Joule Thief 101

[tinman]

No Brad, the test points are ambiguous.  I don't see a definitive ground connection.  I don't see any probe colours matching the scope channel colours like I am used to seeing before.

Here is the bloody point:  Every time I look at a scope capture with a provided schematic from you I don't want to have to play a guessing game and spend 90 seconds figuring out what is what.  I don't give a damn if you say it is "obvious."  It is pretty straightforward in this case but I still don't give a damn.  It's a pain in the ass.

I literally just saw the text "CVR 1 trace" in the upper right quadrant of the image after staring at the image about 20 times.

You took the trouble to stitch together your scope capture with the schematic using an image editing program.  You couldn't be bothered to spend just one minute while you were in the image editing program to label where the scope channel was connected in a clear and unambiguous manner.

Look at the attached image.  I updated your graphic.  I can look at that graphic and in 1/2 second I see exactly what is going on, no muss, no fuss, no bullshit looking at "options."

Well im so sorry MH,i did not know just how dyslexic you are,and you need spoon feeding with every single diagram,because you are just too stupid to know that the black marker indicatse  scope ground,the yellow marker indicates the yellow channel on the scope,and the blue marker indicates the blue channel on the scope.

Even when i write  in large capital letters on the diagram,exactly what the scope shot is showing-you still get lost.
It is not my fault you have trouble reading very clear explanations  as to what the scope shot is showing.
It is clear that when you have nothing to complain about,you just make crap up.

Grow up you whining little child.


Brad

[tinman]

Below is a graph showing some test results of various toroid inductors tested on the same JT circuit,along with the straight DC power mark to gain 200 LUX from the LED array.

Circuit used also pictured below.


Brad

[T-1000]

Below is a graph showing some test results of various toroid inductors tested on the same JT circuit,along with the straight DC power mark to gain 200 LUX from the LED array.

Circuit used also pictured below.


Brad

Ooo, the magnetic material mixed in the core!
So the cats are out of the bag, good luck with maximising output power from mixed cores.

[MileHigh]

Well im so sorry MH,i did not know just how dyslexic you are,and you need spoon feeding with every single diagram,because you are just too stupid to know that the black marker indicatse  scope ground,the yellow marker indicates the yellow channel on the scope,and the blue marker indicates the blue channel on the scope.

Even when i write  in large capital letters on the diagram,exactly what the scope shot is showing-you still get lost.
It is not my fault you have trouble reading very clear explanations  as to what the scope shot is showing.
It is clear that when you have nothing to complain about,you just make crap up.

Grow up you whining little child.

Brad

But you were embarrassed when you put up a scope capture and were too lazy to put up the schematic and Picowatt told you he couldn't make head or tail of your scope capture, weren't you?  You avoided my question.

Stop acting like a stupid semi-literate oaf when it comes to your communication skills for presenting scope capture data and schematics.  There is no bloody yellow marker on the schematic, there is an orange marker.  Or do you have male colour vision deficiency perhaps and could not tell?

Just get your act together and expend the minimal effort required to present your data properly.

For example, the chart that you just did for the milliwatts in and Lux out for different cores is very good.  But then why would you only plot a single point for the straight DC mark for 200 Lux?  Don't you think your audience would be interested in seeing you plot another five or six points so they could see what the straight DC curve is like?  Because I can assure you they would.  Are you plotting the power to the whole Joule Thief circuit, or are you only plotting the power that is delivered to the LED array itself?  We don't know because you are too lazy to tell us or you lack the communication skills to realize that you should be telling us.  We certainly can't tell from the schematic because there are no test points on it.

[TinselKoala]

Brad, your graph is kind of hard to interpret, because your grid lines don't line up with the axis number values. But going just by the positions of the numbers, it looks like your DC-equivalent value is indicating about 200 Lux at an input power of 20 mW, which translates to a whopping 10000 Lux/Watt.  But in my setup, using the superefficient LED that I've been using all the time, to get 200 Lux at the sensor in my 5x5x18 inch lightbox I have to drive the LED at around 81 mA, 2.96V, which is about 240 mW, and is near the top end of its rating. This corresponds to about 830 Lux/Watt.  For any length of time running this would need a heatsink on the LED. These are just about the most efficient LEDs on the market.

So it seems that there must be something funny about the numbers, either yours or mine, because they are clearly not comparable. Are you using an 18 inch lightbox? How are your 9 LEDs connected, and what kind are they? How are you measuring voltage and current in the DC case?

I have some confidence in my measurements because, as I indicated before, I developed this apparatus and methodology for comparison with values that another lab was getting in some tests we both were running.

I can get around a 200 Lux reading by holding my LED at 4-5 inches distance to the lightmeter sensor and providing about 7.5 mW (3 mA at 2.54 V).