Is joule thief circuit gets overunity?

[TinselKoala]

@TK

I just followed your advice and swapped the probes.  The result is the same.  So the problem most probably lies with the scope.

Correct.

One of the boards you refered to showed unusual high voltage output and hence high COP.  My mistake was to return it to Mr. Zhou together with the "rejects".  His people "recycled" some components without a thorough investigation.  The rejects were replaced by good ones. 

The voltage discrepancy that I have been asking about was NOT with one of your boards. It was when you posted the traces from the scope's calibrator output. One of your probe/channel combos showed an excessively high voltage _From the Calibrator_ and so was introducing a large error. This could not have been a simple compensation issue, it was a discrepancy of several times the proper voltage level, IIRC.
I've attached the calibration traces you posted, before compensation adjustment, below. Each and every channel should be displaying the _same_ voltage level--- from the calibrator output. But as you can see... I hope.... the "Scope1 Channel 2" trace is indicating nearly 17 volts as the peak level of the square wave output.
For about the seventh time.... what caused this discrepancy, how did you resolve it, and can you PLEASE show a new set of calibration traces that are all properly obtained, and properly displayed, so that we may know that these basic calibration issues are resolved, or at least identified.

Now I am keeping the rejects.  I do not have the expertise to indentify the problem.  So they are just being stored until I can find the right person to check them out.  If you are interested, I can send you some of these rejects and you can tell us what might be wrong with them.

You should have kept ALL your boards until all the problems we have identified are resolved. Your claims of OU are not supported by your data, which at this point seem to be indicating NOT OVERUNITY.... but rather, that a cheap tool is no bargain.

[TinselKoala]

@TK

I do not have an accurate "known low voltage source " at home.  Since the problem appears to be with the Atten Scope and at least one of them is still under warranty, I shall get the manufacturer to check it out with their experts.

All my three Atten Scopes showed the crossing 0 reference line behavior.  If it were a bug, the manufacturer would be and should be interested.  They need to fix it or provide a solution for their customers.

As I posted and as PW corrected with proper resistor values, a simple voltage divider made of a couple of resistors in series, and connected to a AA battery or to your power supply set to 1.5 volts, will be just fine, as long as you have an accurate DMM for a crosscheck.

And I believe you have some kind of Platinum Visa card to draw upon. Please spend a few dollars and obtain a voltage reference, like the 35 or 61 dollar boards or the 3 dollar chip that I told you about earlier. Surely you can see that a person who claims OU based on small voltage measurements MUST be able to show that the voltage measurements are correct, and this requires measurement of a KNOWN STANDARD. The only known standard that we have seen is your scope's calibrator output... which cannot be trusted, apparently.

The ATTEN scopes are what they are. The manufacturer may be interested in the poor performance of the one channel on the one scope, but there are reasons why the ATTEN scopes are so cheap and the Tektronix scopes are so expensive.... and one reason is accuracy.

[ltseung888]

@PW,

I shall try to get in touch with the ATTEN Experts asap and resolve the issue.  A 12-14 mV error will be too much when the reading is 6mV!  The typical CH2 Vavg reads from 8mV to -30mV or more.  The 8mV falls within the error range.  There maybe no crossing the 0 reference line effect.  (Even though the screen capture and the video both showed such effects.)  Cannot believe what you see???

I shall wait for the Expert Comments before doing any more tests - playing with my grand daughters is much more enjoyable and less confusing.

[TinselKoala]

You are getting lots of expert comments here already.

Let me review a few points.

1. The AC vs. DC input coupling issue. You didn't understand the significance or use of this setting and many of your initial experiments and data captures were made using an AC coupled channel, which invalidates that data for power measurements. Hopefully you now understand the coupling issue, how it's done in the scope, and the significance and usage of each input coupling mode.

2. The probe compensation issue. Evidently, much of your data was taken with large probe errors caused by improper compensation adjustment and some kind of large voltage discrepancy. This invalidates _all_ of the data taken up to the point when you checked and adjusted your probe compensation, and even afterwards if that probe/channel voltage problem.... which you _still_ haven't explained or even addressed.... isn't cured.

3. The issue of the directionality of current at the input current sensing resistor. It seems that the "negative" current values were being incorrectly interpreted by you to indicate reversed current flow and hence your "negative" COP numbers resulting. Now I think we've gotten that bit straight, and you realize that negative values here mean normal ordinary current, and power flowing out of the battery to dissipate in the circuit, not the other way around. Many of your recent experimental analyses claiming "negative COP" values, up to the point where this issue was understood by you, are invalid.

4. The issue of the need to adjust the input battery voltage value measured at the probe, by subtracting the (negative) voltage drop at the CVR. This required some review of basic algebra (subtracting a negative number is the same as adding its absolute value) and also means that your earlier, uncorrected data reflect an input battery voltage that is lower than the actual input battery voltage. The proper correction, when made, takes your measurements further away from OU because the true input power is greater than what you calculated and reported. Your data and conclusions up to the point of this correction are invalid because you don't have the correct input power figures.

5. The presently discussed issue of the DC offset, or rather the voltage measurement accuracy of the Atten scope/channel/probe combos. Apparently you shipped a board to .99 that DID show OU performance on your scopes and spreadsheet analysis, but when he tested it using a more accurate oscilloscope he found no OU indications, and particularly not the "reversed" current implied by a zero-crossing measurement. Do you have any reports at all from anyone you've sent your boards to, who have tested them on more accurate equipment than the Atten scopes? We are in the middle of this issue at present so one can't yet say just when or how this issue invalidates your experimental data..... but until we get some measurements from known accurate test kit, we have to take the position that your OU readings are likely due to the inaccuracy of your low-end DSOs. Precision and accuracy are not the same thing, but both are clearly needed to support any revolutionary claims.


Other issues regarding the spreadsheet data analysis are also relevant, but I haven't spent time analyzing them.... yet.

[poynt99]

Lawrence,

On your ATTEN scope, can the bandwidth be set differently on each channel? On the Tek scope it can. As PW alluded to, the difference in apparent noise could be due to different BW settings on both channels. A 20MHz BW will most likely appear less noisy than the full 100MHz setting.

I would suggest you try the 20MHz setting on both channels. This is what I did on the Tek scope measurements. The reason I did this?; the triggering was much more stable this way, and it made no difference in the measurement results.