Joule Thief

[xee2]

@ jadaro2600

For symetrical AC you should experiment with circuits like this

http://www.aaroncake.net/circuits/inverter.asp

[gadgetmall]

I've noticed that the associated parts do change the dynamics of the circuit - if you want to throw more current at your load, then you will need to get a new transistor.

Personally, I've toyed with the idea of using this CRT transistor..high frequency, higher current and higher overall tolerance.

The 3904 will give you more range to work with.  Some people have mentioned stressing the components - after all, most of them only cost about 15c each save for the LED itself, which I have actually blow on more than one occasion.

There are arguments for an against all ideologies of mechanics regarding how you setup you joule thief circuit.

@555 timer interested people,

Try using a transistor as a switch between the to be tested joule thief and the 555 timer circuit.  This will isolate the 555 timer from the joule thief elements.  You will need two batteries, of course.

@all, this thread has jumped 16 pages in two days, ad before that, when there was so much confusion about how to wind a toroid, it jumped 10 pages.  Very interesting.

Nice setups everyone.  Lately I've been working with two jtc's on one toroid, I'm attempting to use a single resisted source for a switch.  When one jt turns on, the other is off, and the inductance which causes the oscillation to turn off then activates the other jt.  This has been working, but at reduced voltages.

I'm actually having problems figuring out how to wind it, I want to create AC, not a malformed DC-biased AC.

SO I have a problem, How do I form AC from three wires, one is common ground ( - ) and the other two are positive, yet one if off and the other is one while in operation?  I imagine a Diode arrangement might do the trick, ..but I'm thinking it's a bit more complicated than this.

If this works, I won't need a mechanical switch, or a drinking bird ( which operates through evaporation, and thus it's timing varies with the atmosphere )

Hi . you dont need two batteries . One will will run a 555 . they will operate on very low volts and current if given the proper circuit . . So they are juts like leds in a way they are all measured at dc values not PDC . PDC will run brighter with less current . . Yes its cool that you are trying to reinvent the inverter , i want to too but run it off the earth instead of Mucho batteries . Lets .get to work !!

Gadget ..

[jeanna]

just thinking of something...
what is your scope's probe set at, 1X or 10 X ?

Hi theNOP

It was set up as 1x.

If 10x, I would have had to divide by 10 to get the real voltage figure.

jeanna

[xee2]

The switches need to be replaced by complilmentary square waves from the 555 timer. You will have to figure out how to do that yourself.

[jeanna]

@xee2,

Thank you for that diagram. It makes me think that if things are arranged well, the only adjustment needed is in the base resistor.

And many of us have been doing a lot of preliminary investigation on that one ! 

Thanks you,

jeanna