Joule Thief

[jeanna]

When I post a diagram, the number is the number as it is measured with my DMM.  0.120uF is just that.
I see, then this would be why I'm getting lower results with my setup.

I don't have a dmm that tells capacitance. That is cool.

If I helped, I am glad.
I was amazed myself to see the 85volts hit this place in the circuit took with that cap.
I better remove it before I forget! 

@Hazens,

Would you be willing to share your ebay source for those leds?

thank you,

jeanna

[TheNOP]

The capacitance needed is dependent on the induction effects in the toroid.

you are playing with a RCL circuit that have almost 0 resistance(wire resistance only).
changing the cap value is changing the frequency.

for a ~ 10k frequency
i use a tuned circuit, a 5 uH and 47uF, to the base(4 turns).
a ~10 ohms ~10 uF also work.

i can even go higher then 10k Hertz with my home made laminated iron cores and still have go results. are they better at a higher frequencies ?, i don't know because lack of proper tool.
but they do go down with a tuned circuit for 400k Hertz.
same for my power supply toroids.
i have not calculate for other frequencies yet, my caps collection is a bit low.
mean i don't have a lot of different caps values.

my only one ferrites toroids need a higher frequency and more turns to work ok.
tuned circuit 400k Hertz
it is a black one, no paint on it.

i can only guess the real frequency tho, because the base coil also affect the tuned circuit.

tuning the frequency to your core is a key factor.
reducing the off time is an other, for maximising the currents.

are you seeing something else ?

[TheNOP]

@jeanna
always keep an eye on the frequency when playing with caps at the transistor's base.
get it as high as possible while looking for the best output voltage.
then you will know what is the best frequency for that specific toroid.

you have a scope, you can do this without having to calculate componantes values, by trail an error.
i am sure you will get the hang of it very quickly. 

if you notice, not only the trace as change in the pictures you posted, the frequency changed too.

if you go for a lower currents as possible for, lets say, only 3 leds, to extend the battery's life.
then lower the frequency as much as it is possible.
use a piece of iron instead of a toroid.

if you go for cfl at lowest current as possible, then use insulated laminated iron
and lower the frequency as much as it is possible

for each applications use the most appropriate materials and componants...

[jadaro2600]

I'm having issue with my secondary, it's not picking up as much as the coil to collector.

I've seen all of the MK designs, I've even come up with a few of my own, ..the most I'm getting is around 100v or so.

any suggestions?

[TheNOP]

I'm having issue with my secondary, it's not picking up as much as the coil to collector.

I've seen all of the MK designs, I've even come up with a few of my own, ..the most I'm getting is around 100v or so.

any suggestions?

keep on playing with RC or LC to the base.
since you have a frequency counter in your DMM, you can do as i suggested to jeanna, trial and error.
changing the cap and/or the resistance and/or inductance.

litz wire and a high frequency core will help at very high frequency.
adding more turns on the collector's coil will help too, but it change the ratio, so you will need more pickup turns as well.

me, a 556 dual timer to feed the transistor base is my next step.
i plan for a separate power supply ( 7805 )

p.s. do you have your DMM model number ?
i can't find any meters at all in sears's online catalog.