Is joule thief circuit gets overunity?

[TinselKoala]

.99,

I now believe it is correct. 

I stared at it too long yesterday and in the midst of it all forgot that in the end, Pin(avg) is removed from Pout(avg) when the net power calculation is performed. 

PW

Whew.... I was afraid we'd lost you there for a moment. I couldn't quite agree with (my interpetation of) your reasoning about the output power not including everything that was actually measured at the output.

[TinselKoala]

.99

I am beginning to wonder if Lawrence's scopes need to have their input channel offsets checked.  Looking at the raw output data listing, when Q1 is on, Vout is 80mV.  At that same time, there is 12ma being indicated as the output current.  I have checked the current flow through several LED's of various "colors" and cannot find any that indicate anywhere near 1ma at that applied voltage.  Possibly his LED is different than those I have tested, but if that channel is applying a 12ma offset to all Pout calculations, that would be significant.

PW

Yep, I think I mentioned that possibility as well, even before seeing the present data. 1 mA at 80 mV is huge, for a good LED.
I've asked before that some measurements be taken of the voltage drop across the CVRs in DC conditions using ordinary DMMs on the millivolt or microvolt scale and comparing their voltage drop readings with those obtained by the scopes.
I don't know how the Atten scopes function in re DC offset/bias or if their power-on startup checks will detect out-of-spec conditions here. Some scopes do.

[TinselKoala]

@Lawrence:
Cheap tools are no bargain.

[TinselKoala]

@Lawrence: Congratulations on the measurement of COP vs. Input Voltage. That is an important bit of information. Your graph does not present the data correctly, though.

In graphing data one generally puts the "independent variable" on the horizontal axis and the "dependent variables" on the vertical axes. The IV is what the researcher is controlling and the DVs are what the researcher is measuring. In this case the Voltage Input is the IV and the COP is the DV. You have plotted "trial number" on the horizontal axis and both Vin and COP on the vertical axis and so your graph is garbled.

You could re-do this graph. It would display only the single COP line. The horizontal axis would be the voltage levels, and the vertical axis the calculated COP. Then your graph would display the relationship between Vin and COP properly.

[ltseung888]

@Lawrence: Congratulations on the measurement of COP vs. Input Voltage. That is an important bit of information. Your graph does not present the data correctly, though.

In graphing data one generally puts the "independent variable" on the horizontal axis and the "dependent variables" on the vertical axes. The IV is what the researcher is controlling and the DVs are what the researcher is measuring. In this case the Voltage Input is the IV and the COP is the DV. You have plotted "trial number" on the horizontal axis and both Vin and COP on the vertical axis and so your graph is garbled.

You could re-do this graph. It would display only the single COP line. The horizontal axis would be the voltage levels, and the vertical axis the calculated COP. Then your graph would display the relationship between Vin and COP properly.

I just made the seven minute video to show that when the Input Voltage drops, the average Input Current as detected on the Atten Oscilloscope can change from -14mV to +1.6mV in about 7 minutes.  This change means that the Average Input Power can be very low and also can change from negative to positive.  The Average Output Power was always positive and increased with increasing Input Voltage.

The end result is that a large range of COP is possible with the same Board 80!

See:
http://www.youtube.com/watch?v=HSfd8UeKDAg&feature=youtu.be