Joule Thief

[gravityblock]

@Jeanna:

I think the k is referring to a core that has an internal magnetic field and not a core where the magnetic field is located on the outside.  In a toroid, the flux is inside, thus the k.  If it said, "Relative permeablitiy of the core -k = xx,xxx", then the flux would be on the outside and the calculations may be different.

-k means external magnetic field and k means internal magnetic field such as a toroid.  This is my best guess at the moment.

This is interesting and I'll keep an open mind that they could be unrelated to each other.

GB

[jeanna]

Yes gravityblock,
that seems right. It does stay inside.

@gadget.
Wow look at those prices. It is what I had heard and want to avoid.

It is going to make it really hard for someone to make a 24 or 30 dollar circuit for lighting a cfl. I think some bright colored electronic gadget will win.

BTW, I never took note of the acrylic fill you mentioned.
You say it does not gas out but it gasses in, so I am interested.
I promise to make a bookmark right away this time.

jeanna

[jeanna]

2" cores will work. If you can find my old posts, you will see that is what I used first. But I changed to the 3" coil because it is easier to wind. The 5 for $1 Goldmine cores will light a fluorescent tube. It is to bad that the 3" cores are no longer being made. I was hoping that Gadgetmal would stock them.

I thought I remembered that you were using a 2"
I will skip finding your old posts, but I did save things.

I do not believe the goldmine 5/$1 to be capable of 500v.
but...
It is a good idea to try again because they are so cheap.

I could try out my new winding which is so very powerful.
It will be a good test for it.

jeanna

[gadgetmall]

Here is the two Coils One was Xee2 trying to replicate his filament experiment . Cant light a CFL , blew several Diodes , will light a neon "LOVE Bulb " 800+ is Goldmine 5/$1  . So they will produce high volts with the right transistor .I went over and back on this one because it ran out of room so its double layer. I may just unwrap  and see if works without snuffing with overlaping .

Second one is Jeannas light core  420 on secondary tried tuning and winding different way 2 volts max . I dont see any shorts here  ?? Hmm? transistor maybe I wrapped some paper and tape over it to hold the secondary still till i get it going. this is single layer wrapped 420 turns . Not getting any volts but BJT works Bright .

@jeanna here is the Clear stuff and the Latex rubber . Get this and the little cubes at www.tapplastics.com . The Clear resin will DEGAS itself so no bubbles will be in the Final Product . The latex Rubber can insulate HV cores and also you can paint it on an object and peel it off and pour Clear Stuff to make a Lucite water clear replica  or make a mold of something .  . This Clear stuff Amplifies Led light and Protects it . you can in case Solar cells and complete circuits in Cubes ,rectangles balls .whatever ? They will last a lifetime and no little bubbles in it .

[jeanna]

Thanks gadget,

This is not the same toroid.
Mine is dark charcoal color. Yours has the grey paint.
So, it might be very different.

But if it is not shorting, then maybe the primary is not turning the transistor on (or off)
So, it could be the primary,
or
the transistor,


Is it possible that the primary wires got mixed up and you no longer have the center tapped?
I am not coming up with much here, I know, but 420 turns  will get you around 450 volts and more.

Is that a new transistor?

Is the wire scraped off enough? (that is usually my problem)

Maybe I will think of something else.

jeanna