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Author Topic: Joule Thief  (Read 6275717 times)

jadaro2600

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Re: Jule Thief
« Reply #13680 on: June 09, 2010, 09:30:00 AM »
That would be nice - ...I'll obviously be looking for a way to reduce that interference, if I have to put it in a brass case, I will.

The diagram is rather tricky to get a good picture of, please post one.

- - - - -

I have also been looking for a decent cheat-sheet on transistor terminology.  ..what the significance of a particular stat means is becoming tedious.  I've found some, sparse, but nothing solid.

mscoffman

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Re: Jule Thief
« Reply #13681 on: June 09, 2010, 05:39:35 PM »

So, my considerations are for operating a mosfet in linear mode, I need a voltage controlled resistor or some rigging of a mosfet which scales predictably in ohmic mode.  Has anyone had any experience with rigging mosfets in this manner?


@jadaro

There are numerous ways of doing this, but they require lots of components,
potentially dual polarity stable power supplies, and some are not efficient
uses of electric power - all of these characteristics are inconsistent with
the design of the basic JT JouleThief. The best bet probably is some sort
of bipolar transistor series regulator.

Here's the thing - these things should not stop you from setting up a
system
that will behave as you want...and if what the system does,
looks good to you, you can reduce that operation of the system to simpler
components in a separate experimental step.

Too many experimenters don't do this, they want to combine learning
how a circuit operates with greatly reduce component setup, and then
they can't do both sides of this simultaneously. I hate complexity too,
but I hate end unit complexity and not intermediate development complexity.
So what I am saying is learn how control the circuit and battery charger
to do what you want separately from reducing component complexity. I'm
telling you, I think you are correct about this, and I think you can do it, and
maybe make an actual contribution on here.

---

The methods for linearizing a MOSFET are:
Putting a negative feedback-loop operational amplifier in front
of the MOSFET that has sufficient accuracy to deal with the mosfet
voltage gain of about one million. Operating a transistor in linear
gain mode is not efficient at all when the device is in intermediate
part of the transfer curve. Bipolar transistor are easier to control
because they have less numerical gain...but their gain is in the current
domain (I) and you often need to convert that to the voltage or
power domain to be useful.

If you need output signals with bandwidth of 30Khz or less, look up
"MOSFET switching amplifiers". These synthesize the required voltage
by switching on and off at very high frequencies. Because the mosfet
is either on or off all the time, power efficiency is increased.

A "digital potentiometer" is an easy way to get what you want but
you will need to design a digital front-end for it.

There are a couple of IC amps designed for ACG operation - Automatic
Gain Control, where a voltage input can act as a "volume control"
on the output. But most of the time VFC Voltage Frequency Control of
an astable oscillator is all that is required and even the lowly NE555 has
that. (on pin5 - Control Voltage)
 
:S:MarkSCoffman

jeanna

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Re: Jule Thief
« Reply #13682 on: June 09, 2010, 07:39:47 PM »
very interesting my batter were set to only allow 10ma of power well the led was very dimm i adderd a capaciter across the + and - input lead of the joule thief and the led got brighter
Yeay!

Thank you for trying this and reporting it!

The nexy step is to get another tiny one that keeps the joules tossing back and forth across the secondary leads.
Keep going.
good work.

jeanna

Quote
this is cool cos no matter what i do nothing can draw more then 10ma the strange thing is i thoght the joule thief would pull the full 10 but it dosent seem to also i have a pot instead of a resister and the really funny thing is as you ajust the pot the light gets brighter then dim then brighter again and so on amlost like im changing gear
 also putting a cap inline with the battery after the pot made thing brighter

When you see the light get brighter or dimmer you are watching the circuit go in and out of resonance.
good job.
It is easier with a scope, but as you can tell, you can see the resonance this way.

j

jadaro2600

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Re: Jule Thief
« Reply #13683 on: June 09, 2010, 11:05:01 PM »
@jadaro

...

Here's the thing - these things should not stop you from setting up a
system
that will behave as you want...and if what the system does,
looks good to you, you can reduce that operation of the system to simpler
components in a separate experimental step.

Too many experimenters don't do this, they want to combine learning
how a circuit operates with greatly reduce component setup, and then
they can't do both sides of this simultaneously. I hate complexity too,
but I hate end unit complexity and not intermediate development complexity.
So what I am saying is learn how control the circuit and battery charger
to do what you want separately from reducing component complexity. I'm
telling you, I think you are correct about this, and I think you can do it, and
maybe make an actual contribution on here.

...
 
:S:MarkSCoffman

Thank you for the information.  I've been dealing with the peculiarities of the devices as of late.

I was reading somewhere on the Berkley website that switching diodes act like resistors until they reach they reach their saturation voltage.

I may wind up using a mosfet for other purposes, since their usually on or off.

I'll continue looking for a scaling resistor, it just seems logical to use one which is voltage oriented.

Also, I too have notices extreme reductionism occuring on circuits.  Although this may be good for hobbyists, it usually doesn't bode well for production runs, the pass/fail system would just as readily have most of them thrown out.   The idea is to make a quality product with predictable operation.

More often than not, the JTC is sensitive and prone to wild fits of good and bad behavior.  It's the Bi-Polar circuit, in other words.

dasimpson

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Re: Jule Thief
« Reply #13684 on: June 10, 2010, 12:46:50 AM »
have abread board now with a jt setup on it i have a cap on the in terminales
i then have it going to a bridge rectifire then to a cap after that i connects leds with the cap in the secondory the leds also get brighter
haveing the cap and bridge makes it easyer to measure the voltage

edit ps also have some 2n3904 trannys now

dasimpson

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Re: Jule Thief
« Reply #13685 on: June 11, 2010, 03:18:30 PM »
a question to light a tube fully would we need more voltage or is there a limit to how much we can get them to light with voltage only
i mean could we get the as braight using the jt as they are when in normal usage

conradelektro

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Re: Jule Thief
« Reply #13686 on: June 11, 2010, 04:56:01 PM »
you can run air coil with this at low ma's.. or you can just make your cat go nuts..
robbie

@ robbie (kooler)

I want to replicate your "backwards JT" circuit and wounder how many turns (instead of the 3T/5T/15T on a toroid) one should put on an air coil for your backwards JT?

What diameter should the air coil have?

I guess you propose an air coil to increase the frequency?

Greetings, Conrad

jeanna

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Re: Jule Thief
« Reply #13687 on: June 11, 2010, 08:34:00 PM »
a question to light a tube fully would we need more voltage or is there a limit to how much we can get them to light with voltage only
i mean could we get the as bright using the jt as they are when in normal usage
Hi dasimpson,

It is a good question.
We do not know.
There has been speculation that the full brightness comes from the warmth component.

Keep trying.

I recently wanted to try the capacitor-joule-toss I spoke of before, where all the joules except for the ones being turned into photons return to the other side of the secondary, again and again, but that is just my latest idea.

Try anything you can think of.
and, of course, report it.  ;) ,

jeanna

Pirate88179

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Re: Jule Thief
« Reply #13688 on: June 11, 2010, 08:46:36 PM »
Hi dasimpson,

I recently wanted to try the capacitor-joule-toss I spoke of before, where all the joules except for the ones being turned into photons return to the other side of the secondary, again and again, but that is just my latest idea.


jeanna


Jeanna:

If you attempt this I think there is a slight possibility that all matter in the universe will spontaneously disintegrate.  I could be wrong though.


(Grin)

Bill

dasimpson

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Re: Jule Thief
« Reply #13689 on: June 11, 2010, 11:07:11 PM »
oh i am a long way from anything like that im haveing trouble getting the 2n3904 to light off 11 turns bifoiler were as my bc337-25 will go from about 5
Quote from: jeanna link=topic=6123.msg244655#msg244655 A=1276281240
Hi dasimpson,

It is a good question.
We do not know.
There has been speculation that the full brightness comes from the warmth component.

Keep trying.

I recently wanted to try the capacitor-joule-toss I spoke of before, where all the joules except for the ones being turned into photons return to the other side of the secondary, again and again, but that is just my latest idea.

Try anything you can think of.
and, of course, report it.  ;) ,

jeanna

nealc99

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Re: Jule Thief
« Reply #13690 on: June 17, 2010, 09:40:54 PM »
FIRE SALE!

Found some "super cheap" 1/2" N45 Neo magnets at a price you might be interested in - $0.95 each!  Might be perfect for bedini motor.

http://www.magnet4sale.com/Sphere-Neodymium-Magnets-Dia-0.5-N42-NdFeB-Rare-Earth-Magnets.html

SkyWatcher123

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Re: Jule Thief
« Reply #13691 on: June 19, 2010, 06:14:48 AM »
Hi Folks, i was wondering if anyone can help me solve this heat issue with my joule thief circuit. at 6volts i see no problems with heat, however at 12v or greater, the transistor heats up when powering a fluoro bulb off the secondary, however it barely heats up when charging a 12v battery off the primaries flyback with diode. My guess is that when powering fluoro off secondary, that some of the collapse is induced into feedback winding of the bifilar and creating an issue at the base of transistor. Where as when charging a separate 12v battery off primary flyback diode, almost all the collapse is used up in charging battery leaving little to induce in the feedback winding. Hopefully some can help me understand what needs to be done with the circuit to prevent this heating. Thanks.
peace love light
Tyson :)

sparks

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Re: Jule Thief
« Reply #13692 on: June 19, 2010, 06:33:43 AM »
  Did it again.  Left the lights on in my infernal combustion machine.  The ridiculous machine for some reason needs to compress the air fuel mixture before the fuel will combust.  Why engineers havent been able to figure out how to add fuel to the cylinders past top dead center and combust same without having to resort to wasteful fuel air compression is beyond me.  The steam engine didnt have to compress the steam it just valved it into the cylinder at the proper time and the cylinder expanded.  Some idiot says gosh I can bypass the boiler and use the cylinder as the heater upper directly. Start that there fire right inside the piston.  After millions if not billions of hours of engineering the automotive industry insists on producing the same most inefficient engine ever created.  The wasted fuel is incredible.  On the scale of energy efficiency star system this piece of shit wouldnt even rate a moon.  When you have to use 3horsepower just to prepare for the chemical to kinetic conversion event something is wrong.  Just the three horsepower in a properly designed vehicle will suffice.  I dont need 150 horespower to travel 10miles in 30minutes.  I need an electric go cart with a rain tight enclosure and some windshield wipers.  Headlights are useless just a pair of nightvision goggles and I'm good to go.  All headlights do is blind other motorists so they have to use their headlights that blind other motorists.  A chain reaction of rendering vehicle operators blinded making it necessary to light the roadways and waste more energy.
When someone has to tell you you have a headlight out it tells me they arent really needed.  Sylvania needs em I dont.  My eyes dialate when it is dark I dont know about yours.
   Anyway as I have posted before if you have a functioning jule thief I would get on down to the patent office and patent it as a device for emergency starting of the infernal combustion engine.  A big jt should be able to tap a battery on down to 1/2 a volt or so.  Since the starter motor needs 9volts  to get through the compression resistance of the engine and about 1000  surge amps the Jt should be able to take a bunch of juice from a "dead" battery and boost it up to charge a small carbon lithium battery to give the surge needed to crank the engine.  The carbon lithium could be charged up to 300volts which would drop quickly to 9volts and give the 1000amp surge and the 300 cranking amps needed to get the oil burner ignited.  Most home furnaces just need a 1/6hp motor to blow air and pump oil and a highvoltage transformer to get them going but not the infernal combustion engine.  The use of a highvoltage battery allows for a great reduction in weight.  Why 12volts dc distribution in a car anyway.  A highvoltage starter motor would require minimal amps especially if it spun up a flywheel and at the desired rpm engaged the clutch instead of brute force battery versus compression.  No heavy cables and contacts.  Wire diameters reduced by 10fold.  No sulphuric acid to handle.  Probably has something to do with highvoltage and oil all over the place associated with the piece of crap engine that has a tendency to waste oil in every conceivable manner possible short of pouring it straight into the oceans.  Oh they figured that one out too.

jadaro2600

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Re: Jule Thief
« Reply #13693 on: June 19, 2010, 09:23:21 AM »
Hi Folks, i was wondering if anyone can help me solve this heat issue with my joule thief circuit. at 6volts i see no problems with heat, however at 12v or greater, the transistor heats up when powering a fluoro bulb off the secondary, however it barely heats up when charging a 12v battery off the primaries flyback with diode. My guess is that when powering fluoro off secondary, that some of the collapse is induced into feedback winding of the bifilar and creating an issue at the base of transistor. Where as when charging a separate 12v battery off primary flyback diode, almost all the collapse is used up in charging battery leaving little to induce in the feedback winding. Hopefully some can help me understand what needs to be done with the circuit to prevent this heating. Thanks.
peace love light
Tyson :)

You'll need to determine what the resistance at the base is and scale this properly with increased source voltage.

Know your transistors: ..most of them in the to-92 plastics only require 1 volt to fully cut on, in the to-220, usually 2.4 volts.

The 2n3904 only needs 2k resistance at base, on a 1.4v source to 'cut on'.  It uses about 1mA.

If I were to increase the source voltage, then I would need to increase the base resistance likewise.

dasimpson

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Re: Jule Thief
« Reply #13694 on: June 19, 2010, 03:02:34 PM »
found my problem dead tranisister opps