Joule Thief 101

[Bob Smith]

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]

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]

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]

Smoky2:

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.

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.

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.

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]

Smoky2:

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.

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."

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.

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