Joule Thief

[kooler]

xee2 and all
in the whole building this circuit.. i had in my mind that i would be able to recover the bemf back to the cap.. but i have yet to find any
this being weird for me cause i have built a bunch of 12v ign coil pulser... with bemf enough to pop a 200v 12a mosfet....?
well now i am pulsing a coil with 300+ volts with no bemf??

many of thanks to jeanna and mk1 cause i wouldn't be able to charge this cap
w/o the toroid setup

so what you think of the emf thing
i know the scr opens and closes much sharper than a transistor
but wouldn't that cause more bemf

thanks
robbie

[xee2]

@ kooler

xee2 and all
in the whole building this circuit.. i had in my mind that i would be able to recover the bemf back to the cap.. but i have yet to find any
this being weird for me cause i have built a bunch of 12v ign coil pulser... with bemf enough to pop a 200v 12a mosfet....?
well now i am pulsing a coil with 300+ volts with no bemf??

many of thanks to jeanna and mk1 cause i wouldn't be able to charge this cap
w/o the toroid setup

so what you think of the emf thing
i know the scr opens and closes much sharper than a transistor
but wouldn't that cause more bemf

thanks
robbie

Back EMF is caused when the circuit is opened while current is flowing through the coil. This circuit is not opened until there is no longer any current flowing through the coil. Thus no back EMF.

[xee2]

@ kooler

Video of circuit 16 with 2 uF capacitor making filament of 120 volt light bulb glow. This is not very impressive but could not be done with a 1.5 volt battery without the current boost circuit. This is a pretty heavy duty 7 watt bulb, your nite light probably glows brighter. Coil was replaced with bulb.

[kooler]

thanks for the reply
i see now.. because this circuit is closed while current is building up to be released

i am still learning alot...

well you can see i was wrong while thinking this circuit up..lol

oh, one more thing how come when  i put two toroids side by side and wind my base and collector on it drops my ma draw by half..
well lets say i got two toroids with 300 turns on each then put them side by side and wind on one set of the turns for the jt it still gives me 456 volts which is only half of what i get if i done two separate jt's but it drops by half.. lets say 101ma's to 49ma's.. but it still charges a cap just as fast but no faster
if this is confusing i will make one and take a pic

[xee2]

@kooler

thanks for the reply
i see now.. because this circuit is closed while current is building up to be released

i am still learning alot...

well you can see i was wrong while thinking this circuit up..lol

oh, one more thing how come when  i put two toroids side by side and wind my base and collector on it drops my ma draw by half..
well lets say i got two toroids with 300 turns on each then put them side by side and wind on one set of the turns for the jt it still gives me 456 volts which is only half of what i get if i done two separate jt's but it drops by half.. lets say 101ma's to 49ma's.. but it still charges a cap just as fast but no faster
if this is confusing i will make one and take a pic

This is a great circuit for doing tests like that (comparing one toroid output against a different design). I am not sure I understand your question, but doubling the thickness of the toroid will increase the inductance per turn which means that 300 turns will produce a higher output voltage using the thicker core. Can you explain a bit more about what you are doing?