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Author Topic: Joule Thief 101  (Read 926691 times)

Pirate88179

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Re: Joule Thief 101
« Reply #165 on: February 12, 2016, 03:29:35 AM »
Mags, you can also check out the original JT topic where there are hundreds of schematics and design variants that we tested.  Many, many folks posted a lot of neat devices over there.  It is really fun to play with the variables and try different circuits.  It really all depends on what you want to do.  Do you want a lot of light?  Or, do you want some light that lasts a very, very long time?  Or, do you want to try to get as much of both conditions as possible?

This is what we played with back then and, we all learned a lot about electronics from working with these circuits.  Check TK's video collection as he has some great circuits he made on his youtube channel.  I have a lot of JT circuit videos but, TK actually explains what is happening and why in his vids.  Mine are more like..."Holy crap, this lights up!  Wow!!"

Bill

MileHigh

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Re: Joule Thief 101
« Reply #166 on: February 12, 2016, 04:15:40 AM »
Smoky2:

Quote
This is the minimalist version of the circuit, that uses no consideration to system losses.

I am not sure what you mean by the "system losses" because we are back to the issue of the informational scope of the clip that I posted.  The clip aims to simply explain how a Joule Thief works and no more than that.

"Minimalist version of the circuit" is another issue.  When is a circuit a Joule Thief or not?  I think that there is a simple answer to that one.  If the circuit can power a LED with a battery whose output voltage is lower than the normal drive voltage for the LED, and the LED is driven using the technique of a discharging inductor acting as a current source, then you have a Joule Thief.  If the circuit does not meet these two conditions then it is not a Joule Thief.

Obviously I can't comment on the various oscillator circuits that you have made reference to, but I suspect that many of them may not in fact be Joule Thief circuits as per the two criteria that I outline above.

Quote
stating that it works and that we don't need to know any more than that to turn the lights on, is all fine in dandy.

That's a straw man argument, I never said that.

Quote
But compare an old style filament bulb to a newer LED bulb of the same luminescence.
and compare their energy consumption

Now, do the same with the Joule thief.

My response to this may surprise you and a lot of people, but not if they were paying attention to the beginning of this discussion.

Nobody is going to argue about an incandescent light bulb compared to an LED light bulb.

You are implying that a Joule Thief gives you even better efficiency than an LED light bulb.  For purposes of a fair discussion let's put aside the "Thief" part of the Joule Thief that can extract energy from nearly dead batteries.  In other words, let's just look at lumens per watt of supplied power.

A lot of the efficiency is due to the fact that the LED in a Joule Thief is flashing and taking advantage of the persistence of human vision.  To accomplish this the Joule Thief has the overhead associated with the lossy energizing of the main coil and the associated overhead for the timing circuit.

So what if we just compare a flashing LED using a very efficient timing and switching circuit and a Joule Thief?

The answer is that a flashing LED light will beat a Joule Thief light hands down.  Now the Joule Thief doesn't seem so glamorous, does it?

I am going to take a guess here:  I am willing to bet you that LED lights don't flash to save power.  There are several reasons for this.  The first reason is that you are saving so much power anyway compared to incandescent bulbs that it is not an issue.  The second reason is that you simplify the design and save costs and have a more reliable light.  The third reason is just pure speculation:  If you are under lights for a long time each day, you are better off if they don't flash because even though you can't perceive the flashing, you might be able to perceive it subconsciously and some people might be prone to getting headaches just like some people don't like flashing fluorescent lights.

MileHigh

tinman

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Re: Joule Thief 101
« Reply #167 on: February 12, 2016, 05:31:42 AM »
Thanks Brad. Thats pretty cool. So if it was a long core without the separation there isnt any current through the core? Seems odd.  But Ill take your word for it. ;)

I wonder if you interleaved the laminations(insulated) some near the center to increase surface area if there might be helpful to generate more charge.

In this circuit below from a pdf on this thread, to me there seems to be a problem. Not that the circuit doesnt work. But the led is across the transistor in the same direction.  I understand that the batt doesnt have enough voltage to conduct the led. But when the transistor turns off, the inductors collapse current flows through the led AND the battery, thus further discharging the battery more besides the transisitor switching. So wouldnt it be better to put the led across the transformer winding where the batt isnt being drained during the led discharge also?

Mags

Well personally,i would put the LED across the emitter and core-providing the core is conductive. This way you reduce the power consumption of the device,due to the removal  of the charge build up in the core.

sm0ky2

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Re: Joule Thief 101
« Reply #168 on: February 12, 2016, 10:12:26 AM »
Smoky2:

I am not sure what you mean by the "system losses"

in general I am referencing resistive and inductive/reactive losses in the USE of the JT.
compared to the PROPER USE of the Armstrong Oscillator.

or in the comparative example, the resistive and inductive/reactive losses in the use of a filament
compared to the use of an LED.

I never anywhere stated that a JT circuit was better or more efficient than a household LED.
that is topic for another discussion, wherein I use the parts already inside the LED lightbulb to form a JT circuit,
throw away the extra misc. components found inside, and power the LED with a mostly dead battery,
and compare that to an unaltered LED powered by the Mains.

Quote
"Minimalist version of the circuit" is another issue.  When is a circuit a Joule Thief or not?  I think that there is a simple answer to that one.  If the circuit can power a LED with a battery whose output voltage is lower than the normal drive voltage for the LED, and the LED is driven using the technique of a discharging inductor acting as a current source, then you have a Joule Thief.  If the circuit does not meet these two conditions then it is not a Joule Thief.


hmm, there are a lot of different devices referred to as a "joule thief". But at some basic level, we have to agree that there are certain aspects, features, and components of the circuit, that define is as the 'fad' known as a JT.
I am not sure if I would use the same criteria you offer above. Mine would be more like:

1) transformer (or suitable equivalent switching device)
2) inductor
3) low voltage power source
4) optional load

the LED is optional, and serves only as an indicator that the circuit is in operation.
The fact, or should I say phenomena, that people are amazed by, and use the LED as a source of light, is quite frankly irrelevant to what is or is not a joule thief.

The entire argument of it using the "last bit of current in a battery" is complete hogwash,
you can run these off nearly any voltage potential, from any source.
 from the earth itself, broadcast radio signals, to the voltage built up in the metal frame of your computer desk....

The things TK and Bill did, without a standard "battery" are worth going back and looking at.

What is a Joule Thief?

a Joule Thief is: An Armstrong Oscillator

Most of the instructables, and do-it-yourself JT webpages use a very simplified (minimalist) version of the oscillator,
and do so with completely mismatched components.
No thought was given to most of their designs other than
the switching range of the transformer vs the inductor, and the cut-on voltage of the transistor and diode.
Furthermore, taking an equivalent circuit replacement works for digital electronics. We do it all the time.
But taking an analog circuit, and forcing it to be digital, you lose certain qualities of the signal.
go talk to an old guitar player about digital equipment vs their older counterparts, and hear what he has to say.

there is no JT "standard" for the transistor, the resistor, the ferrite, or the coil.
Some here have put forth a considerable effort to standardize the components, but this was an aftermarket thought.
Not the definition of the device.

What I am trying to do is teach others how it was designed to be used in the most efficient manner.


Quote
Obviously I can't comment on the various oscillator circuits that you have made reference to, but I suspect that many of them may not in fact be Joule Thief circuits as per the two criteria that I outline above.

again, I'm not sure I can agree with your observational criteria.



Quote

A lot of the efficiency is due to the fact that the LED in a Joule Thief is flashing and taking advantage of the persistence of human vision.  To accomplish this the Joule Thief has the overhead associated with the lossy energizing of the main coil and the associated overhead for the timing circuit.

MileHigh

Most of what I have been talking about is not necessarily comparing the Joule Thief to another circuit.
But comparing the Joule Thief to itself, under different operating conditions.
What those operating conditions are, and how to use them to build the best possible JT circuit.

Efficiency of the JT vs other devices can only be done analyzing the duty cycle of the power across the transistor.
This is generally done outside the linear mode of the transistor, and at frequencies far from a resonant node.
Comparison in this manner shows that the Joule Thief is a rather inefficient circuit. We can and have done better.

a JT in resonance, sometimes cannot even be measured.
Equipment can get destroyed, and capacitors explode, stray voltage spikes in unexpected parts of the circuit.
This is because people don't pay attention to the impedance of their oscilloscope,
or that a diode can create a return current path, which is preferred by the current when resistance through the coil peaks.
DMMs are usually the first to go, people think since they run it through a diode that its no longer "AC"......

There is a whole range of mathematics and rules that must be adhered to when it comes to resonant circuits.
these have been around for 200 years, people mainly ignore that which we do not use.
I don't get too deep into these concepts here, because most of them apply to much larger resonant circuits, than a simple JT. - but they CAN and sometimes DO apply, when you are taking measurements of the JT circuit in resonance.

Also note, that a resonating inductor produces large amounts of interference to the surroundings.
If not properly shielded, this can disturb instruments and equipment nearby.
Our circuits are not designed to operate in this manner, it is a whole other branch of technology that never went anywhere. We went with the predictable, more consistent route.
It is now our time to experiment with this.

As it pertains to "flashing" LEDs::

persistence of human vision varies from person to person. One human can see very fast flashes, where another human cannot perceive them. There is an "average", based on a number of test samples, but generally any testing done to the JT is done using an assessment of the actual circuit, not some arbitrary visual aspect.
Also, there are frequencies your brain cannot process. points where the LED will appear to dim to you, but in fact it is producing a greater amount of "light" than a lower frequency you were able to see.

We know by the diode data sheet, how much "light" is produced with a given voltage/current put through the diode, and we also know the decay function or Cut-off time, that this "light" is dissipated over after the pulse cuts off.
What we "see" from the LED does not matter.
I think what you will find, is that in most set-ups, the LED itself never fully turns "off".
Therefore, the persistence of human vision doesn't even come into play.

The LED itself doesn't even matter. more accurate testing can be done using other components as a load.

sm0ky2

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Re: Joule Thief 101
« Reply #169 on: February 12, 2016, 10:24:11 AM »
I am trying to bring everyone up to speed on this, because once we all get it, we can go to the next level.

If people are still getting hung up on the very basics, we must communicate the information more effectively.

Simply put, once the JT is operating at a resonant frequency, we can remove the LED/load completely,
and couple to it, using the inductor as a transformer. By winding a secondary onto the ferrite.

With an appropriate capacitance, this secondary coil can be set resonate with the frequency of the rest of the circuit, and used to power a load.

Bob Smith

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Re: Joule Thief 101
« Reply #170 on: February 12, 2016, 07:10:54 PM »
Smoky2
Thanks for the helpful explanations. I think the direction with a secondary is where Jeanna was going some years back. She had some YT videos using multiple secondaries - very interesting stuff.  IST had a slightly different approach, and often used a kind of caduceus winding for his multiple secondaries. 
Looking forward to a more purposeful kind of build that would enable us to produce the resonant effect and draw from it.
Bob

Magluvin

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Re: Joule Thief 101
« Reply #171 on: February 12, 2016, 10:54:31 PM »
Someone said here earlier that we cant take, as in load, from a parallel rc?  Below is a pic and the code for the circuit in the pic for Falstads Circuit sim.

When you hold the switch on and charge the parallel rc then release the switch, the rc goes through a near full cycle then dumps back into the source through the diode across the switch. So the rc goes into full swing in the forward direction of the inductor, as we know, charges up the cap, then reverses direction and the inductor at near full bore dumps into the source.

I chose to use the 10uf cap so there is time to see the circuit work as in visual current flow. The cap can be small where the action happens 'almost' instantaneously, and reducing the amount of current when the switch goes on and dumps into the cap also, as seen as a big current spike when the cap is 10uf or just larger than a tiny cap. Not too tiny of a cap. There needs to be a short time period for the switch to become fully opened before the collapse current develops enough voltage to jump the gradually opening gap.

So this circuit can be used in a simple pulse motor to direct the coils field collapse currents back to the source, and also saves the reed switch from arcing when released because the inductors forward current has a place to go other than the switch gap when opening.


$ 1 5.0E-6 10.20027730826997 50 5.0 43
s 640 224 704 224 0 1 true
l 640 224 640 496 0 1.0 -1.6114345942577624E-6
v 704 496 704 224 0 0 40.0 20.0 0.0 0.0 0.5
r 640 496 704 496 0 1.0
w 640 176 640 224 0
w 704 176 704 224 0
d 640 176 704 176 1 0.805904783
w 640 496 576 496 0
w 640 224 576 224 0
c 576 224 576 496 0 1.0E-5 8.604227041654291E-4
o 1 64 0 35 0.009765625 9.765625E-5 0 -1



Mags

Magluvin

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Re: Joule Thief 101
« Reply #172 on: February 12, 2016, 11:02:44 PM »
I am trying to bring everyone up to speed on this, because once we all get it, we can go to the next level.

If people are still getting hung up on the very basics, we must communicate the information more effectively.

Simply put, once the JT is operating at a resonant frequency, we can remove the LED/load completely,
and couple to it, using the inductor as a transformer. By winding a secondary onto the ferrite.

With an appropriate capacitance, this secondary coil can be set resonate with the frequency of the rest of the circuit, and used to power a load.

Hey Smoky

Does making the secondary resonant with the primary have to be load specific on the secondary? Like does the value of the load affect the resonant freq of the secondary? Does the secondary have to be tuned to a specific load?

Thanks

Mags

MileHigh

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Re: Joule Thief 101
« Reply #173 on: February 13, 2016, 01:28:22 AM »
Smoky2:

Quote
the LED is optional, and serves only as an indicator that the circuit is in operation.
The fact, or should I say phenomena, that people are amazed by, and use the LED as a source of light, is quite frankly irrelevant to what is or is not a joule thief.

Okay, fair enough.  So let's strip it down to the bare bones then.  All that you are left with is energizing an inductor and then discharging that inductor into some kind of load.  The inductor acts like a current source when it discharges and the majority of people on this forum don't understand that.  And if you want you can take advantage of that fact and create a small cottage industry.   You can give it the fake label of "radiant energy" and sell DVDs all about it but never actually explaining what is going on to your target audience.

There is nothing "exciting" about a discharging inductor to an informed electronics hobbyist, you may as well be watching paint dry.

Quote
The entire argument of it using the "last bit of current in a battery" is complete hogwash,
you can run these off nearly any voltage potential, from any source.
 from the earth itself, broadcast radio signals, to the voltage built up in the metal frame of your computer desk....

It's a huge stretch to claim you can run one off of "the earth itself, broadcast radio signals, to the voltage built up in the metal frame of your computer desk.."  You need to keep this discussion rooted in some measure of reasonableness and reality.  You are never in a million years going to run a Joule Thief on the voltage built up in the metal frame of a computer desk.

Quote
What is a Joule Thief?

a Joule Thief is: An Armstrong Oscillator

No, an Armstrong Oscillator is based on an LC resonant tank and a Joule Thief is not in any way, shape, or form based on an LC resonant tank.

If you disagree then I already suggested that anyone is welcome to present evidence that is comparable to the clip that I linked to that describes the operation of a Joule Thief with a full and complete description of the entire switching cycle.

Quote
But taking an analog circuit, and forcing it to be digital, you lose certain qualities of the signal.

I am not a fan of vague and ephemeral language when it comes to electronic circuits. The quote above is meaningless.

MileHigh

MileHigh

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Re: Joule Thief 101
« Reply #174 on: February 13, 2016, 01:51:10 AM »
Smoky2:

Quote
Most of what I have been talking about is not necessarily comparing the Joule Thief to another circuit.
But comparing the Joule Thief to itself, under different operating conditions.
What those operating conditions are, and how to use them to build the best possible JT circuit.

That I can wholeheartedly agree with and you also made earlier references with respect to trying different component values.  That would be a great learning exercise for many but I fear that it is above the knowledge and skill set of the average electronics experimenter on the free energy forums.

Again, stripping it down to its bare bones:  You can make a Joule Thief circuit (or say a 555 based circuit) that adjusts the parameters related to a discharging inductor:  the size of the inductor, the initial current and energy in the pulse, the pulse repetition rate, and how that custom designed train of inductive pulse discharges will go into your chosen load.  That's all there is when you strip it down to the bare essentials.  You notice I am restricting my discussion to a "normal" Joule Thief.

Quote
a JT in resonance, sometimes cannot even be measured.
Equipment can get destroyed, and capacitors explode, stray voltage spikes in unexpected parts of the circuit.
This is because people don't pay attention to the impedance of their oscilloscope,
or that a diode can create a return current path, which is preferred by the current when resistance through the coil peaks.
DMMs are usually the first to go, people think since they run it through a diode that its no longer "AC"......

It all sounds fine and dandy and clearly you have a following here.  But I have yet to see what I would call a Joule Thief in "resonance" and if you can't demonstrate that or link to tangible proof that what you are alleging is real, for right now I have to consider it to be pie-in-the-sky.  Again, I am not saying that you cannot have oscillator circuits that light LEDs or drive loads, but I would have to be convinced that there are "Joule Thieves in resonance."

Quote
Our circuits are not designed to operate in this manner, it is a whole other branch of technology that never went anywhere. We went with the predictable, more consistent route.
It is now our time to experiment with this.

It all sounds very cool and very cutting edge to some people around here, but not to me.  I will just repeat that electronics is very well understood and what you are alleging about some kind of "outside the box" study of electronics is simply not the case at all.

Quote
I think what you will find, is that in most set-ups, the LED itself never fully turns "off".

With a standard Joule Thief circuit the LED does switch off so the persistence of human vision does come into play.  I do appreciate how you stated that the persistence of human vision is a complex process and not necessarily a one-size-fits-all proposition.

MileHigh

MileHigh

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Re: Joule Thief 101
« Reply #175 on: February 13, 2016, 01:57:08 AM »
Smoky2:

Quote
I am trying to bring everyone up to speed on this, because once we all get it, we can go to the next level.

If people are still getting hung up on the very basics, we must communicate the information more effectively.

Simply put, once the JT is operating at a resonant frequency, we can remove the LED/load completely,
and couple to it, using the inductor as a transformer. By winding a secondary onto the ferrite.

With an appropriate capacitance, this secondary coil can be set resonate with the frequency of the rest of the circuit, and used to power a load.

I am all for that because I am all talked out about this.  The proof is in the pudding.

Not to be too cynical but often you see experiments around here that are all about a "new way" to power a load.  The catch is this:  Can your circuit outperform two wires?   Of course I am oversimplifying but I think you get my point.

MileHigh
   

MileHigh

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Re: Joule Thief 101
« Reply #176 on: February 13, 2016, 02:03:07 AM »
Smoky2
Thanks for the helpful explanations. I think the direction with a secondary is where Jeanna was going some years back. She had some YT videos using multiple secondaries - very interesting stuff.  IST had a slightly different approach, and often used a kind of caduceus winding for his multiple secondaries. 
Looking forward to a more purposeful kind of build that would enable us to produce the resonant effect and draw from it.
Bob

All of Jenna's clips about this were just an exercise in experimenting with a transformer with multiple secondary windings.  How does a transformer distribute power when there are multiple secondary windings wiith different numbers of turns and perhaps each secondary is driving a different value of resistive load (or different LEDs)?

This is a basic nuts and bolts transformer question that any serious electronics hobbyist should try to answer for themselves.  When Jenna did this there was never a manifestation of extra power.

Magluvin

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Re: Joule Thief 101
« Reply #177 on: February 13, 2016, 02:10:22 AM »
Smoky said...
"I think what you will find, is that in most set-ups, the LED itself never fully turns "off"."


With a standard Joule Thief circuit the LED does switch off so the persistence of human vision does come into play.  I do appreciate how you stated that the persistence of human vision is a complex process and not necessarily a one-size-fits-all proposition.

MileHigh

With the led across the driver coil, not the trigger coil, the inductor collapse winding down could possibly still be passing current(and light output) through the led by the time the transistor is triggered again.  Also white leds have phosphorous that has a persistence of emission also. ;D


Mags

tinman

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Re: Joule Thief 101
« Reply #178 on: February 13, 2016, 03:14:05 AM »
With the led across the driver coil, not the trigger coil, the inductor collapse winding down could possibly still be passing current(and light output) through the led by the time the transistor is triggered again.  Also white leds have phosphorous that has a persistence of emission also. ;D


Mags

The LED will be off during the on time of the primary coil,as the voltage is inverted across the coil during the on time,and that voltage cannot exceed the voltage of the supply battery. You could of course use a diode and cap with an LED across the cap,and it will be on 100% of the time.


Brad

seychelles

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Re: Joule Thief 101
« Reply #179 on: February 13, 2016, 05:15:39 AM »
as always i will give away my top secret coil winding system..check it out..the winding is in bifilar configuration..