Joule Thief

[Mk1]

@stprue

Well , the x2 is not needed to get 850v , usually when i test a toroid and winding i drive the base of the transistor with lower resistor value to get it a the right freq , but lower base resistor also mean that the battery drains faster, i order to get
the same freq but with a higher base resistor value , so the battery will last longer.I have design the x2 .

I hope this make sense.

Mark

On the jt side i still use 22 bell wire, but the pickup coil 30 gauge.

Edit i also use some 26 gauge but never got good result from them, i don't know why.

[TheNOP]

Tell me if the freq would be set by something else then the base resistor like a quarts or a resonant circuit would the  freq be more stable, then with just a resistor.

yes.
stability is not required at this point tho.

if by "stability" you meant will always stay the same then the answere is yes too.
it will always stay the same, no matter if there is a load or not on the pickup coils.
the base coil will have no purpose anymore, it can be removed.

with a quarts oscilator, 555 or 556 timer, a normal transformer can be use for frequency up to 10k Hz.
maybe more since hesteresis is not a problem with pulsed DC.
toroid can be used for higher frequencies.

one important thing to know about core's materials is that the min/max frequencies overlaps with each other.

ex:
iron = up to 10kHz (ac) insulated laminated iron only
ferrite = min 5kH, max 200kHz (ac)
some other ferrite type might = min 100kHz, max 800kHz (ac)
etc...

if someone ever find  charts with (materials = frequencies) or (material = coefficient of coupling) data, please post the link.
thanks


N.B.
i will not be as much present here then i was lately.
my forced vacation is over, i'm going back to work.
so don't worry if it take long for me to reply.  

[stprue]

@ Mk1

Yes this makes since.  I usually connect a POT to my JTC's so I can tune to specific frequencies and for those of you that may not know this CAN be beneficial depending on the load you are testing.  It's funny that you have had no luck with 26 gage.  My last attempt at the Hazens 1 7-7-70-70 coil which I could only fit 10-10-41-41 on I used 26 for everything and when I finally got it to work I was only able to get 6-7vdc out of it.  Disappointing considering the time and effort. 

@ All & @ Hazens 1

I will post some pic's (soon) of my 10-10-41-41 maybe I'm doing something wrong that you can help me with.

[stprue]

@Mk1

I forgot to ask you if you are using 1 inch goldmine torroids?

[stprue]

@Mk1

How is the primary and secondary hooked up?  Can you please provide a complete pic like the one above?

If so I will make an Mk x2 this weekend