Joule Thief 101

[tinman]

Brad:

This is quickly approaching a dead end.

You said this:

The first scope shot is of your death spike.
The second scope shot is showing the trace over a 1 ohm CVR at the collector.

I responded with this:

The cycle time is 75 microseconds for one trace (spike) and 60 microseconds for the second trace (collector). 

Your response was this:

Essentially everything in that response is wasted energy, a bunch of mush.  The reason it is mush is because you did not make the connection between "death spike" and "spike" and "CVR at the collector" and "collector" and you are talking about something completely different.

The gross difference in periods between the two captures suggested to me that your circuit had changed or the scope probe was changing the circuit frequency though loading.  Incidentally, putting the scope ground on the transistor collector node is a somewhat bizarre thing to do.  But of course you didn't even mention the different periods or different voltages when you posted the captures and only after the fact did you mention that the battery voltage was significantly different between the two captures which explained the different frequencies.  It's mass confusion.

It's exhausting and it never ends.

MH
As I stated, the spike shot was across the 1k resistor on the base. This makes it a current source. This voltage will come after voltage seen across the inductor.
The second scope shot is as per schematic attached to that scope shot.

The point of the test was to show you that there was no current flow through the collector during the off time of the transistor.
I am also confused as to why or how you went from emitter/base junction breakdown, to collector/base junction breakdown. Just out of the blue, you make this switch, and I was doing my best to check your claim, and try to work out where this switch came from.
I then spent more of my time tracing back through the thread, trying to find some posts I must have missed by PW.
I still have no answer from you for the reason for the switch from emitter/base breakdown, tocollector/base breakdown.

You asked Chet to complete the current path due to this collector/base junction breakdown, and you abused me for saying it is non existent.

So please tell me what I am suppose to see at the collector during the off period of the transistor.?


Brad

[tinman]

I am at work ATM, and will not know the below to be true until I get home, and carry out further test.

After thinking about it for some time, I believe the reverse voltage spike seen across the base resistor---is a phantom voltage, and no actual current is flowing through the resistor as the scope may suggest.
It is either due to the miller effect between the base/emitter or base/collector junction, that make the actual value look much larger than it is.
The second possible explanation is as PW said--there is some sort of capacitive conection with the scope and leads.

All this can be checked  using my FG to simulate the pulses across the 1k resistor.


Brad

[sm0ky2]

https://www.youtube.com/watch?v=K53beWYdIpc

How to make an authentic Joule Thief. By BigClive


Clive is the guy that coined the term Joule Thief way back when and here he shows how to make a "real" one.


Bill

PS  He also gives a detailed explanation on how the circuit works.

Thanks Bill

I don't know how much you remember of this, but we were playing with this circuit, prior to the 1999 magazine article.
What was sent to the magazine, and later became the "Joule Thief",
is a variant of BruceTPU's oscillator circuit.

I think you were there for that. '97 maybe?

[sm0ky2]

Brad:

Why do you say such nonsensical trash talk idiocy like the comments about voltage leading current?  Why do you lower yourself into the gutter and make such a fool of yourself like that?  It just destroys your credibility and why should anybody trust you for anything when you play ridiculous mind games like that?  It feels like a crank call from a 12-year-old sometimes.

I never said anything about the time bases being different.  Brain ricochet!  I asked you why the periods are different and you did not offer up any kind of real explanation.

I am getting exhausted with the stream-of-consciousness/churning spaghetti/brain-ricochet talk from you.  It's like you need a bloody Google translator just for you.  Throw in the ridiculous immature trash talk that is embarrassing and you are left with Dr. Brainfry on overload.  Perhaps later I will try to deal with it but not now.  I get a headache just thinking about it.

MileHigh

this is the kind of nonsensical argumentation that I am talking about....

You could have just as easily stated that it is the current that leads the voltage,
then explained why.

I think that would be the more productive approach.....

[wattsup]

@tinman

The scopes of base/collector junction show 20 something volts so one side of the scope probe (ground or probe) had to receive 0 volts (or near 0) while the other side had to receive the higher volts to produce that scope shot. So where did that 0 come from while the transistor is on (closed).

As per my last post, can you please as per your test "explain 2.JPG" where you have the cvr placed between the collector and L1, now try it with the cvr between the emitter and ground. That's the one I want to see and maybe even you too. Then put the cvr between the LED ground and ground and do it again. If you can do that, it will help explain this circuit.

So in essence the present location of the LED is the main bummer in this circuitry always bleeding and not helping to find the real (stabilized) circuit effect because it is placed parallel to the collector/emitter.

Here is a curiosity? Try repositioning the LED between L1 and the collector. Since the LED would require a ground from the collector, what will happen? Will it light or not? I can get into more detail showing the actual circuit flow with dots, if these tests can be done. The "effect pattern" because it is not really a "flow pattern", because there is not really any flow, should marry perfectly to the scopes wave pattern.

Then, for more confirmation try with the LED between the emitter and ground and this will show if positive will now pass the transistor when it is on. The LED is good because it can delimit up to where the negative can reach before it is consumed with the positive from the other side.

The final test is across the L1 to provide the full effect during those pulses. With these I can draw out the effect patterns to match the wave forms and it will amaze you to know what is really happening in that circuit. No EE Kool-Aid but fully logical and fully provable.

@MH

EE Kool-Aid is fine for our day to day toys but for OU we need something better. Better tasting, more nutritious and no additives. The Kool-Aid is stunting our growth where growth is required to pass to the next level. Otherwise, maybe you can find a better way to advance but downing jugs of Kool-Aid all day will not do it.

Also, I think your free attacks on @tinman are highly unwarranted and will soon approach some level of indecency. Best you stop it. We are all in the same damn boat. All a bunch of ignorant assholes, all of us trying to cope with both observation and logic. Your logic is not God given, it is man derived and thus highly fallible. The day you accept it is the day you will advance as well. If you don't think @tinman has a shred of credibility here, then why waste your time? This one little furty circuit could help learn mountains of information but only if you ask the right questions.

wattsup