Joule Thief

[resonanceman]

Mark,
I would like to make one of each of those.
Would you be willing to describe how you made them in detail?

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@All,
So, when does a transformer not act like a transformer?

Gary alluded to this once and I have been finding it a lot on my last circuit.
I wound a 200T on the other side of a 20T and wanted to have it act like a step up transformer, but it went way down instead of up...

Any ideas on what gives with this?

The frequency stayed the same,  and the voltage went from 5v to 1.3v

jeanna

Jeanna

I made  quite a few of those  when  I first started out

I was trying to hard   to  get my voltage higher/

I am guessing that  each toroid has  a maximum power that it can handle
If  you   try to  go over that power level   the voltage crashes .

I never  really found a solution  ........other than to  keep the number of  turns  lower .
I would  try  taking  some  of  the  wraps off of your  secondary ........ if you want to learn  something ........ do it like you are tuning  the coil .
Take a few  wraps off and hook  it up and measure the   results .

If I am  right  ........and it is  a power handling  thing .  you should  see little  change   as you take off the  windings .     Until  you  reach the critical area.
Then   I would expect   a large   jump  in voltage over just a few windings .
After that  point  the voltage  should  follow normal  transformer  rules .


gary




Edit
I would  do this myself ........but I am to lazy



I also  am not good at documenting  stuff  like this .

[jeanna]

@MK1,
Thanks for the details. I think I will give this a try.

@Gary,
Thanks for the confirmation...information.

I guess this is what I will need to do.
I will, then I will make a rodin like the one MK1 just described.

This toroid is one of 2 I got that are the same material as my favorite little ones tor-23 but much bigger ID.
The other one just lit the 4 watt fluoro so it is not that the toroid cannot get that high in voltage, but, since I can't think of anything else to do, I will take out turns until voltage gets better/higher.

Also, I rewound this once already. The first time had 56T and those turns went over the 'primary' turns. I guess it did not make much difference either way. The 56T gave me about 5.6v in the usual way, but it gave a higher reading when coupled with an additional bifilar type wound on top as I described the other week. And even then, it was only 7.7v in 2 directions as a sinusoidal wave.

Oh, this is so odd that it will not follow the transformer rules.
I wonder what is stopping it. I wonder if Iotayodi's thought that the field is not collapsed enough is it.
Then, I would try to use a toroid exactly like the one in the basic joule thief spot, because IT can handle the collapse speed.
Or, since the basic has 74T secondary, maybe I need to limit it to that for a good collapse.
Hmm.

I will let you know what happens, of course.

Thank you,

jeanna

[IotaYodi]

If I am  right  ........and it is  a power handling  thing .  you should  see little  change   as you take off the  windings .     Until  you  reach the critical area

That would be right. The more wraps the larger the field, the longer it takes to collapse. If voltage is induced before the collapse it will oppose the field. The size of the wire may come into play also. If you make the secondary a smaller finer wire it may help. As I see it the pulse rate,# of turns and the forward voltage on the secondary dictates the field. It has to balance out overall to be effective.

[resonanceman]

I am  math impaired .

Can  someone  help me  with  find  the  right  size resistor  for  using a  higher voltage battery ?

I checked on the  web ...... all  the  stuff I found about voltage drops was  for power lines .

I want to  be able to  run  a 3055  JT with a 12 V battery .

I want the  3055 to  run at LESS than  half  power  so  it  will stay relatively cool .

I was  thinking   of  dropping  about 9.5 V  with the  resistor  circled .

My  pot  has a minimum  of .5 ohms . 

Any help  will be appreciated

Thanks


gary

[xee2]

I am  math impaired .

Can  someone  help me  with  find  the  right  size resistor  for  using a  higher voltage battery ?

I checked on the  web ...... all  the  stuff I found about voltage drops was  for power lines .

I want to  be able to  run  a 3055  JT with a 12 V battery .

I want the  3055 to  run at LESS than  half  power  so  it  will stay relatively cool .

I was  thinking   of  dropping  about 9.5 V  with the  resistor  circled .

My  pot  has a minimum  of .5 ohms . 

Any help  will be appreciated

Thanks


gary

The 2K pot should be enough to limit current so you do not need another resistor. Just do not go to zero on the pot. But you could add a 2K resistor to be safe. You are going to need ten times larger base resistor with 12V than with 1.5V.