Author Topic: Joule Thief 101 (Read 938601 times)

Magluvin · « **Reply #495 on:** February 27, 2016, 11:30:03 PM »

Quote from: TinselKoala on February 27, 2016, 10:32:35 PM

http://www.ktvn.com/story/31260413/13-year-old-creates-energy-harvesting-device

Watch the video.

Comments?

Thats and impressive demo lighting those 12v led strips, of which I have 3 rolls of here. The strips have current limiting resistors between every few leds, like say 3 for blue or white in series with a resistor.

if it is radio freq he is absorbing, looks maybe am. Or possibly 60hz? Fm wouldnt have coils like that I think.

Thanks for posting.

Mags

Magluvin · « **Reply #496 on:** February 27, 2016, 11:32:48 PM »

Quote from: Magluvin on February 27, 2016, 11:30:03 PM

Thats and impressive demo lighting those 12v led strips, of which I have 3 rolls of here. The strips have current limiting resistors between every few leds, like say 3 for blue or white in series with a resistor.

if it is radio freq he is absorbing, looks maybe am. Or possibly 60hz? Fm wouldnt have coils like that I think.

Thanks for posting.

Mags

In fact, that looks like enough to power a cell phone, according to the strip around his brother there. Might not be 2A like many newer chargers, but could charge probably slow charge one from what I know.

Mags

Nink · « **Reply #497 on:** February 27, 2016, 11:36:12 PM »

Quote from: Magluvin on February 27, 2016, 11:32:48 PM

In fact, that looks like enough to power a cell phone, according to the strip around his brother there. Might not be 2A like many newer chargers, but could charge probably slow charge one from what I know.

Mags

They did not say what was in the coffee can in addition to the rectifier. My guess is a capacitor that was charged over an extended period of time and then discharged in order to power the LED's. A little bit of a party trick but not exactly a lie the LED's were being powered by harvested energy.

MileHigh · « **Reply #498 on:** February 27, 2016, 11:48:28 PM »

He should go beat up Clock Boy and then sail off in a balloon.

gyulasun · « **Reply #499 on:** February 28, 2016, 12:13:47 AM »

Quote from: tinman on February 27, 2016, 07:38:51 AM

Self charging JT

https://www.youtube.com/watch?v=tx3bpSKRuF0

Brad

Hi Brad,

From your video it seems the variable capacitor is not used for tuning the main coil on the ferrite rod antenna: I think you would pick-up more power from the AM radio station by resonating that coil at the 963 kHz (or so) AM broadcast frequency.

Also, the direction or orientation of the ferrite rod with respect to the location of the AM transmitter also counts in the amplitude of the received signal, you surely know this. You may wish to connect the variable capacitor in parallel with the coil and find the maximum sinewave peak to peak amplitude at 963 kHz, watching the amplitude on your scope, while turning the board with the ferrite rod on it also for maximum amplitude. Sorry if you have done this or are aware of all this, you have not mentioned or showed these yet.

Gyula

Nink · « **Reply #500 on:** February 28, 2016, 12:25:14 AM »

Quote from: MileHigh on February 27, 2016, 11:48:28 PM

He should go beat up Clock Boy and then sail off in a balloon.

I get how the Radio Shack clock shoved in a case works but what does the spoon stuck in a tripod do ?

Pirate88179 · « **Reply #501 on:** February 28, 2016, 12:52:20 AM »

Quote from: Nink on February 28, 2016, 12:25:14 AM

I get how the Radio Shack clock shoved in a case works but what does the spoon stuck in a tripod do ?

That is the remote detonation device reflector. It is not on the original schematic.

Bill

tinman · « **Reply #502 on:** February 28, 2016, 02:53:55 AM »

Quote from: Lidmotor on February 27, 2016, 07:45:21 PM

Brad:
This is what I have been trying to do for years with zero success. I don't have a strong enough AM station near me. Congratulations on doing it. Please make sure that you are not getting any energy from the scope ground lead A ways back a bunch of us tried to replicate Dr. Stiffler's PSEC only to find out the power came from the scope ground he had hooked up. To really convince people what you say is actually happening you will probably have to take the whole setup outside. I hate to say that but I see it coming. If you are getting that much energy into the system without a big/long antenna then you have stumbled onto something wonderful. Frankly even if the energy is coming from somewhere else I would like to know about it anyway.

MH:

I have been looking at that 'out of the box' circuit you presented and backed away from it. Too much work and not enough fun factor for a hobby guy like me with poor test equipment. I did try something a little different based on it though. I built a simple flip flop circuit and drove two separate NPN transistors off that. The NPNs pulsed two 1mH chokes with leds across them backwards to make the light. I powered the flip flop with a 3v coin cell and the inductor circuit with AA. I made an interesting experiment but was horribly inefficient.
Here it is and what it looked like on the scope: https://www.youtube.com/watch?v=_X_g52LsVnU

Hi Rusty.

I will look into it further for sure. I did think about the scope ground,but it is just a common ground,and i also have it hooked to the positive side of the cap,with the scope channel inverted.
That particular radio station is only about 4km away from me,and the reason it is the strongest signal in my area. That little electronics kit allows you to build a fox hole type radio receiver,and it works very well. Going to go down to my local electronics store today,and see if i can buy one of these ferrit core aerials today,and build it on a plexiglass board--just for clarity.

Brad

MileHigh · « **Reply #503 on:** February 28, 2016, 03:56:24 PM »

Quote from: tinman on February 26, 2016, 03:53:19 PM

author=MileHigh link=topic=8341.msg475491#msg475491 date=1456418556]

MileHigh

So show us your smart's MH--design a simple circuit that lowers the base resistance as the voltage in the battery drop's. You pride your self on bench time and knowledge,so show us some of that smarts. You draw up the circuit,and i'll spend the time and money putting it together,and testing it. I'll post the results and video's here.

Brad

Quote

You have to back up first. Who says that you need a variable resistor for a Joule Thief? I am not aware of that requirement. The only thing that I am aware of is that it was done all the time in the old days of this thread, presumably without any serious circuit analysis or scope work done to see what was happening. It was just an anecdotal observation that the LED changed in intensity when you changed the base resistance.

You are suggesting it so it suggests a question for you: Why do you want to have a variable base resistor in a standard Joule Thief?

No response on this and I am not surprised. This is an example of leading yourselves down a garden path. You talk about varying the base resistor "just because" and you can't actually explain why you want to do it.

Likewise, I will predict with high confidence that nothing will come from a "resonant Joule thief." It's another idea where you can't actually say why you want to do it. I speculated that you might get better performance because you may be emulating how a standard DC-to-DC converter works, which means that "resonance" has absolutely nothing to do with it at all. The silence was deafening.

There is no point in approaching electronics like this, sort of like alchemists. You need to approach electronics like chemists.

tinman · « **Reply #504 on:** February 28, 2016, 05:24:07 PM »

Quote from: MileHigh on February 28, 2016, 03:56:24 PM

No response on this and I am not surprised. This is an example of leading yourselves down a garden path. You talk about varying the base resistor "just because" and you can't actually explain why you want to do it.

Likewise, I will predict with high confidence that nothing will come from a "resonant Joule thief." It's another idea where you can't actually say why you want to do it. I speculated that you might get better performance because you may be emulating how a standard DC-to-DC converter works, which means that "resonance" has absolutely nothing to do with it at all. The silence was deafening.

There is no point in approaching electronics like this, sort of like alchemists. You need to approach electronics like chemists.

Do you need an answer to understand the need for a variable base resistor MH?-or will your batteries simply remain at the rated voltage of 1.5 volt's?.
That was a bit of a silly statement by your self MH.

Asking why the need for resonance is also a silly question.
Try pushing a child on a swing both in and out of resonance,and see which uses more energy for less motion. Why can you jump higher on a trampoline with less effort,than you can on the ground with more effort?.

MH-are you board again?.

Brad

Magluvin · « **Reply #505 on:** February 28, 2016, 06:24:52 PM »

Quote from: tinman on February 28, 2016, 05:24:07 PM

Do you need an answer to understand the need for a variable base resistor MH?-or will your batteries simply remain at the rated voltage of 1.5 volt's?.
That was a bit of a silly statement by your self MH.

Asking why the need for resonance is also a silly question.
Try pushing a child on a swing both in and out of resonance,and see which uses more energy for less motion. Why can you jump higher on a trampoline with less effort,than you can on the ground with more effort?.

MH-are you board again?.

Brad

For example. If a person of say 100lb is on a particular playground swing, and say it takes 2 seconds to swing a full 'resonant' cycle, then measure how much energy it takes to keep that cycle going. Now try to apply input energy to make that same person on the same swing complete that same cycle in .5 seconds. It will definitely take more energy in to run that swing at .5 second cycles because there would need to be a constant control from the input, of which in my mind would be a tremendous amount of energy to accomplish compared to the input of the 'resonant' 2 second cycle. Or even a 5 second cycle. The input would have to apply some kind of 'constant control over the course of the cycle, including 2 places in the cycle of braking and 2 places in the cycle of pushing up from the low position, once for each direction.

It is very clear that the input energy at 2 seconds per cycle would be minimal compared to forcing a .5 second or a 5 second cycle

To repeatedly hear that operating anything at resonance has no advantages over operating everything out of resonance, sounds a bit out of fiction instead of reality.

Like how many ways can it be described. Can an am radio pull in music from 910khz while tuned to 1200khz? How about when the radio is right next to the transmitter of the 910khz station? It takes a lot more input to do such a thing. When I was a kid with my radioshack electronics kits, if I had made an am radio with an audio amp circuit to hear it better, and tuned into a very local station, the audio was loud and clear. But even if I just put an ant on the input of the amp alone, I could hear the same radio station, but it wasnt nearly as loud as with the am tuner connected.

Mags

MileHigh · « **Reply #506 on:** February 28, 2016, 07:19:05 PM »

Quote from: tinman on February 28, 2016, 05:24:07 PM

Do you need an answer to understand the need for a variable base resistor MH?-or will your batteries simply remain at the rated voltage of 1.5 volt's?.
That was a bit of a silly statement by your self MH.

Asking why the need for resonance is also a silly question.
Try pushing a child on a swing both in and out of resonance,and see which uses more energy for less motion. Why can you jump higher on a trampoline with less effort,than you can on the ground with more effort?.

Brad

No, that won't cut it Brad. Don't try to play the "It's so obvious that I don't have to explain it" game. Right now you are the one making the silly statements. The Joule Thief is an electronic circuit and if you are stating that you need a variable base resistor for it then you must have an explanation and one or more reasons for saying that. I would like to hear why you need a variable base resistor.

Requesting the requirement for resonance is a perfectly sensible question. I will remind you that nobody here can even explain how a Joule Thief operates "in resonance." That is a fact. At this point nobody even knows what they are talking about or can explain what it even means. The best we have so far is that Smoky2 said "tweak the base resistor and look for a sine wave." Seeing a sine wave doesn't necessarily mean you are in resonance. Plus like I already said, if you are looking at high frequency signals in a circuit, they all eventually become sine waves.

The child on a swing is a failed analogy and I will cover that in my next posting.

The whole point of this is to deal with real electronics and to stop repeating cliches that don't mean anything and to stop going down garden paths and blind alleys.

I would like to hear your explanation for the Joule Thief.

MileHigh

MileHigh · « **Reply #507 on:** February 28, 2016, 07:54:06 PM »

Quote

For example. If a person of say 100lb is on a particular playground swing, and say it takes 2 seconds to swing a full 'resonant' cycle, then measure how much energy it takes to keep that cycle going. Now try to apply input energy to make that same person on the same swing complete that same cycle in .5 seconds. It will definitely take more energy in to run that swing at .5 second cycles because there would need to be a constant control from the input, of which in my mind would be a tremendous amount of energy to accomplish compared to the input of the 'resonant' 2 second cycle. Or even a 5 second cycle. The input would have to apply some kind of 'constant control over the course of the cycle, including 2 places in the cycle of braking and 2 places in the cycle of pushing up from the low position, once for each direction.

It is very clear that the input energy at 2 seconds per cycle would be minimal compared to forcing a .5 second or a 5 second cycle

To repeatedly hear that operating anything at resonance has no advantages over operating everything out of resonance, sounds a bit out of fiction instead of reality.

Sure, let's take the swing as an example but let's get real about it and also talk about a real output. Without having a real output you are just spinning your wheels and going nowhere.

For starters, resonance is simply a method for storing energy. So you have to put energy into the resonant system, and by definition take energy out of the resonant system if you are going to accomplish something.

What you can't do is not keep your eye on the energy ball, and I don't think either of you are doing that properly.

The child is at rest on the swing. You give him regular pushes of 20 joules. The swinging gets higher. The child's swing energy goes something like 20 joules, 40 joules, 60, 80... 180, and then finally there is 200 joules of energy stored in the swinging. Energy that you put there by pushing on the child. So far the output is zero.

Now that the child is swinging high, let's factor in the air resistance. Let's say the child loses 5 joules per swing. So that means you only have to push with 5 joules of energy per swing to maintain the high swinging, and the output is still zero.

So, now let's talk about an output - you have to have an output. So let's say that next to the swing there is a hanging rope that loops down and the child is wearing a leather work glove in one hand and he grabs the rope during each down swing to slow himself down and burn off some energy. Let's say he burns off 30 joules every time he grabs the rope.

So, you push on the child with 5 joules, and he is one the way down with 200 joules of energy in the swing. But this time he grabs the rope and when he comes back to you on the reverse swing there is only 165 joules in the swing. So that means that this time you can't get away with pushing with 5 joules because of "swing resonance magic," you will have to push back with 35 joules of energy to maintain the swinging.

Where is the "resonance magic" there?

When the child is swinging to output 30 joules you have to input 35 joules.

If there is no swinging and you just grab the rope and pull on it, to output 30 joules you have to input 30 joules.

Exactly the same thing will happen in an LC resonant circuit. The friction looses when swinging will be substituted for the i-squared-R losses in the wires.

So forget about your trampolines and your resonant frequency stuff, it means nothing. Look at the energy and you will find nothing special. It's just another wild goose chase down a garden path.

MileHigh

Magluvin · « **Reply #508 on:** February 28, 2016, 08:14:53 PM »

Quote from: MileHigh on February 28, 2016, 07:19:05 PM

I will remind you that nobody here can even explain how a Joule Thief operates "in resonance." That is a fact. At this point nobody even knows what they are talking about or can explain what it even means.

Well I wouldnt say that. So far I just have not gotten up to the resonant freq of the transformers Ive tried. That is so far. So that deafening silence you are speaking of is not me backing off because of your statements. As I did post that I will be back on it after the weekend when I finish this car audio system.

This week Im winding several different winding configs and doing some 1 shot power disconnects of the windings, where the scope will catch and display as a single shot, then spread the ring wave across the screen so the scope will show the freq. Did this with a pulse motor coil, and it will work here. This will give me the target freq I need to get the circuit to operate.

Now that I have the scope I want to revisit multi core transformers. If we wind a primary on a core, then wind a secondary through the primary core and a secondary core, if the primary is in resonance, loading the secondary wont disturb the primary resonance. I still have a few of those projects in a box.

Mags

sm0ky2 · « **Reply #509 on:** February 29, 2016, 06:52:31 AM »

Quote from: MileHigh on February 27, 2016, 03:54:22 PM

Is it possible that your supercapacitor is self-charging?

this is always a possibility, with certain types of capacitors in certain situations.
Tantalum capacitors can be exploited in this manner.
I have not had a chance to play with these new "supercaps"
but it is indeed possible that they may under the right circumstances, display this phenomenon.
Some electrolytic capacitors are designed NOT to do this, for stability purposes.

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