Joule Thief

[jeanna]

@lady jeanna

If you read the @mk1 explanation on the posted graphic composition. He says that every time he changes the JT number of turns he also tune the base resitor, usually using a 1k pot trying tp get the highest voltage on the voltmeter. Keeping the voltage data and resistance at the base by checking the resistance used by the pot in the circuit.

Then my qestion is how do I check the resistance used by the pot in the circuit?

Jesus

@Jesus,
I think what he means by this is that he changes the resistance until he gets the highest rectified voltage from the secondary. Then he pulls out the battery and checks what the resistance is that he has just turned the pot to, then he writes it down and then puts it all back together and takes the next step.

I have not yet been able to make myself take all those steps. I am sure he is right and I should.
For now, My MK1 and MK2 remain un-tuned.

I just used the same numbers of winds that he used and saw that the way he makes these MK's is far better than anything I have made in all the other ways I have tried.
Even untuned, these are way better.

If I have still not answered your question, please try again.

@the NOP

then your scope know on what scale you are on, so the values are always displayed accordingly.
i just wanted to make sure.

I have a button for x1 and x10. It toggles between the 2 levels. It reads volts as though it knew, but it does not. I need to divide by 10 when I am on the x10 level unless the probe switch is also switched.
I am sure you have a better understanding than I have.
For now, I am muddling through. I am looking at the "pretty" wave forms, but do not really know what I am seeing. Like a child, I think.

thanks for your help,

jeanna

@theNOP,
I object. If you use ohms law you are making assumptions that may keep you from finding the truth.
Measurement is the only way for an experimenter.
MHO

jeanna

[nievesoliveras]

@jesus

A pot has 3 leg , you will need to use leg 1 and 2 or 2 and 3 , you can test any pot for overall value between leg 1 and 3 , now if you use 1 and 2 take the resistance reading between 1and 2 , if you use 2 and 3 then check resistance between those two.

You find first the spot where the voltage for the pickup coil is at his highest .


Mark

the best way is to take it out of the circuit then measure it.

an other way is to go with ohms law, but the spikes might get in the way.
R = V / I

Thank you @mk1,  thank you @thenop.

Jesus

[nievesoliveras]

Thank you @jeanna

Jesus

[TheNOP]

I have a button for x1 and x10. It toggles between the 2 levels. It reads volts as though it knew, but it does not. I need to divide by 10 when I am on the x10 level unless the probe switch is also switched.

that is what i meant, and it show you also understand what is happening.

your scope don't know when the probe is at 1x nor when it is at 10x unless you tell it to your scope.
or it has an other 10 times divider in series with your probe at the push on a button.

meanning the 10x button is either to tell the scope the probe is set at 10x, or it is an other 9 meg ohms resistor in series with the 1 meg or 9 meg resistor of the probe.

that is why xee2 asked you to test with a know fixed supply.

I object. If you use ohms law you are making assumptions that may keep you from finding the truth.
Measurement is the only way for an experimenter.
MHO

i make no assomptions when using ohms law, voltage and currents are also measurements.
all depend on the accuracy of those measurements.
that is why i sayed "the best way is to remove then measure the resistance" 

i perfectly know that Ohms law does not hold all the time, that it is a law of specific case.
but in the case of the above measurements, the way they are done, it does apply.

[jeanna]

OK theNOP or xee2 or other scopies,

I have another question about where to put probes. I have this circuit. It is a complicated loop going from the second tier toroidal secondary through its own toroid and around to the first tier secondary. This has 2 spots with leds brightly shining all in parallel with each other.  I just put the probes on the second tier secondary and the orphaned wire that is connected to one parallel array of leds. I read 4.11 volts.
I did not disconnect anything so like a dmm, it was reading across the ... whole thing from one end of the secondary to one wire of the toroid the secondary is wrapped around. I get the same number if I put the probe on the positive incoming wire of the first tier secondary. 

My question is, if this is a kosher way to measure with a scope. I got a waveform that is very complex and repeats, but I am not sure.
I think it is reading the whole second tier along with the secondary from the first tier. of course there are also 8 leds in there that I did not remove.

I am comparing this to how you measure across a resistor. Everything is connected as is and undisturbed.

thank you,

jeanna

This schematic may help.