Joule Thief 101

[seychelles]

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

[tinman]

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]

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]

 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.

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.

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

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.

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.

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]

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