Is joule thief circuit gets overunity?

[picowatt]

I value my Atten Scope more now.  Just repeated the Input Waveform capture on Board 80.  You can draw the zero axis yourself.  It definitely shows current crossing the axis.....

Lawrence,

Although your Board 80 input current trace does show some excursion above the zero ref line, overall, there is much more area under the zero ref line.  Everything under the zero ref line is current being drawn from the battery.  Looking at that board's input and output power captures demonstrates an efficiency of about 75 to 85%.

TK's reply 522 definitely looked like it was OU by a significant amount.  The apparent equal area above and below the zero ref line on the input current trace made me wonder, however, if he had inadvertantly switched to AC coupling.  Although the jury may still be out on that completely, it is the most likely explanation for that anamalous capture.

PW

[ltseung888]

Lawrence,

Although your Board 80 input current trace does show some excursion above the zero ref line, overall, there is much more area under the zero ref line.  Everything under the zero ref line is current being drawn from the battery.  Looking at that board's input and output power captures demonstrates an efficiency of about 75 to 85%.

TK's reply 522 definitely looked like it was OU by a significant amount.  The apparent equal area above and below the zero ref line on the input current trace made me wonder, however, if he had inadvertantly switched to AC coupling.  Although the jury may still be out on that completely, it is the most likely explanation for that anamalous capture.

PW

I got 10 more boards from Mr. Zhou yesterday.  Six of them have similar characteristics as Board 80.  Two could not light up the LED. Two showed unusual behavior (Broad 107 and 113.)

Instead of returning them to Mr. ZHou as "reject", I shall keep them and work on them more.  We may be able to learn much more from such "unusual boards" as TK recommended.

Here, I shall show the Input Waveforms of the "usual boards".

[ltseung888]

I did the DSO analysis on Board 80 again with the latest "correct" setting.

The negative Input Power is now taken to be Current drawn from the battery.  Thus the COP is now positive.

The COP is still 1.41.  The Average Output Power is still greater than then Average Input Power.

More research is worthwhile.

[ltseung888]

Input and Output Waveforms for the unusual Board 107.

[ltseung888]

Input and Output for the unusual Board 113