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Author Topic: Possible breakthrough with the JouleThief (JT) circuit  (Read 48256 times)
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  I've been playing with the Joule Thief self-resonator for months and learning a lot.  And I obtained ONCE a result using the Tektronix 3032 that the efficiency n (= COP = Pout/Pin) was 113%, that is looking like overunity.  I'll get to that result soon, after some background.  And note from earliest thread on this bench, that a requirement for believable "overunity" is that the experiment must be repeatable.

 The basic JT circuit schematic is shown in the attached -- and follows from development on the following thread, from which I quote a brief portion:

@PhysicsProf
Thus, I would say yes for the sake of simplicity! Here is the proposed method:

1. take CSR2 out and connect the LED directly to the ground (or just leave as is and don't measure V4, measure V2 instead if you were using two scopes).

2. measure V1, V2, V3 as before.

3. calculate Pitotal by MEAN [V1*V2], which gives the time average input power.

4. calculate Pototal by MEAN [V3*V2] over time, similar to finding the Pitotal.

5. then n = Potatal/Pitotal, which is EXACT as the error in the value of CSR1 is balanced out in the way n is calculated.  O0

This seems to be as simple as it can be. Also, it only leaves tiny energy leaks out of consideration, namely the leaks in the 1k resistor and the coils.
cheers,

lanenal


  Now I say the JT is a self-resonator because the JT "finds" its own natural frequency very rapidly when voltage is applied.  This frequency depends on the combination of components chosen and can be easily varied over a wide range by changing or adding components.  The major changes I have made lately to the basic JT circuit, in an attempt to find OU, are:

1.  Replacing the LED with a resistor -- it still rings! but you need an oscilloscope to see it.  
2.  Applying a capacitor across (in parallel with) the L2 (feedback) loop, turning it into its own LC side-circuit.
2b.  Applying a capacitor (and resistor if desired) in series with the L2 loop, forming a pulsing system.
3.  Applying a capacitor across the L1 primary loop, another LC side-circuit.  
4.  Changing the transistor used, resistances, cap values, etc. -- a broad parameter space with such a simple circuit to start with.


The discussion on the JT has been proceeding for some time on another thread, and I'm not going to repeat everything, so for important background material on my and others' results I refer the reader back to that thread; perhaps start here:

 Interesting results yesterday as I traveled to the University and used the Tektronix 3032 there, to derive Pin and Pout mean values, as we have been discussing.

I will start with a few "normal results", in part to get us all used to reading the waveforms and the calculated power.

Result 1:  Using toroid "A" (from prototype A sent to me for testing by Lawrence Tseung; but just using the primary and feedback windings, not the secondary winding).  Attached shows the resultant waveforms and calculated Power, with the input Power in red on the left and the output Power in red on the right.  Channel 2 is always the voltage drop across the one-ohm resistor (see Lanenal's circuit diagram above in this thread), that is, the current waveform.  Here, a nice sawtooth.  Channel 1 is the voltage across the battery -- or, in these tests, the DC power supply -- for Pin, on the left.  For Pout on the right, Channel 1 is the voltage drop across the transistor and (red) LED.

Notice that per the schematic, the voltage across the 1 ohm resistor is Negative, hence both Pin and Pout show up as negative -- for the discussion that follows, and to be consistent with what we know, I will set the y axis to be POSITIVE DOWNWARDS consistent with the power in and out being positive quantities.  The shapes are interesting -- a saw=tooth for Pin and a single U-shape for the Power Out.

The 3032 calculates ch1*ch2 = V * I = Power and displays the result in RED waveforms, and it calculates the MEAN Power for us, given in the right- hand column.  Per our previous discussion, to a reasonable accuracy over a dozen or so cycles, we get:

n = Pin / Pout = 36.11/ 40.15 = 0.9.  

The estimated error, +- 2% based on .99's simulation and on the repeatablility I find for this ratio in these tests (for a given toroid and set-up).

High efficiency, but not surprising.

The second pair of scope-shots homes in on the input and output signals, showing detail.  This juxtaposition will be useful for later comparisons.
« Last Edit: 2011-03-12, 00:29:43 by PhysicsProf »
   
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  It is worth repeating my post from last week on the possible breakthrough using the JT circuit, before turning to more recent results.

  Without further ado, let me share with you -- inviting comment -- the most interesting result of yesterday's (4 March 2011) tests at the University, using a Tektronix 3032 scope.

  Here I am using the eJ toroid that I wound.  I began with a Jameco toroidal inductor (100 uH, Jameco part # 386601), and wound fifteen windings bifilar of 22-gauge insulated (one with plastic, the other enamael) copper wire.  The inductance of EACH of my windings came out to 24 uH.  The Jameco winding is not involved in this test run, and the wires are left unconnected from this winding (which would be the secondary winding for a Tseung-type system).

I have given results with this SAME eJ toroid above... where we observed Pin as a simple sawtooth and Pout a single hump or spike.  Now -- please look closely at the waveforms for this run at 0.996 V (in from the power supply), in the attached.

First, we look at the detail for roughly 1.5 cycles in the first attached screen-shot.  The red Pin waveform is approximately what we have seen before, a saw-tooth pattern.   But the (red) Pout waveform is quite different!
Instead of a single hump or spike essentially bounded at zero-power as we have seen in the past, we now see a U-shape that significantly OVERSHOOTS ZERO, demonstrating current and voltage Out of Phase, as we also see comparing the voltage across the (LED+transistor) in yellow, and the current in the 1-ohm CSR shown in blue. 

Further, notice the oscillations/wiggles in the waveforms for the output power and voltage waveforms.  Very interesting.  To me, this is striking and rarely-seen behavior, and I have been working with these types of circuits for months now.

To get the efficiency with some accuracy, we have the Tektronix 3032 calculate Mean Power for both Pin and Pout over numerous cycles -- with this interesting result:

n = 44.8 / 39.8 =  1.13 = 113%

+- about 3% as previously noted.


If you are visually comparing Pin and Pout waveforms in the attached, note that the scale in the screen display for Pin is 20 mVV whereas the scale for Pout is 50 mVV (which does not change the result above), which I did because the Pout curve was getting clipped on the 20mVV scale as i recall.

In order to encourage and facilitate comparisons, I include a final attachment which shows Pin and Pout for these data at 0.996V juxtaposed with the data for the same eJ toroid ran at nearly the same voltage (0.993 volts), but where the latter displays the "normal" pattern with just one spike.  The two waveforms in the center of this attachment (trace 2 and 3 ) give Pout and Pin both on the same scale, 50 mVV, to make visual comparisons more straightforward for you.  If you think the Tektronix 3032 may be making a mistake when calculating the Mean power in the case where the power is sometimes negative and sometimes positive, I invite you to evaluate the areas under the Pin and Pout curves for one cycle, subtracting the opposite-signed power region, and then evaluate n from this integral (that is, using n = Ein/Eout, as I have demonstrated before).  It would be a worthwhile check.  I have done this roughly, and the Tek 3032 calculation seems good.

You have a dozen questions?  I have many also...   ;)

After seeing this result, I returned twice to the same circuit and getting the voltage as close as I could, but could not generate the unusual "spiky" Pout waveform again in the limited time I had on the Tek 3032 at the University.  And those results came out with COP = n of about 90%.
I recall having seen such a waveform at home before, but I do not know just how to reproduce this spiky waveform  -- wish I did.  And I am very open to suggestions.

I will say that I looked first at the many-cycle Pout (attached), then looked at many-cycle Pin (moving the channel-1 probe to do so), then moved the channel-1 probe back in order to re-measure Pout and record the approx detailed Pout waveform (attached).  The Pout waveform remained the same over the several minutes required to do these measurements and record them on the computer, about 15-20 minutes.   So however I got in this mode, with the unusual waveforms, zero-crossing Pout and COP evidently greater than one, the condition remained for a while.

When I saw that n was coming out larger than one, I was a bit excited and did go back and get the detailed waveforms recorded.  However, I was thinking that I could simply come back later and get more data at this condition after running at other voltages, which was not the case yesterday afternoon -- I'm glad I got as much data as I did and recorded it for you all to see. 

Now the question is -- what does this all mean? and how can one get back to this out-of-phase relationship between V and I in the output circuit??   (I have reported this condition before as you may recall, some time ago, but that was with the LT-type circuit and this is a simple JT.) 

To me the result is striking and noteworthy and something of a breakthrough.  But can it be repeated?  Repeatability is a core requirement for solid science and progress.
   
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PhysicsProf,

Have you tried this variant? In a normal JT you waste the base current.
In my variant the base current is through the coil and is not wasted.
The R must be a high Ohm value. It is only to bias the transistor at
start up. When the oscillation starts then the capacitor takes over.
Suggested values: R=330K to 1M Ohm. The base coil capacitor
can be approx. 1nF. Some experimenting may be needed.

(EDIT) There was a small error in the drawing, uploaded the correct one.

Regards,
GL.
« Last Edit: 2011-05-28, 09:53:29 by Groundloop »
   
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PhysicsProf,

Have you tried this variant? In a normal JT you waste the base current.
In my variant the base current is through the coil and is not wasted.
The R must be a high Ohm value. It is only to bias the transistor at
start up. When the oscillation starts then the capacitor takes over.
Suggested values: R=330K to 1M Ohm. The base coil capacitor
can be approx. 1nF. Some experimenting may be needed.

Regards,
GL.


Hmmm... another very good idea to test -- thank you, GL for sharing.  If we all share notes like this, we can progress more rapidly.  I haven't tried it yet but will soon... first to report on an effort to get the OOP waveform described above (see first attachment).


I don't have a scanner, so I will describe a circuit with an added capacitor.  After a fair amount of trying different things (but not GL's idea...), a 151 pF cap was added after L2, in parallel with a 15.4Kohm resistor, and then into a 500ohm (instead of 1K) resistor that goes to the transistor base.  
The result is a waveform that mimics somewhat the waveform observed at the University with the Tek 3032 -- clearly the out-of-phase spike is seen in Pout --  Attach #2 (sorry the camera is fuzzy for close-ups, but you can see the waveforms in green, Pin on the left, Pout on the right.)  Comparing, we see that I have with this added cap and R, achieved a somewhat similar pattern as for the 113% condition... well, maybe.  I will have to take the circuit to the Tek 3032 to make the detailed measurements and to get an accurate value for n.

  Is it possible that the capacitance of the L2 winding came into play with the 113% condition?  
Still working,... trying to ferret out the OU condition...
   
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PhysicsProf,

Have you tried this variant? In a normal JT you waste the base current.
In my variant the base current is through the coil and is not wasted.
The R must be a high Ohm value. It is only to bias the transistor at
start up. When the oscillation starts then the capacitor takes over.
Suggested values: R=330K to 1M Ohm. The base coil capacitor
can be approx. 1nF. Some experimenting may be needed.

Regards,
GL.

I find that to be a highly unusual circuit Groundloop.  There is no inductor discharging into a load.  The "output" looks like it's just the battery source current flowing into the transistor collector and then out through the emitter and through the diode and into the load.  In other words it's just the battery or power supply going into the load through the switched-on transistor.

When the transistor switches off, the second coil will discharge in an unusual way.  It looks to me like the potential at the emitter will spike negative for a very short amount of time.  That will cause the transistor to switch on again for a short amount of time.  That will not conduct any power through the diode into the load.

Anyway, this is just a preliminary analysis in my head and I am not even covering the precise oscillation mechanism.  It would be a fun pSpice simulation, I just have to install it first!  From what I can see with a 1.5 volt power source this will not be able to light up 10 LEDs in series like a conventional JT can.

MileHigh
   
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Physicsprof,

I have spent much time in the past with blocking oscillators and have noticed strange behavior. Not seeking ou operation but its reaction to external magnetic fields and their influence.

It was possible to even create a compass of sorts where changing the oreintation changed the mode considerably.
I achieved this condition by using a magnet and arranging things including supply to be sensitive to the magnet(sweet spot) . Not close to the device but some distance .
It might be interesting for you do tinker with this condition (if you have not already)as I am sure you will be surprised at how sensitive the units can be to the external field .
I found it perplexing and extremely interesting.
It just migh be that magnetic mode (non technical sorry) is a part of the unusual condition you have found
   
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Physicsprof,

I have spent much time in the past with blocking oscillators and have noticed strange behavior. Not seeking ou operation but its reaction to external magnetic fields and their influence.

It was possible to even create a compass of sorts where changing the oreintation changed the mode considerably.
I achieved this condition by using a magnet and arranging things including supply to be sensitive to the magnet(sweet spot) . Not close to the device but some distance .
It might be interesting for you do tinker with this condition (if you have not already)as I am sure you will be surprised at how sensitive the units can be to the external field .
I found it perplexing and extremely interesting.
It just migh be that magnetic mode (non technical sorry) is a part of the unusual condition you have found

I will try it again -- I did try a small magnet once near the toroid, did not see much at that time (at least a month ago) -- but not with the toroid I'm using most of the time now.  Thanks for the ideas.  

@MH:  will let you know if the LED lights up with GLoop's circuit ...  certainly the location of the LED in Gl's schematic is most unusual (is that where you wanted the LED, GL?).
   
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I find that to be a highly unusual circuit Groundloop.  There is no inductor discharging into a load.  The "output" looks like it's just the battery source current flowing into the transistor collector and then out through the emitter and through the diode and into the load.  In other words it's just the battery or power supply going into the load through the switched-on transistor.

When the transistor switches off, the second coil will discharge in an unusual way.  It looks to me like the potential at the emitter will spike negative for a very short amount of time.  That will cause the transistor to switch on again for a short amount of time.  That will not conduct any power through the diode into the load.

Anyway, this is just a preliminary analysis in my head and I am not even covering the precise oscillation mechanism.  It would be a fun pSpice simulation, I just have to install it first!  From what I can see with a 1.5 volt power source this will not be able to light up 10 LEDs in series like a conventional JT can.

MileHigh

MileHigh,

The output is via an 1N4148 with ref. to ground.

GL.
   
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I will try it again -- I did try a small magnet once near the toroid, did not see much at that time (at least a month ago) -- but not with the toroid I'm using most of the time now.  Thanks for the ideas.  

@MH:  will let you know if the LED lights up with GLoop's circuit ...  certainly the location of the LED in Gl's schematic is most unusual (is that where you wanted the LED, GL?).

Physicsprof,

It's not a LED. It is just a 1N4148 to show where you can get the output.

Attached is a mosfet version that I did build and test.

GL.
« Last Edit: 2011-05-28, 09:54:12 by Groundloop »
   
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Physicsprof,

It's not a LED. It is just a 1N4148 to show where you can get the output.

Attached is a mosfet version that I did build and test.

GL.

I built your transistor version above as well as I could -- and could not get it to "ring" after several tweaks.  Your Mosfet version is impressive...  have you measured n = Pout/Pin for this version??

I have also added a capacitor (call it C1) in parallel with L1 (see circuit schematic in first post) with interesting results.  Adding C1 makes a tank circuit (along with the primary coil L1).  I've tried this before, but now with different values of C1, seeking still to improve n.  I will have to give details later as wife and I are traveling today.
   
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I built your transistor version above as well as I could -- and could not get it to "ring" after several tweaks.  Your Mosfet version is impressive...  have you measured n = Pout/Pin for this version??

I have also added a capacitor (call it C1) in parallel with L1 (see circuit schematic in first post) with interesting results.  Adding C1 makes a tank circuit (along with the primary coil L1).  I've tried this before, but now with different values of C1, seeking still to improve n.  I will have to give details later as wife and I are traveling today.

Physicsprof,

By "ring" do you mean run? The bipolar transistor version requires a little tweaking of the R and C value to get it to run well.
I have not measured the Pin and Pout for the mosfet version but runs OK.

GL.
   
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I'm off to radio shack to pick up a couple of parts for this Joule Thief COP>1replication... it's going to be somewhat of a letdown to only evaluate this with a 1-channel scope, but you do what you can with what you've got.

By the way, groundloop, what's the fastest MOSFET driver chips you use?  (ucc27322,ucc37322, FAN3228C)?  I want to play around with cheaper MOSFET chips before I drop $200 on the IXDD414 monsters.  I also don't want to fry expensive chips...
   
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I'm off to radio shack to pick up a couple of parts for this Joule Thief COP>1replication... it's going to be somewhat of a letdown to only evaluate this with a 1-channel scope, but you do what you can with what you've got.

By the way, groundloop, what's the fastest MOSFET driver chips you use?  (ucc27322,ucc37322, FAN3228C)?  I want to play around with cheaper MOSFET chips before I drop $200 on the IXDD414 monsters.  I also don't want to fry expensive chips...


Feynman,

I have only tried the IR2106 high/low end mosfet driver and that one is not fast, 180nSec switch on / switch off time.
I did use bipolar transistors as drivers in my three channel switch http://home.no/ufoufoufoufo/fastswitch.rar
that I used in some TPU research.

GL.
   
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I'm off to radio shack to pick up a couple of parts for this Joule Thief COP>1replication... it's going to be somewhat of a letdown to only evaluate this with a 1-channel scope, but you do what you can with what you've got.

By the way, groundloop, what's the fastest MOSFET driver chips you use?  (ucc27322,ucc37322, FAN3228C)?  I want to play around with cheaper MOSFET chips before I drop $200 on the IXDD414 monsters.  I also don't want to fry expensive chips...


Feynman:

You should simply get some ordinary MOSFET gate driver chips and some ordinary MOSFETs.  There is no point in getting a super-high-end integrated MOSFET and driver module all in one.  You are a long way off from ever needing the high-end stuff, if ever.  You will be able to get high enough slew rates in your switching speed with ordinary MOSFETs as you understand how to use them.

I know that you want to get high slew rates and you believe that there is something special about them and that it's an unexplored topic in the realm of engineering.  The truth is that's not the case; there is nothing special about high slew rates and these issues are completely and perfectly understood.  High slew rates don't open a portal to "vacuum energy" but I know you won't take my word for it so you will have to do the experiments yourself.

A good primer even through it's not specifically about MOSFETs is "The CMOS Cookbook" by Don Lancaster.  The first chapter is available on Scribid and it's the most important chapter:

http://www.scribd.com/doc/26629325/Cmos-Cookbook-chapter-1

The whole book might be available for download somewhere covertly.  From the Google search it's obvious there is a cat and mouse game going on.  If you like the first chapter and are interested in the rest you can always buy the real book on Amazon.

MileHigh
   

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Buy me some coffee
I've been using mcp1406 drivers which i found a bit better than TC4429's with IRF840 fets but can only get about 40-60nS after delays ect
http://www.overunityresearch.com/index.php?topic=241.msg2732#msg2732
   

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Hi all,

i did a quick replication of "groundloop's" circuit in reply #2, and i can confirm it does oscillate after some tweaking.

I used R=1K, C=1NF, toroid with 24 turns each and a MJE13007 transistor.
Instead of the 1n4148 diode i used a led to ground which lit up on the 4.6 VPP.

Here a short video from this setup:  http://www.youtube.com/watch?v=IXWWXZ7xDuM

I will do some additional tweaking / measurements. 

Regards Itsu.
   

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Feynman:

You should simply get some ordinary MOSFET gate driver chips and some ordinary MOSFETs.  There is no point in getting a super-high-end integrated MOSFET and driver module all in one.  You are a long way off from ever needing the high-end stuff, if ever.  You will be able to get high enough slew rates in your switching speed with ordinary MOSFETs as you understand how to use them.

...

MileHigh


This is very good advice.  Select an inexpensive Gate Driver chip
which will provide the needed high current impulse - some are
now rated at 9 Amperes or more.

The mounting techniques are of paramount importance.  It is essential
to use good RF construction procedures with all leads as short as
possible.  The gate driver and the MOSFET must be very intimately
located.

The Gate Driver chip must also have a good high quality capacitor
attached directly to it with very short leads to provide the gate
charge impulse - approximately 1.0 microFarad.

Bone up on how UHF power amplifier circuit boards are constructed
and laid out to optimize high frequency performance while minimizing
reflections which will produce standing wave interference.

Yes, it is possible to make your own.


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Hi all,

i did a quick replication of "groundloop's" circuit in reply #2, and i can confirm it does oscillate after some tweaking.

I used R=1K, C=1NF, toroid with 24 turns each and a MJE13007 transistor.
Instead of the 1n4148 diode i used a led to ground which lit up on the 4.6 VPP.

Here a short video from this setup:  http://www.youtube.com/watch?v=IXWWXZ7xDuM

I will do some additional tweaking / measurements. 

Regards Itsu.


Ltsu,

Thank you for replicating my circuit and welcome to the forum.

I'm not surprised that you had to use that low resistor value.
The MJE13007 needs a lot of base bias in this setup.

GL.
   
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Regardless of what anyone (paid disinformer, honest helpful experimenter, or otherwise) says to me, I'm going for the fastest rise time/fall times possible .  

Saving money is always nice though, and I welcome suggestions in that regard.   But from all the research and experience I have done in the past, the speed and performance of the switching and amplification circuitry is a critical variable in success of tapping anomalous electromagnetic behaviour.

The reason for this is that the sharp gradient is often necessary to modulate longitudinal waves -- also known as scalar waves.   Tesla discovered these waves over 100 years ago, and I have posted experimental proof for the existence of these waves here: http://www.overunityresearch.com/index.php?topic=754.msg11722#msg11722.  I want to experiment with extreme and unusual electrodynamic conditions in order to learn more about the universe -- specifically scalar waves -- learning on an experimental workbench, not from brand new textbooks written by corrupt institutions with political and monetary agendas.  

I have plenty of microcontroller experience, and have driven amplified MOSFETs in the past with crappy driver chips and got crappy results (piss-poor amplified waveforms).

I recommend anyone experimenting with square/pwm waves go for as FAST a risetime/falltime as possible, making sure to take into account propagation delay as well as MOSFET input capacitance in their frequency experiments.  Phase, frequency, flux, permeability, hysteresis , inductive coupling etc are also critical factors that need to be considered.   I will be building my equipment in this manner (going for the best performance for a given budget) and will be publishing all my research publicly.

Now that I've made it clear I will not be swayed from my conviction that risetime/falltimes are critical for square/pulse wave research,  for I moment I would like to discuss my preliminary experiment from earlier:

JOULE THIEF RESULTS:

Resonant Frequency: approx 8kHz
Loaded LED voltage: 3-4V P-P
Unloaded Resistor Voltage:  Up to 80V P-P , variable

I replicated the professors Joule Thief earlier , and I had interesting results.   Replacing the LED with a 5K variable resistor resulted in a 'sweet spot' of very dynamic change , as well as significant variation of the oscillation waveform, including amplitude, shape, phase, etc.   The waveform changed shape significantly on my oscilloscope, along with variations in frequency which were not as dramatic.  I will publish further results once I get my digital camera back.

As others have observed, Joule Thief is a very sensitive circuit to its local environment, so waveforms changes as the circuit was moved around physically, leads were touched with the body, etc.

FUTURE FAST GRADIENT RESEARCH:

Joule Thief aside -- It is imperative for square/pwm based scalar wave research to have the fastest switching speed, risetimes/falltimes etc as possible .  New experimenters -- do not let anyone tell you otherwise.  Two of the authorities on this subject -- SM and Bob Boyce -- have both stated risetime/falltime is critical.  You also want a crisp and clean a waveform as possible all the way up to your max VDS, with phase under complete and precise control for proper experimentation.  Sloppy amplification of waves is a recipe for crappy results.

In terms of inexpensive MOSFET drivers, I am looking at the following: (I've left out other important statistics to focus on switching speed.)

IXDD414 -recommended to me here on OUR  by a CTO of an energy technology company
(rise time 25ns , fall time 22ns , propagation delay 30ns)

FAN3228 - found these on digikey, and their specs seem to fit well with your standard IRF840, IRF820, IRF510 MOSFETS and related types.
(rise time 12ns , fall time 9ns, propegation delay 15ns)

UCC27322,UCC32322 - these were used by Bob Boyce in his HEX controller unit , which was successfully used for overunity experimentation with longitudinal energy  (rise time 20ns, fall time 20ns, propegation delay 25-35ns)

I have a list of datasheets I am considering, and I will be using cheap (yet fast) MOSFET drivers first as I scale up to the experimental hardware for high voltage 200V - 1000V amplified pulse wave research.   I have a 1kV regulated power supply with some HV capacitors, so there should be some interesting experiments here as well.

More Joule Thief results tomorrow..

   
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Feynman:

Quote
I replicated the professors Joule Thief earlier , and I had interesting results.   Replacing the LED with a 5K variable resistor resulted in a 'sweet spot' of very dynamic change , as well as significant variation of the oscillation waveform, including amplitude, shape, phase, etc.   The waveform changed shape significantly on my oscilloscope, along with variations in frequency which were not as dramatic.  I will publish further results once I get my digital camera back.

Sometimes it's wise to bite off a little bit at a time and digest that fully.  I am assuming that in your test above you are talking about looking at the JT output going into a variable resistor.  The setup still has an output diode which connects to the variable resistor and then to ground.

Here is my suggestion:  Instead of a variable resistor, how about you look at the waveforms for three different low-valued resistors.  I am not sure of the exact values, perhaps 100 ohms, 200 ohms, and 500 ohms.  Try something like that and look at your scope data and then formulate your conclusions and share them with us.  I hope that will be of interest to you.

MileHigh
   
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Hi all,

i did a quick replication of "groundloop's" circuit in reply #2, and i can confirm it does oscillate after some tweaking.

I used R=1K, C=1NF, toroid with 24 turns each and a MJE13007 transistor.
Instead of the 1n4148 diode i used a led to ground which lit up on the 4.6 VPP.

Here a short video from this setup:  http://www.youtube.com/watch?v=IXWWXZ7xDuM

I will do some additional tweaking / measurements. 

Regards Itsu.


Quite a dramatic first post, Itsu == good work and welcome to the forum!

I looked at your video and look forward to seeing your other videos as time permits.  Where did you get the toroid -- did you wind it yourself?
   
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Feynman:

Sometimes it's wise to bite off a little bit at a time and digest that fully.  I am assuming that in your test above you are talking about looking at the JT output going into a variable resistor.  The setup still has an output diode which connects to the variable resistor and then to ground.
[snip]
MileHigh

No, I'm quite sure Feynman did as I did and reported earlier, actually replacing the LED with a resistor.  I look forward to your scope screen shots, Feynman -- keep up the good work.

I like to see folks working with this JT circuit.  Lots of interesting stuff here...
   
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  Interesting result while adding a capacitor (different values) to the JT circuit in various places. 

An example is provided in the attached screen shots (again apologizing for the fuzziness of my little HP camera).  Note that I drew a line with a black non-permanent marker to help identify the ZERO for the green POWER waveforms ( V * I as explained above).  You see that in both Pin (first attached) and Pout that I have easily achieved the out-of-phase (OP) condition, as shown by both negative and positive output power.  And this is with an LED in place!  I will soon repeat this with a resistor replacing the LED (Not in addition to the LED, replacing).

I tweaked the input voltage until the Pin showed about equal positive and negative input (looking at AREAS above and below the zero line) -- best at this low voltage IN of 0.56 volts -- still oscillates (as you see from the waveforms).
So the mean Pin must be small.

 Then the Pout is mostly from the OP situation, that is, output voltage and output current out-of-phase.   And the positive and negative for Pout are not equal, from visual inspection.
 STrange but intriguing result...  I can hardly wait to get to the Tektronix 3032 and measure the MEAN Pin and Pout for this set-up...   in a couple of days I'll get back up to the University.

OK -- so where did I put the cap?  In this case, I used a 100 nF cap from the point between L2 (the feedback loop) and the 500 ohm resistor going to the transistor base -- connecting the Cap on the output side, that is, across both the LED and the transistor.
   

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Hi groundloop,

thanks for the welcome.
I tried a BC547 transistor instead, but as it indeed needed less base bias, i did not manage to lit the led, varying the R between 1K and 1M.
Optimum was around 330K.  Perhaps i need to vary the C as well.
So the MJE13007 was not such a bad pick i guess.


Hi PhysicsProf,

I got the toriod "as is" from our local dumpshop, see this link:

http://www.baco-army-goods.nl/componenten-elektronica-onderdelen/ferriet-en-ontstoorspoelen/ferriet-ringkern-met-spoel.html

Sorry for the Dutch, but it probably comes from some PC power supply vendor.
It reads "Ferrite toriod with coil", and mentioned the inductance as 2x 4mH (confirmed by my measurements).
Also the dimensions are mentioned (outsite D 32mm, inner D 18mm, thick 13mm).

I just build a joule thief with a similar toriod as above, and will start measuring/experimenting with it now.

Regards Itsu.

« Last Edit: 2011-03-14, 22:09:17 by Itsu »
   

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I replicated the LTJT2 as being used by PhysicsProf, but with these differences:
transistor is a BC547, toriod with L 7,2mH (both), outer d:37mm, wire:0,8mm 40 turns each.
The video of this setup/measurement is here: http://www.youtube.com/watch?v=BS8XpOY3bLg

The values measured were:

Pitotal  = Mean(V1*V2) = 1.291 * 0.021 = 0.027111
Pototal = Mean(V3*V2) = 1.272 * 0.021 = 0.026712

So,  n = (Pototal/Pitotal)x100% = (0.026712/0.027111)x100% = 98.5%

Not bad for an initial run, but no breakthrough.
I will do some tweaking/tuning with C's.

Regards Itsu

   
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