgX1gYlmVsk&feature=related
  That was his best and strongest circuit to date, but has not been replicated as far as I've seen.  As I am still using mostly pc toroids I can't get anywhere close to the duration time or the mA draw.  The toroids are very important, even though almost any coil and turn ration will work to some degree.

[NickZ]

  Here is the picture of the small BwJt replication so anyone can clearly see how it is wired together.  The bigger circuits are wired the same way, only he add an inductor, and runs some of the leds off of the negative side of the battery, as well and some off of the secondary of his coil.
  The second picture is of one of my many Jtc that I'm in the process of converting to BwJt circuits to gain some duration time on the battery.
   If people don't know it yet, you will not get the highest possible light from an led by connecting it to a joule thief, as each led does need the 25 mA or so, to output the same light intensity as when using 2 or 3 AAs, as the AA batteries have A LOT more current than most Jt circuits output.  The TIP31 is probably the closest to give the highest light intensity, as two or three AAs do,  as when connecting the AAs direct to the leds.
One exception is that in the video kooler gets 70 leds to light off of only 4 volt spikes that are read by his scope on the secondary coil output.  This is using the same output as is recommended for only one led (27mA).  So, there is some magic to his circuits... and using the secondary is part of the secret, but not all.  "Special Diodes"  also he said.