Joule Thief

[resonanceman]

I just  made my first MK2 .......at least that is what I think it is .

4 windings  2 on each  side of the toroid .......each  winding   wound  in the opposite  direction as the one next to it .
the windings  cross in the middle  of the  toroid .  ( goldmine  5 for $1  toroid )

It lit up  the  very first try .
I have not  added a secondary yet .

I have not  tried to  tune it .
I have a question .........   I  made it with 10  wraps   on  each  leg     I think I remember  that 7  worked well
Isn't   tuning it  mostly about matching the  input  windings to the toroid ?
If so .......if I tune it now .....it should  stay tuned  after I add  my secondarys .

I put  a few extra  wraps  on   so tuning  should be a matter of  removing  wraps .......   I   am going for   high voltage with this ......so  ......once it is tuned I plan on  filling  the  rest of the   toroid  with  secondary windings .

I used  #28 wire for the  primarys    what about  #30 for the secondary?   


Any comments or suggestions ?

gary 

[TheNOP]

@theNOP,
Ahh finally. I see it.
Thank you. and thank you for your persistance.

you are welcome.
my pleasure.  

And, that is the reason it has been hard to figure it out by logic. Its behavior changed as more time went on or at closer resolution. But not having to do with anything I was doing, just where the scope was picking up the wave at the moment.
WHEW!

i see you are begining to understand it.
but the way you are saying it could cause confusion.

to show you what i meant, a bit better :
take a ruler and put it on your scope screen.
look at the distance between spikes, they are not evenly spaced.

at higher rate you see less spikes on the screen.
that mean that at a higher(ex: ns) rate setting, you don't have an accurate representation of the whole thing.
at lower rate( ex: ms), you have a more representative sample, so even if the cycles are not evenly spaced, it cause less calculations innacuracy.

I will try again, but so far I have only been able to use .1 .2 .4 .8 4 8 and 20v/div.  (Unless I switch to the x10. I have more there, but I am not yet sure what this resolution is. I feel it is better to keep to the simple beginners level for a while, unless forced by a higher voltage spike problem.)

a 4v/div while measuring 12volts will be ok for you to see how DC is shown on a scope.

Ah, I have been wanting to know what that means. Now, I have 'experienced' it, so to speak.

where does it come from?
so, it was evidence of the high high frequency in that particular trial, wasn't it?
And this is a jt with the secret. NO?

there are two ways circuits can couple, induction and capacitance.

one is a magnetic coupling, like transformers, that can only go as far as the mag field itself.
note : the coupling rise with the frequency and lower with distance.

the other is a potential(charges, volts) difference between 2 points.
note : the coupling rise with the frequency and lower with the distance, but that distance is much greater then a mag field(ex: radio waves).

call it aether if you like, i prefer capacitive coupling because capacitance explain that phenomena.

view it as a capacitor between your led and the battery because its what it is.
in your case the plates are the led lead and the wires of the jt,
separated by a dielectic, that in this case is air.

Is there a 'normal' or other way to step up the step up?

the "normal" way to step up is one properly made transformers and/or with voltage doubler circuits.
voltage doubler circuits have currents limitation that can be problematic in some applications.

the unconventionnal way is like what the jt is doing, with kicks(spikes).
but a jt is not able to step down.  <--hint to all.

If I used a matched pair of jt cores and 1^o windings but made the second tier a 'step up' from the first tier, would that possibly give me more, rather than less?

I better try that!
(even if physics says I won't.   )

it can't give you more that way.
the more you add resistive componants the less output you will get.
in a transformer, the losses are not only resistive, there is also coupling/hesterisis/eddy currents losses.

i am not trying to discourage you.
by all means do your experiments, see for yourself.

the more you get to know something, the more you will be able to find ways to get around it.
sometimes you can get around it, sometimes you can't.

[jeanna]

I just  made my first MK2 .......at least that is what I think it is.

It is a MKx because the number after the MK part is defined by how many secondary wires you wind. one on each side of the primary = 1

4 windings  2 on each  side of the toroid

.
Well, that's a new one. Keep it, I say. Let's see what it will do.

It lit up  the  very first try

yeay!

I  made it with 10  wraps   on  each  leg     I think I remember  that 7  worked well
Isn't   tuning it  mostly about matching the  input  windings to the toroid ?
If so .......if I tune it now .....it should  stay tuned  after I add  my secondarys .

Since each is double does that count as 5 and 5?

Yes, tune this by removing the primary winds till the light brightens then one partial turn lowers it again. Did I say that in a confusing way?
I think you are supposed to be turning the pot for this too. I am not sure, because MK1 makes a secondary commitment before he tunes his primary, so he can check with a bridge on the output. But I think that is a refinement for a later MKx.

After you tune the primary to the toroid the rest does not affect it.(supposedly)

what about  #30 for the secondary?

Mark used heavy wire (22 gauge) until last night. He used 30 gauge on the one he reported last night. Was that 850V?
In January, I did a test for Mark that showed that the thickness of the wire of the secondary does not make much difference. He just proved that again.
 
I wound the MK 0.8 which is less than 1    with a secondary made using 10 up then 10 down then across (not cut)  then 10 up then 10 down. I would like to suggest this to you. The wire I used was green magwire from RS and the length of the wire was 44 inches. I was winding the "filter" which is close in size to the medium you are using..I think it (may be) a better one for our purposes. It gives 120volts by itself when in a jt circuit.


                    BTW, when you are winding the 'down' direction, you must snuggle the wire in between the previous up direction wires.
                    This will give a cross of the wire.
                    I am wondering if where that cross is makes a difference. For now, I am keeping the cross on the inside of the ring.

The reason I am suggesting this is it will work, and it will not take too much wire while you get the hang of how to wind it and the twisting and kinking that happens. The longer your wire the more your fingers get in the way! etc.

I have a medium that does well and it has 8T,8T for the primary winding.
That means 8T going one way before the tap that combines the 2 wires, and 8T the other way.
I have yet to do the grunt work of tuning to frequency. theNOP has just gotten through to me about that. I will be providing more, but I think you are in a pretty good starting place with 10 and 10.

Great going!

jeanna

[TheNOP]

I have not  tried to  tune it .
I have a question .........   I  made it with 10  wraps   on  each  leg     I think I remember  that 7  worked well
Isn't   tuning it  mostly about matching the  input  windings to the toroid ?
If so .......if I tune it now .....it should  stay tuned  after I add  my secondarys .

good question, hard to answere.

tuning is an art.
it is much like troubleshooting.

the thing is hard because multiple parameters are at play.
i will only write about the more important ones for the jt.

adding a pickup with a load will change the natural bjt's frequency.
changing the base's resistor value can fix that most of the time, but not always.
adding a RC to the transistor base, a capacitor in parallel with your potetiometer, might be required.
capacitor and resistance value can vary

cores(toroid) can be made from various material.
some have low coeficient of coupling(ferrite, best at higher frequencies), some have high coeficient of coupling(iron, best at lower frequencies)
higher here does not nescessarly mean mHz and lower does not mean 60 Hz either.

to fix poor coeficient of coupling you can do 2 things :
get the transistor to work at an higher frequency. <- most effective on some materials
or add turns to your bjt's base and/or collector coil.
sometimes both methods are required.
spreding the turns around the toroid can help too, but never forget that the mag field is at 90 degree to the wire creating it.
wire at \ and at | does not make exactly the same effect on the core.

the first thing you must do is to find what problem(s) your core have.
too low frequency ?
poor coupling ?
both ?
EDIT: too high frequency ?  <--not usual, but possible

i hope this will help everyone.

[resonanceman]

It is a MKx because the number after the MK part is defined by how many secondary wires you wind. one on each side of the primary = 1
.
Well, that's a new one. Keep it, I say. Let's see what it will do.

yeay!


Since each is double does that count as 5 and 5?

Yes, tune this by removing the primary winds till the light brightens then one partial turn lowers it again. Did I say that in a confusing way?
I think you are supposed to be turning the pot for this too. I am not sure, because MK1 makes a secondary commitment before he tunes his primary, so he can check with a bridge on the output. But I think that is a refinement for a later MKx.

After you tune the primary to the toroid the rest does not affect it.(supposedly)

 

Mark used heavy wire (22 gauge) until last night. He used 30 gauge on the one he reported last night. Was that 850V?
In January, I did a test for Mark that showed that the thickness of the wire of the secondary does not make much difference. He just proved that again.
 
I wound the MK 0.8 which is less than 1    with a secondary made using 10 up then 10 down then across (not cut)  then 10 up then 10 down. I would like to suggest this to you. The wire I used was green magwire from RS and the length of the wire was 44 inches. I was winding the "filter" which is close in size to the medium you are using..I think it (may be) a better one for our purposes. It gives 120volts by itself when in a jt circuit.


                    BTW, when you are winding the 'down' direction, you must snuggle the wire in between the previous up direction wires.
                    This will give a cross of the wire.
                    I am wondering if where that cross is makes a difference. For now, I am keeping the cross on the inside of the ring.

The reason I am suggesting this is it will work, and it will not take too much wire while you get the hang of how to wind it and the twisting and kinking that happens. The longer your wire the more your fingers get in the way! etc.

I have a medium that does well and it has 8T,8T for the primary winding.
That means 8T going one way before the tap that combines the 2 wires, and 8T the other way.
I have yet to do the grunt work of tuning to frequency. theNOP has just gotten through to me about that. I will be providing more, but I think you are in a pretty good starting place with 10 and 10.

Great going!

jeanna

Jeanna

I am posting the   schematic  that  I was  going by .

I might  have  caused  some  confusion  by  the  description   I used .
To me  the  windings  that make  the   JT  itself work  are  primarys ......no  matter how many  there are ......  the  JT  will not  work  without  at least 2 primary windings .

To me a secondary  is   added  in addition to  the  primarys ..... the  JY will work   with out the  secondarys

SO   .......according  to my way of  thinking   the  JPG   has  4 primary  windings ......no  secondarys

Mine  looks  just like this   except   the  picture shows 3 windings on each   leg ......mine has 10 .
Just in case I did   do something  different  than  the  rest of  you ..... I connected   it  by   hooking  the  leads  on the l left  side of the  picture together and  plugged them into  B+   
The  wires  on the  right side of the  picture  connnect to my pot and  my transistor .
A  cap  across the pot  didn't  seem to help  anything .

Thanks for the  details  about  tuning  ......I have  been doing that   some on my  other JTs ........but   adding a partial  wrap  and  checkinig again is  a step  beyond  what I was doing ...........thanks


I am  thinking  of  adding  4 secondarys   to  what I  have now .....
After  I tune  it I am thinking of  winding   half way to the other   winding  and back .....repeating that  on the  other  side .......and  then repeating the whole  process   again   om the opposite side ......that  gives me  4 secondarys ..... I should  be able to  put  them in  parrallel  or series


My next  JT  is going to be  a little one .......  I have a toroid that I got out of a CFL     it is just  a little  over  1/4 inch   across .
I have  been looking at those   LED lights that clip in  a hat .........I can make one  smaller than that      I am thinking of  using a rechargable  button  cell for the  battery

I have not  figured   out how I am going to  connnect  a  charger to the  battery ....  any connector  would  probably double the size of the unit .     
I am  thinking   an inductive   coupling  might  be best ......  just not  sure  exactly how to get it  done .......maybe  a small pancake  coil  in  the  unit  and  another in the charger .