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Author Topic: Is joule thief circuit gets overunity?  (Read 600436 times)

ltseung888

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Re: Is joule thief circuit gets overunity?
« Reply #285 on: February 28, 2013, 04:22:02 AM »
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

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Re: Is joule thief circuit gets overunity?
« Reply #286 on: February 28, 2013, 01:18:16 PM »
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

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Re: Is joule thief circuit gets overunity?
« Reply #287 on: February 28, 2013, 02:58:14 PM »
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

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Re: Is joule thief circuit gets overunity?
« Reply #288 on: March 01, 2013, 08:33:21 AM »
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

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Re: Is joule thief circuit gets overunity?
« Reply #289 on: March 01, 2013, 05:50:46 PM »
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?

gyulasun

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Re: Is joule thief circuit gets overunity?
« Reply #290 on: March 01, 2013, 09:04:22 PM »
Hi Neo-X,

It surely depends on the excitation current flowing in the coil but I do not know by heart what relationship governs the vibration amplitude to the current strength when the AC or pulsed current is at the core's mechanical resonant frequency. It needs some studying of the technical literature of the 50s and 60s when ferrites were extensively researched.

Gyula

xee2

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Re: Is joule thief circuit gets overunity?
« Reply #291 on: March 02, 2013, 01:56:11 AM »
Out of the 20 boards from Mr. Zhou, 18 showed Average Output Power greater than Average Input Power as measured on the Atten Oscilloscope. 

ltseung888
How is average output power being measured? The scope probably assumes that load is resistive. If the output measurement includes the LED then the scope will not compute the output power correctly (LED does not obey ohms law).

ltseung888

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Re: Is joule thief circuit gets overunity?
« Reply #292 on: March 02, 2013, 03:20:12 AM »
ltseung888
How is average output power being measured? The scope probably assumes that load is resistive. If the output measurement includes the LED then the scope will not compute the output power correctly (LED does not obey ohms law).
The Output Power Computation is based on:
Instantaneous Power = Instantaneous Voltage x Instantaneous Current.
 
It does not matter whether the power is DC, AC or pulsed.  The Output Voltage Measurement is across the load.  The load can be LED, small motor or resistor.  It also includes the 1 ohm resistor.  The Output Current Measurement is across the 1 ohm resistor.  The Output Voltage Waveform can be seen from the top curve.  The Output Current Waveform can be seen from the bottom curve.  The Output power Waveform comes from the analysis of the CSV file.  The Average Output Power value comes from the CSV file.
 
Thus with the captured CSV file, we do not need to worry about whether the load is non-resistive.  Hope that answers your question.  That is why all the testers have digital oscilloscopes so that they can do such analysis.

xee2

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Re: Is joule thief circuit gets overunity?
« Reply #293 on: March 02, 2013, 04:00:23 AM »
The Output Power Computation is based on:
Instantaneous Power = Instantaneous Voltage x Instantaneous Current.
ltseung888
This is only true for a resistive load. When there are diodes in the load the voltage is increased by the diode junctions as well as the current. The power consumed by a diode is current squared times the forward resistance of the junction, not current times voltage across diode.

ltseung888

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Re: Is joule thief circuit gets overunity?
« Reply #294 on: March 02, 2013, 12:11:45 PM »
Just received another 20 oscilloscope test-ready boards.  Will do the double and triple checks in Hong Kong.  The boards for the three forums are already in the mail.  According to the Hong Kong post Office - arrive within 10 working days.  Thus independent testers with their oscilloscopes can do the detailed analysis.
 
Let the experts do their job and post their findings.

xee2

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Re: Is joule thief circuit gets overunity?
« Reply #295 on: March 03, 2013, 02:43:59 AM »
ltseung888
Perhaps this is a better explaination of the problem:
When you are measuring volts times amps you are measuring both real and reactive power combined. A battery delivers real power. Therefore, to measure efficiency of a circuit, the output power measured must also be real power. Real power is measured using a resistive load. Thus the output power must be measured using a resistor.

poynt99

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Re: Is joule thief circuit gets overunity?
« Reply #296 on: March 03, 2013, 03:58:16 AM »
Real power is measured using a resistive load. Thus the output power must be measured using a resistor.
Real power measured in a load (PL) of any kind can be performed by taking the average of the instantaneous voltage across the load times the current through that load. It is critical however to ensure that the current measurement is across a pure resistance such as a high quality CSR resistor.

PL(AVG) = AVG[v(t) x i(t)], where i(t) might be obtained from the instantaneous voltage across a known pure current-measuring resistance; i(t)=v(t)/Rcsr.

xee2

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Re: Is joule thief circuit gets overunity?
« Reply #297 on: March 03, 2013, 06:38:34 AM »
Hi poynt99
Thanks for the explaination. To measure the real component of power, as I recall, the voltage vector and the current vector need to be in phase with each other. If the voltage vector is measured across a reactive load I do not see how averaging the values will produce the correct answer. I will have to think about that for a while. However, this is certainly true when both voltage and current are measured across the same resistor.

poynt99

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Re: Is joule thief circuit gets overunity?
« Reply #298 on: March 03, 2013, 04:29:07 PM »
To measure the real component of power, as I recall, the voltage vector and the current vector need to be in phase with each other.
To be precise, allow me to rephrase the above;
In order for real power to manifest and be measured as real power, the current and voltage vectors must be in phase.

Quote
If the voltage vector is measured across a reactive load I do not see how averaging the values will produce the correct answer.
Keeping in mind that the stated method is to acquire instantaneous samples of current and voltage, what happens to the product of v(t) x i(t) if they are 90º out of phase? Is the p(t) for these samples not 0W?

This method inherently compensates for the samples where the phase is skewed. In other words, it takes care of the fact that the current and voltage may not always be in-phase. Only those samples that are in phase, or partially in phase will result in a real power product, and if the wave forms are periodic (in 99% of the cases they are), then taking the average of this product will yield an accurate measurement of the over-all average power.

Pirate88179

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Re: Is joule thief circuit gets overunity?
« Reply #299 on: March 03, 2013, 05:50:35 PM »
xee2 and .99:

We in the JT topic discussed long ago that if there was any more power in than out, a self-runner was the proof.  Especially using a supercap, which I believe Lawrence is, would this not be the best proof of even a tiny bit of more P in than out?  It would continue to run right?

Once that is achieved, then he, or someone, can attempt to place values on how much extra is there.

I do not think that his circuits are any where near 100% and certainly not above.  Looping one to a supercap would prove this very quickly.

Just my thoughts.

Bill