Is joule thief circuit gets overunity?

[ltseung888]

Ok, that is interesting. However, something doesn't look right with your input current waveform. It is showing as mostly negative when it should be positive current pulses, at least for the most part. That could be where the problem is. Can you confirm that you had channel 2 set to DC coupling? It looks like the coupling was set to AC?

*** There was no problem with CH2.  It was set to DC.  Please read the poynt99 explanation related to the circuit diagram allowing common connection for all 4 probes.

I believe the RMS readings will not be useable if your waveform is not completely positive (pulsating DC) or if the waveform has both positive and negative swings and the positive and negative swings are not very symmetrical. In the scope shots you posted it looks like you didn't have your channel 2 probe set to DC coupling when you measured the input current. If the current waveform were showing as pulsating DC (all positive), I think the RMS reading would provide you with a quite different result.

I did a quick test with the input voltage set at 0.4V, and I do not get much noticeable negative swing on the input or output current waveforms. The output current is starting to get down fairly close to the noise level at this input voltage however. I also tried setting the input voltage to 0.36V, and although my LED still glows dimly at this input voltage, the output current is just barely detectable as very tiny blips on the scope trace, so the output current is unmeasurable on my scope at this input voltage. The output current is right in the scope's noise level at this input voltage.

*** I am not surprised that your results do not show the Zhou Board effects.  Two thirds of the Boards I built myself did not show that - even though they all lighted the LEDs.  The passing test of the Zhou Boards is the crossing of the 0 ref line.  I shall send you Boards 118 and 119 after the tests on them are done in here.  Take your time.  Be parepared to find a 4-CH Tektronics to do the final confirmation.

[Void]

Please read the poynt99 explanation related to the circuit diagram allowing common connection for all 4 probes.
I am not surprised that your results do not show the Zhou Board effects. 
Two thirds of the Boards I built myself did not show that - even though they all lighted the LEDs. 
The passing test of the Zhou Boards is the crossing of the 0 ref line. 
I shall send you Boards 118 and 119 after the tests on them are done in here. 
Take your time.  Be prepared to find a 4-CH Tektronics to do the final confirmation.

Hi Lawrence. Ok, if the scope probe was set to DC then I believe that the problem with the input current waveform is that your input current waveform is inverted. Looking at the way you have your scope probes connected for the 4 channel scope measurement method (based on a diagram you posted earlier this year), it seems to me that this will invert your input current waveform. I believe this will throw off your instantaneous power calculations unless you set channel 2 for the input current measurement to the Inverted setting in your scope. The input current waveform should be pulsating DC, but I do see that it does go a bit negative in your waveform (when viewed inverted from what you showed in your scope screenshot). I can explain further if you like, but it has to do with the direction that the current is flowing and the way you have the channel 2 scope probe connected for the input current measurement in your 4 channel scope measurement method.

[poynt99]

Void,

It does not really matter which way the current-measuring probe is placed, as long as there is not a grounding issue (i.e. placing the probe grounds at different points in the circuit).

The real issue is not whether the current trace is positive or negative (we know the battery loses energy), but if it is BOTH. I have shown, using two different scopes, a 4-CH Tek, and a 20MHz analog Hitachi, that the current trace does NOT cross the zero reference line while measuring board #33 that Lawrence sent me.

The ATTEN scopes seem to have a serious issue with DC offset when making this measurement, as there is a relatively significant 12mV or so causing the apparent "bipolar" current trace.

[TinselKoala]

@void: I think we've been over the meaning of the negative value for the current trace as detected by the probes in use according to the schematic posted earlier. Lawrence understands that a negative value for the current detected here means normal, conventional current flowing from positive to negative, moving power from the battery to be dissipated in the circuit. Not only that, the spreadsheet recorded values do not respect the "channel invert" function, so as long as the probes are positioned as they are, the spreadsheet will have negative values when the current is "normal", no matter whether the _displayed_ trace is inverted or not.

As .99 says, the important issue is the zero-crossing behaviour. I thought briefly that I had detected zero-crossing on my system but I had accidentally selected AC coupling for that measurement and didn't notice it... there's no indication on my analog screen of the coupling setting, like there is on the Atten screen. It's easy to see that Lawrence is using DC coupling for all his recent measurements, although he didn't appreciate the difference until we pointed out that his earlier use of AC coupling was an error. All my more careful measurements do not show this zero-crossing with my boards after all; the current is always "negative" meaning normal conventional current flowing out of the battery to dissipate power in the circuit.

The Atten scopes would appear to be not suitable for these measurements, and should be put away. They simply are not precise and accurate enough to support claims of overunity or unusually high COP in electrical circuits of such low absolute power.

[Void]

Void,

It does not really matter which way the current-measuring probe is placed, as long as there is not a grounding issue (i.e. placing the probe grounds at different points in the circuit).

The real issue is not whether the current trace is positive or negative (we know the battery loses energy), but if it is BOTH. I have shown, using two different scopes, a 4-CH Tek, and a 20MHz analog Hitachi, that the current trace does NOT cross the zero reference line while measuring board #33 that Lawrence sent me.

The ATTEN scopes seem to have a serious issue with DC offset when making this measurement, as there is a relatively significant 12mV or so causing the apparent "bipolar" current trace.

Hi Poynt99. Ok on that.  I wonder if Lawrence has ever run the self-calibration routines on his Atten scopes?
However, I would think that if the current waveform is inverted it will give errors in the instantaneous power calculations, as many of the input current waveform data points will be recorded as negative when they are actually positive, and vice versa if there is any actual negative component to the current waveform.  This would make the instantaneous power calculations and average power calculation invalid, no?