Author Topic: Joule Thief 101 (Read 940681 times)

seychelles · « **Reply #300 on:** February 17, 2016, 01:13:40 PM »

NOW THAT IS WHAT YOU CALL A REAL JEWEL THIEF MILE HIGH.

tinman · « **Reply #301 on:** February 17, 2016, 01:18:02 PM »

Quote from: seychelles on February 17, 2016, 01:11:17 PM

NOW NOW YOU HAVE BEEN A BAD BOY AGAIN MICROM LOW.. I TOLD MY MOTHER IN LAW ABOUT YOU ML.

Dude--really

Could we maybe remove that post and image ?

Cheers

Brad

MileHigh · « **Reply #302 on:** February 17, 2016, 01:18:11 PM »

Quote from: tinman on February 17, 2016, 01:02:43 PM

I have proven that your videos and explanations are incorrect-others will see this MH,so why try and deny it?.
Speaking of all talk and no action-->where are your JT video's MH ?,i cant seem to locate them

It is very clear who is all talk,and who is all action around here MH-->can you guess what one you are?

So far,i have 377 video's up on youtube of my various projects. This of course dose not reflect the time taken to design and build each project. Then there is the time to shoot each video,convert it to a Jpeg format,and upload to youtube. How many hours in total do you think i have spent doing all this MH,while you sit back in your arm chair,and play God.
Who is the talker,and who is the one performing actions?.

Brad

So you are just using a bunch of stalling and deflection tactics.

Apparently you can't explain to the readers how a Joule Thief works.

tinman · « **Reply #303 on:** February 17, 2016, 01:38:46 PM »

author=TinselKoala link=topic=8341.msg474430#msg474430 date=1455707224
I find this discussion highly amusing. Because you're both right, and you're both wrong, about the same and different things. The blocking oscillator is the key.

Quote

One thing I haven't seen mentioned yet (as far as I remember) is transistor saturation. TinMan's circuit (the SSG one with the pot) is a good one to demonstrate what happens when the base is overdriven higher than the collector. The system can stop oscillating because the transistor stays off (Vb too low) or because it stays on (Vb too high).

The 2n3055 is a very robust transistor,and very forgiving as well. As you can see in my last video,the base voltage is 3 times that of the collector voltage,and it still keeps on oscillating quite fine,even with a duty cycle of around 70%--way to high i know.

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And all 2n3055s are not created equal... this is an extremely common transistor to be "faked" by unscrupulous Chinese sources. Performance varies wildly.

The one's i am using start to conduct with a base voltage of 692mV--so very close to the stated 700mV

Quote

The 3055 transistor is "kicked" into oscillation in the first place even though the voltage supplied seems too low, by ... wait for it... .stray capacitance.

I actually have to start mine by a quick shorting of the emitter/collector junction,as there is very little stray capacitance in this simple circuit.

Quote

Once it starts oscillating, then it's getting plenty of base voltage because of the 8:1 transformer.

Indeed,and the very reason for the 8:1 ratio. This circuit is designed to run at very low input voltages. It will still light the LED at 170mV--not bad for a big metal can transistor.

Quote

The last two variants (LEDs connected "across coil" vs "C to E") that TinMan shows are also the same as those shown by Mags back up in the thread as "wrong" and "right" except that the SSG coil connection is used rather than the center-tapped "standard" version. A blocking oscillator by any other name is still a blocking oscillator.

In my last video,i have the LED across the base/emitter,and this is a far more efficient JT than the standard version. The flyback from L2 is a good way to drive the LED,it lowers current draw,and increases light output from the LED.

tinman · « **Reply #304 on:** February 17, 2016, 02:29:15 PM »

Quote from: MileHigh on February 17, 2016, 01:18:11 PM

So you are just using a bunch of stalling and deflection tactics.

Apparently you can't explain to the readers how a Joule Thief works.

Well i was waiting to see one of your JTs in action MH,but i believe the cobwebs would take over first

Which one would you like me to explain,and do i have to explain your JT circuit after countless pages of getting you to see how it actually work's--which is not by way of the battery switching on the transistor as you claimed by way of video's and documented writings.

My JT circuit operates in a different manner to your JT circuit MH,as my two windings are parallel,and not crossed over like your JT circuit has them. You see,the current flow in my L! and L2 is in the same direction when the magnetic field collapses,where as the current flow in your L1 and L2 is in opposite directions when the magnetic field collapses. As you seen in my last video,when the transistor switches off,both L1 at B+, and L2 at the base both go negative,and so cannot switch the transistor on at that point like your JT circuit dose. So what triggers the initial switching of the transistor,so as the 8:1 winding ratio can kick in,and switch on the transistor hard?. Where could there be a higher voltage potential being stored for the initial switch on of the transistor,due to our very low supply voltage of only 250mV ?.
Im just seeing if your on the ball MH,and not just going to go and have a googlegasm,and post more incorrect information,as we have just all been witness to.

We have not yet covered junction capacitance,and as you refuse to believe that the circuit is actually an RLC due to this transistor junction capacitance,then there really is not much point in going into it--is there?. But i will give you a little information MH. The BC junction output capacitance for the 2n3055 can be as high as 700pF at frequencies 0 to 100KHz,with voltages up to 10 volt's.

Brad

tinman · « **Reply #305 on:** February 17, 2016, 02:51:05 PM »

Quote from: hoptoad on February 17, 2016, 12:29:00 PM

The problem with your explanation for the specific alternative circuit shown by Tinman, is that , at turn on, no current can flow through the collector junction until the base has been turned on, and by your explanation the base cannot turn on, because no current is induced into the coil that feeds, because no current can flow through the collector coil while the collector junction is open, until the base turns on.

There is no direct source voltage coupling to trigger the base because there is no direct DC connection to the base, only an inductive connection which requires current through the collector coil. A severe case of chicken and egg, unless their is something else in the circuit momentarily allowing the base to initially trigger. That initial trigger mechanism lies in the tiny capacitance in the transistor junction.

Cheers

Thank you Hoptoad.
It is good to see some one is on the ball here.
The 2n3055 BC capacitance can get as high as 700pF. This is more than enough to start the transistor conducting.

Internal capacitances are due to the storage of charge at the PN junction's. These PN junctions act just like the plates of a capacitor,where in they can store charge. This stored charge is enough to trigger the transistor when in circuits like my cool joule circuit. This is where the miller effect kicks in,and this stored charge is what switches the transistor on. This charge exist weather or not the transistor is being pulled on harder by a second current input source--such as MH JT circuit. This is the C in the LRC circuit--it exists,and is there.
There is junction capacitance,and diffusion capacitance.
Junction capacitance-where the charge is stored in the depletion region of the PN junction.
Diffusion capacitance--quote wiki: Diffusion Capacitance is the capacitance due to transport of charge carriers between two terminals of a device, for example, the diffusion of carriers from anode to cathode in forward bias mode of a diode or from emitter to baseforward-biased junction for a transistor.
We do not have to worry to much about diffusion capacitance with everyday JT circuit's.

Brad

MileHigh · « **Reply #306 on:** February 17, 2016, 02:51:28 PM »

That's a complete and total fail Brad. No bait and switch. Why would a few hundred picofarads of capacitance affect anything? It's just a rhetorical question.

Just explain to the readers how an ordinary Joule Thief actually works. How does the timing work and how does the switching work?

The floor is yours.

MileHigh · « **Reply #307 on:** February 17, 2016, 03:28:01 PM »

Post #288 was edited and text was added in bold to address some of Brad's "objections."

Brad, in the last four or five postings you have dropped the line that you have "corrected my mistakes."

I already addressed this issue in an earlier posting when I said this, "So you are taking a counter-measure strategy where you are doing a "play." The "play" is to try to feign that I am the one that doesn't understand what is going on, so you are asking me questions. The backdrop to all of this is that I have been around long enough so that you, and nearly everybody else watching, already has a very decent idea what my knowledge level is."

So don't try to "play" me. Just get on with it and explain to the readers exactly how a regular Joule Thief works with no muss, no fuss, no misdirection, no bait and switch, no "plays," and no shenanigans.

The floor is yours.

tinman · « **Reply #308 on:** February 17, 2016, 03:45:17 PM »

Quote from: MileHigh on February 17, 2016, 02:51:28 PM

The floor is yours.

That junction capacitance is enough to make the transistor switch on,and a circuit to oscillate,where there is no inductive coupling between L1 and L2. Myself and many others have proven this,and was also confirmed by MarkE,and worked out by Vortex1. Are you going to argue with all them MH ?--i didnt think so.

Quote

Just explain to the readers how an ordinary Joule Thief actually works. How does the timing work and how does the switching work?

I have given you two examples of ordinary JT circuit's,that have different operating parameters.
But before you burst a bubble,i will give a quick and simple rundown on the one below--seen as you like it so much. Why im doing this again,i do not know,because we have just spent the best part of 3 days trying to get you to describe the correct switching and operation of the JT circuit you provided.
What do you mean by timing MH ?. If you are referring to frequency,on times,off time's ETC,how can i possibly do that from a picture?. Where is all the information needed to calculate this?--battery voltage,torroid size and grade.wire size and type-ETC ?.
Or,if by timing,you mean how each event takes place for one complete cycle,then that is much the same as how it work's-is it not?.

Before i can give an accurate description of the operation MH,i will need you to provide some information on your transistor. I need to know the required base current and voltage for the transistor to start conducting. Without that,there is no way of giving an accurate operation description,as it can go two way's,and this depends the required current and voltage needed at the base to switch the transistor on. Even if we have the full 1.5 volt's on the battery,the base of the transistor will only receive a maximum current from the battery of 1.5 mA. So for example,if the 2n2222 needs 2mA of current at the base to switch on,then we need a 2v battery-which we do not have. So this would in turn drop the available base voltage down--see what i mean. So i need the required base voltage and current to switch on the 2n2222 transistor. Once you give me that,then i will provide the operation description you so much require.

Brad

MileHigh · « **Reply #309 on:** February 17, 2016, 04:00:56 PM »

Brad:

If you really believe that the transistor junction capacitance is relevant, then put it into your description. The schematic shows a 1K base resistor and a 2N2222 transistor but that is not even relevant to the discussion. Nor are the specifics of the toroid and the windings truly relevant to the discussion.

So don't get hung up on the details and use that as an excuse. Or if you insist that you need these kinds of details (which you don't) then put in some reasonable values by yourself.

Descriptions of how circuits operate are done without needing to have component specifics all the time. You saw how I posted three descriptions of how a Joule Thief operates and there were no component specifics.

I am looking forward to reading your complete description of how a standard Joule Thief works.

MileHigh

Magluvin · « **Reply #310 on:** February 17, 2016, 06:23:36 PM »

Ive figured that the shorted winding just causes the inductance of the primary and trigger windings to be much lower than without the shorted winding.

In a normal say 60hz transformer, if we short out a winding it causes the primary to pull lots of current from the source. But here it is different because the operating freq of the JT depends on the reactions in the transformer, and with the shorted winding the drive coils inductance is lowered and the circuit self adjusts to operate at a much higher freq. But with a normal 60hz transformer, the input doesnt change so the input current rises hard.

Got the thing to get up to 2.5mhz but at that point the led is fairly dim. Havnt seen any resonant nodes so far. I tried some caps on the 3rd coil and there seems to be certain band widths that the led jumps to a decent brightness and jumps back down when out of that band width. But nothing brighter than normal running.

Id like to make a new thread to work on JT mods experimenting with resonance, but I dont want it to become a thread like this one has become in the past days. And there are sooo many JT threads that Im not sure another should be made. Stumped on that idea. If I title the thread for JT Mods Experimenting with resonance, then there shouldnt be any bickering about resonance because the thread should be about how to get the JT to have resonance. But I dont believe that would be enough to keep the thread on target.

Still fiddling with it.

Mags

Pirate88179 · « **Reply #311 on:** February 17, 2016, 08:40:52 PM »

Quote from: Magluvin on February 17, 2016, 06:23:36 PM

Ive figured that the shorted winding just causes the inductance of the primary and trigger windings to be much lower than without the shorted winding.

In a normal say 60hz transformer, if we short out a winding it causes the primary to pull lots of current from the source. But here it is different because the operating freq of the JT depends on the reactions in the transformer, and with the shorted winding the drive coils inductance is lowered and the circuit self adjusts to operate at a much higher freq. But with a normal 60hz transformer, the input doesnt change so the input current rises hard.

Got the thing to get up to 2.5mhz but at that point the led is fairly dim. Havnt seen any resonant nodes so far. I tried some caps on the 3rd coil and there seems to be certain band widths that the led jumps to a decent brightness and jumps back down when out of that band width. But nothing brighter than normal running.

Id like to make a new thread to work on JT mods experimenting with resonance, but I dont want it to become a thread like this one has become in the past days. And there are sooo many JT threads that Im not sure another should be made. Stumped on that idea. If I title the thread for JT Mods Experimenting with resonance, then there shouldnt be any bickering about resonance because the thread should be about how to get the JT to have resonance. But I dont believe that would be enough to keep the thread on target.

Still fiddling with it.

Mags

There is no resonance in a JT circuit.

Yes there is.

No, there isn't.

Yes there is.

No, there isn't.

Is too.

Is not!

Too!

Not!

Mags, that is what your topic would look like.

Bill

tinman · « **Reply #312 on:** February 17, 2016, 09:11:39 PM »

Quote from: Magluvin on February 17, 2016, 06:23:36 PM

Ive figured that the shorted winding just causes the inductance of the primary and trigger windings to be much lower than without the shorted winding.

In a normal say 60hz transformer, if we short out a winding it causes the primary to pull lots of current from the source. But here it is different because the operating freq of the JT depends on the reactions in the transformer, and with the shorted winding the drive coils inductance is lowered and the circuit self adjusts to operate at a much higher freq. But with a normal 60hz transformer, the input doesnt change so the input current rises hard.

Got the thing to get up to 2.5mhz but at that point the led is fairly dim. Havnt seen any resonant nodes so far. I tried some caps on the 3rd coil and there seems to be certain band widths that the led jumps to a decent brightness and jumps back down when out of that band width. But nothing brighter than normal running.

Id like to make a new thread to work on JT mods experimenting with resonance, but I dont want it to become a thread like this one has become in the past days. And there are sooo many JT threads that Im not sure another should be made. Stumped on that idea. If I title the thread for JT Mods Experimenting with resonance, then there shouldnt be any bickering about resonance because the thread should be about how to get the JT to have resonance. But I dont believe that would be enough to keep the thread on target.

Still fiddling with it.

Mags

Moderate your thread mag's,and just remove the junk.

Brad

sm0ky2 · « **Reply #313 on:** February 17, 2016, 09:44:58 PM »

Quote from: TK

The 3055 transistor is "kicked" into oscillation in the first place even though the voltage supplied seems too low, by ... wait for it... .stray capacitance. Once it starts oscillating, then it's getting plenty of base voltage because of the 8:1 transformer. Again, this effect may be easier to see with other transistors, which will need more stray capacitance to start oscillating (like by touching the Collector or Emitter lead with a finger or a small cap lead.) And all 2n3055s are not created equal... this is an extremely common transistor to be "faked" by unscrupulous Chinese sources. Performance varies wildly.

Quote from: MileHigh on February 17, 2016, 12:34:02 PM

TK:

Nope, see my previous posting. The transistor is initially "kicked" on by pure transformer action. There is a regenerative cycle (positive feedback) to turn the transistor ON, and a regenerative cycle (positive feedback) to turn the transistor OFF.

Brad, the floor is yours.

MileHigh

You are both correct from different perspectives, in that the feedback IS related to a stray capacitance value.
And while a "current" cannot be measured prior to the transistor switching on, there IS a voltage induced at the base of the transistor.

sm0ky2 · « **Reply #314 on:** February 17, 2016, 10:18:30 PM »

unfortunately Bill speaks the wisdom of the ages.

Even if you stated resonance as a prerequisite of experiment,
there would still be those that subject the topic to conjecture, and disinformation.
(I think I may have attempted that at one time, when I was less articulate in discussions of this topic)

I can give you a (generic) set of guidelines, that may vary slightly, depending on the particulars of your design.
That may help identify if your particular circuit is able to converge with resonant nodes of the various parts of the circuit.
an "ideal" situation would be to have every component, and every portion of the circuit at resonance,
however, this is sometimes more difficult that I made it seem in the words of my previous posts.
Mathematically, we can see how this is done, as I have shown.
But in reality, even the tiniest resistances and capacitances from our wiring can change the resultant frequency node, and where it lay on the scale of frequencies the device can operate at.

this is why I recommended using your oscilloscopes

It simplifies the whole ordeal because (provided your scope is of quality) the mathematics are performed for you by the machine.

I recommend starting with the standard setup, (LED in either location), the only modification is the use of a VR instead of the set resistance at the base of the transistor.

1) The first step should be taking the transistor out of digital mode. With a scope across the Emitter and the center tap of the coil,
adjustments are made to the base resistor until this signal closer resembles a sine-wave, than a sharp peak and long slope.
There is a range in which this occurs, depending on the transistor, this can be a very small range in resistances.
The actual frequency data is available from the manufacturer, labeled: linear mode, or linear freq range, etc.
to give you a guideline of what you are looking for.

2) expand your scope image, so that you can see the fluctuating details within the signal. You don't need to go TOO deep, just enough that the little spikes and whatnot are visible to you on the screen.
Now, within the range of step 1, so that you don't throw the switch back into digital mode, make adjustments to the base VR,
to attempt to locate nodes that clean up the spikes, a smoothing effect will occur, and you may notice certain of those little spikes getting larger. (this looks like a problem, but let it be, it actually raises the RMS of the total signal amplitude)
What you are doing here, in a sense, is reducing the amount of conflicting feedback, that damages the quality of the signal.
Or as I state it: bringing the system closer to a "total circuit resonance".
or minimizing destructive interference.

3) Pay close attention to the quality of your coils, not just the number of turns, but where the first and last turn begin and end, as well as the straightness of the wire and spacing between coils / slope.
This may seem trivial, but when you examine what this does to the circuit, imperfections create variances in capacitance and inductance along the length of the coil. This can destroy some of the effects of positive feedback.

There are more, most of which I have already gone over last week, so will not regurgitate here.
But an important thing to remember, about resonance:
Your scope is your friend, scoping multiple parts of the circuit and comparing changes in one, to changes in the other.
This will assist in identifying destructive interference (negative feedback), and otherwise signal disrupting events occurring within the circuit.

Quality is important, not just peak values.
resonance has pure qualities, an inverse or reflection of itself.
anything other than that is disruptive.

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Author Topic: Joule Thief 101 (Read 940681 times)

seychelles

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