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Author Topic: Joule Thief 101  (Read 926712 times)

MileHigh

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Re: Joule Thief 101
« Reply #420 on: February 22, 2016, 04:10:26 AM »
As expected

Was it good?

I found the posting and am looking at it.  #337 right?  Don't get too excited.

MileHigh

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Re: Joule Thief 101
« Reply #421 on: February 22, 2016, 04:36:02 AM »
Brad's posting #337:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>

As can be seen in the scope shot below,all of the flyback energy in L1 is dissipated before the transistor once again switches on. This is because the flyback energy from L1 is what is pulling the base of the transistor down(keeping it off).

You continually ignore the junction capacitance of the transistor MH,and this is why you cannot understand as to how the circuit actually work's. Current flows through L2 before any current flows through L1, so L2 is the coil that starts to create the magnetic field within the toroid core first-not L1. Current can flow in L2 before the emitter/collector junction starts to open,due to the junction capacitance in the transistor. This in turn creates a voltage potential in L1 that is opposite that to L2,and add's to the voltage being supplied to the base of the transistor via the base/collector junction capacitor/capacitance. Although very small in capacity,it is enough to get the emitter/collector junction to start to open. Once this happen's,then a stronger magnetic field starts to build in the toroid. Now you start to get your transformer action between L1 and L2,and this then starts to pull the transistor on hard. The magnetic field builds to a point where the available current can no longer keep the magnetic field amplitude rising,or the core reaches a point of saturation,and the induced current in L2 stop's. The magnetic field begins to collapse due to the transistor no longer receiving enough current,and begins to switch off. As the magnetic field is now decreasing in strength,a reverse current flow is produced in L2,and this pulls the transistor hard off--as can be seen in the scope shot below.Some of this stored energy in L1 is used to drive the LED,and the rest is used to pull the transistor down/off. Once all the stored energy in L1 has been depleted,and no longer can hold the transistor off,the cycle starts all over again.

This is why your JT circuit is not very efficient MH,as most of the stored energy in the magnetic field that we want to use to drive the LED, is fighting against the energy being supplied by the battery ,to keep the transistor switched off. So the battery is trying to switch the transistor on,and the flyback energy is trying to keep the transistor switch off. This is why i like to use circuit's that disconnect the battery during the flyback part of the cycle.


Brad.

MileHigh

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Re: Joule Thief 101
« Reply #422 on: February 22, 2016, 05:34:07 AM »
In your original post #337, you don't actually identify it as "your" explanation of how the Joule Thief operates at low voltage, you just seamlessly transition into it.  And I did read it.

I'm not sure if your scope shot is for the standard Joule Thief running at 500 mV with a 1K resistor, or, to get it to run you tweaked the base resistor down really low.   Because for your comment about your scope captures in the next posting you made, #338, is the following comment:

Quote
Because MH,the pot was turned right down to it's lowest resistance,so it would make no difference to which side the scope probe was on.

I have no idea what the base resistance is for your original post #337 but I will push on.  The ideal case is to have a standard Joule Thief circuit running at a normal frequency, and then observe as the frequency jumps up and the waveforms change at very low voltages - without changing the base resistor value or anything else about the Joule Thief.

Quote
You continually ignore the junction capacitance of the transistor MH,and this is why you cannot understand as to how the circuit actually work's. Current flows through L2 before any current flows through L1, so L2 is the coil that starts to create the magnetic field within the toroid core first-not L1. Current can flow in L2 before the emitter/collector junction starts to open,due to the junction capacitance in the transistor. This in turn creates a voltage potential in L1 that is opposite that to L2,and add's to the voltage being supplied to the base of the transistor via the base/collector junction capacitor/capacitance. Although very small in capacity,it is enough to get the emitter/collector junction to start to open. Once this happen's,then a stronger magnetic field starts to build in the toroid. Now you start to get your transformer action between L1 and L2,and this then starts to pull the transistor on hard. The magnetic field builds to a point where the available current can no longer keep the magnetic field amplitude rising,or the core reaches a point of saturation,and the induced current in L2 stop's. The magnetic field begins to collapse due to the transistor no longer receiving enough current,and begins to switch off. As the magnetic field is now decreasing in strength,a reverse current flow is produced in L2,and this pulls the transistor hard off--as can be seen in the scope shot below.Some of this stored energy in L1 is used to drive the LED,and the rest is used to pull the transistor down/off. Once all the stored energy in L1 has been depleted,and no longer can hold the transistor off,the cycle starts all over again.

This sounds plausible but it didn't come from you.  You have probably been hunting around a long time for information on Joule Thieves, and in one of your links you found a good technical article that described how a Joule Thief operates at low voltages and basically copied that information and wrote it into your posting.  Is that a fair assessment?

What you did not tie into all of this is the explanation for the high frequencies but it is probably there in the article.  If the very short transistor on and off times and short discharge pulses of the coil are because of small amounts of charge stored in the internal capacitors of the transistor, then I suppose the roughly one microsecond transistor-off-time/coil-discharge-times may make sense.

Without that article, you would be lost for a description and lost on the bench.  Without that article I would have to be on the bench for a very long time while I simultaneously reviewed transistor small signal and low voltage and transient behaviour.  I would have had to work on it myself, and if I found the same article that you found it would have helped me out tremendously.  Even without the article this would probably be child's play for people like Verpies and Picowatt.

So I missed your copy/paste because you didn't identify it outright.  I simply told you I wasn't going to discuss it because I was talking about a Joule Thief in normal operating mode at that point.

In the scope capture there appears to be an issue with the causality that I can't explain.  I think the transistor should still switch off before we see the voltage spike but I am not sure.  The scope probe placement issue may be a factor there.

MileHigh

MileHigh

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Re: Joule Thief 101
« Reply #423 on: February 22, 2016, 06:02:40 AM »
Brad:

Quote
just like you refused to give me any specifications of the components in the JT circuit you wanted me to explain.  Like i said MH--it cant be done without these specifications. For example-if i make up a circuit,and use a set length of wire for each coil, and use a ferrite toroid,then the JT will oscillate at a certain frequency. If i do nothing other than change the ferrite torroid out for a steel laminated torroid(while everything else remains the same) then the frequency would drop by over 1000 %.

nor that stupid and incomplete question you asked EMJ. You try and trap people like this all the time MH--but they are all waking up to you.

As you could see in your no-link hidden copy/paste about the operation of a Joule Thief circuit at lower voltages, you can indeed fully describe the operation of a circuit without having to have component values.  This concept is freaking you out because it is outside your realm of experience and your way of thinking or capacity of thinking with respect to electronics.  The reality is that it's done all the time and it's the normal way that people describe the operation of a circuit.

You are really hung up on the EMJ question and accusing me of it being incomplete which of course is ridiculous again because I never even said what the question was.

Do you want to get the question so you can try to answer it?  You seem to be chomping at the bit so I can give it to you if you want it.

MileHigh

tinman

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Re: Joule Thief 101
« Reply #424 on: February 22, 2016, 06:38:40 AM »
In your original post #337, you don't actually identify it as "your" explanation of how the Joule Thief operates at low voltage, you just seamlessly transition into it.  And I did read it.

I'm not sure if your scope shot is for the standard Joule Thief running at 500 mV with a 1K resistor, or, to get it to run you tweaked the base resistor down really low.   Because for your comment about your scope captures in the next posting you made, #338, is the following comment:

I have no idea what the base resistance is for your original post #337 but I will push on.  The ideal case is to have a standard Joule Thief circuit running at a normal frequency, and then observe as the frequency jumps up and the waveforms change at very low voltages - without changing the base resistor value or anything else about the Joule Thief.



What you did not tie into all of this is the explanation for the high frequencies but it is probably there in the article.  If the very short transistor on and off times and short discharge pulses of the coil are because of small amounts of charge stored in the internal capacitors of the transistor, then I suppose the roughly one microsecond transistor-off-time/coil-discharge-times may make sense.

Without that article, you would be lost for a description and lost on the bench.  Without that article I would have to be on the bench for a very long time while I simultaneously reviewed transistor small signal and low voltage and transient behaviour.  I would have had to work on it myself, and if I found the same article that you found it would have helped me out tremendously.  Even without the article this would probably be child's play for people like Verpies and Picowatt.

So I missed your copy/paste because you didn't identify it outright.  I simply told you I wasn't going to discuss it because I was talking about a Joule Thief in normal operating mode at that point.

In the scope capture there appears to be an issue with the causality that I can't explain.  I think the transistor should still switch off before we see the voltage spike but I am not sure.  The scope probe placement issue may be a factor there.

MileHigh

Quote
This sounds plausible but it didn't come from you.  You have probably been hunting around a long time for information on Joule Thieves, and in one of your links you found a good technical article that described how a Joule Thief operates at low voltages and basically copied that information and wrote it into your posting.  Is that a fair assessment?

This most certainly dose come from me MH,and is !!!NOT!!! a copy or paste,or re-edit from any other article.
Now that you can see that i do have an amount of sound knowledge ,and know what im talking about,you revert to your next tactic--trying to discredit the experimenter.
I have told you time and time again--i have had good teacher's,like Vortex1,Poynt-etc. I then take what i have learned,and apply it to devices that !do! work based around what i have been taught.

So dont try your crap with me MH. I had the balls to post what i knew,while you just say--im not even going to try and work it out.
I have put you in your place once again MH,and you need to suck it up princess.

And your welcome.


Brad

tinman

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Re: Joule Thief 101
« Reply #425 on: February 22, 2016, 06:48:23 AM »
Brad:





Do you want to get the question so you can try to answer it?  You seem to be chomping at the bit so I can give it to you if you want it.

MileHigh

Quote
As you could see in your no-link hidden copy/paste about the operation of a Joule Thief circuit at lower voltages, you can indeed fully describe the operation of a circuit without having to have component values.  This concept is freaking you out because it is outside your realm of experience and your way of thinking or capacity of thinking with respect to electronics.  The reality is that it's done all the time and it's the normal way that people describe the operation of a circuit.

Go find that copy and paste article MH--you wont,because it came from me.
You are a sore looser-and that's is very evident here.
I wipped your ass,and you did not think i could, But now you know i can,you resort to some other type of discrediting tactic's.
EPIC fail MH--and here for everyone to see.
I bet you had it planed all along--the backup plan just in case i came good on the explanation--which you did not expect.
You didnt even have the balls to have a go your self,and the reason for that is--you just do not understand your self how it works-->facts MH,fact's.

You only have the ability to go by the book's,and when things are outside that realm,you fail--and fail badly-->as you have done on this thread.

Quote
You are really hung up on the EMJ question and accusing me of it being incomplete which of course is ridiculous again because I never even said what the question was.

Bullshit
It;s posted on this thread--another fail MH
A question even your self cannot anser. You know you have fell in your own hole,and now it's that deep,you cant get out.
Facts MH,facts


Brad

sm0ky2

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Re: Joule Thief 101
« Reply #426 on: February 22, 2016, 06:51:47 AM »

I'm not sure if your scope shot is for the standard Joule Thief running at 500 mV with a 1K resistor, or,...
MileHigh

when this started, we used 100 Ohm (standard),  at what point did this become 1k Ohms?
JT's can be used with virtually any range of base resistor (depending upon the transistor used)

This is the problem with trying to claim a "standard" circuit.
Once you define this you eliminate all other Joule Thief circuits created before or after the one you specifically reference.

You are still missing the point that Armstrong's equations still hold true , REGARDLESS of what components you choose!!

MileHigh

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Re: Joule Thief 101
« Reply #427 on: February 22, 2016, 06:56:22 AM »
Not a chance.  It's more like you were too immature to just tell me which posting and likewise you are too immature to admit that it's just a paste from somewhere else.  It's just like when you are challenged about Joule Thief operating voltages and your fake response is to say "Everybody is only interested in Joule Thieves operating at lower voltages."  It's a pattern.  It's Brad's continuous BS on the fly to make it look like you are never wrong - which is extremely immature.

MileHigh

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Re: Joule Thief 101
« Reply #428 on: February 22, 2016, 06:59:49 AM »
Quote
You are still missing the point that Armstrong's equations still hold true

What's the dance floor about?  That's what I want to know.

sm0ky2

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Re: Joule Thief 101
« Reply #429 on: February 22, 2016, 07:27:31 AM »
What's the dance floor about?  That's what I want to know.

Well, you see....

when you are out on the dance floor, surrounded by Trons and Hoes...

It doesn't really matter what your theory is,
the fact that you bothered to participate Is all that is necessary to get laid...

tinman

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Re: Joule Thief 101
« Reply #430 on: February 22, 2016, 07:36:01 AM »
 author=MileHigh link=topic=8341.msg475158#msg475158 date=1456117360]
Brad:






MileHigh


Quote
You are really hung up on the EMJ question and accusing me of it being incomplete which of course is ridiculous again because I never even said what the question was.

Post 389 Quote MH:  I called his bluff and asked him how a circuit worked that consisted of only two components, a voltage source and a coil, and was unable to answer the question after he was talking about coils for months.


Brad

tinman

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Re: Joule Thief 101
« Reply #431 on: February 22, 2016, 08:16:55 AM »
Not a chance.  It's more like you were too immature to just tell me which posting and likewise you are too immature to admit that it's just a paste from somewhere else.  It's just like when you are challenged about Joule Thief operating voltages and your fake response is to say "Everybody is only interested in Joule Thieves operating at lower voltages."  It's a pattern.  It's Brad's continuous BS on the fly to make it look like you are never wrong - which is extremely immature.

Face it MH--you got smoked.
I did what you were no expecting me to be able to do--something you yourself couldnt explain.
My info and teachings come from all sorts of source MH--not just the book's.
Now we see you trying to save face,and say i just did a copy and paste job lol.
Trying to divert your losses by way if trying to discredit the experimenter. We all know you will not find any papers or links that show i did that,and all the evidence will indeed point toward my learnings from real EE guy's here and at OUR.

You see MH,i post the truth,and you post garbage. I have freely admited that i had no idea as to how the cool joule circuit was running without that inductive coupling between L1 and L2. But after some great debate on the OUR thread nearly 3 years ago,Vortex1 came up with the answer,and from that answer i have learned. Along with additional information found in many places,we can put all this knowledge together,and get circuits to work based around that information--we learn MH ;)
You were not even going to give it a go--and i did-and i got it right-->much to your shock.
Always expect the unexpected MH,as you have seen here-it can bite you on the ass.

You made the mistake MH, that i could not possibly learn that fast,and now you know different. Now you go to plan B,because you do not like to be out done by some amateur benchtop experimenter. Now your next angle is to try and discredit the experimenter,as loosing to him is not on your acceptable list. Your angle here on this thread alone,has become quite evident.

Thank's-but no thank's MH


Brad

Magluvin

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Re: Joule Thief 101
« Reply #432 on: February 22, 2016, 10:30:19 AM »
Here is a circuit from Lasersaber that seems to use the 'capacitance' between the 2 windings to complete the base trigger circuit. lrC anyone? ;)

Mags

MileHigh

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Re: Joule Thief 101
« Reply #433 on: February 22, 2016, 12:23:20 PM »
Brad:

My objective on here was to discuss how a Joule Thief normally operates because a lot of incorrect information was being given.  That has been successfully done.  During the battle over that subject you talked a lot of whackadoo nonsense at times.  You said all of the online references were wrong.  You even were parroting the transistor junction capacitance stuff over into the discussion about the Joule Thief in normal operating mode because at first you were failing to distinguish between the two modes.  The use of language in that paragraph is totally different from the style and cadence of how you normally compose text.

In post #157 you said this:

Quote
Set up a bifilar coil with a steel laminated core,where the core is two separate halves -1 half will see the flow of charge into the magnetic center,and the other half will see the flow of charge out from the magnetic center. Set up a simple self oscillating circuit,and run the LED off the two core halves,where you two core halves act like capacitor plates,and are charged every pulse. this way you can bring your frequency up to a resonant state,where the amplitude is at maximum,and power draw at a minimum.

That's a typical "Brad from Planet Bizarro" posting.  So you can't just go from your typical puzzling and awkward technical prose to a decent discussion of transistor modeling at low voltages with internal capacitance coupling like some magical Mr. Hyde to Dr. Jekyll transformation.

That discussion from somewhere else that you posted sounded quite credible but you never "wrapped it up and made it whole" and discussed a full oscillation cycle from start to end.  You never made reference to how the operating frequency was determined.  So my instincts are telling me the parroting got you close, but not quite all the way there.

Your post #430 is another one of those "shaking my head" moments and that would apply equally to all of the readers of the thread also.  Just another jaw-dropping moment.

Finally, Magluvin posted another Joule Thief schematic that was taken from a posted pdf from the early days in this very thread and I am reposting it here.  What a shocker eh?  They list the battery voltage as having a range of 0.3 volts to 1.5 volts.  It makes all of your whining and pleading that "Everybody wants to use a Joule Thief at low voltages only!" to justify your bullshit to try to make yourself infallible look laughable.

Your low-voltage discussion that came from who knows where might be credible, I am not sure.  I wasn't here for that, I just wanted to go over how a Joule Thief normally operates.  And what a slog that was with all of the battling and baiting and switching, most of it simply ridiculous stuff to keep the imaginary halo over your head.  In the end you stopped challenging me and you agree with the basic pulse circuit operation with the positive-feedback regenerative switching that makes the thing oscillate at an operating frequency, not a resonant frequency.

MileHigh

MileHigh

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Re: Joule Thief 101
« Reply #434 on: February 22, 2016, 12:35:35 PM »
Here is a circuit from Lasersaber that seems to use the 'capacitance' between the 2 windings to complete the base trigger circuit. lrC anyone? ;)

Mags

No kidding, it looks like a circuit that may have been purpose-designed-and-built to use "capacitance."

You can claim that cars have four wheels and I can "get you" by posting pictures of cars that have been purpose-designed-and-built with three wheels.  ;)