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Author Topic: Joule Thief  (Read 4297129 times)

Offline Pirate88179

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Joule Thief
« on: November 20, 2008, 09:07:58 AM »
Can anyone of you electronics guys answer a question for me concerning the Joule Thief? OK my question is this:
The plans I have call for a 1k resistor.  From everything I have learned in electronics thus far, resistors limit the flow and dissipate overage as heat.  This seems wasteful to me since the idea of this device is to improve efficiency, as in use all or most of the available energy in a battery or similar system.  I am wondering why the resistor is needed?  If it gets "warm" at all it is wasting power correct?  Is this required to protect the transistor?

I would really appreciate any input here as this is my first Joule Thief.  I know they have been around a while and I have a pretty good idea on how they work, at least in relation to the lighting of LEDs.  I am also going to experiment with these using supercaps as the power source both with, and without batteries.  This will all be tied into my work with earth batteries from which I can already light an LED.

If I need the resistor to protect the transistor, then fine, that's the way it is.  It just seems a little counter intuitive from my limited electronics knowledge at this point.  Thank you.

Bill
« Last Edit: June 08, 2014, 03:24:40 AM by Pirate88179 »

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Joule Thief
« on: November 20, 2008, 09:07:58 AM »

Offline capthook

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Re: Jule Thief
« Reply #1 on: November 20, 2008, 10:11:47 AM »
I=V/R  :  Amps = Voltage / Resistance

A small battery (AA, A,C,D cells) can push over 1.0 amps.  An LED or transistor often can't handle 1.0 amp.  (check the rating on the package) So you can either: reduce voltage or increase resistance to lower your amps and protect your component.  Increasing resistance by adding a resistor is easier (and usually more efficient) than reducing voltage.  Your resistor value will be determined by your voltage and how many amps you can safely draw using the I=V/R equation.  Resistors are in fact lossy components, but the losses are minuscule in low-power operations and required to keep your other components from frying.

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Offline capthook

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Re: Jule Thief
« Reply #2 on: November 20, 2008, 10:21:18 AM »
Not familiar with the joule thief - sounds like it's a voltage booster?

If you are trying to increase the voltage of your output, you could design a simple voltage doubler (4x, 8x etc) by using a circuit like the attached pic. and/or google voltage doubler.


Offline Yucca

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Re: Jule Thief
« Reply #3 on: November 20, 2008, 12:10:11 PM »
Hi Bill,

You should get good performance using 1 Farad supercap and a joule thief. I have a few 1 Farad 5.5V caps and just running straight into a white 3V LED it lights for quite a while.

I think I´ll have a go at building one too, it may make a good quick chargeup minilamp for nightime paper doc reading etc.

I´m not sure which circuit you´re referencing but I´ll build something like this (I´ll probably end up using different tranny and core):
http://www.bigclive.com/joule.htm

circuit from that page:
(http://i280.photobucket.com/albums/kk164/bigclivedotcom/joule6.jpg)

I think the 1K resistor is just there to limit the base current on the transistor, which should only be a miniscule current, certainly not enough to cause any noticable heating. So yes it´s as you first thought to protect the transistor base from getting a heavy hit from the trigger coil.

I´ll be posting pics and run times for my circuit it will be interesting to compare results with you.

Yucca.


Offline Groundloop

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Re: Jule Thief
« Reply #4 on: November 20, 2008, 01:30:09 PM »
Hi Bill,

Attached is a Joule Thief circuit that uses less current to the base of the transistor.
The resistor can be very high in value, thus less energy is dissipated through the resistor.

Groundloop.

Free Energy | searching for free energy and discussing free energy

Re: Jule Thief
« Reply #4 on: November 20, 2008, 01:30:09 PM »
Sponsored links:




Offline nievesoliveras

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Re: Jule Thief
« Reply #5 on: November 20, 2008, 05:24:31 PM »
@all

How many turns of bifilar you used for the coil?

Jesus

Offline pese

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Re: Jule Thief
« Reply #6 on: November 20, 2008, 06:32:44 PM »
HERE SOM HELP for Beginners.

 simply electronic schematics


http://ca.youtube.com/watch?v=z7ABqJ1CKww&feature=related   Resistor LED
http://ca.youtube.com/watch?v=SvqvRNt4fBU&feature=related   Capacitors
http://ca.youtube.com/watch?v=WAZMjLMSd2o&feature=related   Transitors
NEWS:


i have Links up to  Univrity study - i any need this . please place an messy

PESE

Free Energy | searching for free energy and discussing free energy

Re: Jule Thief
« Reply #6 on: November 20, 2008, 06:32:44 PM »
Sponsored links:




Offline Yucca

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Re: Jule Thief
« Reply #7 on: November 20, 2008, 07:04:35 PM »
@all

How many turns of bifilar you used for the coil?

Jesus

Hi Jesus,

I'm using 22 turns of 30 awg wire.

Yucca.

Offline nievesoliveras

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Re: Jule Thief
« Reply #8 on: November 20, 2008, 07:07:32 PM »
Thank you pese!
Thank you yucca!

Offline Yucca

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Re: Jule Thief
« Reply #9 on: November 20, 2008, 07:29:30 PM »
@Groudloop, I will also try your mod of the thief to compare it to what I've built.

@Bill & All,

OK, I've completed my first joule thief as per the circuit I referenced above except I've used a 2N3904 instead of the BC part. My apologies to all for the poor picture quality, I had to use a webcam and it doesn't have focus on it  :'(.

I tried to wire it up without labelling the coil wires to begin with and did not wire it up right so it took longer than it should have. Maybe I shouldn't have had that pre teatime beer!

The scope shot is accross the LED when the supercap was at about 0.7V. It shows 3V peaks at about 480kHz

Note:
When I charge the supercap up to 5v and let it run it discharges fairly briskly to about 1V and then slows down, on the scope you can see long coil on times at the higher voltages so the circuit will need modding for a higher working voltage range.

Yucca.



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Re: Jule Thief
« Reply #9 on: November 20, 2008, 07:29:30 PM »
Sponsored links:




Offline Yucca

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Re: Jule Thief
« Reply #10 on: November 20, 2008, 07:42:29 PM »
@Jesus
I should have said I used 22 bifilar turns so thats 44 turns of copper in total.

@All
After looking at the posted pohto of the circuit I can't see the 1k res (its under the orange wire) and can only just see the tranny to the right of the LED. I am charging my batteries for my better camera as I type and will post a better photo tomorrow.

Yucca.

Offline WilbyInebriated

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Re: Jule Thief
« Reply #11 on: November 20, 2008, 07:45:29 PM »
you guys should check out amigo's joule thief post over a energeticforum.com
http://www.energeticforum.com/renewable-energy/1170-ssg-joule-thief-other.html
he showed a simple modification to the joule thief that runs at 14mA if i recall.
with the proper selection of components, it doesn't even budge my 0-500mA analog ammeter.


Offline Pirate88179

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Re: Jule Thief
« Reply #12 on: November 20, 2008, 09:01:07 PM »
http://uk.youtube.com/watch?v=gTAqGKt64WM


@ All:

Wow, thank you all for your responses.  Above is the video posted by Innovation Station on another topic that I am using for my thief.  I am using a .825" OD x .500" ID x .250" thick ferrite toroid salvaged from a computer monitor.  I wrapped the coil (bifilar) using 22 ga. solid wire (insulated) with 18 turns. (9 wraps).  I don't recall what the transistor is on the video but I will watch it again and write it down and try to get from Radio Shack. (Only local source here)

I am on my way to work but I will respond in more detail to as many of the posts as I can when I get back.

I really appreciate all of your posts.  For those not familiar with the joule thief, watch the above video as I believe it explains it really well.

Thanks again to all who answered me.

Bill


Offline Pirate88179

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Re: Jule Thief
« Reply #13 on: November 21, 2008, 12:50:13 AM »
@ All:

I am back now, having purchased a few 2N3904 transistors.  I was not sure if it called for stranded wire, or solid.  I wrapped the first one in solid as it was all I had.  I now bought some stranded 22 ga. and I will use that on one of my other ferrites.  I am building the first one per the video.  Then, I will try Groundloop's circuit.

@ Yucca:

Yes, that circuit looks pretty much like what I am building.  Thanks for the info and also for posting your scope shot. I am also glad to hear this will work with supercaps.  A while ago, when I first read about the joule thief, some said this only exploited a chemical cell battery due to the nature of their construction.  Now I see that it is pulsing the energy which I thought would work with supercaps, and you said it does, so that is good news.  I really appreciate your help.

@ Wilby:

Thanks, I will check that out also.

@ pesse:

Thank you also.  I found some electronic engineering classes online videos from MIT which I have been watching.  They are each an hour lecture by Dr. Walter Lewin and so far, I have watched 12 of them or so.  Almost like going to MIT for free.  In one of them, he says his one class costs his students over $20,000! (USD)  If you, or anyone else is interested, let me know and I will post some links.  I have learned more from the helpful folks on here, and from the video courses, than I have learned from reading (and re-reading) my 4 electronics textbooks.

If I have left anyone out, I am sorry.  I got a much larger response than I anticipated.  I will begin soldering my circuit in a few minutes.  If it works ok....meaning if I don't screw anything up, I will shoot some video and post it on youtube with a link posted here.

This stuff is so much fun and, like most things in my life, the more I learn, the more I realize there is to learn.

Bill

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Offline Pirate88179

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Re: Jule Thief
« Reply #14 on: November 21, 2008, 06:57:50 AM »
So far so good.  I will have two joule thief's here in a bit.  One with stranded wire, one with solid.

Bill

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Re: Jule Thief
« Reply #14 on: November 21, 2008, 06:57:50 AM »

 

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