Joule Thief 101

[tinman]

Yes, that pretty much confirms that your Joule Thief circuit is running in some wonky spastic oscillator mode.  The observed pulse is a mere five microseconds which is way too short.  The transistor is supposed to be ON both before and after the LED ON pulse, and we can clearly see that the transistor is OFF before and after the LED ON pulse.  So you are absolutely running in some wonky spastic oscillator mode.  You failed to get the circuit to run properly, and your own expanded scope trace is clearly showing you that the circuit is failing to operate like it is supposed to and yet you gloat.  The problem is right in front of your face and you don't even see it.

It's just one never-ending "Keystone Cops" misadventure with you.

What is really happening in your clip?  I can tell you on a top-level without digging into the nuts and bolts of the circuit operation.  The potentiometer is acting like a frequency adjustment for your wonky oscillator.  As the frequency lowers, you can see the duty cycle for the LED ON vs. OFF does not change.  So with a lower frequency, presumably there is more time for current to build up in the main L1 coil, and therefore you get a higher peak current through the LED and therefore a brighter LED, although the duty cycle does not change.

So it's the potentiometer acting like a frequency control, giving the main coil a longer time period to energize and build up current, that results in the LED getting brighter.  That has nothing to do with the normal switching operation of a Joule Thief.

The clip is a farce.

MileHigh

You truly are lost MH.
The circuit is running quit fine,and nothing out of the ordinary is going on.
We have the needed 800mV switching on the transistor cleanly--see scope value's.
We have the needed 2.6+ volts to light the LED--see scope shot below.

You think something is wrong because we do not have nice square edges like Mags has in his scope shot?--laughable 
You really have no idea as to what you are looking at-do you .


Brad

[tinman]

So the parts are assembled and the system is brought into run in a fashion that you did not expect,,

Just because something CAN do something does not mean it MUST do something and just because something DOES something does not mean you MUST use it,,,

MH is lost-that much is clear.

The only time he likes what you do,is when it is in agreeance with his statements,and the way he thinks things work--that is the only time he will be happy.

He knows he has been caught out again,and he is now looking for anything that will distract from his mistakes.
In the next video,i have cleaned the test setup up,and he simply will not be able to deny that what i said is fact.

He seems to think that every JT circuit made should show exact same result's. But even a different LED,different windings,and different sized cores will show different result's.
He is lost as to why my JT is running at around 20KHz,and Mags was running at only 4KHz--my frequency is far to high !apparently! lol,but to me,it seems quite low.

Anyway,we will continue on with the testing.


Brad

[tinman]

Quote from MH

You have a pretty big toroid so why is your setup running somewhere between 20 kHz and 30 kHz when Magluvin's ran at 4.2 kHz?
Look at the crappy zoomed-out waveform capture from your clip

Did you take note of the supply voltage MH when i was shooting that clip?
See anything familiar in the two scope shot's below?
Wonder what would happen to Mag's wave form and light output if he reduced his base resistance?.
Oh,and dont forget to take a peak at Mag's frequency value while your at it.

Like i said--you just do not understand how JTs operate--and that much is very clear.

[MileHigh]

You truly are lost MH.
The circuit is running quit fine,and nothing out of the ordinary is going on.
We have the needed 800mV switching on the transistor cleanly--see scope value's.
We have the needed 2.6+ volts to light the LED--see scope shot below.

You think something is wrong because we do not have nice square edges like Mags has in his scope shot?--laughable 
You really have no idea as to what you are looking at-do you .

Brad

That's it Brad, be a clown one more time and make a fool of yourself and show the world that you have no idea what you are looking at and no idea what you are doing.  Your Joule Thief isn't even running properly therefore all that you can do is generate junk data but don't let that stop you.  Just plow forward in a grotesque display of willful ignorance.

Take a look at the three attached scope shots and bathe in your foolishness and wilful ignorance.

[MileHigh]

That's it Brad, be a clown one more time and make a fool of yourself and show the world that you have no idea what you are looking at and no idea what you are doing.  Your Joule Thief isn't even running properly therefore all that you can do is generate junk data but don't let that stop you.  Just plow forward in a grotesque display of willful ignorance.

Take a look at the three attached scope shots and bathe in your foolishness and wilful ignorance.

I am going to have to take my statement back and qualify it.  On closer inspection of your scope shot I can see that indeed the base waveform is showing that the transistor is ON and you are correct that the level is 800 mllivolts.

What are the root causes of the misunderstanding?  The first is that I wasn't observant enough to see the fact that in your close up shot that the trace is just hugging a point above the zero volt line.  I thought it was zero volts, not hugging just above zero volts.  A not too distant second factor is that your presentation skills are generally very poor and it's easy to get thrown off because of that.  A third factor is in your original clip it looks like a zero-volt baseline with a big positive spike - sloppy presentation and poor communication skills come back to haunt you.

However, you still have a problem and it could be related to the low voltage of the battery and loose wiring.  In Magluvin's capture it takes about 30 microseconds for the LED to discharge and it runs at 4.2 kHz with a total period of about 238 microseconds.  There is no reason that your setup shouldn't have comparable timing.  You are supposed to get a nice clean "crisp" set of waveforms like in Magluvin's capture.

MileHigh