Joule Thief

[MrMag]

Ist,

You want to run it in resonance. You will have the lowest current drain on the battery in resonance. Believe me it will not blow up.
It will only be a problem if you use positive feedback that is causing a steady increase in the output.
That will NOT happen here.

[innovation_station]

i know i can configure this a million ways ...

i know this yes mr magg i agree resonance is important!! but all depends upon its use ... 

i choose not to use resonance ...  it is not required .... 

to achive big output

plus when in resonance add a load you need a self tuneing unit.....

so it will always adjust its self

wrong way!!!!


lol

this is the pain in the ass way of doing it!!!

ist!

[TheNOP]

I think if you study this link here, many questions on the basic Joule thief circuit operation will be answered:

http://www.tpub.com/neets/book9/36e.htm

thanks
this confirm what i was thinking.

it also clarify, for me, the role played by the base coil.
with the resistor, it set the frequency as well as the duty cycle.

[jadaro2600]

@gyulasun, I have one that will start without it ( the resistor ), without a switch as well, it's pictured here: http://www.overunity.com/index.php?topic=6123.msg165655#msg165655 and here http://www.overunity.com/index.php?topic=6123.msg166453#msg166453 as a recitation.

@MrMag, thankyou for that confirmation.  This makes things more clear now.

REgarding the oscilloscope ghosts, this is probably an effect similar to when you remove the probes from a voltage reading.  Sometimes I get a sudden increase in voltage before it drops.  This sometimes happens just as I'm pulling the leads away.

[jadaro2600]

I was making some adjustments to one of my Joule Thief Circuits, and made an interesting observation... when setting the circuit up as shown in the diagram below, the result voltages are higher, not by much, but, the diode or other load can be put in place of the upper capacitor, with no connection to ground, the flyback just goes through back to the coil rather than shorting through a load to ground or 'slamming' into the transistor...

I suppose it wants to take the circular path.