Joule Thief 101

[tinman]

Tinman,

As you change the scope ground connection point, different portions of the circuit become dynamic with respect to stray capacitance (mainly to your bench top or nearby equip).  This can produce some "not really there" spikes or other anomalies as the strays are charge/discharged.

Consider using a short and neat circuit layout and placing the entire circuit on a piece of glass/plexiglass elevated above your bench by insulators. 

PW

I have the circuit pretty much as small as i can get it,but i do believe that the voltage seen across the base resistor is not showing a reverse current flow,but is more some sort of artifact that you mention above.

As i said in my previous post,i am looking into it a little further,and will post my findings here when they become apparent.

I have been trying to keep up with schematics along with every scope shot,but it was late last night,and it gets hard to keep up,so i post a quick description instead of a schematic with every scope shot.

Brad

[Magluvin]

Just found my JT with the 11t by 11t transformer running low and turning on and off, like 10sec on 30 sec off.  Running the 33 ohm resistor, 3904, the batt is at .44v when it dies out then the battery recoups and back on.   Ill try to eliminate and the resistor and see if I can get it to stay on below .44v.

Anyway, it seems to be a battery cycling thing if the jt is blinking, so far.

Just ditched the resistor and goes down to .43v, cuts out, and back on at .45v. seems odd. I might expect the need to go higher before coming back on.

Mags

[tinman]

 author=MileHigh link=topic=8341.msg478791#msg478791 date=1459185829]




   

MileHigh

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.

Quote from you MH : The cycle time is 75 microseconds for one trace (spike) and 60 microseconds for the second trace (collector).

First off,you have that ass about,where the cycle time for the spike(blue trace as marked with attached schematic) is about 45uS,and as i said,this is from a voltage source,and the scope is being triggered from that voltage source.
The yellow trace is across the 1 ohm CVR,and there for is reading the voltage drop across that 1 ohm CVR,and so that is from a current source.
The two dips in the traces in the center of the scope screen,are showing you the OFF period. The blue trace shows a positive voltage(take note of where zero volts is for blue trace)-transistor switching on,before the yellow trace shows a voltage rise,as that trace is measuring the voltage drop across the CVR,and as current lag's voltage,the yellow trace will show a longer off time period than the blue trace.

As i clearly stated in my reply,the difference is because voltage lead's current when it comes to inductors. Quoting my post where you said i left no explanation
Quote: The spike trace--blue base trace is shorter than than the collector current trace-the yellow trace.
Can you not follow a very simple schematic and scope placements?--do you not know that voltage leads current in an inductor,and thus the reason for the blue trace(base trace) being slightly shorter than the yellow trace-collector current trace in time period-->voltage leads current MH-you doofus.

I am getting exhausted with the stream-of-consciousness/churning spaghetti/brain-ricochet talk from you.

From me ??>
Things are clearly explained to you,but you say they are not.
Then you say that i agreed with you and PW on the collector/base breakdown thing--but i did not do anything of a kind.
You first agree on emitter/base breakdown voltage being the cause of the reverse current flow(that i still think is not there),and then out of no where you come up with plan B,and switch to some !unicorn! collector/base breakdown voltage claim.

It's like you need a bloody Google translator just for you.

For me?.
How did we go from emitter/base breakdown voltage, to collector/base breakdown voltage??
Where did that translation go,and how did it come about?
I never agreed to anything about collector/base breakdown voltage's,as the V/cb for the 2n3055 is over 60 volt's.

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.

You are in need of a break MH.
One minute we are talking about the breakdown voltage of the emitter/base junction--which i was in agreeance with--along with the junction capacitance being the first order of events for the reverse base current flow,and then out of the blue,you switch to collector/base junction breakdown.

You have people running all over the place here MH,and you are getting hard to follow,with these leap's from one theory ,to the next.

I tried to show you that there was no reverse current flow spike at the collector,and you just continued to insult me.
I then explained as to why the two time periods are different,and still you kept insulting me.
I then ask you to go back and read what PW said,and still you kept insulting me-as can be seen with nearly every reply you make to me,and so i give them right back to you.

Why have you switch to collector/base breakdown voltage?. Is this another of your attempts to catch me out?--another loaded question?.

You continue to insult me every chance you get,but as you can see,it is you that is wrong every time.
So please stop your insults toward me--at least until !you! get it right.


Brad

[TinselKoala]

I have the circuit pretty much as small as i can get it,but i do believe that the voltage seen across the base resistor is not showing a reverse current flow,but is more some sort of artifact that you mention above.

As i said in my previous post,i am looking into it a little further,and will post my findings here when they become apparent.

I have been trying to keep up with schematics along with every scope shot,but it was late last night,and it gets hard to keep up,so i post a quick description instead of a schematic with every scope shot.

Brad

Here's a scopeshot you might find interesting.

[MileHigh]

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:

First off,you have that ass about,where the cycle time for the spike(blue trace as marked with attached schematic) is about 45uS,and as i said,this is from a voltage source,and the scope is being triggered from that voltage source.
The yellow trace is across the 1 ohm CVR,and there for is reading the voltage drop across that 1 ohm CVR,and so that is from a current source.
The two dips in the traces in the center of the scope screen,are showing you the OFF period. The blue trace shows a positive voltage(take note of where zero volts is for blue trace)-transistor switching on,before the yellow trace shows a voltage rise,as that trace is measuring the voltage drop across the CVR,and as current lag's voltage,the yellow trace will show a longer off time period than the blue trace.

As i clearly stated in my reply,the difference is because voltage lead's current when it comes to inductors. Quoting my post where you said i left no explanation
Quote: The spike trace--blue base trace is shorter than than the collector current trace-the yellow trace.
Can you not follow a very simple schematic and scope placements?--do you not know that voltage leads current in an inductor,and thus the reason for the blue trace(base trace) being slightly shorter than the yellow trace-collector current trace in time period-->voltage leads current MH-you doofus.

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.