Is joule thief circuit gets overunity?

[ltseung888]

Feedback from a tester:

"Just send me the board.  I have oscilloscope and DC Power Supply.  Do not confuse the issue with unnecessary components."

[Neo-X]

Feedback from a tester:

"Just send me the board.  I have oscilloscope and DC Power Supply.  Do not confuse the issue with unnecessary components."

Hi itsung888 can u try to seek the resonance of ferrite? I have a feeling that ferrite has series and parallel resonance characteristic like piezo where its vibrates at less current. See the graph below.

[gyulasun]

Hi Neo-X,

Mechanical resonance for toroidal cores does exist, and there is a formula to approximately calculate the frequency from the sizes of a particular ferrite toroidal core.  See this link to the  data sheet for a Ferroxube toroid core and just read the 'Remark' under Fig. 4,  PDF file Page 3:  http://www.ferroxcube.com/prod/assets/3r1.pdf

for instance for sizes of OD=25mm  ID=12mm   you get about 98.1 kHz 

This would mean that for cores of that size the Joule thief operating frequency should be tuned to near 98.1 kHz or so. Subharmonics like 49 kHz or 24.5 kHz may also be good.

I am not aware of dedicated series or parallel mechanical resonance for ferrite toroids, only a 'normal'  mechanical resonance like most structures, bodies etc have. 
Piezo devices as you wrote and quartz crystals do have both a series and a parallel resonance frequency and when such a device is excited with any of those frequencies then the mechanical mass starts vibrating. It is important where the body of such piece of piezo or quartz is supported i.e. fixed mechanically because you can easily attenuate vibrations by holding it at a strongly vibrating place (manufacturers of such devices know this).  This may be also valid for the toroidal cores so experimentation is needed of course, maybe hanging down a core by its coil wires is the simplest precaution to make.

Gyula

[ltseung888]

Out of the 20 boards from Mr. Zhou, 18 showed Average Output Power greater than Average Input Power as measured on the Atten Oscilloscope.  This is a very good acceptance rate for the elusive "magical overunity device".

Mailed 5 boards out today and will prepare 5 more.  With 100 "guaranteed OU" boards circulating around the World, suppression of such technology is virtually impossible.

[Neo-X]

Hi Gyula

Thanks for posting those link. Now i know why a ferrite should not operate in its mechanical resonance frequency cause it may break apart the ferrite due to exessive vibration. Now my question is what would be the effect of magnetostriction or mechanical resonance of the ferrite to the current and voltage coil?