Joule thief voltages:

El cheapo joule thief setup, with a spare blue LED, a ferrit from an old mainboard coiled with a pair ripped of a 80 pin ide cable (be lucky - one has a colored stripe, 39 other pairs not ;-)

[pic TBD]

here three dso pics with a battery voltage at about 1.2 volt (bright light), 0.6 volt (still lighting) and 0.5 volt (no light):

at about 1.2 volt we have about 35 khz: (please click to enlarge)
the 3.6 or 3.7 volt peak makes a bright light.


at 0.6 volt or so its about 140 khz: (please click to enlarge)
the ~3 volt peaks are good enough to get some light.


and with 0.5 volt there is no light, but it is still oscillating at 200 khz: (please click to enlarge)


about 2.6 volt peaks are left for the led - not enough...

ok, maybe i took the numbers total wrong,
but it was fun playing with the dso ;-)

see the dso 2090 at (german site).

anyway, have fun!

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Tue Jul 21 21:43:32 CEST 2009