Joule Thief

[gyulasun]

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@all: I am thinking of a circuit (for duplication of LTseung's work)  that will automatically recharge the reservoir cap by briefly connecting it to a battery when the cap's voltage drops below a set limit. I imagine an op-amp comparator, 741 or similar, looking at the cap voltage and comparing that to an adjustable reference voltage. When the comparator flips state, it will trigger a monostable 555 to deliver a pulse (also of adjustable duration) to the gate of a mosfet that will make the battery connection to the cap,  for the duration of the monostable pulse. Cap voltage rises and comparator flips, monostable timer resets when its duration is complete, and system is back at "run" state running on the cap only.
What do you think of this idea, and can anyone help with the circuit design?

Hi TinselKoala,

Your above idea reminds me a circuit from Jean-Michel Cour where his goal was to discharge a puffer cap into a battery at determined voltage levels of the puffer cap, see here: http://www.google.com/patents/US20070222411  (he got the patent on it too: US 7928700)

I think you can change that circuit to your exact needs. The patent text includes the complete operation with component values

Gyula

[gyulasun]

Tk . are those old color Tv's ? I am an x tv repair man  and that is the delay line ?. I did not know they had magnets on them .Now i wil have to hunt for a relic . I threw hundreds of them away three years ago ;(

Hi Gadget,

They are not delay lines but horizontal linearity correction coils and the permanent magnet attached at one end of the core caused a variable partial saturation in the core, hence the coil inductance could be changed from outside. There was no need for slug-tuning method with a screwdriver because it detuned greatly the linearity coil to make it impossibly for correct adjustment. (and at the 15kHz involved the steel of the screwdriver would have been heated up-- induction heating by eddy current)

Sorry to chime in...

Gyula

EDIT:  sorry but now that I watched Tinsel's earlier video on Joule Thief:Supplement ( http://www.youtube.com/watch?v=y9ZN5QJZClY&feature=channel&list=UL ) the transformer he showed is a current choke usually placed into the mains voltage input of television receivers or computer monitors to prevent switch mode noise getting out from the set to cause interferience on the mains line voltage and they normally are between 2.2mH to 4.7mH double coils but they have no permanent magnets.  So if Tinsel used the same ferrite choke coils in his Goast circuit then it was not a horisontal linearity correction coil.Of course Tinsel will have a say here.. LOL

[totoalas]

Tk . are those old color Tv's ? I am an x tv repair man  and that is the delay line ?. I did not know they had magnets on them .Now i wil have to hunt for a relic . I threw hundreds of them away three years ago ;(

NickZ .. good luck . i think you are using to much juice and that light is bright though . Yes let us know the start volts and the end volts ...


Mine has climbed to 1.272 from 1.228 and still rising . Not much light on 8 led 220 bulb but the amazing thing is it is a COLD circuit like really colder than the room if i shoot it with a laser thermometer. The other ones ran a few degrees above ambient .

Mine is boxed now and setting in my room by itself . I will check it threwout the day to confirm my findings..

In the meantime i am replicating my replication with the other homemade coil .

TK . if you have a spare delay line i'll trade ya for 4 nice germanium transistors (antiques)  they are 39 bucks each now.
Nice results   Gadget.....
Hope you can test with solar panels / 12 v   with micro Amps    output      lol
totoalas

[gadgetmall]

totoalas no i hate 12 volts . A real Joule thief operates at a very low voltage . In fact just enuff to trigger a transistor into switching . Any more than that and you will never know what you got . The fact is most leds are drivable without  any circuit at all above 2.7 volts,some 1.9(red) (clear green). If you use leds as most here will it is important to keep the voltage way below 1.5 volts / After that it is a matter of coil ratio to light anything such as cfl or many led bulbs.
On the other hand there is a place for 12 volts IF you can keep your 12 volts at that voltage and do work at the same time .

But 12 volts in the middle of a field is not easy to come by in an emergency and as of not it just is a big battery .
1.2 volts is easy to obtain from the ground with carbon magnesium rods and they can produce for 5 to 20 years without going "dead"

Hey guys i have replicated my replication and it is repeatable    Using other parts like that homemade choke coil and mpsa05 pairs . The schematic is exactly like lasersabers ,no start cap but the difference is the extra diode cap feedback on the oppisite leg. It dam works !  I am glad i kept at it . On my third replication with the Biting Coil . AHHHHH. now this is HIGH voltage with 1.2 volts and i am a bit scare of it cause this is not normal Hf . this is splatter hvrf . ..

[totoalas]

Thanks gadget
The reason lasersaber and slayer made some 12v mod for practical home lighting in my place with a 5w 18v solar panel i have 20 Pcs of 220v ac led lamps 160 ma input to a jr ckt 60% light output for outdoor lighting
Theoutput from my jr is connected back   to the battery when the lights are off and charging via in4007 diode 
Same goes with my six filar ss ssg one xtra coil with diode charging back the battery when solar is off   but @ a certain time when no more oscillation takes place

Totoalas