Is joule thief circuit gets overunity?

[picowatt]

Pw,

Your analysys is brilliant and detailed as usual, but is your effort made in vain?

I have not looked at Lawrences xls files, but I will take your word for how he is computing Pout. That method is incomplete. The correct method to obtain Pout (avg) is to average the instantaneous Pout readings exactly the same as is done for Pin. Now this of course assumes that Lawrence feels that Pout is in fact the power in the LED only.

.99,

And no, I dont believe it was in vain.  It is just a thought puzzle that has been gnawing away at me for some time, and I feel confident that what I have presented sheds a bit of light on the puzzle.

Glad to see you are still "hangin' around" even if it is from Pheonix...

PW

ADDED:  Possibly you can help me work out the correct formula for Pout based on what I have presented.  You're much better at that!

[picowatt]

.99,

I have looked through the raw input/output data files for board 80 as presented in slide 12 and 13 and am confident that the raw data is representative of slide 12 and 13.  There is a smaller error in that there are approximately 3 full input cycles of collected data and closer to 4.75 cycles of collected output data.  A difference in the integral number of cycles of data collected will not affect the Pin(avg) versus Pout(avg) calculation, but that extra .75 output cycle will produce a slight error in favor of Pout(avg).

However, I believe this to be an error of 5% or less (the extra .75 of an output cycle did not contain a Pout power peak).

PW

[picowatt]

.99,

Lawrence's Pout(avg) calculations and raw data are in the file "DSO Analysis1.xls" in his post #552.

The raw input data is the "Input.xls" file at the bottom of his post 503.  That is just the raw input data with no math performed, but in his post 575, he did do the input calculations and a beginning an end portion of the xls file is provided there as well (along with the Pin(inst) math).

PW

[ltseung888]

@PW,

Please study reply 581.  If we vary the Input Voltage, we can get different COP (-10 to +9).  Vout (B1) is the voltage including LED and the 1 ohm resistor.  Iout(B3) is the current (voltage across the 1 ohm resistor).  We can change the load easily by connecting a component at B1 and B3.  That is effectively connecting it in parallel with the LED.  We can also take out the LED and the Load will be whatever is across B1 and B3.  Board 71 has this feature.

In reply 581, we can get different COP just by tuning the Input DC Power Supply.  We can also avoid all this discussion on possible Output Power Measurement Error by using a secondary winding on the Toroid.  The Output can then be calculated by the Secondary Voltage x the Secondary Current.  I used to do that.  Recently, I found that I can get COP >1 without the use of the secondary Coil.  I shall dig out some old winding-toroids and do the Output Power Measurements.

*** I have to admit that I could not follow your logic in the long Output Measurement posts.  Normally, in instantaneous measurements, we do not need to worry about the Load and the Voltage/Current fluctuations.  We just take the Instantaneous Voltage value and multiply it by the Instantaneous Current value to get the Instantaneous Power.  I thought that is simple and solid Physics.....

Do you have a 2-CH or 4-CH DSO and a DC Power Supply?    If so, I can send you one of these Zhou boards and you do not have to "guess".....  I believ TK now has an equivalent Zhou Board.  He is seeing the crossing of the zero axis by Input Current (CH2 Vavg).  If he had a DSO and a DC Power Supply, he could have performed the same experiments as reply 581...

[ltseung888]

Pw,

Your analysys is brilliant and detailed as usual, but is your effort made in vain?

I have not looked at Lawrences xls files, but I will take your word for how he is computing Pout. That method is incomplete. The correct method to obtain Pout (avg) is to average the instantaneous Pout readings exactly the same as is done for Pin. Now this of course assumes that Lawrence feels that Pout is in fact the power in the LED only.

@poynt99

Please hook up your 4-CH scope to get the Input and Output waveforms as the first experiment.  That will immediately solve the problem of "non-simultaneous" capturing of Input and Output values.  They should correspond to the "separate Input and Output" waveforms from the 2-CH Atten Scopes.

I blieve that you also have a DC Power Supply.  Vary the DC Power supply from zero to just lighting the LEDs and slowly increase it to 1.5V.  See if you can detect the Iin (Input CH2 average value) changing from positive to negative value.  That will confirm that there are no experiment or equipment errors.

We can try to understand PW's logic later.  I read it six times now and still could not grasp it....  With the experimental set up, we can always make Iin (Input Current Average) very low.  That will force a high COP.  COP can be greater than 1 no matter what his new formula says....