Joule Thief

[PaulLowrance]

Like I said, there's something wrong with gadgetmalls meter readings. That kind of Fluke meter (e.g., Fluke model 27) has ~ 5.6 ohms input resistance in mA current mode, not 100 ohms.

If you get bad measurements then put it on the scope. All I see is something definitely wrong with the measurements. The scope will always save the day.

[jeanna]

... this appears as a unique JT . unlike any i have made before ..
................ i tried to make a copy of it using the exact same parts last night  .it will not do the same as that  one ? the only difference is parts placement .  I do not get more out than in on the exact replication of my own design . The problem is...
Gadget

Hi Gadget,
There is another difference that I can see.

In the one you sent out I see a 12 or maybe 11 turn inductor wire which appears to be coming out of the toroid.

Did you "clean this up?"
I do not see it on the new one.
I believe this would add significantly to the output of your circuit even if it is not on the secondary, wherever it is if it is getting pulses, it is converting them to higher volts.

I am referring to the tight spiral on the upper right of pic 1 and I see no such thing on the pic2 same but different one.

jeanna

[MrMag]

Like I said, there's something wrong with gadgetmalls meter readings. That kind of Fluke meter (e.g., Fluke model 27) has ~ 5.6 ohms input resistance in mA current mode, not 100 ohms.

If you get bad measurements then put it on the scope. All I see is something definitely wrong with the measurements. The scope will always save the day.

Agreed.

Also, I know a lot of people don't agree with me that the secondary should have a load on it to take measurements. It's like Xee's post showing that you need to put a load on a battery to actually test it. The secondary winding falls under the same category.

[jeanna]

Agreed.

Also, I know a lot of people don't agree with me that the secondary should have a load on it to take measurements

The reason I do not agree with that for measuring anything on the primary, is that empirically  the amps draw diminishes when there is a load put on the secondary.

And I do agree that the scope is the way to know what is happening.
thank you,

jeanna

[PaulLowrance]

Agreed.

Also, I know a lot of people don't agree with me that the secondary should have a load on it to take measurements. It's like Xee's post showing that you need to put a load on a battery to actually test it. The secondary winding falls under the same category.

That's a good point, there should be a proper load, or use the scope. Don't dump the toroid energy into the poor meter.  Who knows what issues that will cause. The Fluke meter gives maximum voltage* for the mA current mode, and also significant spikes might cause error readings. Put the bcap0650 on the output. It can be charged to say 1.3 volts.

Otherwise get that beautiful scope out!