Joule Thief 101

[sm0ky2]

Here is a clip that shows the Joule Thief schematic and gives a very good verbal description of how a Joule Thief works from start to finish.  It describes the Joule Thief as a switching device with positive feedback, which is exactly what I have been saying.  The word "resonance" is never stated.  The description is not too technical but it is verbose and complete and anyone that has a basic knowledge of electronics should be able to follow it and understand it.

https://www.youtube.com/watch?v=0GVLnyTdqkg

Now, that's in contrast to the previous two postings in this thread.  Sorry, but they are a bunch of mumbo-jumbo talk and both don't make any sense.  I know that it's not politically correct abound here to say this but it is what it is.

If you want to try to convince myself and others that you are making a valid case and supposedly making sense, then use the clip above as a standard that you can try to meet.  Fake pseudo electronics talk with nonsensical terms and the old "they don't want you to know" boogeyman talk just won't cut it.

This is the minimalist version of the circuit, that uses no consideration to system losses.
Yes it works, so does the filament lightbulb.

stating that it works and that we don't need to know any more than that to turn the lights on, is all fine in dandy.

But compare an old style filament bulb to a newer LED bulb of the same luminescence.
and compare their energy consumption

Now, do the same with the Joule thief.

[Magluvin]

Set up a bifilar coil with a steel laminated core,where the core is two separate halves -1 half will see the flow of charge into the magnetic center,and the other half will see the flow of charge out from the magnetic center. Set up a simple self oscillating circuit,and run the LED off the two core halves,where you two core halves act like capacitor plates,and are charged every pulse. this way you can bring your frequency up to a resonant state,where the amplitude is at maximum,and power draw at a minimum.

Brad

Can you make a diagram of the cores and where the windings are on the cores. Sort of a magnetically induced capacitor?

Mags

Thanks

[tinman]

Can you make a diagram of the cores and where the windings are on the cores. Sort of a magnetically induced capacitor?

Mags

Thanks

Exactly

[tinman]

Can you make a diagram of the cores and where the windings are on the cores. Sort of a magnetically induced capacitor?

Mags

Thanks

Here is an earlier video showing the charge build up on the laminated core. This clearly shows the capacitor effect between the winding's,and the core it self. It also show's that some of the consumed current is due to this core charge being forcefully discharged during each pulse. By allowing this charge to be reduced by way of driving the LED,we can see less current is drawn by the circuit.

https://www.youtube.com/watch?v=cJB_cnx9Rx8


Brad

[Magluvin]

Thanks Brad. Thats pretty cool. So if it was a long core without the separation there isnt any current through the core? Seems odd.  But Ill take your word for it.

I wonder if you interleaved the laminations(insulated) some near the center to increase surface area if there might be helpful to generate more charge.

In this circuit below from a pdf on this thread, to me there seems to be a problem. Not that the circuit doesnt work. But the led is across the transistor in the same direction.  I understand that the batt doesnt have enough voltage to conduct the led. But when the transistor turns off, the inductors collapse current flows through the led AND the battery, thus further discharging the battery more besides the transisitor switching. So wouldnt it be better to put the led across the transformer winding where the batt isnt being drained during the led discharge also?

Mags