Joule Thief

[innovation_station]

puttin on the BRAKES......

now not toooooo fast lol......


but that looks like a self timming curcuit 

or darn close.....   might be good to sync things up    lol 

ist!

[sparks]

@Artic

        If a transformer core is already saturated and we hit the core with another pulse what does this do to the core magnetic circuit?  The second pulse would be producing some kind of magnetic response in the field inside it's turns but wouldn't the impedance normally associated with core saturation be negligible.  In other words would there be an instantaneous flow of current in phase with the applied voltage even though it is flowing in a conductor geometry that would normally not allow this to happen.    I'm talking about a torroidal transformer driven to saturation by a first pulse followed in very short order by a second pulse.

[Artic_Knight]

well according to the page, the cap builds up a suitable voltage (9v) then the transistor cant hold it back anymore so its allowed to pass through, once the cap discharges below the breakdown voltage it starts to recharge again, i believe its the zeener diode that has a low primary bias and high flyback bias but is able to operate backwards and that could be used for higher voltages to accomplish the same thing essentially. the transistor is a diode that is able to lower its breakdown voltage as the "base" voltage increases so any diod in this curcuit that is able to operate backwards (and forwards in some cases) can have a voltage control timing effect to it.

so boys and girls if you need a simple timing curcuit well it doesnt get any better than that! will require some tinkering though!

if im not poorly mistaken there is a variable capacitor as well... however i do not know if it would be the voltage or the capacitance that would vary and we would want to vary the capacitance to vary the timing (however a variable RF choke might serve as a magnetic capacitor? they should be variable). that combined with a variable resistor (if needed to prevent burn out of curcuit or to slow the discharge of cap) and you have a perfectly configurable timing curcuit that should be easy to build, it can certainly take a variety of parts in its creation.

it should be similiar to what your playing with minus the transformer.

[slapper]

Transistors and many other semiconductor devices exhibit interesting characteristics in the circuits presented in this thread.

Do a web search for negative differential resistance oscillators.

Here is a link to Naudin's JLN Labs web page that goes into negative differential resistance circuits in some detail:
http://jlnlabs.online.fr/cnr/negosc.htm

Thanks for all the good work guys. Take care.

nap

[gadgetmall]

@Artic_Knight
yep already built this one 2 weeks ago . i discovered putting a cap thru the base with a couple resistors  . "electrolytic "that it blinks thus conserving the 1.5 volts for days longer however i did notice when she finally reached a lower voltage on the battery the blinking gets slower  and stops and the led remains lit  acting like a normal JT letting me know that i have a day or so before it dies completely .. . this is one of the ones i gave my little girl . it is covered with clear goop to keep it intact .Edit forgot to mention that i put this little green thing on it across the electrolytic . It was in a computer power supply glued on top of a capacitor so i think  it is a thermistor . Its not Exactly the same using two legs of the transistor but Blink can be made from the 1 volt battery instead of 9 v and i suspect a tuning cap there across the same spot  will accomplish a blink also .I thought is was interesting that they can make that transistor run with two legs though . COOL.