Is joule thief circuit gets overunity?

[poynt99]

Do you by chance have a differential voltage probe and a current probe for it?

My boss forgot to order the current probe, and by mistake I ordered a High voltage diff probe.

I think that scope can probably do two live math traces, so you could display input voltage and current, instantaneous power, and the integral of the power all on one screen.

I'm not sure about that. I did try to see if I could get both Pin and Pout on screen at the same time, but it doesn't appear to be able to do that. Doing an integral of the power trace should not be a problem though.

I also think that it's pretty clear that there is a DC offset issue happening with the Atten scopes at this very high sensitivity setting.

Agreed. It's either the scope or the probes, or both.

[TinselKoala]

Yah, that's right, you can display more than the 4 live probe traces, but only one live math trace, I guess. But the integral can be shown in the math trace easily enough.

Remember this blast from the past? Better "evidence" of "OU" than anything that Ainslie ever showed.

[poynt99]

Lawrence,

Look at the first slide in this post of yours.

http://www.overunity.com/12686/is-joule-thief-circuit-gets-overunity/msg356970/#msg356970

The input voltage is only 0.38V which is not enough to get the circuit oscillating. That means the circuit is OFF. In this state the output current probe should be reading 0V, yet the scope is clearly showing 13.6mV.

I would strongly urge you to short the current probe to itself and confirm that the reading is 0V. I don't believe it will show 0V. I believe you have a +13.6mV offset in that channel.

[ltseung888]

Lawrence,

Look at the first slide in this post of yours.

http://www.overunity.com/12686/is-joule-thief-circuit-gets-overunity/msg356970/#msg356970

The input voltage is only 0.38V which is not enough to get the circuit oscillating. That means the circuit is OFF. In this state the output current probe should be reading 0V, yet the scope is clearly showing 13.6mV.

I would strongly urge you to short the current probe to itself and confirm that the reading is 0V. I don't believe it will show 0V. I believe you have a +13.6mV offset in that channel.

@poynt99,

For Board 80, 0.38V just managed to turn the LED ON - dimly and flickering.

I shorted the Probes on CH1 and CH2 and the screen pictures are attached.  Ch2 turned out to be the more quiet channel.

I am trying to get organizations with high end 4-CH scopes and expertise to help me in Hong Kong as suggested by TK.  Your one probe costs more than my two Atten Oscilloscopes (USD$600 vs USD400)!  I hope that we can always rely on you to do the double check with your Tek Scope and your expertise.

[poynt99]

@poynt99,

For Board 80, 0.38V just managed to turn the LED ON - dimly and flickering.

I shorted the Probes on CH1 and CH2 and the screen pictures are attached.  Ch2 turned out to be the more quiet channel.

I am trying to get organizations with high end 4-CH scopes and expertise to help me in Hong Kong as suggested by TK.  Your one probe costs more than my two Atten Oscilloscopes (USD$600 vs USD400)!  I hope that we can always rely on you to do the double check with your Tek Scope and your expertise.

Lawrence, I would recommend you try to find out why your scope consistently shows a 12-13mV offset when measuring the input current. I would like to see that scope shot duplicated and show the LED as well. It sure appears that the circuit is OFF.

Also, did you do any number crunching on my data from board #33? What were the results?

What is your comment on my scope results? How do you explain that the current never crosses the 0-ref line?