Joule Thief 101

[MileHigh]

Okay the analogy is fine.  Using gravity and Mgh is a little bit less intuitive than the analogy I normally think of.

If the mass is horizontal and on a frictionless surface and connected to a spring is the analogy that I prefer.  Then the energy in the moving mass and energy in the displacement of the spring are in perfect quadrature.  Depending on how you view the variables, the mass is the capacitor and the spring is the inductor, or vice-versa.

MileHigh

[MileHigh]

Magluvin:

You notice that at 655 kHz you can start to see sloping edges for the rise and fall of the LED voltage.  So you are really pushing up the frequency there.  At very high frequencies the whole switching setup will start to get "sloppy" and get over affected by parasitic capacitance in the circuit.

The glitch on the battery voltage may or may not be there.  It could be due to coupling between the two channels.  I suggest that you do a low trigger on the battery voltage glitch and then disconnect the channel connected to the LED voltage and see what happens.  It's possible that the glitch will remain the same, or get very attenuated and you might lose trigger, or it might disappear completely.  You figure looking at the battery voltage alone will give you a "cleaner" view of it.

MileHigh

[tinman]

 author=MileHigh link=topic=8341.msg474187#msg474187 date=1455549610


MileHigh

All that you are really doing is baiting and switching yourself in a case like this.  You were playing around with Joule Thief circuits and you stumbled across the "Cool Joule" circuit and decided for yourself that it was a "Joule Thief."  It simply does not work like that.

It works exactly like that MH,and i have explained to you before that a JT circuit is !not! MHs choice of circuit,but is a circuit that can extract the remaining energy from an otherwise dead battery-->did you not read the wikipedia link i provided ?.

No, they are not Joule Thief circuits because it looks almost certain that they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery that has a low voltage-high impedance output.

Please define !performance! MH. Lots of light output with a heavy drain on the battery-short run time--or, less light output,lighter drain on the battery,but longer run time?. Are you now going to set the parameters on how a joule thief should operate as well ?

Neither did you make any attempt at all to explain how your circuit worked.  That's not electronics Brad, it's just show and tell and don't explain.  As TK said many times and I echoed him, you are not doing an experiment, your are just observing and nothing more than that.

I told MarkE how the circuit was able to function,and he too did not believe me at the start,but then figured out for him self that it did indeed operate as i stated. But one more time for you MH-->it works due to the miller capacitance effect-->the C in LRC MH.

Those circuits that you see in the clips and the circuit schematic that you posted are simple oscillators based on amplification and feedback.Since the transistor is firing you take advantage of that to energize an inductor and light an LED.

And your JT circuit works different how?.

You guys are blindly saying there is no coupling between one coil and the other coil.  Well, I hate to tell you this but there is some kind of coupling taking place somewhere to get the positive feedback oscillation going.  It could be inductive, it could be capacitive,

Yes,the C in LRC MH.

Perhaps the biggest issue is that you yourself have no clue exactly how and why the circuit is oscillating.  It's not necessarily easy either because sometimes just putting a scope probe on the circuit may stop the oscillation.  This is just a "black box" show and tell and you don't know what's inside the black box.

Well thats incorrect MH,as i have stated many times how the circuit operates-and again just above.

But going back to the standard Joule Thief, I believe that when the battery is even below the switch-on voltage for the base-emitter diode in the transistor, the Joule Thief can still operate and keep switching on the transistor.  That's because the "primary" side of the transformer can still boost the battery voltage before it gets to the transistor base resistor.  The "Cool Joule" is nothing more than an oscillator that takes advantage of the transistor switching to do the old coil-light-an-LED trick, but there are no extra tricks to keep it running when the battery voltage gets very low.  So it's not a Joule Thief because it does not do anything special to extract energy from a very-low-voltage battery.

When the correct coils are used,the cool joule can keep running with battery voltages as low as 200mV. It dose this in the very same way !your! JT circuit dose. Look again at the two circuits below MH--are the circuit's any different ?-other than the absence of the 1k resistor and core ?

You are not going there Brad.  You have been fully aware of what the standard Joule Thief circuit is for years and you are fully aware that that's exactly what I have been talking about.
It is absolutely NOT an LRC circuit.  There isn't even a capacitor in the schematic and if hypothetically you could somehow remove all of the stray/parasitic capacitance in the circuit the standard Joule Thief would still operate perfectly.  Time to get real and stop this nonsense talk.

Once again MH,a joule thief is not one circuit,but any circuit designed to drain the remaining energy from what otherwise would be considered a dead battery. There is !no! one MH JT circuit,just the same as there is !no! one vehicle designed to transport people.
As i have stated before,there is two capacitance values in your JT circuit. 1 being the capacitance between the two winding's,and even though small,it dose have an effect on a circuit that operates at these low voltages and high frequencies. Take !your! JT circuit,and get it up and running. Now ,place a 1 or 2 pF cap across the two winding's,and see how that effects the running of the circuit.
And then there is the capacitance within the transistor it self.
Quote: In electrical circuits, parasitic capacitance, or stray capacitance is an unavoidable and usually unwanted capacitance that exists between the parts of an electronic component or circuit simply because of their proximity to each other. All actual circuit elements such as inductors, diodes, and transistors have internal capacitance, which can cause their behavior to depart from that of 'ideal' circuit elements. Additionally, there is always non-zero capacitance between any two conductors; this can be significant at higher frequencies with closely spaced conductors.
So you see MH,you are wrong when you say that the JT is not an LRC circuit,as every circuit has some C value. We do not operate within perfect conditions here MH,we operate in reality-as do our circuit's. This small C value starts to play a big part when in higher frequency ranges such as Mags is at now. Your ideal conditions do not exist in these circuit's MH-->and you know this.

It is funny to watch you pick and choose,as we go along in these threads. One time you insist that the extremely small inductance found within an incandescent bulb running on 60hZ AC can have an effect on the operation of a circuit,and yet here you dismiss the small C value that exist in your JT circuit .  You cant have it both way's MH,and pick and choose what values you wish to include-when you want to include them. You either have to be accurate all the time,or dismiss these small values all the time-->you just cant pick and choose as it suit's you-as you seem to do many times.

It is also funny how you constantly insist that the experimenters here test and understand what they are seeing with there circuits operation. What i have seen in this thread alone,is Smokey and Mag's doing all the research,building,testing,and presenting there findings from years of this,while you sit in your armchair,rocking back and forth,and deciding whether or not they are correct. It's almost like you are flipping a penny-heads there right,tails there wrong. Your beloved electrical theory itself tells you that there is a C value in all these circuit's,and still the coin falls tail up for you. . Even whan i present !your! JT circuit functioning from the C value of the transistor alone,you still insist that the JT circuit is not an RLC circuit.

I would be interested in seeing what capacitance Mags measures between his two windings on his JT,and then set it into operation,and place a cap of that value across the two windings,and see how much it effects the operation of the circuit.

Brad

[Pirate88179]

Interesting that the fellow that started this topic is named Resonance Man.

Just an observation.

Bill

[allcanadian]

@tinman

It is funny to watch you pick and choose,as we go along in these threads. One time you insist that the extremely small inductance found within an incandescent bulb running on 60hZ AC can have an effect on the operation of a circuit,and yet here you dismiss the small C value that exist in your JT circuit [/size].  You cant have it both way's MH,and pick and choose what values you wish to include-when you want to include them. You either have to be accurate all the time,or dismiss these small values all the time-->you just cant pick and choose as it suit's you-as you seem to do many times.

Strange isn't it tinman?, do you see the trend here in the forums as more and more people catch on?. I think it scares the hell out of people like MH and when it does catch it will be a shit storm of epic proportions. Just around the corner MH... it's just around the corner and when Pandora comes there is no closing that box, she's wide open.


AC