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Author Topic: Joule Thief behavior question.  (Read 20292 times)

Offline Legalizeshemp420

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Joule Thief behavior question.
« on: October 24, 2013, 09:04:05 AM »
I just created a simple JT that you see around the net using my own wound bobbin (4t:~40t) using a S8055.  As soon as I put in a BC337 along with the other transitor the LED will get brighter.  It doesn't matter if it is a 20ma or a 700ma one and frankly I forgot what that means.

Anyone re-enlighten me please.

Free Energy | searching for free energy and discussing free energy

Joule Thief behavior question.
« on: October 24, 2013, 09:04:05 AM »

Offline gyulasun

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Re: Joule Thief behavior question.
« Reply #1 on: October 24, 2013, 07:57:10 PM »
I just created a simple JT that you see around the net using my own wound bobbin (4t:~40t) using a S8055.  As soon as I put in a BC337 along with the other transitor the LED will get brighter.  It doesn't matter if it is a 20ma or a 700ma one and frankly I forgot what that means.

Anyone re-enlighten me please.

The S8055 has been an unknown transistor type for me.  If you did not make a typo, my search resulted as it is a thyristor, see here:
http://www.littelfuse.com/products/switching-thyristors/scr/sxx55x/s8055n.aspx   

So what you think?

By the way, if the S8055 is indeed a normal bipolar transistor and you parallel a BC337 with it, then the two work together as an improved transistor for instance with less saturation voltage between collector and emitter, increased Beta (dIC /dIB) etc.
And if the S8055 is a thyristor, then the BC337 takes the "role of the boss" for sure   i.e.  mainly the BC337 parameters dominate and the thyristor has a "second hand job".    8)

Free Energy | searching for free energy and discussing free energy


Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #2 on: October 24, 2013, 09:13:00 PM »
Sorry that was a typo I meant S8050 not S8055 and when you go to look up the datasheet they have this part wrong it is a NPN transistor NOT a PNP.

Offline MileHigh

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Re: Joule Thief behavior question.
« Reply #3 on: October 24, 2013, 09:31:26 PM »
For fun, here is a mini treatise on the behaviour of a Joule Thief:

-----------------------------------------------------
MECHANICAL EQUIVALENT CIRCUIT OF A JOULE THIEF

Imagine you go to the gym and you find an old-style exercise bicycle.  The type with a seat and pedals and a chain link to a big flywheel, like a regular bicycle.  There is a friction belt that goes around the circumference of the flywheel.  You set the tension on the friction belt to adjust the difficulty level.

Imagine the belt is completely loose.  You pedal for a few seconds and get the flywheel spinning and then you stop pedaling.  Then you add tension to the belt and the flywheel spins down and stops.  Then you loosen the belt and repeat the whole process all over again.

Even when you are completely exhausted, it's still possible for you to pedal and get the flywheel spinning if you pedal slowly and take your time to build up the speed.  Don't forget that the friction strap is loose when you pedal.

That's a Joule Thief.  You are the battery.  When you are exhausted it's like you are a dead battery.  The flywheel is the coil.  The friction belt is the LED.

The torque that you put on the flywheel from pedaling is the battery voltage.  The torque that the flywheel puts on the belt during the braking is the coil voltage when it's de-energizing.  The rotational speed of the flywheel is the current through the coil.

You pedal for a few seconds and get the flywheel spinning - in the alternate universe the battery did the work required to get current flowing through the coil.  You stop pedaling and engage the brake and the flywheel spins down and heat is produced - in the alternate universe the Joule Thief circuit snaps off and the inductor discharges through the LED and light and heat are produced.

-----------------------------------------------------

MileHigh


Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #4 on: October 24, 2013, 10:40:27 PM »
So, what does it mean when you add another transistor in parallel with the other one and the LED gets brighter to the naked eye?

Free Energy | searching for free energy and discussing free energy

Re: Joule Thief behavior question.
« Reply #4 on: October 24, 2013, 10:40:27 PM »
Sponsored links:




Offline gyulasun

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Re: Joule Thief behavior question.
« Reply #5 on: October 24, 2013, 11:07:20 PM »
So, what does it mean when you add another transistor in parallel with the other one and the LED gets brighter to the naked eye?

I answered your question in my above post.

Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #6 on: October 24, 2013, 11:20:59 PM »
I answered your question in my above post.
It isn't a Thyristor though and has way better stats than the BC337-25.  The thing is I have done this before and did not achieve these results.  How many can I parallel before diminishing returns sets in?

Free Energy | searching for free energy and discussing free energy

Re: Joule Thief behavior question.
« Reply #6 on: October 24, 2013, 11:20:59 PM »
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Offline xee2

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Re: Joule Thief behavior question.
« Reply #7 on: October 26, 2013, 01:24:12 AM »
So, what does it mean when you add another transistor in parallel with the other one and the LED gets brighter to the naked eye?


Normally two transistors are paralleled to generate the equivalent of one transistor that has a lower collector-emitter resistance so that more current will flow through the circuit. As the current is increased in the collector coil the output voltage and power will also increase. However, if the transistors are not well matched, one of the transistors may end up hogging most of the current and thus reducing the benefit of having a second transistor.

Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #8 on: October 26, 2013, 06:13:26 AM »

Normally two transistors are paralleled to generate the equivalent of one transistor that has a lower collector-emitter resistance so that more current will flow through the circuit. As the current is increased in the collector coil the output voltage and power will also increase. However, if the transistors are not well matched, one of the transistors may end up hogging most of the current and thus reducing the benefit of having a second transistor.
Heyas, Xee :)

Well, my next question is the Imaginary transistor that is a combination of all of my transistors in parallel how do I determine what its stats are?  I would like to figure out what my stats are and see if a single transistor solution is possible, or close enough.  Is there a formula for figuring out the stats of the iTransistor?

In my recent video I have 5 transistors in parallel and it got brighter and brighter with each one but by #5 it was so small of an improvement that #6 would have been redundant.  Diminishing returns and all of that.

Offline xee2

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Re: Joule Thief behavior question.
« Reply #9 on: October 26, 2013, 09:47:15 AM »
Heyas, Xee :)

Well, my next question is the Imaginary transistor that is a combination of all of my transistors in parallel how do I determine what its stats are?  I would like to figure out what my stats are and see if a single transistor solution is possible, or close enough.  Is there a formula for figuring out the stats of the iTransistor?

In my recent video I have 5 transistors in parallel and it got brighter and brighter with each one but by #5 it was so small of an improvement that #6 would have been redundant.  Diminishing returns and all of that.


Paralleling transistors is like paralleling resistors. The more you put in parallel, the lower the e effective resistance will be. However, paralleling transistors can be tricky. I recommend only paralleling identical transistors.




Free Energy | searching for free energy and discussing free energy

Re: Joule Thief behavior question.
« Reply #9 on: October 26, 2013, 09:47:15 AM »
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Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #10 on: October 26, 2013, 09:59:33 AM »

Paralleling transistors is like paralleling resistors. The more you put in parallel, the lower the e effective resistance will be. However, paralleling transistors can be tricky. I recommend only paralleling identical transistors.
So, there is no way to know what numbers are changing so you can go out and look for a transistor that has the same specs as the multiple ones in parallel end up having?

Offline xee2

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Re: Joule Thief behavior question.
« Reply #11 on: October 26, 2013, 03:38:28 PM »
So, there is no way to know what numbers are changing so you can go out and look for a transistor that has the same specs as the multiple ones in parallel end up having?


When using identical transistors, every time you double the number of paralleled transistors the effective "on resistance" is cut in half. However, paralleling transistors is usually done to allow switching a current that exceeds the maximum collector current spec.


Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #12 on: October 26, 2013, 04:31:25 PM »

When using identical transistors, every time you double the number of paralleled transistors the effective "on resistance" is cut in half. However, paralleling transistors is usually done to allow switching a current that exceeds the maximum collector current spec.
Which value is that on a typical transistor datasheet?

Offline xee2

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Re: Joule Thief behavior question.
« Reply #13 on: October 26, 2013, 05:02:56 PM »
Which value is that on a typical transistor datasheet?




Free Energy | searching for free energy and discussing free energy


Offline Legalizeshemp420

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Re: Joule Thief behavior question.
« Reply #14 on: October 26, 2013, 10:56:51 PM »
Something isn't making sense.  You show the collector current of 1.5 amps so if I put two of those in parallel you said that would be cut in half so that would make it 750ma which i not good.

Free Energy | searching for free energy and discussing free energy

Re: Joule Thief behavior question.
« Reply #14 on: October 26, 2013, 10:56:51 PM »

 

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