Joule Thief

[resonanceman]

Have you tried Power Mosfets, basically easyer to work with when experimenting, they have a high input impedance (no high base bias current) and the source to drain resistance is extremely low, so much better for your experimental projects.

crowclaw

I tried a couple of MOSFETS  when I was just starting  out  with JTs
I didn't  have any luck with them .
I know alot more now .....so  it might be time to  try them again .

Because  of the  high input  impedance ......wouldn't  a  MOSFET require  a much higher resistance ? ( for my voltage dropping resistor ) 
It seems to me  it would not  take much   to  charge  up  a circuit  that has almost no output .             
Maybe a zener diode  would  be required to  protect the  MOSFET from spikes.


Have you  tried  using  MOSFETS  for JTs ?
From  the spec sheets  that I have seen most MOSFETS  have  a  diode across  the  source and drain  .    I am not sure .....but I do not  think that  a MOSFET with a diode in it would  work  very good for  a JT.

gary

[resonanceman]

No kidding. That is interesting.
thanks for that.
true!! 
the tor-23  (10/$1)  are only 3/8 inch across and that is what I am using to light the first 10 leds from only one secondary.

---
I am thinking that you could make a very simple breadboard circuit with a 2k r resistor and a single led. back to your 12v battery.

Jeanna

Although  I have to admit  that  it  is very hard to find  something  as effective  as  a toroid  for JTs
I still  am not satified  with   toroids in general   .........what  I dislike  most about them is that they seem so narrow ..... one  type  of  toroid  is good  only for  certian purposes .    For  toroids to be  practical  it should  be  possible to use one type of  toroid for many applications .

Remember  my longwire JT?
It may be at least a partial answer to adapting  toroids to different  applications.

For those that  do not  remember   my longwire JT  is just a  twisted  pair of wires .
The  wire I use comes from a Cat5 cable .
5  or 6 ft  of  twisted pair  will work  as a JT  coil .......no need for a core or even  loops
I  am not sure  how many  ways  the  longwire JT can be used  to connect with secondarys or what  kind of secondarys work  best .     
My original findings are that  if  a string of  toroids   used .......and the  windings  on the  toroids  are connected in series .....it seems to  work  like one  larger  toroid .
The  method of connection so far  has been  either  wrapping  one or  2 windings  around  the  toroid ..........or  feeding  one end of the   longwire JT  though the center of  a string of toioids .
One  wrap or one  pass  through  the center of the string of  toroids may be enough for  low permeability  toroids .... for  higher  permeability toroids  another wrap  or to .....or more passes  through the string might be  needed .

I am  pretty sure that  using   a low number of  passes  through  a string  of  relatively high permeability  toroids will require  a winding in series on all  the  toroids ........  to help  the  toroids act as one .     I think   other  than that  one series winding  the  toroids can be used  independently .
One more detail  about the longwire JT    using   toroids seems to  make it  possible  to use less twisted pair .

This will allow you to check the voltage across that resistor. When it gets to 1.2v you should be home free. If that is still too low you can raise it slowly etc.
this isn't a transistor, but it is the 0.7v to turn on the led and 2 volts to run it.

I had forgotten the 2 volts part. It now seems so high.

You can also read the volts across the led to be sure of that.


jeanna

Great idea Jeanna

I do  not think  I  will  use this  idea  in quite the same way  you were thinking .
I was thinking that   especially   for MOSFETS  I would need  a way to  prevent  accidental  over voltage .
I was  thinking  that a zener diode  might be needed .........but  a LED or 2 would  do the same thing .....and have a visual indication that   the voltage is higher than  needed
WHite  LEDs  have a threshold of  about half of  the safe voltage  of  the 3055 ..... so that is  almost  perfect .
My first thoughts about this  was that it may also  be possible  to use  a 2 V diode  and drive that  diode with my signal  so when  the circuit was working  well  I would  have light from the  2V diode but none from the white diode .  Then I realised  that  the 2 V  diode would  be eating the spikes  of the waveform and   probably cause  a much  smoother output.

 
Anyway ....... having  a  LED in the base  circuit should  be a lifesaver ......or maybe I should say .....transistor  saver .



I  will post  a picture or 2  of  my these  kinds of  circuits .
Mostly  I have just played  with the idea .
I do  have one circuit with  8 medium sized hi perm toroids  ( in a circle  with 4 loops of wire going  through the center of them .)
It seems to  be fairly high power .   That is one reason  I  am working on getting  12 V going .


gary

[resonanceman]

I just   made another attempt to  get  a 12 V system going.

I set up my circuit ......tested  it with 2 AAs

It worked  good .
I  had  a red LED across  the base/emitter     As  I lowered  the resistance of the pot  the red LED would  come on.

I  tried  it  with 3 AAs    it worked the same .....except my LED array was much brighter .

I tried 12 V ......  there was a noticable spark  when I connected the  battery .......then nothing .
another  transistor  gone .  ......just like the  last few times .
No new  knowledge of  why it  happened


gary

[jeanna]

I  tried  it  with 3 AAs    it worked the same .....except my LED array was much brighter .

I tried 12 V ......  there was a noticable spark  when I connected the  battery .......then nothing .
another  transistor  gone .  ......just like the  last few times .
No new  knowledge of  why it  happened


gary

Oh darn! My condolances.
Those are not cheap either.

Allelectronics sells one specifically called HV. Do you have that one?
The number is the same with HV added...
2N3055HV

You did learn that a red led in this place is not going to do it.

Why don't you just limit it at the 12v side as I misunderstood you to mean?
Is this because of the charging you want from it?

I am only using a 33ohm resistor on my ac secondary circuit and the lights are nearly out. It works really well, because the entire circuit works as usual, just with less.
I can easily connect to the full juice to check it out.
Since you are not attempting to light a fluorotube and do not need 450v spikes, it ought to give you the safety with the 12v

I love the idea of  turning the light down then up to read.
It would make a really great bedside reading lamp.
Dim when you are not there, and bright to read.
Great idea.

----

I am wondering if you ever tried to use one iron wire and one copper wire when you made the twisted toroid.
Stubblefield figured out something here, and it makes a lot of sense that an iron wire coupled with the copper wire in the spiral formation would give extra inductance without needing to resort to a ferrite toroid.

I would suggest using what my hardware store has that is called black annealed wire.
It is plain soft iron which ought to have the right properties. Not as much as a core, but more than plain copper.

jeanna

1 more thing... I think I keep forgetting this to you and to jesus.
In the movie bearden says that bedini had a lot of trouble with his feedback when he tried to have the battery that was the source, be the same one that is being charged.
I do not think you are set up that way, but you could be getting something like the same effect which is blowing out your transistors... and jesus' pulse motor.
Just a thought.

[resonanceman]

Oh darn! My condolances.
Those are not cheap either.

Allelectronics sells one specifically called HV. Do you have that one?
The number is the same with HV added...
2N3055HV

You did learn that a red led in this place is not going to do it.

Why don't you just limit it at the 12v side as I misunderstood you to mean?
Is this because of the charging you want from it?

I am only using a 33ohm resistor on my ac secondary circuit and the lights are nearly out. It works really well, because the entire circuit works as usual, just with less.
I can easily connect to the full juice to check it out.
Since you are not attempting to light a fluorotube and do not need 450v spikes, it ought to give you the safety with the 12v

I love the idea of  turning the light down then up to read.
It would make a really great bedside reading lamp.
Dim when you are not there, and bright to read.
Great idea.

----

I am wondering if you ever tried to use one iron wire and one copper wire when you made the twisted toroid.
Stubblefield figured out something here, and it makes a lot of sense that an iron wire coupled with the copper wire in the spiral formation would give extra inductance without needing to resort to a ferrite toroid.

I would suggest using what my hardware store has that is called black annealed wire.
It is plain soft iron which ought to have the right properties. Not as much as a core, but more than plain copper.

jeanna

1 more thing... I think I keep forgetting this to you and to jesus.
In the movie bearden says that bedini had a lot of trouble with his feedback when he tried to have the battery that was the source, be the same one that is being charged.
I do not think you are set up that way, but you could be getting something like the same effect which is blowing out your transistors... and jesus' pulse motor.
Just a thought.

Jeanna

I only have the  regular  3055s    I will have to look up  the HV  version .

I am not  so sure that  a red LED is not enough .
There may be other problems  with the circuit

I am trying to limit only  the  base
If I remember right the  emitter and collector  can handle around 70V
If  I drop  the voltage  down  I will just be making  alot of heat in a resistor .....and  I will not get any more power out than if I used  the voltage that I dropped it to .



I did  try  a bi-metal  winding ......as a matter of  fact  I was  using it when I blew the last  2 transistors .    It  seems to be in  a higher  power range than  any of my toroids . 
That is one reason  I was trying it ....   

I have some rebar  tie wire that I coated with shellac.
It  is  to thick  to do much  with.
The  wire  I used  came from a craft shop .   It is  called florist wire .   Iron wire painted green .....
I coated  it with shellac  to make sure  that it had good insulating properties   then   wound it  around  one of my splitter LMs.     
This  florist wire was as thin as I have ever seen ....... #24

My pot  was set on max when  I connected   the 12 V    24 K ohms
That should  have  been way more than enough .

One other  detail .......the  transistor  did not  even get warm

gary