Joule Thief

[electricme]

Haaaaa Haaaaaa he he he he  haaaaawwww ha ha

I'm tooo silly for words, an its very late.

My two greenies, aint they loverly even got golden eye shadow.

[gadgetmall]

Hi Jim and All,

jadaro2600 opened a new thread for his question and I tried to answer his LED/collector current question there, see this link:
http://www.overunity.com/index.php?topic=6905.0

Now let me briefly discuss how the JouleThief circuit operates and how may you improve it. If the principle was already explained I apologize I did not search for it in these long threads.
So it all boils down to induced voltage in a coil when you interrupt the current flowing in it. The collapsing magnetic field induces a voltage pulse across the coil, the polarity of this pulse is just the opposite of the DC voltage you switch across the coil to make the current flow in it.  The formula for the induced voltage is V_induced=L(dI/dt)  where L is the coil's self inductance in Henry, dI is the current change in the coil in Amper and dt is time in seconds under which the current changes.
So you see the higher the current change and the shorter the time, also the higher the coil's self inductance, the higher the induced voltage you receive across the coil.
This means you can get higher flyback pulse by using a fast switch. A higher amplitude pulse can lite up more LEDs in series  because the LED forward voltages add up and you have to defeat their series resultant voltages. 10 white LEDs in series needs at least a 35-40V peak pulse to create and also get some light with certain intensity. You can combine LEDs in parallel from the series chains.
Let's make a small calculation with the formula above, say you switch on 50mA via your 1mH coil in 1usec.  Then the induced voltage will be:  (0.001H*0.05A) / 0.000001sec=50V  If you are able to switch faster than 1usec in a JT circuit then you get a higher pulse in the calculated example. 
An extreme example is the spark transformer in cars where you switch a 12V battery to the tapped coil and receive 30-50kV peak pulses. (It is a heavy duty JT if you like, inputting some Ampers at 12V.)

Here is link on using a transformer (basically two coils instead of one or one coil with a tap if you like): http://www.maxim-ic.com/appnotes.cfm/an_pk/1109/

No need for using the Maxim specific ICs for the job, a JT can be adapted for the transformer circuit,  basically also an autotransformer with 1:5 or higher up-transformation ratio.  You simply connect the collector to the tap of the coil and instead of the D1 fast diode you connect the series of LEDs towards the negative pole of the battery like in the JT.

rgds, Gyula

Hi . Thanks for the calculations . I don't know how they fit in on a circuit i made . For Instance  take an White 10,000 mcd led that supposed to take 2.9 volts and 20 ma to light it . well i can light 4 of them on .90 volts at .81 ma total  bright . So we are Lighting Basically a 10,000 mcd led with a Modded  Jt for only 0.20 ma rather than 20 ma  and the voltage output  is barley 2 volts rectified measurement . yep its all in this thread somewhere  . The Bemf on these are Playing a factor not in any calculation i suspect . If there is an explanation Its probably more In the Nature of a Higher Bemf or energy from the aether than the actual induced voltage . Again this is in a resonate Mod and the Schematics are posted many times  so i won't bother to post them again. But thanks for a Scientific Approach ! 

[gadgetmall]

@jadaro2600
Ist is correct, you can light up a LED off a single coil both ways.

Take a look at this TWV I just made
Please excuse the fingers

I held a bare LED across the output from my big torid coil
Holding the LED I turned it 180 degrees and it again lit up 

Hope this helped you

General Jim

Hi General  Do you suspect then that as i suspect that true ac is coming off the mk2 rather than pulsed dc . That is the only explanation i see as an led Will light both ways on ac but not pulsed dc . ? so if that is the case  Winding a Jt in this fashion will convert PDC to Ac ? I think so .

[jonnydavro]

Hi.Great work going on here and i am following it closely.
A while back when i made a joule thief powering a pulse motor,Pirate suggested puting a dc motor on top off the pulse motor top and tail fashion as a generator well i had a play a while back with the idea and here is the result.I have not used a pulse motor i have top and tailed 2 dc motors.The top one is powered by the cap which is charged by the joule thief and the bottom motor is the generator.Here is a video off it running.This might have possible feed back to sorce potential or maybe chargeing batteries.
http://www.youtube.com/watch?v=5ynFm-JwYjY
@electricme.If you are still having problems with utube,let me know and i will send you the vid if you like.
                                                                    Regards jonnydavro

[nievesoliveras]

@electricme

Thank you!
I tried the viewer of the link you posted and it seems to be working improperply on my machine.
It says something about the engine of my machine is wrong??
I will try now @gadgetmall's quicktime suggestion.

@gadgetmall
I have a battery pack of two triple A batteries charging with a variation of your idea. I did the test the way you told me and it did not work with my toroid's secondary. I used the primay's output to connect it instead and it is working by itself since last night! The special led goes the other way around.
The fire test will be to test the charged AAA batteires on my camera to see if it is not a ghost charge.

Thank you!

Jesus