Is joule thief circuit gets overunity?

[TinselKoala]

How bright is your LED, anyway? Here's how to find out.

http://www.youtube.com/watch?v=1Kzf7S-pOEM

[ltseung888]

A cheap way to compare the efficiency of different Joule Thief circuits.

I have used the following method for many years:
1. Put a capacitor in parallel with the battery.  An example capacitor value is 10F 2.3V.
2, Connect the battery to charge the capacitor and light the LED for 1 minute.
3. Disconnect the battery and then measure the time the LED remains ON.

See attached.

[hartiberlin]

Hi All,
I finally had time to make some measurements of one Fleet Joule Thief circuit,
that Lawrence Tseung has sent me a few months ago..

Sorry, I was on vaccation and had many other things to do in the meantime,
but finally here are the tests:

Test Part 1
https://www.youtube.com/watch?v=E75I6ka-aa8

Test Part 2
https://www.youtube.com/watch?v=LszgQSa51KY

If you have any questions,
please post and comment below or on the Youtube comments section.

Regards. Stefan.

[TinselKoala]

Nicely done. It's too bad the results weren't better, though. We haven't heard from Lawrence in some time, I hope he's doing well.

It would be nice to understand why his results are so different from yours, on the same board.

[SeaMonkey]

Somehow a tendency has developed in many
explanations to refer to the Current Measurement
Resistor as the "shunt" resistor.

As the resistor is a series resistor within the
circuit, whose purpose is to "convert" current
into voltage for ease of measurement with a
high impedance VoltMeter, there is potential
for great confusion amongst any Newbs who may
be watching and soaking up the technical
jargon (to be repeated endlessly.)

The Current Measurement Resistor is only a
"shunt" (or parallel connected resistor) with
respect to the meter which connects across
the resistor to display the voltage drop.

The "shunt" resistor and the VoltMeter together
make up a milliAmmeter device which is series
connected within the circuit of interest.

Hopefully all who demonstrate the technique
will take pains to clarify the proper relationship.

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