Author Topic: Joule Thief 101 (Read 944412 times)

Magluvin · « **Reply #1080 on:** March 23, 2016, 02:34:11 AM »

In fact, no led at all, 114v across EC. 33ohm resistor.

Mags

picowatt · « **Reply #1081 on:** March 23, 2016, 02:36:37 AM »

Quote from: tinman on March 23, 2016, 12:34:48 AM

The reduction in base current increases pulse width,and increases LED light output

In your video, it appeared that increasing the base current increased the on time pulse width. Perhaps you misspoke.

Note that a bipolar transistor is a current operated device. The forward voltage of the base emitter junction is typically one diode drop (600 to 800 mv for silicon) and varies only slightly as base current is changed (or junction temp varies).

In your video, we might "assume" that the base current increases as you decrease the value of the potentiometer connected to the transistor's base. However, because the base voltage remains constant, there is no way to see (or know) what change is actually occurring to the base current as you adjust the pot with the tests you made in the video.

Just like measuring any other current with a 'scope, to measure the base current you need to measure Vdrop across some kind of CSR and then calculate the current (or use a current probe).

For example, you could preset the pot to 1K and then use both scope channels to measure the Vdrop across the pot and then calculate the base current using Vdrop and the 1K value. You could then preset the pot to 500R and repeat the measurements and calculation. You would then know the base current for those two base resistances at the given battery voltage.

PW

picowatt · « **Reply #1082 on:** March 23, 2016, 02:57:32 AM »

Quote from: sm0ky2 on March 22, 2016, 11:41:26 PM

Taking note of the frequency at the bottom of your scope,

Do not confuse a waveform's repetition rate with its frequency content.

Although Tinman's video shows a waveform repeating at around 31KHz, it is obvious from the observed rise and fall times that the waveform contains frequency components out to 200KHz or more.

This confusion seems to happen quite frequently, as in this example with regard to the coil's SRF, or as occurred further back in this thread with respect to discussions of "subharmonics" and the "pushing a swing" analogy.

PW

tinman · « **Reply #1083 on:** March 23, 2016, 10:33:52 AM »

Quote from: picowatt on March 23, 2016, 02:36:37 AM

PW

Quote

In your video, it appeared that increasing the base current increased the on time pulse width. Perhaps you misspoke.

Yes-it was suppose to read reduction in base resistance= an increase in base current.

Quote

In your video, we might "assume" that the base current increases as you decrease the value of the potentiometer connected to the transistor's base. However, because the base voltage remains constant, there is no way to see (or know) what change is actually occurring to the base current as you adjust the pot with the tests you made in the video.

Not entirely correct.
As the current flow in L1 is set once the transistor is fully switched on,then the only way the LED can receive more current from the inductive kickback is by way of a stronger magnetic field being produced during each on time pulse,and as L1's current is set,then the only way to increase that magnetic field is by way of L2. For this to happen,then L2 must be receiving more current flowing through it,and we know this would be the case if we reduce the base resistance value..

Quote

Just like measuring any other current with a 'scope, to measure the base current you need to measure Vdrop across some kind of CSR and then calculate the current (or use a current probe).

I would do this,only MH had issues with the fact that i had a CVR in my first test setup,and so he said it was not a JT circuit-->it is hard to please everyone

Quote

For example, you could preset the pot to 1K and then use both scope channels to measure the Vdrop across the pot and then calculate the base current using Vdrop and the 1K value. You could then preset the pot to 500R and repeat the measurements and calculation. You would then know the base current for those two base resistances at the given battery voltage.

I would be happy to put a 10ohm CVR inline with the 1kVR,and we could get a clear picture of the current flow through to the base. But as i stated above MH had a tanty,and said by having the 10OHM CVR in the circuit,it was no longer the JT circuit. This just gives him room to make more dismissive comments,so i stuck with the basic circuit in the first test.

Now that i have proven my point,then i will be doing such test,so as we can see everything that is taking place with the reduction of the base resistance.

Brad

picowatt · « **Reply #1084 on:** March 23, 2016, 10:56:40 AM »

Quote from: tinman on March 23, 2016, 10:33:52 AM

Yes-it was suppose to read reduction in base resistance= an increase in base current.

Not entirely correct.
As the current flow in L1 is set once the transistor is fully switched on,then the only way the LED can receive more current from the inductive kickback is by way of a stronger magnetic field being produced during each on time pulse,and as L1's current is set,then the only way to increase that magnetic field is by way of L2. For this to happen,then L2 must be receiving more current flowing through it,and we know this would be the case if we reduce the base resistance value..

Yes, one can "assume" that is what is happening and use what is observed as a proxy for base current. My point was that nowhere is base current itself being directly measured or observed in the video. As well, it is incorrect to state that you are varying the base voltage when adjusting the VR.

Quote

I would do this,only MH had issues with the fact that i had a CVR in my first test setup,and so he said it was not a JT circuit-->it is hard to please everyone

I would be happy to put a 10ohm CVR inline with the 1kVR,and we could get a clear picture of the current flow through to the base. But as i stated above MH had a tanty,and said by having the 10OHM CVR in the circuit,it was no longer the JT circuit. This just gives him room to make more dismissive comments,so i stuck with the basic circuit in the first test.

Now that i have proven my point,then i will be doing such test,so as we can see everything that is taking place with the reduction of the base resistance.

Brad

You originally used a rather large 10R in the emitter leg as a CSR for measuring emitter current. However, resistance inserted into the emitter leg will produce "degeneration" or "negative feedback" which effectively reduces the transistor's gain. If your goal is to stabilize the LED current as Vbatt varies, you might consider experimenting with increased degeneration (i.e., a larger emitter resistor). If maximum efficiency or minimum Vbatt operation is the goal, this would be less desirable. To measure emitter current, use of a smaller value emitter resistor is advised to reduce the effects of degeneration.

The base current, however, must be measured in the base leg circuit and does not require a separate CSR (although you could indeed use a separate 10R in series with the base as you suggest).

All you need to know is what the Vdrop across the VR is and the resistance value the VR is set to. The use of the separate 10R as a CSR as you suggest would, however, allow you to measure the base current real time without needing to know the VR's set value.

PW

tinman · « **Reply #1085 on:** March 23, 2016, 11:39:17 AM »

Quote from: MileHigh on March 23, 2016, 02:12:40 AM

The clip is a complete disaster and proves nothing.

MileHigh

The fact that you dont understand what is going on in my video,and what the scope is showing you ,is scary. Are you truly telling everyone here,that you cant work out if CH1 is inverted or not-->really

. Do you really not understand as to why there is a voltage spike across L1 when the transistor become's open?

Quote

Yeah, sure it was inverted.... or was it inverted? If it wasn't inverted, how do you get somewhere between a 10-volt and and 16-volt spike across a transistor base-emitter junction?

You dont.

Quote

If it is inverted like you claim then how do you maintain somewhere between 10 volts and 16 volts across a transistor base-emitter junction?

What do you mean maintained

. It is only there when the transistor becomes open. When the transistor is switched on,we have only the base voltage of 800mV

Quote

Look at the crappy zoomed-out waveform capture from your clip that isn't even capable of showing the waveforms properly because they are grotesquely undersampled and compare that to the nice clean scope capture that Magluvin did of a Joule Thief operating in normal switching mode with a nice zoom-in on the actual switching cycle so we can see what is going on. We are back in "communication-skills-issue-elephant-in-the-room" mode for you.

Perhaps you should take this up with Poynt,who taught me to fit as many samples as possible in the screen,so as to gain accurate measurement readings from the scope.
You are a big peanut--that's for sure.

Quote

You comment on the high-voltage spike in your clip and just walk past that totally wonky measurement like a zombie.

It is not a wonky measurement. It only looks wonky to you,because you cant work out what is going on,or why it is there

Quote

I can't be 100% certain from your foggy clip, but all of the indicators are pointing to the conclusion that your Joule Thief setup is running in wonky spastic high-frequency mode

For a start,the frequency is quite low for a JT circuit. Mag's has had his running up in the 100s of KHz range.

Quote

and the base-emitter scope channel is not inverted and there really is a super-high voltage spike across the base-emitter junction of the transistor.

Oh dear

Look at the spike from L1 that is driving the LED--dose that tell you when the transistor is off?
Look at the spike on the yellow trace--is that in line with the spike on the blue trace?
Dose this now tell you that the spike on the yellow trace is during the off time of the transistor?
Are you getting the idea now that the yellow trace is indeed inverted?,and why there is such a large spike on the yellow trace.
Are you learning now?.

Quote

Why would you even put your probe across the base-emitter junction when there is so much more information to be learned if you put your probe on the output of the feedback coil?

Why would we not include the VR,when it is the effect of the VR we are looking at?
Why do you jump in so quick,when you know there is more video's to come--hence the title has PT 1 in it.

Quote

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?

Well thats a stupid question if ever i have heard one.
Why dose my large car go faster than my neighbours small car?

Quote

That's what you get when your Joule Thief is running in some unknown spastic high-frequency mode.

Looks to be running quite fine to me. But i guess it may look strange to you,because everything is suppose to be just as you picture it in your head--hey MH

An odd comment from some one that dose not even have a JT,or has no idead as to how different transistors may make things operate differently.

Quote

In other words, your "demonstration" is a total fail and a miserable embarrassment considering the fact that you have been doing this stuff for six years.

I know you must be peeved MH,finding out you were wrong once again.
But i would think that the embarrassment you are feeling,is actually your own. I mean-not being able to tell if a channel is inverted or not,when you have a second channel showing you the off period of the transistor,must be a big blow for some one that prides them self in knowledge of the standard JT. Also not understanding as to why there is such a large spike at the base/emitter junction when the transistor becomes open,must also take a big hit on that pride of yours.

Then there is the fact that i have posted many video's-even on this thread,showing the LED being lit from the emitter/base during the off time of the transistor--but still you dont get it.

Face it MH,you have had another flop-->in many areas this time.

Brad

tinman · « **Reply #1086 on:** March 23, 2016, 11:50:30 AM »

Quote from: picowatt on March 23, 2016, 10:56:40 AM

Yes, one can "assume" that is what is happening and use what is observed as a proxy for base current. My point was that nowhere is base current itself being directly measured or observed in the video.

The base current, however, must be measured in the base leg circuit and does not require a separate CSR (although you could indeed use a separate 10R in series with the base as you suggest).

PW

Quote

As well, it is incorrect to state that you are varying the base voltage when adjusting the VR.

That is in relation to the switch on time between partially on and fully on. This is only during the lower supply voltage ranges,and is where the !transistor switching on harder! part of it was to come into play. As we know,the 2n3055 needs around 700mV to switch on fully,and if the battery voltage is down to around 400mV,then the transistor will be only partially on for a very brief moment until L1 starts to induce a higher current flow through L2. This i will show in the next video.

Quote

You originally used a rather large 10R in the emitter leg as a CSR for measuring emitter current. However, resistance inserted into the emitter leg will produce "degeneration" or "negative feedback" which effectively reduces the transistor's gain. If your goal is to stabilize the LED current as Vbatt varies, you might consider experimenting with increased degeneration (i.e., a larger emitter resistor). If maximum efficiency or minimum Vbatt operation is the goal, this would be less desirable. To measure emitter current, use of a smaller value emitter resistor is advised to reduce the effects of degeneration.

Yes,i understand this,but at these low power level's,a lower value resistor shows a very noisy trace on the scope. It was my intention to use a larger value in order to get a good clean trace on the scope for accurate measurements.

Quote

All you need to know is what the Vdrop across the VR is and the resistance value the VR is set to. The use of the separate 10R as a CSR as you suggest would, however, allow you to measure the base current real time without needing to know the VR's set value.

This is the plan for the next video.

Thanks for your input PW

Brad

tinman · « **Reply #1087 on:** March 23, 2016, 12:17:36 PM »

author=MileHigh link=topic=8341.msg478111#msg478111 date=1458695560]

Look at the crappy zoomed-out waveform capture from your clip that isn't even capable of showing the waveforms properly because they are grotesquely undersampled and compare that to the nice clean scope capture that Magluvin did of a Joule Thief operating in normal switching mode with a nice zoom-in on the actual switching cycle so we can see what is going on.

MileHigh

Whine ,whine,whine.

Below is the expanded view--of the same circuit running on a 600mV supply voltage.
Dose it look that much different from Mag's ?.
I have CH1 now around the correct way--just for you MH.
Dose it make sense now?--Is this good enough for you?
Is my circuit running in some sort of spastic mode-as you put it?.
Can you understand the high reversed voltage spike between the emitter/base junction now?

Is there anything else i can help you with?.

MileHigh · « **Reply #1088 on:** March 23, 2016, 01:40:15 PM »

Quote from: tinman on March 23, 2016, 12:17:36 PM

author=MileHigh link=topic=8341.msg478111#msg478111 date=1458695560]

Look at the crappy zoomed-out waveform capture from your clip that isn't even capable of showing the waveforms properly because they are grotesquely undersampled and compare that to the nice clean scope capture that Magluvin did of a Joule Thief operating in normal switching mode with a nice zoom-in on the actual switching cycle so we can see what is going on.

MileHigh

Whine ,whine,whine.

Below is the expanded view--of the same circuit running on a 600mV supply voltage.
Dose it look that much different from Mag's ?.
I have CH1 now around the correct way--just for you MH.
Dose it make sense now?--Is this good enough for you?
Is my circuit running in some sort of spastic mode-as you put it?.
Can you understand the high reversed voltage spike between the emitter/base junction now?

Is there anything else i can help you with?.

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

MileHigh · « **Reply #1089 on:** March 23, 2016, 02:02:48 PM »

Brad:

Quote

The fact that you dont understand what is going on in my video,and what the scope is showing you ,is scary.

More like after six years of bench experimentation and talking electronics, and trying to sound authoritative about the Joule Thief circuit, it's scary that you couldn't even build one and get it to operate properly. It's double scary that you didn't even notice or try to check to see if it was running properly. It's tripe scary that you gloat and insist that you got it right when it is painfully obvious that you got it dead wrong.

Quote

Perhaps you should take this up with Poynt,who taught me to fit as many samples as possible in the screen,so as to gain accurate measurement readings from the scope.
You are a big peanut--that's for sure.

Put your brain in gear and make the proper decisions to present your data properly and make a conscious informed intelligent decision for when to look at multiple cycles for better averaging, and for when to look at a close up of a waveform.

What you should do is back up and get your Joule Thief to work properly before you do anything else. The long lengths of wire coming off of the toroid are probably not helping.

MileHigh

tinman · « **Reply #1090 on:** March 23, 2016, 03:00:00 PM »

Quote from: MileHigh on March 23, 2016, 01:40:15 PM

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 · « **Reply #1091 on:** March 23, 2016, 03:08:04 PM »

Quote from: webby1 on March 23, 2016, 02:38:24 PM

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 · « **Reply #1092 on:** March 23, 2016, 03:34:48 PM »

Quote from MH

Quote

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 · « **Reply #1093 on:** March 23, 2016, 04:33:20 PM »

Quote from: tinman on March 23, 2016, 03:00:00 PM

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 · « **Reply #1094 on:** March 23, 2016, 05:06:00 PM »

Quote from: MileHigh on March 23, 2016, 04:33:20 PM

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

News:

User Menu

Author Topic: Joule Thief 101 (Read 944412 times)

Magluvin

Re: Joule Thief 101

picowatt

Re: Joule Thief 101

picowatt

Re: Joule Thief 101

tinman

Re: Joule Thief 101

picowatt

Re: Joule Thief 101

tinman

Re: Joule Thief 101

tinman

Re: Joule Thief 101

tinman

Re: Joule Thief 101

MileHigh

Re: Joule Thief 101

MileHigh

Re: Joule Thief 101

tinman

Re: Joule Thief 101

tinman

Re: Joule Thief 101

tinman

Re: Joule Thief 101

MileHigh

Re: Joule Thief 101

MileHigh

Re: Joule Thief 101