Joule Thief

[jadaro2600]

@jadaro2600
In the meantime I have answered it in your Transistor Discussion thread and I noticed you read it already, now some additions to the above:
The transistor is a controlled switch here,  the 20 kOhm resistor establishes how much current will be able to flow through the collector-emitter path from the battery via the coil.  The higher the resistor at the place of the present 20 kOhm, the higher the C-E resistance path becomes,  hence the smaller the coil current :  ---> so magnetic flux also gets smaller,  your observation is correct.

Re on your removing the resistor path from the base (you must have meant your 20 kOhm resistor in schematics, see your Reply #3294, page 330) you practically removed the DC bias from the base-emitter and you still found the circuit working. 

The explanation is that the base-emitter is able to remain switched on from the pulse voltage coming from your 40 turn coil and base current can flow via your 100 nF capacitor.  This kind of operation is called Class-C when the transistor base bias current comes completely from the input AC signal (in this case the input signal is the peak value of the induced current in the collector coil and in the coupled coil) and no any other DC bias is provided.  This is not a stable operation because at low battery voltages like 1.2 - 1.5V the circuit may not start up at the first switch on like in the case when the small DC bias is present via the 20 kOhm.
So do not be surprised you cannot start your jf without the 20 kOhm,  however once you started it with that resistor present, then you may remove it and the jf continues working in most of the cases whenever the induced and transformed voltage to the B-E is able to open (hence control) the transistor.

rgds,  Gyula

My original post contained many error, it was late, what can I say ( type ).  Thanks, this clears things up a bit.  It appears that the tank circuit keeps working even with the BE path tampered with.

Is it possible to run 
21 RGB LED's that require 3.6V/30ma on a single AA rechargeable.
I make LED Hula hoops for my gf and her friends.. I am trying to make them cheaper for the girls. You can see my process at my site.. http://ledhulahoop.com

I have been reading and reading but no deffinite parts list to make what i need.
Does it matter what size the ferrite is for my application? how about resistors.. do i need different ones?
How long will the led's stay lit for on a 2450 mah battery.. 

any help would be awesome and greatly appreciated.

Nothing is impossible - but you may have trouble maintaining duration on your battery.  You will have to divide your battery milliamp hours by the measure of milliamp usage  to get how many hours your lights will stay on.  I think.

[gadgetmall]

Is it possible to run 
21 RGB LED's that require 3.6V/30ma on a single AA rechargeable.
I make LED Hula hoops for my gf and her friends.. I am trying to make them cheaper for the girls. You can see my process at my site.. http://ledhulahoop.com

I have been reading and reading but no deffinite parts list to make what i need.
Does it matter what size the ferrite is for my application? how about resistors.. do i need different ones?
How long will the led's stay lit for on a 2450 mah battery.. 

any help would be awesome and greatly appreciated.

Welcome to Pirates Thread !! You New Guys Dive right in and Yes Its Addictive !! AS for your question dog812 yes its here in the forum  you can run 20 rgb leds from a 1.5 volt battery and will last about a week full throttle .. search for post By jeanna and Gadgetmall  here . and check out the 11 turn primary . one turn secondary . ithink  she was lighting 40 whites bright .all our circuits are 1 volt  I have some nice circuits you might look at if you want to run them longer . Take care

@All
Thanks for the Birthday Wishes . and Beatings all you guys are really cool in your own way . Forgive Me for Flying off the Handle at times .(full mooon)  I enjoy your company and don't want to wear My Welcome out . If i do let Let me know and pm to get the heck out . I Know Pirate can lock this thread and i dont want to be a cause to ruin such a nice thread . This is the Coolest thread of them all . One reason is most o fthe stuff to build these things are free and or cheap and everyone can build them and make them better . My 7 year old can make them now . sooo . keep up the great work and lets make these Gadgets Shine ,

[gadgetmall]

I found an article on how to make a JT, it also had a WARNING "be careful, very addictive".
A year or 2 later, i think it's time to admit that i have an addiction.

been following this topic for a while now, think you are all doing great things, thought i'd say hi

At the moment i only have a few iron powder torroids wich don't perform well, but have been
trying everything to get the most out of them, then
After reading a post from @gyulasun on page 324, wich i'll admit i don't fully understand.
( i have trouble understanding somthing i can't see e.g. the JT, i see the light come on,
i can't see  the magnetic field, the transistor switching, the capacitor charging/discharging,
and so on, ) I thought i'd try something different.

I started with 16 turns primary, 4 turns secondry wich gave me 7vdc 12ma and 42ma draw from battery,

I then wound a third winding, one end went to the collector after a diode, and the LED went between
the emitter and the other end of the third winding, after some tuning i ended up with
8 turns primary, 2 turns secondary and 12 turns for the third winding,
results were - 21vdc 27ma and 39 ma draw from the battery.

Happy with this and not having a ferrite torroid to try this on i decided to add another 6 turn winding
to a fugi transformer
the Existing 8 turn winding ended up as the primary, the new six turn the secondry and the
third winding, well i couldn't count them,

this lit up an un-modded cfl, but only just, and with one hand holding some foil with it beeing attached to
the emmiter, but this was enough to make me smile

i'v attached a couple of pictures, the cfl wasn't as bright as it looks in the photo,
also a edited diagram, first time i have done this, i think it's rite.

must get some sleep now.

Just a Suggestion . you should get more light is you remove the cap and diode .your filtering the half wave and might loose some of the kick . .in that camera transformer it would be nice if you could show the transformer so i can see how you wound over it .. . Slayer007 has bunches of great circuits and i recommend them Highly ! .
Best regards and I offer a Welcome on behalf of Pirate thread .

Al
AKA Gadget

[Pirate88179]

@ mikem and Dog:

Welcome to our topic here.  Great job on the cfl lighting there mikem!  Yes, these circuits are addicting for sure.

@ Dog:

I am glad you made it to our topic here.  Gadgetmall is correct about your leds and the jt circuits here.  You mentioned to me on another topic that you might be interested in some kind of kit to do what you would like to do?  Several of the folks here can help you with that or, you can use some of the circuits posted here, some many pages back, to build your own device for your application.  I agree with Gadgetmall's assessment of running them for about a week on a single AA battery, I think this is completely possible.

If you can't find what you need, I am sure you could pm me, or Gadgetmall, or Jeanna, or IST, or Mk1 and they could help you to find what you are looking for.  Some advice for you in the meantime......do NOT toss out any "dead" AA batteries that you may have.  Save them all.  They are not really dead and will provide you with many, many hours of light with these circuits.  You can even tel your friends to save their "dead" AA's in a baggie for you.  Then the girls will have "free energy" with their hoops.  Your project is a good one.

@ General Jim:

Super caps are cool and you will love them.  The main caution I have found is to never overload them voltage wise as they can and will explode.  So, 5.5 v cap should not be hooked up in such a way that 30 or 40 volts goes into it.  I have been using all of mine just like a battery.

To begin with, just take 3 AA batteries in series and hook them up to 1 supercap for a few minutes.  This will load it up with 4.5 volts.  Then, hook that up to one of your jt circuits and it will run it for a while.  You should be able to light a single led just from the super cap for probably 20-30 minutes.  On your breadboard, you can hook both caps in parallel and juice them up with 4.5 volts and then run your circuit 2 times as long.  This is the main thing I have been doing with them.  I have learned that they do not take as long to charge up as I was originally told.  I have a video where I just touch the battery to the cap circuit for less than one second, and it lights 3 high power leds for a while.  let me know if I can e-mail you the video.  It is on youtube but I think you don't get those if I read right.  It is a large file and may be to large for e-mail.  Can you access metacafe?  A lot of my videos are there also.  Have fun with those, you will love them.

Bill

[gadgetmall]

@all .. for those of you that are looking for Germanium transistors there is a good supply on ebay . I asked the guy i bought mine from and am awaiting a response .  some germanium transistors offer high dc amplification at a fraction of a regular silicon transistor base power up voltage ie 2n3904 etc.. they even have Vintage gold 2n2222 transistor i see and their gain exceeds any made today .  a good germanium transistor will power up as little as 0.15 volts . most are 0.20 volts . a silicon transistor 0.50 volts . or half a volt .
heres mine
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=130279412519
he gave me 50 extra ones too . ask him if he has more

Gadget