Joule Thief 101

[Magluvin]

So far after some time consuming resistance scanning in the sine zone of circuit operation, havnt found any resonant freq going on other than the battery with the 4 disk caps. 1.64mhz. Probably each battery has a diff inductance due to charge level affecting it, and other factors. Will look into that.

Below are scope shots of the coil shown today with 1 shorted winding trying to reach the freq of the battery with the caps. The first one is tuning the resistor just before the resonant freq.  The second is at the resonant freq, and the 3rd is tuned after the resonant freq. You can see the yellow trace of the led is higher when at the battery/cap freq.


Mags

[Magluvin]

Hey Bill

What were some of the higher freq you remember from back then?

Looking at Lasersabers builds. Seems some details are left out like winding turns on some. He calls it the joule ringer. I winder if his are operating at some resonance in the transformers. He seems to have gone up to higher numbers of turns which should allow lower freq of operation. I just seem to not be getting there. 

Im trying some new things Ive come up with and see what I get. Then I gota git.

Mags

Mags

[Farmhand]

Mags, how come you shorted the extra winding rather than place a cap across it ? If you have a shorted winding and you know it's inductance when open as well as the operating frequency then you should be able to determine the correct capacitor so as to create a "resonant tank" rather than short that winding. The battery cap wave is kinda cool.

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[Magluvin]

Mags, how come you shorted the extra winding rather than place a cap across it ? If you have a shorted winding and you know it's inductance when open as well as the operating frequency then you should be able to determine the correct capacitor so as to create a "resonant tank" rather than short that winding. The battery cap wave is kinda cool.

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Hey Farmhand
Seems Im only getting up to under 300khz without the shorted one and some other core/windings up to poss 800khz. The added shorted turn takes me at times just over 2mhz. Just did it to get up to the freq range of the battery with the caps. Like if the circuit were to be driven at a freq(a freq without the shorted winding) and then added the shorted winding, the switching circuit would not self adjust and the shorted winding would become an excessive load. But when the circuit reacts to just a lower inductance, the freq of operation jumps accordingly. Demo'd that earlier one when I jumped in here.

Tried the cap on the shorted winding, and it was too low of a freq compared to the 1 turn shorted. The shorted turn actually makes the led brighter at lower resistance at the base. More input also, but havnt tested if the increase in input is mostly to the led or the winding is soaking it up yet. Just throwing thoughts around with it.  Only killed 1 led so far. 3904 keeps going.

The battery oscillating seems like a cool thing to add to the whole. If I can get the windings to ring with the battery/cap, things should be in total sync. Dunno yet

Mags

[Magluvin]

Would have to get a variable cap to tune a winding. lookin into it.

Mags