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Author Topic: Joule Thief 101  (Read 926730 times)

MileHigh

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Re: Joule Thief 101
« Reply #255 on: February 16, 2016, 05:00:42 AM »
http://makezine.com/projects/joule-thief-battery-charger/

How a Joule Thief works:

 This circuit used in this project is a modified "Joule Thief." A Joule Thief is a self-oscillating voltage booster. It takes a steady low voltage signal and converts it into a series of high frequency pulses at a higher voltage. Here is how a basic Joule Thief works, step by step:
    1. Initially the transistor is off.
    2. A small amount of electricity goes through the resistor and the first coil to the base of the transistor. This partially opens up the collector-emitter channel. Electricity is now able to travel through the second coil and through the collector-emitter channel of the transistor.
    3. The increasing amount of electricity through the second coil generates a magnetic field that induces a greater amount of electricity in the first coil.
    4. The induced electricity in the first coil goes into the base of the transistor and opens up the collector-emitter channel even more. This lets even more electricity travel through the second coil and through the collector-emitter channel of the transistor.
    5. Steps 3 and 4 repeat in a feedback loop until the base of the transistor is saturated and the collector-emitter channel is fully open. The electricity traveling through the second coil and through the transistor are now at a maximum. There is a lot of energy built up in the magnetic field of the second coil.
    6. Since the electricity in the second coil is no longer increasing, it stops inducing electricity in the first coil. This causes less electricity to go into the base of the transistor.
    7. With less electricity going into the base of the transistor, the collector-emitter channel begins to close. This allows less electricity to travel through the second coil.
    8. A drop in the amount of electricity in the second coil induces a negative amount of electricity in the first coil. This causes even less electricity to go into the base of the transistor.
    9. Steps 7 and 8 repeat in a feedback loop until there is almost no electricity going through the transistor.
    10. Part of the energy that was stored in the magnetic field of the second coil has drained out. However there is still a lot of energy stored up. This energy needs to go somewhere. This causes the voltage at the output of the coil to spike.
    11. The built up electricity can't go through the transistor, so it has to go through the load (usually an LED). The voltage at the output of the coil builds up until it reaches a voltage where is can go through the load and be dissipated.
    12. The built up energy goes through the load in a big spike. Once the energy is dissipated, the circuit is effectively reset and starts the whole process all over again. In a typical Joule Thief circuit this process happens 50,000 times per second.

What the heck?   No mention of "resonance" anywhere?!  No mention of "LC" or "RLC" anywhere?!

It must be an NWO plot and they want to hide the truth from you.

Pirate88179

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Re: Joule Thief 101
« Reply #256 on: February 16, 2016, 05:02:24 AM »
http://makezine.com/projects/joule-thief-battery-charger/

How a Joule Thief works:

 This circuit used in this project is a modified "Joule Thief." A Joule Thief is a self-oscillating voltage booster. It takes a steady low voltage signal and converts it into a series of high frequency pulses at a higher voltage. Here is how a basic Joule Thief works, step by step:
    1. Initially the transistor is off.
    2. A small amount of electricity goes through the resistor and the first coil to the base of the transistor. This partially opens up the collector-emitter channel. Electricity is now able to travel through the second coil and through the collector-emitter channel of the transistor.
    3. The increasing amount of electricity through the second coil generates a magnetic field that induces a greater amount of electricity in the first coil.
    4. The induced electricity in the first coil goes into the base of the transistor and opens up the collector-emitter channel even more. This lets even more electricity travel through the second coil and through the collector-emitter channel of the transistor.
    5. Steps 3 and 4 repeat in a feedback loop until the base of the transistor is saturated and the collector-emitter channel is fully open. The electricity traveling through the second coil and through the transistor are now at a maximum. There is a lot of energy built up in the magnetic field of the second coil.
    6. Since the electricity in the second coil is no longer increasing, it stops inducing electricity in the first coil. This causes less electricity to go into the base of the transistor.
    7. With less electricity going into the base of the transistor, the collector-emitter channel begins to close. This allows less electricity to travel through the second coil.
    8. A drop in the amount of electricity in the second coil induces a negative amount of electricity in the first coil. This causes even less electricity to go into the base of the transistor.
    9. Steps 7 and 8 repeat in a feedback loop until there is almost no electricity going through the transistor.
    10. Part of the energy that was stored in the magnetic field of the second coil has drained out. However there is still a lot of energy stored up. This energy needs to go somewhere. This causes the voltage at the output of the coil to spike.
    11. The built up electricity can't go through the transistor, so it has to go through the load (usually an LED). The voltage at the output of the coil builds up until it reaches a voltage where is can go through the load and be dissipated.
    12. The built up energy goes through the load in a big spike. Once the energy is dissipated, the circuit is effectively reset and starts the whole process all over again. In a typical Joule Thief circuit this process happens 50,000 times per second.

What the heck?   No mention of "resonance" anywhere?!  No mention of "LC" or "RLC" anywhere?!

It must be an NWO plot and they want to hide the truth from you.

Yes, but Make got the JT design from Big Clive.  (see links in my earlier posting)

Bill

MileHigh

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Re: Joule Thief 101
« Reply #257 on: February 16, 2016, 05:09:36 AM »
http://www.talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html

CIRCUIT A
The first circuit in this discussion is the simplest design.
It consists of a transistor, resistor and transformer, with almost any type of LED. The circuit will drive a red LED, HIGH BRIGHT LED, or white LED.
The circuit produces high voltage pulses of about 40v p-p at a frequency of 200kHz.
Normally you cannot supply a LED with a voltage higher than its characteristic voltage, but if the pulses are very short, the LED will absorb the energy and convert it to light. This is the case with this circuit. The characteristic voltage of the LED we used was very nearly 4v and this means the voltage across it for a very short period of time was 4v. The details of the transformer are shown in the photo. The core was a 2.6mm diameter "slug" 6mm long and the wire was 0.95mm diam. In fact any core could be used and the diameter of the wire is not important. The number of turns are not important however if the secondary winding does not have enough turns, the circuit will not start-up.

HOW THE CIRCUIT WORKS
The transformer is configured as a BLOCKING OSCILLATOR and the cycle starts by the transistor turning on via the 2k7 base resistor.
This causes current to flow in the 60-turn main winding. The other winding is called the feedback winding and is connected so that it produces a voltage to turn the transistor on MORE during this part of the cycle.
This winding should really be called a "feed-forward" winding as the signal it supplies to the transistor is a positive signal to increase the operation of the circuit. This is discussed in more detail in Circuit Tricks.
This voltage allows a higher current to flow in the transistor and it keeps turning on until it is saturated.
At this point the magnetic flux produced by the main winding is a maximum but it is not expanding flux and thus it ceases to produce a voltage in the feedback winding. This causes less current to flow into the base of the transistor and the transistor turns off slightly.
The flux produced by the main winding is now called collapsing flux and it produces a voltage in the feedback winding of opposite polarity. This causes the transistor to turn off and this action occurs until it is completely off.
The magnetic flux continues to collapse and cuts the turns of the main winding to produce a very high voltage of opposite polarity.
However this voltage is prevented from rising to a high value by the presence of the LED and thus the energy produced by the collapsing magnetic flux is converted to light by the LED.
The circuit operates at approx 200kHz, depending on the value of the base resistor and physical dimensions of the transformer.
The circuit draws 85mA from the 1.5v cell and the brightness of the LED was equivalent to it being powered from a DC supply delivering 10 - 15mA.

Say what??  No mention of "resonance" or "RLC" again!

MileHigh

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Re: Joule Thief 101
« Reply #258 on: February 16, 2016, 05:13:41 AM »
http://www.talkingelectronics.com/projects/CircuitTricks/CircuitTricks-2.html

CIRCUIT 3:

The third circuit uses feedback from a transformer to turn the circuit ON to a point where it is fully turned on. It is taken from our LED Torch Circuits article. The cycle starts with the 2k7 resistor feeding current into the base of the transistor. This starts to turn the transistor on and current flows in the 60 turn winding and produces magnetic flux that cuts the turns of the 40 turn winding. The 40 turn winding produces extra voltage that adds to the original voltage and this allows extra current to flow into the base of the transistor to turn it on more.
This continues until the transistor is fully turned on. This action is called positive feedback or more accurately REGENERATION.

The three circuits operate in exactly the same mode. This mode is called a SWITCHING MODE.  They change from one state to another VERY QUICKLY.
This action is called a SWITCHING ACTION or DIGITAL ACTION or DIGITAL MODE. There are basically two types of circuits, DIGITAL CIRCUITS and ANALOGUE CIRCUITS (also called audio circuits). An audio circuit operates over a smooth range of low output to high output. A digital circuit goes from one state to the other very quickly.
When this change is produced by the components within the circuit, the action is called REGENERATION because the action cannot be stopped and takes the transitor(s) from the state of not being turned on to the state of being fully turned on.

What the hell?

hoptoad

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Re: Joule Thief 101
« Reply #259 on: February 16, 2016, 06:09:09 AM »
snip...
Quote from Clive in above video info: "There are a few variants on the design which add extra components to improve efficiency, but a true Joule Thief uses a single transistor, 1K resistor, hand wound ferrite bead transformer and the LED you want to light."
Bill
So if I substitute the 1K resistor for a 980 ohm, or I substitute hand wound for machine wound, or ferrite for air, etc, then it's not a JT.
Can you see how arbitrary and silly that notion is.?

Since JT is a vernacular term, and not an accepted Electrical Engineering term, then quite frankly, we can call anything a JT if we like and still be correct.

General language dictionaries (like Wikipeadia) reflect common usage and are therefore descriptive not proscriptive.

It seems that MH is not the only person who wants to place arbitrary parameters on what constitutes a JT.
So he (Clive) may have been the first to coin the term JT, but he doesn't own the term any more than the person who first used the term electronic to describe a particular device. As if arbitrarily deciding that only that very specific device can in any way be called 'electronic'.

A f.....g storm in a teacup really.
@Tinman, thanks for your sharing of your time on the bench.

cheers

allcanadian

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Re: Joule Thief 101
« Reply #260 on: February 16, 2016, 06:38:00 AM »
Quote
7. With less electricity going into the base of the transistor, the collector-emitter channel begins to close. This allows less electricity to travel through the second coil.
8. A drop in the amount of electricity in the second coil induces a negative amount of electricity in the first coil. This causes even less electricity to go into the base of the transistor.


Induces a negative amount of electricity in the first coil?, a negative amount of something is less than nothing. Sounds like some kind of woo woo perpetual motion claim to me, has no credibility.
Although according to a scientific study just made up by me 9 out of 10 people under the age of four may believe in negative lectricity.


AC

Lakes

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Re: Joule Thief 101
« Reply #261 on: February 16, 2016, 09:53:03 AM »
Negative Electrickery Generator. :)

tinman

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Re: Joule Thief 101
« Reply #262 on: February 16, 2016, 10:31:26 AM »
http://makezine.com/projects/joule-thief-battery-charger/

How a Joule Thief works:

 This circuit used in this project is a modified "Joule Thief." A Joule Thief is a self-oscillating voltage booster. It takes a steady low voltage signal and converts it into a series of high frequency pulses at a higher voltage. Here is how a basic Joule Thief works, step by step:
    1. Initially the transistor is off.
    2. A small amount of electricity goes through the resistor and the first coil to the base of the transistor. This partially opens up the collector-emitter channel. Electricity is now able to travel through the second coil and through the collector-emitter channel of the transistor.
    3. The increasing amount of electricity through the second coil generates a magnetic field that induces a greater amount of electricity in the first coil.
    4. The induced electricity in the first coil goes into the base of the transistor and opens up the collector-emitter channel even more. This lets even more electricity travel through the second coil and through the collector-emitter channel of the transistor.
    5. Steps 3 and 4 repeat in a feedback loop until the base of the transistor is saturated and the collector-emitter channel is fully open. The electricity traveling through the second coil and through the transistor are now at a maximum. There is a lot of energy built up in the magnetic field of the second coil.
    6. Since the electricity in the second coil is no longer increasing, it stops inducing electricity in the first coil. This causes less electricity to go into the base of the transistor.
    7. With less electricity going into the base of the transistor, the collector-emitter channel begins to close. This allows less electricity to travel through the second coil.
    8. A drop in the amount of electricity in the second coil induces a negative amount of electricity in the first coil. This causes even less electricity to go into the base of the transistor.
    9. Steps 7 and 8 repeat in a feedback loop until there is almost no electricity going through the transistor.
    10. Part of the energy that was stored in the magnetic field of the second coil has drained out. However there is still a lot of energy stored up. This energy needs to go somewhere. This causes the voltage at the output of the coil to spike.
    11. The built up electricity can't go through the transistor, so it has to go through the load (usually an LED). The voltage at the output of the coil builds up until it reaches a voltage where is can go through the load and be dissipated.
    12. The built up energy goes through the load in a big spike. Once the energy is dissipated, the circuit is effectively reset and starts the whole process all over again. In a typical Joule Thief circuit this process happens 50,000 times per second.

What the heck?   No mention of "resonance" anywhere?!  No mention of "LC" or "RLC" anywhere?!

It must be an NWO plot and they want to hide the truth from you.

Wow-what do you know--works the very same as the good old ssg pulse motor circuit.
Remember me trying to explain that to you MH--the cascade effect that takes place when the transistor starts to conduct due to the current generated in the trigger coil by the passing magnet.
The solid state version works exactly the same.

I have told you a number of times now MH,you do not get to define what a JT circuit is--it is !NOT! one circuit,it is a circuit that work on an effect,and results in the near total drain of what would otherwise be a dead battery.

I would suggest that you have another look at how these circuits work,and how the transistor can still switch on when the battery voltage is lower than the minimum required base voltage to switch the transistor on. You assume that the base voltage has to be high enough to switch on the transistor,but that is not correct at all. You either raise the base voltage,or pull the emitter voltage down to a negative voltage-which is what L1 dose in these circuits.

Lets test this theory of yours that the (your) JT circuit is the best at what it dose.
I will use the good old SS SSG circuit,and we'll make a comparison. Then we'll see what is the best JT circuit.


Brad

sm0ky2

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Re: Joule Thief 101
« Reply #263 on: February 16, 2016, 10:37:27 AM »
Okay the analogy is fine.  Using gravity and Mgh is a little bit less intuitive than the analogy I normally think of.

If the mass is horizontal and on a frictionless surface and connected to a spring is the analogy that I prefer.  Then the energy in the moving mass and energy in the displacement of the spring are in perfect quadrature.  Depending on how you view the variables, the mass is the capacitor and the spring is the inductor, or vice-versa.

MileHigh

This is the analog to the LC circuit, using no ferrite in the inductor. (or the permeability of free space, which is negligible in this case.)

adding both gravity, and friction, is analogous to an RLC, with a ferrite core.

if gravity had a "resonant frequency", this spring would be something strange.......

tinman

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Re: Joule Thief 101
« Reply #264 on: February 16, 2016, 11:33:22 AM »
What is a joule thief.

Quote Makezine.com-->A “Joule Thief” is a simple voltage booster circuit. It can increase the voltage of a power source by changing the constant low voltage signal into a series of rapid pulses at a higher voltage.

Quote wikipedia-->A joule thief is a minimalist Armstrong[1] self-oscillating voltage booster that is small, low-cost, and easy to build, typically used for driving light loads.
It can use nearly all of the energy in a single-cell electric battery, even far below the voltage where other circuits consider the battery fully discharged (or "dead"); hence the name, which suggests the notion that the circuit is stealing energy or "joules" from the source. The term is a pun on the expression "jewel thief": one who steals jewelry or gemstones
Apparently MH thinks some one high jacked wiki,and th explanation is wrong ::)

Quote Rimstar.org-->The joule thief (aka blocking oscillator) is an electronic circuit that allows you to make use of batteries normally considered dead. A battery is often considered "dead" when it can't power a particular device.

Quote lizarum.com-->A Joule thief allows you to boost the voltage of a dying battery.

The list go's on.
So the JT is not one single circuit,but can be many types of circuits that perform the same operation -->and that is to drain the last remaining energy from a nearly depleted battery.

The circuit dose not even require the use of a transistor,and can be achieved in many different ways--as long as we get the LED to light,while draining the remaining energy from the battery.


Brad

tinman

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Re: Joule Thief 101
« Reply #265 on: February 16, 2016, 01:32:59 PM »
Here is the simple SS SSG circuit being used as a joule thief circuit.
As you can see,no problem at all driving a 10mm LED quite brightly at .25v(250mV)

So be wary of those here that quote things like-->No, they are not Joule Thief circuits because it looks almost certain that they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery that has a low voltage-high impedance output.

Or-->So it's not a Joule Thief because it does not do anything special to extract energy from a very-low-voltage battery.


Or-->they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery."

Comments like this are untrue,and as can be seen in my video,there are many circuits that operate just as well as a !MH! joule thief circuit. The one pictured in the video (the simple SS SSG circuit)is now running on a battery with a voltage of only .14v--even with the large 2n3055 transistor--you dont get much better than that.

Next we will be building a mechanical JT,and im hoping that it will operate near the .1v area.

https://www.youtube.com/watch?v=1f1DG4syHCw

Brad

Nink

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Re: Joule Thief 101
« Reply #266 on: February 16, 2016, 03:49:22 PM »
Anyone know if a JT is a good solution for charging a NiCad battery from a low voltage trickle source.  I need to include JT in a circuit to run LEDs but I figured if I could use the same circuit for both
1) When turned off Tickle Power Source => JT => charges Nicad
2) When turned on uses Nicad => JT=> LED

If this is the case what would be the best JT circuit to use. Low voltage Low amp power source <1v DC  ~5 to 20mA   




MileHigh

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Re: Joule Thief 101
« Reply #267 on: February 16, 2016, 04:32:04 PM »
Quote
So the JT is not one single circuit,but can be many types of circuits that perform the same operation -->and that is to drain the last remaining energy from a nearly depleted battery.

What's language if we don't use it properly?  You want to be an effective communicator and this doubly applies to electronics where you want to use the right concepts, and use the correct nomenclature so as to avoid confusion.  If you don't do that then you can lose Mars satellites because someone was too lazy to say they were using metric units instead of English units.

A Joule Thief is a pulse circuit that is a type of blocking oscillator.  There can indeed be variations on Joule Thief designs but they are all types of blocking oscillators.  Feedback oscillators based on some kind of RLC circuit on the other hand are not pulse circuits at all.

Both Joule Thief/blocking oscillators and feedback oscillators can drain a battery no doubt.  For both types of designs there will be a minimum battery voltage where they can self-start.  Chances are that Joule Thief designs can self-start at lower voltages than feedback oscillators.  Then for both Joule Thiefs and feedback oscillators if they start at a higher voltage and run continuously they can keep on running lower than the minimum self-start voltage and keep on running to some minimum operating voltage.  As long as the oscillation takes place the circuit can stay alive.

So a feedback oscillator can drain a battery to a quite low voltage also as long as you don't stop it from oscillating, but it is not a Joule Thief.

Now, is that such a hard concept to understand?  I don't think it is.

For both designs, by carefully choosing the configuration and the component values you might be able to get self-starting going at a quite low voltage and sustained oscillation down to an even lower voltage.

Different Joule Thief designs are like variations on Romance languages, like comparing Spanish to French.  A feedback oscillator is a totally different beast, like comparing it to Mandarin Chinese.

MileHigh

MileHigh

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Re: Joule Thief 101
« Reply #268 on: February 16, 2016, 04:39:50 PM »
Here is the simple SS SSG circuit being used as a joule thief circuit.
As you can see,no problem at all driving a 10mm LED quite brightly at .25v(250mV)

So be wary of those here that quote things like-->No, they are not Joule Thief circuits because it looks almost certain that they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery that has a low voltage-high impedance output.

Or-->So it's not a Joule Thief because it does not do anything special to extract energy from a very-low-voltage battery.


Or-->they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery."

Comments like this are untrue,and as can be seen in my video,there are many circuits that operate just as well as a !MH! joule thief circuit. The one pictured in the video (the simple SS SSG circuit)is now running on a battery with a voltage of only .14v--even with the large 2n3055 transistor--you dont get much better than that.

Next we will be building a mechanical JT,and im hoping that it will operate near the .1v area.

https://www.youtube.com/watch?v=1f1DG4syHCw

Brad

<<< as can be seen in my video,there are many circuits that operate just as well as a !MH! joule thief circuit. >>>

Facepalm.

In an ironic, but not surprising twist, all that you are doing is proving my point.

Your SSG circuit IS a blocking oscillator.  So it is a variation on a Joule Thief.  From what I could see in the clip, it is self-clocking so it's basically a Joule Thief that you are showing in your clip.

I know that you are not going to provide a schematic, who needs pesky details like that...

Pirate88179

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Re: Joule Thief 101
« Reply #269 on: February 16, 2016, 04:48:25 PM »
Brad:


Quote from BigClive: "There are a few variants on the design which add extra components to improve efficiency, but a true Joule Thief uses a single transistor, 1K resistor, hand wound ferrite bead transformer and the LED you want to light."


You forgot to use BigClive's definitions of the JT circuit.  He is the one that came up with that name in the first place so, I think he gets to decide what it is, and is not. 


Of course, according to BigClive's definitions, a lot of my circuits are not JT's.  Maybe we here should come up with our own name to describe a blocking oscillator/feedback type circuit that boosts voltage and runs down batteries? 


I used the name "Joule Pirate"  on several of my circuits as Pirates have been known to steal stuff, ha ha.  I am not saying we need to use that but, all of my Fuji type circuits are not really JT's using Clive's definition.  They need to be called something.


Bill