Joule Thief

[sparks]

Mag wire scroungers ,when ever Im looking for wire i go to the local electric motor shops where they repair commercial electric motors and offer to purchase the left overs at the scrap price which is what they sell it off at to be recycled with the wire they shred off burnt motors.
  Im not talking about little bitty radio shack size rolls.The rolls I get still have many pounds of wire left on them sometimes they have 15lbs left on a roll.The rolls are really big honking ones like the type you would see used to stock rope. Plus these shops also save caps ,stock cap, collect caps. Boxes and boxes of caps of all sizes. The place I used to go to sells mixed boxes of caps by the pound.
  Check out your local electric motor shops.

   You may even find an old variable ac voltage supply or variac hanging around.  It is a torroidal transformer that has one winding wound around the core.  A sliding brush determines how much of the torroidal winding is primary and how much is secondary.  This is all low frequency stuff so the current levels are high so the core would need a pretty good sized battery to work with.  The impedance of the circuit to high frequency could be overcome with the use of series capacitors in both windings input and output but the core of the autotransformer would have a lot of hysterisis losses due to the hf.  Well anyway it kinda shows you what is going on in the jt.  The jt is an autotransformer type setup working off of pulsed dc which is what you get when you rectify ac.  Then they use capacitors and torroidal chokes to change it into cleaner dc when they want a nice bias level in an amplification circuit or battery charging for that matter.  The torroidal choke impedes the ripple riding the dc current.  The choke takes the ripple and changes it into heat in the core of the choke.  The torroidal transformer takes the ripple and transforms it into usable voltage.
   
Mod

   The jt is also very efficient.  As soon as induced voltage appears on the secondary output it shuts down the primary bias and limits any wasted current going into core saturation.  Now the majic can begin by imposing these highfrequency oscillations on different things to get different reactions.

[Pirate88179]

Jeanna:

You mean like this?  (Ha ha, amazing what you can do with ms paint)

Bill

[xee2]

Xee2 Very Nice . I have to ask what is being drained from the battery . Its got to be over 300 milliamps . In this case a 2000mah battery will only last a few hours . No ? What would be the advantage Verse running the bulb directly with the AA battery ?

These are just test to see what kind of performance I can get out of the SCR. Goal is to add ignition coil and generate very high voltages.

[xee2]

@Xee2,
Do you really have that secondary connected back to the battery?

Yes. But I think it will work either way.

EDIT: Whoops, I thought it was, but I just check and it is not. Thanks for asking. I want to keep accurate records of my tests.

[Pirate88179]

Jeanna:

I just found this while searching for TIP3055's:  (From RS's Website)

[5 of 6 customers found this review helpful] Its really a MJE3055By TIP-less from Iowa on 3/29/2008Cons:IncompatibleComments about RadioShack TIP3055 NPN Transistor:
The transistor works fine, but its NOT a TIP3055... its a MJE3055, which is rated at 75W not 90W.Was this review helpful to you? Yes / No- You may also flag this review.


I ended up ordering 10 from Digikey as they were cheaper and, hopefully, TIP3055's.

Bill