These videos remind me of the days I learned "electronics" by reading Popular Electronics. The magazine always had very interesting and fun projects one could build but, more importantly, they explained in easy terms how the components and circuits functioned. Good job.
That answers my unasked question. It works because it's only on half the time, but persistence of vision fills in the blanks. I have a small jar of toroids that I haven't known what to do with and this looks like a fun project. And just to brag a bit; today I managed to get a crystal radio to light up an LED. It was flickery and weak but, hey, I figured out how to grab electrical energy out of the air and make light light with it. Thanks for the uploads.
*best explanation of basic electronics by far, electricity can be very hard to understand, at least for me, i need analogies, and every single video on youtube does not use analogies, and it doesnt matter how good you are at teaching, to me explaining electricity without analogies is like trying to tell me how witchcraft works.*
Super vid :D This is the best one I've seen on how a JT works & is right.I've seen in other places where they give a much harder/wrong explanation.And just for anyone else who reads this know that a joule thief/ringer is one of the simple(best to me)circuits there are to turn on ANY TRANSFORMER.So hook this circuit up to Any transformer that has a center tap (or just rap one on the core if possible)& use the secondary for what ever you like(minus the LED of course to give energy to secondary) ;p
Sir, you explained the concept beautifully, I had no idea how it worked, it seemed very confusing to understand when I read it, but now it feels so easy, thank you.
my husband studies this , and since I watch your videos , I understand so much more about led and stuff , he also built a cnc machine that cuts stuff out , I love your videos, thank you :) Amelia
this explanation helped me a lot. thanks ..... this is the first time i understood a joule thief circuit completely..... i seen lot of videos, but only this one could be understood
This is one of your simpler videos but normally I have to speed up videos because they bore me. You sir, almost 100% of the time I have to slow down your videos and I definitely learn a lot from your channel. Thank you very much sir! Godspeed.
Typically a resistance of roughly around 1000 to 2000 ohms is used for this circuit. I happened to have a 820 ohm resistor so I used that. The resistor is to protect the transistor from too much current but it also affects the timing of the cycles. A good idea is to use a potentiometer (variable resistor) instead so you can easily try different resistances.
Thanks! And welcome! The time frame depends on a few things and is usually controllable by replacing the fixed value resistor with a variable one (a potentiometer). In my "Make a Joule Thief for Zombie Batteries" video at 0:36 I show on the oscilloscope a cycle time of around 40 microseconds, so a frequency of around 25 kilohertz. In my "Fun with Joule Thief Powering a Compact Fluorescent Light" video i show 60 microseconds. So somewhere in the tens of microseconds of tens of kilohertz.
Thank you for this video. It is well made and understandable. It has opened my eyes to new ways of thinking. I've probably heard dozens if not hundreds of engineers speak about circuits, and none showed such a neat concept. Thanks.
It's not cycling based on a resonant frequency. In the video I talk about the cycle reversing because the core becomes saturated. But I mention that as one of a few possible reasons depending on things like the battery voltage. At these low voltages, most likely the cycle reverses when the current between base and emitter is too low for the increasing current between the collector and emitter. So the timing is due to the transistor specifications rather than a resonant frequency.
Thank you sir Of all other videos I have seen everyone gave a vague explanation about the switching off of the transistor but your explanation seems quiet convincing .
+Vignobles Lac Saint-Jean I've used it for a number of things, which I've shown in other videos. The most frequent use is to power an LED using a battery whose voltage would otherwise be too low to meet the LED's minimum required voltage. I show that one in my "Make a Joule Thief for Zombie Batteries" video ruclips.net/video/B61DU7yEsPM/видео.html Then I found you can power a CFL using 2 AA batteries by modifying the coils ruclips.net/video/FkLET8MhRbU/видео.html. And then I learned how to modify the coils again to use this to transmit electricity wirelessly ruclips.net/video/31Rxi8JMIys/видео.html. Don't be misled by the "thief" in the name. This is just what's also called a blocking oscillator circuit. It provides higher voltage and current by repeatedly building up energy in a magnetic field and then releasing it in a short burst. The higher voltage and current exist only during the brief burst. The total energy out is smaller than the energy in. PS There's no Reply button under your comment because of your Google+ settings. - go to your Google+ page, - in the top, right corner click on your thumbnail icon, - in the popup that appears, click on "Settings". - for the 2nd question down "Who can comment on your public posts?" set it to "Anyone".
RimstarOrg the power to charge the batteries comes from the solar panels. It does make sense. Get a small low voltage panel from a calculator and try your joule thief on it with an led that shouldn't be powered.
adolthitler Ah, my bad. It was a case of skimming through comments at a time when I was going through a ton of them. I remember thinking he was talking about doing it at night when there was nothing from the solar panels, which clearly he wasn't saying at all! Yes, it could probably extend the useful time of solar panels to when the clouds some out. That'd be an interesting demonstration in fact.
Rohan Zener If you're referring to just the coils and the toroid core then it's one-to-one, no transforming would take place since both coils have the same number of turns. If you're talking about he whole joule thief circuit being x2, then no, it's much more than that. Also, the output is neither DC nor AC. You can see the output waveform in my video about how to make it at 0:38 ruclips.net/video/B61DU7yEsPM/видео.html. Here a 1.5 volt battery is on the input and the output is the waveform shown with a peak-to-peak voltage of around 24 volts and a frequency of around 22 kilohertz. Both the voltage and frequency are affected by a number of things, including the resistance of the resistor used, as I demonstrate in this other video here ruclips.net/video/yz_99oVMbSI/видео.html. I don't have any way of calculating what you should get as output.
Thank you for letting me know that it was clear. I know I sometimes speak too fast for some to understand. I'm happy to hear you had no problem. Cheers from Canada.
I had the same problem. I was still trying to process and understand what he was saying, and then visualize it, but before I could, he was already on to the next step so I was trying to listen to what he said and not miss anything. For anyone else that couldn't keep up on the first play through, try playing the video at 75% speed. It slows it down enough that you can work through it. It also helps to break it into sections, let him explain one part, pause, think it through, make sure you understand what he's saying and why it works that way, then move onto the next section. Once you do that, it becomes a pretty simple concept to understand.
Very nice explanation, I can only imagine how good Your explanations would be if You could do them "at Your own pace" rather than having to adhere to RUclipss time limits. Still great vids, it's ppl like You that makes the W3 worth while Keep up the good work Cudos.
I'm glad to hear you like the explanation. I'm actually enabled for longer than 15 minutes per video but I'm always wary of going on too long for fear of only a few watching. I have done 10 to 15 minute videos though. I do regret not talking about some of the other reasons a joule thief does the reversal step - bad decision on my part :(. Oh well. Thanks for the feedback!
+Kennynva T. If you're reading the same voltage then it's possible your circuit isn't right and you're just powering the LED off of the battery. Does you battery light the LED without the circuit? If the battery alone doesn't power the LED then you wired the circuit correctly and the joule thief is doing it's thing. Check the wiring going to your coil to see if it's the same as the circuit diagram. It's not wired the way you'd expect.
Yes that is whats weird..the battery will not light the led by itself..but it does in the circuit..So how does the capacitor make the led brighter...no matter which way you turn the electrolytic capacitor?
+Kennynva T. That's not weird. That's what's supposed to be the case. It means your circuit is working properly. This video is supposed to explain how, but basically it works by increasing both the voltage and the current at the LED by simply building up energy in the coil's magnetic field with the LED off, and then dumping that energy to briefly turn on the LED, and then repeating it. I haven't given much thought about the electrolytic capacitor, but it's also an energy storage medium so maybe the answer's in that. Regarding the polarity not mattering, that would be the case if it's in the circuit where there's AC, as with AC it would function in at least one orientation, and luckily not be damaged.
The Transistor in a joule thief, just acts as an automatic on/off switch, while the 2 coils act sort of like a rechargeable battery. So the magic isn't really the Transistor, the MAGIC actually happens with those 2 coiled wires. So, it starts out with a (street Traffic) Red Light. The wire coils, act like traffic getting backed up at a red light (storing the extra energy in a magnetic field). The Transistor is the traffic light, which waits for enough cars waiting in line, before turning to a green light, which releases the cars, while also blocking traffic from other directions. The Transistor does not really amplify energy, instead, the wire coils amplify the energy and the transistors only job is to be forced open from excessive electricity built up, which quickly drains, which forces it back closed. Without the transistor, the Gate/Switch/Traffic-Light would have to be MANUALLY toggled by a human (like jiggling the second wire on/off the negative). I made one without a transistor, and successfully lit an LED with 1 AAA battery. This is a horrible picture, but I didn't expect it to work, so, forgive me for the bad image quality and having nothing labeled. i.imgur.com/NOknJv1.jpg
Yep, this is the fundamental part, and basic principle with any switching converter. But that's, however, quite easy to understand, but the hardest part to understand with blocking oscillator is how it actually makes the oscillation. This video got me closer to get a grasp about that, still have to process it in my brain though.
Yup. I agree they're pretty much the same. Build up energy in coil, then dump it in a burst. One added point about the joule thief is that the way the primary coil interacts with the secondary coil (green in this video) opens up and shuts down the transistor faster than it would without the secondary coil.
OMG ! Sorry to say that but the term « joule thief » is misleading ! Nothing gained here. This is a very old concept called a « multivibrator circuit » or « oscillator circuit » that is fed through a toroïdal transformer to step up voltage (not current). You could use a regular transformer 110v:6v reversed and you'd get about 20-25 volts. You just made an inverter ! Actually you could do the same using a single SPST relay and a 9v battery hooked up as a vibrator; in that case, you might get thousands of volts on the coil as Back EMF. Usually, to counter that effect. we put a diode across the coil because back EMF can be damaging to electronic components. In this case, we don't need the diode because WE WANT the effect to create EMF. The « Noise » you are hearing in the coil is normal ! It's the vibrator circuit creating resonance !
Yes, it is misleading. But that's one of the names very commonly used for this circuit. Blocking oscillator is another. But nothing in my description points to any energy gain. Just accumulated energy being released in a burst and repeated.
RimstarOrg Blocking oscillator..makes more sense... so does this circut drain the battery faster due to it needing to build up a charge to light the LED? thus no real extra power or "thieving" is achieved? it just spends the energy in a more lump some effect?
Ohm Zen If you have a battery with sufficient voltage and current to light the LED then I would think you'd be better off using the battery directly. And yes, to your other two questions.
The transistor is off when the voltage is sufficient to run current through the LED. The opposite wiring of the coils makes sure of that. During the collapse of the magnetic field, the red coil induces current in the green one in a direction that further aids in shutting off the transistor.
It's hard to say if the light flashes. The frequency is too high for a human to see. We really need a high speed camera to tell or a photo diode circuit. It's pure speculation on my part but there might also be some delay in an LED turning off that causes it to still be on when the current flows again.
Thanks! I don't have any garden lights to play with and the circuits I just saw online either had more parts than a joule thief or used a chip as one of the parts, meaning the parts were combined into a chip. Interesting that one of the descriptions I read showed that they were doing pretty much what a joule thief does, though with slightly different circuits.
the joule thief does two things almost simultaneously 1) it creates an electromagnet 2) it creates voltage with the electromagnet. normally when you create voltage with magnet and wire, you are moving the magnet by the wire, or moving the wire by the magnet. The rate of change has a significant impact on how much voltage is produced (how fast the movement happens) - the force that moves the magnet, is the same pressure that moves the electrons (and that is the voltage). now imagine instead of moving the magnet or wire, you could simply make the magnet appear. Thats a big change - no magnet, then lots of magnet. If appears very slowly or casually, you might not get much voltage, cause it's not a big rate of change, sort of like blowing up a balloon puff by puff. things move baby step by baby step. lots of tiny bits of force that add up to something. But, what if you could also make the magnet disappear? that's also a big change - lots of magnet to no magnet. If it disappeared suddenly - like if you popped the balloon (!) that would be a BIG change in a small amount of time, with a lot of force behind it (all the little bits of force from blowing up the balloon are all let out suddenly in a single instant). things would REALLY move, fast (namely electrons). unfortunately magnets can't disappear and appear. BUT electromagnets can turn on and off, which makes a magnetic field that appears and disappears. Luckily, when it shuts off, the magnetic field collapses much more suddenly than it took to inflate with electricity. When it collapses there is an explosion of electrons that shoot through the wire - imagine all the air from an exploding balloon shooting through a drinking straw. things move with the same amount of energy that was put into the balloon, but it is more forceful because its all happening at once (greater acceleration, covering the same distance shorter amount of time) so the transitor allows the joule thief to switch between too phases. phase one creates an electromagnet using the voltage of the battery. when the electromagnet appears it also creates a tiny bit of extra voltage which completes phase one and switches the transitor to phase two. in phase two the electromagnetic balloon POPS condensing all the force put into it into a small point in time creating a tremendous pressure which is strong enough to light the LED. ultimately the joule thief uses time as its currency to buy more power. the joule thief relies on self inductance. here is a simple video on self inductance m.ruclips.net/video/pKKsco9EgBQ/видео.html the only difference between the device in the video and a joule thief, is the transistor replaces the person that has to repeat the step of pressing and releasing the button.
The TL;DR version is that it charges up in the torroid until it's full, then when that happens the transistor lets go which forces the current through the LED. Instead of giving it 1.5 volts over a second, it gives it 3 volts over 2 seconds.
I love your videos. You explain them very understandably. Completely without unnecessary details. That was the best explanation of a transistor that I've seen yet.. How about a video on a PNP transistor, I'm a beginner in electronics. I would really enjoy that and I'm sure many others will too.
+ThomasTheSailor Chubby Thanks. A PNP transistor just has the reverse direction of flow from the collector to the emitter and the base has to be negative with respect to the emitter for it to flow. But conceptually it's the same.
Thanks and you're welcome! I don't know how efficient the joule thief is. It's basically just a way of stepping up voltage. It's definitely making good use of batteries that are normally considered dead, so in that way it's efficient. I looked at the store bought solar light circuit and IIRC the one I examined was basically a joule thief circuit.
Yes, at a conceptual level in that it steps up. Though it steps up both the voltage and the current, sort of, by accumulating energy in the magnetic field over a period of time, and then dumping it all in a brief period of time, and then repeating. So functionally it's different than a transformer.
30 AWG and 26 AWG. I used two different sizes because that was the only way I could get two different colors. But you could use even up to 18 AWG. There are 13 turns of each but I chose that number at random, it's what fit on the core. See my "Make a Joule Thief for Zombie Batteries" video where I show the parts and me making and testing it. There's a link to it in the description below this video or you can find it on my channel page.
Yep. Great explanation! There was a few points I wasnt sure about that I am now! The simplest explanations are the ones that are understood the most! thanks for that..
Nice play on words, but I love these videos,,electrical engineering is a bit beyond me, but I love the projects and lessons, understandable , get a better understanding
@ RimstarOrg: Sir, I have now viewed two of your electronics presentations (Crystal Radio & now this one). Technically, you’re a talented man who has put together presentations for the “lay person.” Also, your very pleasant speaking voice brings everything together. Thank you.
You have the best explanation out there about a Joule Thief and you really got me interested. I am currently putting together DIY kits to be available on ebay for those who want to experiment with this and not wait a long time getting parts or scavenging for parts. I'd say let's all experiment someday one of us would have that "Aha" moment and the world is changed forever for the good I hope. :)
What do you mean by dropping the voltage? What are you using to measure it? Where in the circuit? You'd need an oscilloscope to see the voltage. A digital meter with numerical display on the DC or AC scales won't work since the voltage is spikes with low voltage in between the spikes. What are you trying to power, an LED?
i wired a little speaker to the circuit just a minute ago and it gives of the same tone only a bit louder so i assume the noise is correlating to the frequency of the joule thief :) thanks for the quick response!
Thanks. It's around 20,000 to 30,000 hertz. You can control it by replacing the fixed resistor with a variable resistor or potentiometer. See my latest video "Fun with Joule Thief Powering a CFL" where I show the waveforms on the oscilloscope and also using the potentiometer and its effect. There's a link to the video in the description below this one. It's also the most recent video on my channel page.
The resistor is there to protect the transistor along the base to emitter path from too much current. Resistors reduce current flowing through them. These coils don't really serve the purpose of a normal step-up or step-down transformer but the primary is considered to be the red coil in the video, the one going through the collector and emitter path and to the LED. The secondary is the green coil, the one going through the base and emitter path.
Mine was only 26 AWG, so that's fairly thin. But I didn't think about what you're saying and my red wire was even thinner, 30 AWG. Keep in mind, when the red coil dumps into the LED, the collapsing magnetic field also induces current into the green coil, which shuts down the gate faster.
Can you tell me how long the battery will last ?? Can using two batteries of the same voltage really increase the voltage avalible for a bank of LEDs ???
I haven''t measured how long the battery will last so I can't say. This is a fairly inefficient circuit though but at least it allows a battery that's at too low a voltage to power the LED with a normal circuit to work.
I don't know what the maximum voltage would be but a lot of people run compact fluorescent light bulbs off of them and they require high voltage. Their ferrite cores are usually larger and they use higher power transistors.
What do you mean by "doesn't seem to work very well". What's it doing? Is it intermittent, or just dimmer, or not lighting at all? How many turns did you have before on each coil and how many do you have this time?
There are lots of variations but this is the basic one. You can see it working and how I put it together step-by-step in my "Make a Joule Thief for Zombie Batteries" video. There's a link to it in the description below this video or you can find it on my channel page. If you watch that you might get some tips on how to get yours to work.
I recall having the battery voltage at the LED at one time too. I don't recall what it turned out to be but it wasn't a bad transistor. It might have been that had the connections to the coils wrong. If you look at them closely you'll see that they're supposed to be crossed in a way. Maybe check that.
That depends in large part on the resistance of the resistor but at one point I measured a single cycle taking 40 microseconds, so 25,000 times a second. You can see this measurement on my oscilloscope in my "Make a Joule Thief for Zombie Batteries" video. There's a link to it in the description below this video.
Very nice video. It would be great if most people who view it read all of the comments that relate to saturation. There are only 20 or so, but enough to help the viewer know what is really going on. In many other online videos and written explanations of how a Joule Thief works, core saturation a common explanation and it really does not happen here, as the comments clearly state. For fun, as a Christmas project, I built a Joule Thief using a styrofoam torus (outer major diameter of 1 foot) wound with a bit more than 900 turns for both coils. That results in inductances of about 2mH. It works fine, but the pulses are a bit short because I used AWG 26 wire so the resistance is larger than it really should be. I wound 15 turns on a ferrite core with an inductance factor of about 11uH which worked almost the same except the pulses are longer due to lower losses. I also simulated both circuits with LT-Spice and linear inductors (no nonlinear core material) and everything is in excellent agreement. In all three cases, you can see that transistor saturation is what causes the cycling of the circuit. Keep up the good work and have fun with the many, many comments. BTW, I am a professor of electrical engineering and use the Joule Thief in my classes. Students love it.
Hi, and I'm glad you like what I do. I'm guessing your LED is one that can turn on at 1.5 volts or less (if you're battery is fully charged then it's likely over 1.5 volts.) Do you have any packaging with your LED that tells you what voltage it needs? The LEDs I use require 1.85 volts, and that's why I need a joule thief.
I don't have any plans for overunity/free energy generators, only some rough ideas on vacuum engineering that are likely wrong. See my rimstar.org website for that. Meanwhile, see the description below this video for links to my other videos on how to make joule thiefs, one for lighting an LED and another for a CFL if you need details. And I'm glad to hear this video helped. Thanks for watching!
The first thing is go back and check all you connections to see if they're good and if they're right. That's especially the case for the coils since they have to be connected backwards from what you'd expect. Another thing is to try an LED with a higher mcd rating. The higher the mcd, the brighter it lights up. Of course it's a trade off with the LED's voltage requirements. I find 1,400 mcd works great. Also, LEDs don't always emit light in all directions so look at it from various directions.
Yeah, there are three things that I know of that end the first step in what goes on, and leads to the transistor shutting off and the whole process reversing - if that's what you mean by the current being limited. Due to time restrictions and not wanting to bore people to death by going over all three, I decided to go with just the saturation reason. That's why I said "one a few things that can cause this process to reverse." I'm glad you liked the video despite it's limitations.
Connecting the LED between collector and + terminal makes the circuit even more efficient! Only the 'spikes' generated in the coil are used to power the LED. Works 24/7 for about a month on a single battery! Brightness is also ratherr consistent since oscillating frequence increases when battery voltage drops.
If I recall correctly, yes, lower voltage gives lower frequency. If the induction coil is continuously feeding power to the LED then it won't be the same. The joule thief builds up energy over time in the coils/core and then releases it in a burst at high voltage and current. Then it builds up again and releases in a burst again. With continuous feeding to the LED, the energy will be too low at all times.
3:55 absolutely incorrect explanation. When transistor gate is open red wire induces opposite voltage on green wire through the coil, and transistor is closing, and the rest of the magnetic energy goes to LED, then cycle repeats.
I'm not sure if it's using the power more efficiently. It's hard to say if the total power it's using by flashing on and off is less than the total power it would use without the circuit by staying on all the time. It's still possible that during those 'on' times it's using double or triple the normal amount of power. The peak voltage is way above what the LED requires. I measured 24 volts in my other video. But it is making use of otherwise dead batteries, and that's good.
Its the low impedance coil & high inductance ferrite toroid. Low impedance windings inducts high current and generates large flux in the ferite core, so when the field collapses the high flux translates to voltage potential. It just adds a series voltage pulse on top to the battery voltage. The physics gets more complicated, but this is a good start. BTW the opposing polarity of the 2 coils, the larger coil chokes the smaller coil as soon as the NPN opens, and in turn shuts the NPN.
I'm just going by what my scope showed me. If you look at my Make a Joule Thief for Zombie Batteries video at 0:37 you'll see the waveform for the voltage. There may just not be much current in the reverse direction. I don't see why there would be.
Oh, sorry to hear you had difficulty. The anode/positive/long lead is connected to the collector of the transistor which is also connected to the red wire going to the red coil. The cathode/negative/short lead is connected to the emitter and battery negative. Maybe your confusion is because I drew the long lead connected directly to the transistor's collector without any intermediate wire. Maybe that made you think those weren't the leads and that they were missing?
I agree, in this case it's not because the core is saturated. In the video I said there were a few possible ways the cycle could reverse. I should have explained them all, and wish I hadn't chosen not to. Too late. With this small a battery it's more likely it reverses for the reason you say. If it were a larger battery and a ferrite core then core saturation is a possible reason.
With some changes, like a bigger battery and more turns on the primary and a higher power transistor, you can power the tubes of a compact fluorescent lightbulb.
Did you use an oscilloscope to measure it? If you look at the oscilloscope output in my Make a Joule Thief for Zombie Batteries video you'll see it's not something a DMM is designed to handle as either AC or DC.
Yes, it's the same type of toroid, just different coils/wires wrapped around it. But it's easy to remove the wires and wrap your own around it. I removed my toroid from an old power supply, removed the wires and then wrapped my own. You can see me wrapping them in my other joule thief video "Make a Joule Thief for Zombie Batteries" which you can find a link to in the description below this video. And I agree, it is amazing and beautiful and delightful when you see a circuit you made working.
RimstarOrg, My analysis was wrong. I was working without a scope. When I used a 1.5v and removed the Transistor from the circuit,the LED turned off. When I used a 3.7v and remove the Transistor from the circuit, the LED stayed on. I thought this was because, the circuit did no vibrate. I Was wrong. Thank you for responding. You videos are excelent!
Thanks. Glad you like it. One thing I should have added was more of the possible ways in which the transformer could shut down besides a saturated core. Oh well.
The noise is normal. If you watch a lot of joule thief videos you'll hear it in many, sometimes very loud. My understanding is that it's the coils and/or core vibrating that's causing it. I don't know offhand how to change it to get rid of it.
It powers the LED with batteries whose voltage is so low that they'd normally be considered dead and thrown out. I guess another is that you can power the tubes of a compact fluorescent light bulb when its circuitry dies by replacing that circuitry with a joule thief, and run it on batteries. And for those so inclined, they're fun circuits to toy with.
The one in my Make a Joule Thief for Zombie Batteries video was oscillating at 46 microseconds per cycle or 21,739 times a second. If you watch that video you can see this in the oscilloscope clip at 0:36 into the video. Each horizontal division on the scope screen is set to 10 microseconds.
These videos remind me of the days I learned "electronics" by reading Popular Electronics. The magazine always had very interesting and fun projects one could build but, more importantly, they explained in easy terms how the components and circuits functioned. Good job.
Yeah, a lot of people have had a lot of fun experimenting with this circuit. It could probably win an award for most played with! :)
Excellent...
You're welcome! I'm glad to hear you like it so much. And yes, the LED is actually turning on and off faster than you can notice.
That answers my unasked question. It works because it's only on half the time, but persistence of vision fills in the blanks. I have a small jar of toroids that I haven't known what to do with and this looks like a fun project. And just to brag a bit; today I managed to get a crystal radio to light up an LED. It was flickery and weak but, hey, I figured out how to grab electrical energy out of the air and make light light with it. Thanks for the uploads.
*best explanation of basic electronics by far, electricity can be very hard to understand, at least for me, i need analogies, and every single video on youtube does not use analogies, and it doesnt matter how good you are at teaching, to me explaining electricity without analogies is like trying to tell me how witchcraft works.*
Super vid :D This is the best one I've seen on how a JT works & is right.I've seen in other places where they give a much harder/wrong explanation.And just for anyone else who reads this know that a joule thief/ringer is one of the simple(best to me)circuits there are to turn on ANY TRANSFORMER.So hook this circuit up to Any transformer that has a center tap (or just rap one on the core if possible)& use the secondary for what ever you like(minus the LED of course to give energy to secondary) ;p
Sir, you explained the concept beautifully, I had no idea how it worked, it seemed very confusing to understand when I read it, but now it feels so easy, thank you.
my husband studies this , and since I watch your videos , I understand so much more about led and stuff , he also built a cnc machine that cuts stuff out , I love your videos, thank you :) Amelia
this explanation helped me a lot. thanks .....
this is the first time i understood a joule thief circuit completely.....
i seen lot of videos, but only this one could be understood
This is one of your simpler videos but normally I have to speed up videos because they bore me. You sir, almost 100% of the time I have to slow down your videos and I definitely learn a lot from your channel. Thank you very much sir! Godspeed.
Typically a resistance of roughly around 1000 to 2000 ohms is used for this circuit. I happened to have a 820 ohm resistor so I used that. The resistor is to protect the transistor from too much current but it also affects the timing of the cycles. A good idea is to use a potentiometer (variable resistor) instead so you can easily try different resistances.
Thanks! And welcome! The time frame depends on a few things and is usually controllable by replacing the fixed value resistor with a variable one (a potentiometer). In my "Make a Joule Thief for Zombie Batteries" video at 0:36 I show on the oscilloscope a cycle time of around 40 microseconds, so a frequency of around 25 kilohertz. In my "Fun with Joule Thief Powering a Compact Fluorescent Light" video i show 60 microseconds. So somewhere in the tens of microseconds of tens of kilohertz.
Well done! There are a lot of websites with inaccurate descriptions of operation. Nice to see one that reflects reality.
Thank you for this video. It is well made and understandable. It has opened my eyes to new ways of thinking. I've probably heard dozens if not hundreds of engineers speak about circuits, and none showed such a neat concept. Thanks.
It's not cycling based on a resonant frequency. In the video I talk about the cycle reversing because the core becomes saturated. But I mention that as one of a few possible reasons depending on things like the battery voltage. At these low voltages, most likely the cycle reverses when the current between base and emitter is too low for the increasing current between the collector and emitter. So the timing is due to the transistor specifications rather than a resonant frequency.
What I find amazing is just how fast these things happen. It's mind boggling how fast a transistor can switch on and off again.
Even if it does that just above 60 -70 times per second, it's enough for us to see the led always on!
i.e 60-70Hz
Actually, it switching at around 22,000 Hz.
This is nothing compared to, say, an FM radio, broadcasting at 100,000,000 Hz
or a microprocessor... where stuff is happening at Giga Hertz
(1,000,000,000 Hz)
Thank you sir
Of all other videos I have seen everyone gave a vague explanation about the switching off of the transistor but your explanation seems quiet convincing .
You're welcome.
Try searching for Joule Ringer. lasersaber has some powerful joule thiefs.
thanks to this man ....among all explaination i couldnt understand how transistor works untill this man shows a simple water technique ...:)
that was an awesome explanation of a transistor for an amateur. thank you!
That is definitely the best Joule thief / blocking oscillator video ever. Well done.
+Vignobles Lac Saint-Jean I've used it for a number of things, which I've shown in other videos. The most frequent use is to power an LED using a battery whose voltage would otherwise be too low to meet the LED's minimum required voltage. I show that one in my "Make a Joule Thief for Zombie Batteries" video ruclips.net/video/B61DU7yEsPM/видео.html Then I found you can power a CFL using 2 AA batteries by modifying the coils ruclips.net/video/FkLET8MhRbU/видео.html. And then I learned how to modify the coils again to use this to transmit electricity wirelessly ruclips.net/video/31Rxi8JMIys/видео.html.
Don't be misled by the "thief" in the name. This is just what's also called a blocking oscillator circuit. It provides higher voltage and current by repeatedly building up energy in a magnetic field and then releasing it in a short burst. The higher voltage and current exist only during the brief burst. The total energy out is smaller than the energy in.
PS There's no Reply button under your comment because of your Google+ settings.
- go to your Google+ page,
- in the top, right corner click on your thumbnail icon,
- in the popup that appears, click on "Settings".
- for the 2nd question down "Who can comment on your public posts?" set it to "Anyone".
*****
No.You'd still need to power it with batteries so that you can charge the batteries. It doesn't make sense.
RimstarOrg the power to charge the batteries comes from the solar panels. It does make sense. Get a small low voltage panel from a calculator and try your joule thief on it with an led that shouldn't be powered.
adolthitler Ah, my bad. It was a case of skimming through comments at a time when I was going through a ton of them. I remember thinking he was talking about doing it at night when there was nothing from the solar panels, which clearly he wasn't saying at all! Yes, it could probably extend the useful time of solar panels to when the clouds some out. That'd be an interesting demonstration in fact.
Rohan Zener Yes, structurally the coil and core are the same as a transformer should you need one like that.
Rohan Zener If you're referring to just the coils and the toroid core then it's one-to-one, no transforming would take place since both coils have the same number of turns.
If you're talking about he whole joule thief circuit being x2, then no, it's much more than that. Also, the output is neither DC nor AC. You can see the output waveform in my video about how to make it at 0:38 ruclips.net/video/B61DU7yEsPM/видео.html. Here a 1.5 volt battery is on the input and the output is the waveform shown with a peak-to-peak voltage of around 24 volts and a frequency of around 22 kilohertz.
Both the voltage and frequency are affected by a number of things, including the resistance of the resistor used, as I demonstrate in this other video here ruclips.net/video/yz_99oVMbSI/видео.html.
I don't have any way of calculating what you should get as output.
Thank you for letting me know that it was clear. I know I sometimes speak too fast for some to understand. I'm happy to hear you had no problem. Cheers from Canada.
i wish you would speak slowly Mr Rimstar, i don't drink coffee, so i'm not going that speed, but when I replay each bit I find this very informative.
I had the same problem. I was still trying to process and understand what he was saying, and then visualize it, but before I could, he was already on to the next step so I was trying to listen to what he said and not miss anything.
For anyone else that couldn't keep up on the first play through, try playing the video at 75% speed. It slows it down enough that you can work through it. It also helps to break it into sections, let him explain one part, pause, think it through, make sure you understand what he's saying and why it works that way, then move onto the next section. Once you do that, it becomes a pretty simple concept to understand.
ruclips.net/p/PLh8HTLB-VWMkqsKIpgXFHg5sJDN5eGqtN
ジュール泥棒
Very nice explanation, I can only imagine how good Your explanations would be if You could do them "at Your own pace" rather than having to adhere to RUclipss time limits.
Still great vids, it's ppl like You that makes the W3 worth while
Keep up the good work
Cudos.
You speak very fast like a coil collapsing.
Best Explanation so far!
I would recommend to change the polarisation of the transistor because it draws less current.
Thank you for the video!
And for my next magic trick, I will make even more joules disappear! :D
That is the BEST explanation of how a Transistor works that I have ever heard ..
I'm glad to hear you like the explanation. I'm actually enabled for longer than 15 minutes per video but I'm always wary of going on too long for fear of only a few watching. I have done 10 to 15 minute videos though. I do regret not talking about some of the other reasons a joule thief does the reversal step - bad decision on my part :(. Oh well. Thanks for the feedback!
So your saying the LED is pulsing...but our eyes cant see this pulse..is this right..???
+Kennynva T. Yes.
Seems Im reading the same voltage on the led as the battery has..so how does it get brighter?? just by current??
+Kennynva T. If you're reading the same voltage then it's possible your circuit isn't right and you're just powering the LED off of the battery. Does you battery light the LED without the circuit? If the battery alone doesn't power the LED then you wired the circuit correctly and the joule thief is doing it's thing. Check the wiring going to your coil to see if it's the same as the circuit diagram. It's not wired the way you'd expect.
Yes that is whats weird..the battery will not light the led by itself..but it does in the circuit..So how does the capacitor make the led brighter...no matter which way you turn the electrolytic capacitor?
+Kennynva T. That's not weird. That's what's supposed to be the case. It means your circuit is working properly. This video is supposed to explain how, but basically it works by increasing both the voltage and the current at the LED by simply building up energy in the coil's magnetic field with the LED off, and then dumping that energy to briefly turn on the LED, and then repeating it. I haven't given much thought about the electrolytic capacitor, but it's also an energy storage medium so maybe the answer's in that. Regarding the polarity not mattering, that would be the case if it's in the circuit where there's AC, as with AC it would function in at least one orientation, and luckily not be damaged.
A great video: the whole process is fully explained in plain English and very easy to understand.
The Transistor in a joule thief, just acts as an automatic on/off switch, while the 2 coils act sort of like a rechargeable battery. So the magic isn't really the Transistor, the MAGIC actually happens with those 2 coiled wires. So, it starts out with a (street Traffic) Red Light. The wire coils, act like traffic getting backed up at a red light (storing the extra energy in a magnetic field). The Transistor is the traffic light, which waits for enough cars waiting in line, before turning to a green light, which releases the cars, while also blocking traffic from other directions. The Transistor does not really amplify energy, instead, the wire coils amplify the energy and the transistors only job is to be forced open from excessive electricity built up, which quickly drains, which forces it back closed. Without the transistor, the Gate/Switch/Traffic-Light would have to be MANUALLY toggled by a human (like jiggling the second wire on/off the negative). I made one without a transistor, and successfully lit an LED with 1 AAA battery. This is a horrible picture, but I didn't expect it to work, so, forgive me for the bad image quality and having nothing labeled. i.imgur.com/NOknJv1.jpg
Yep, this is the fundamental part, and basic principle with any switching converter. But that's, however, quite easy to understand, but the hardest part to understand with blocking oscillator is how it actually makes the oscillation. This video got me closer to get a grasp about that, still have to process it in my brain though.
Yup. I agree they're pretty much the same. Build up energy in coil, then dump it in a burst. One added point about the joule thief is that the way the primary coil interacts with the secondary coil (green in this video) opens up and shuts down the transistor faster than it would without the secondary coil.
OMG !
Sorry to say that but the term « joule thief » is misleading !
Nothing gained here. This is a very old concept called a « multivibrator circuit » or « oscillator circuit » that is fed through a toroïdal transformer to step up voltage (not current). You could use a regular transformer 110v:6v reversed and you'd get about 20-25 volts. You just made an inverter !
Actually you could do the same using a single SPST relay and a 9v battery hooked up as a vibrator; in that case, you might get thousands of volts on the coil as Back EMF.
Usually, to counter that effect. we put a diode across the coil because back EMF can be damaging to electronic components. In this case, we don't need the diode because WE WANT the effect to create EMF.
The « Noise » you are hearing in the coil is normal ! It's the vibrator circuit creating resonance !
Yes, it is misleading. But that's one of the names very commonly used for this circuit. Blocking oscillator is another. But nothing in my description points to any energy gain. Just accumulated energy being released in a burst and repeated.
RimstarOrg Blocking oscillator..makes more sense... so does this circut drain the battery faster due to it needing to build up a charge to light the LED? thus no real extra power or "thieving" is achieved? it just spends the energy in a more lump some effect?
Ohm Zen
If you have a battery with sufficient voltage and current to light the LED then I would think you'd be better off using the battery directly. And yes, to your other two questions.
Thank you for answering all of "our" youtube questions! you are my favorite youtube professor haha ;D
The transistor is off when the voltage is sufficient to run current through the LED. The opposite wiring of the coils makes sure of that. During the collapse of the magnetic field, the red coil induces current in the green one in a direction that further aids in shutting off the transistor.
Does the light flash rapidly?
Because the gates open and close.
So D/C to A/C.
It's hard to say if the light flashes. The frequency is too high for a human to see. We really need a high speed camera to tell or a photo diode circuit. It's pure speculation on my part but there might also be some delay in an LED turning off that causes it to still be on when the current flows again.
If you add an adequate capacitor, you can resolve the light flashing rapidly.
Thanks! I don't have any garden lights to play with and the circuits I just saw online either had more parts than a joule thief or used a chip as one of the parts, meaning the parts were combined into a chip. Interesting that one of the descriptions I read showed that they were doing pretty much what a joule thief does, though with slightly different circuits.
@_@... Totally confused.
haha. try reading about Electromagnetism you will be better introduced there :)
Lol, try watching it several times.. dude talks FAST!
Hahaha try it you will understand better
the joule thief does two things almost simultaneously 1) it creates an electromagnet 2) it creates voltage with the electromagnet.
normally when you create voltage with magnet and wire, you are moving the magnet by the wire, or moving the wire by the magnet. The rate of change has a significant impact on how much voltage is produced (how fast the movement happens) - the force that moves the magnet, is the same pressure that moves the electrons (and that is the voltage).
now imagine instead of moving the magnet or wire, you could simply make the magnet appear. Thats a big change - no magnet, then lots of magnet. If appears very slowly or casually, you might not get much voltage, cause it's not a big rate of change, sort of like blowing up a balloon puff by puff. things move baby step by baby step. lots of tiny bits of force that add up to something.
But, what if you could also make the magnet disappear? that's also a big change - lots of magnet to no magnet. If it disappeared suddenly - like if you popped the balloon (!) that would be a BIG change in a small amount of time, with a lot of force behind it (all the little bits of force from blowing up the balloon are all let out suddenly in a single instant). things would REALLY move, fast (namely electrons).
unfortunately magnets can't disappear and appear. BUT electromagnets can turn on and off, which makes a magnetic field that appears and disappears. Luckily, when it shuts off, the magnetic field collapses much more suddenly than it took to inflate with electricity. When it collapses there is an explosion of electrons that shoot through the wire - imagine all the air from an exploding balloon shooting through a drinking straw. things move with the same amount of energy that was put into the balloon, but it is more forceful because its all happening at once (greater acceleration, covering the same distance shorter amount of time)
so the transitor allows the joule thief to switch between too phases. phase one creates an electromagnet using the voltage of the battery. when the electromagnet appears it also creates a tiny bit of extra voltage which completes phase one and switches the transitor to phase two. in phase two the electromagnetic balloon POPS condensing all the force put into it into a small point in time creating a tremendous pressure which is strong enough to light the LED.
ultimately the joule thief uses time as its currency to buy more power.
the joule thief relies on self inductance.
here is a simple video on self inductance
m.ruclips.net/video/pKKsco9EgBQ/видео.html
the only difference between the device in the video and a joule thief, is the transistor replaces the person that has to repeat the step of pressing and releasing the button.
Well done ! Great
i've been looking for an explanation for joule theives for ages. thanks
...so how does a joule thief work??
The TL;DR version is that it charges up in the torroid until it's full, then when that happens the transistor lets go which forces the current through the LED.
Instead of giving it 1.5 volts over a second, it gives it 3 volts over 2 seconds.
So If you connect two end points of a capacitator, we can make a basic alternator.
It charges it up, discharges it by letting current go through the led, and so on it starts over and over again.
So the stored energy in the magnetic field "pumps up" the voltage in the red wire when the magnetic field collapses. Very cool!
I love your videos. You explain them very understandably. Completely without unnecessary details. That was the best explanation of a transistor that I've seen yet.. How about a video on a PNP transistor, I'm a beginner in electronics. I would really enjoy that and I'm sure many others will too.
+ThomasTheSailor Chubby Thanks. A PNP transistor just has the reverse direction of flow from the collector to the emitter and the base has to be negative with respect to the emitter for it to flow. But conceptually it's the same.
Thanks and you're welcome! I don't know how efficient the joule thief is. It's basically just a way of stepping up voltage. It's definitely making good use of batteries that are normally considered dead, so in that way it's efficient. I looked at the store bought solar light circuit and IIRC the one I examined was basically a joule thief circuit.
Yes, at a conceptual level in that it steps up. Though it steps up both the voltage and the current, sort of, by accumulating energy in the magnetic field over a period of time, and then dumping it all in a brief period of time, and then repeating. So functionally it's different than a transformer.
30 AWG and 26 AWG. I used two different sizes because that was the only way I could get two different colors. But you could use even up to 18 AWG. There are 13 turns of each but I chose that number at random, it's what fit on the core. See my "Make a Joule Thief for Zombie Batteries" video where I show the parts and me making and testing it. There's a link to it in the description below this video or you can find it on my channel page.
Yep. Great explanation! There was a few points I wasnt sure about that I am now! The simplest explanations are the ones that are understood the most! thanks for that..
Nice play on words, but I love these videos,,electrical engineering is a bit beyond me, but I love the projects and lessons, understandable , get a better understanding
Agreed. It is pretty cool, and easy to make. Glad you like it.
@ RimstarOrg: Sir, I have now viewed two of your electronics presentations (Crystal Radio & now this one). Technically, you’re a talented man who has put together presentations for the “lay person.” Also, your very pleasant speaking voice brings everything together. Thank you.
I've watched a ton of these explanations and yours is the best. Thank you
You have the best explanation out there about a Joule Thief and you really got me interested. I am currently putting together DIY kits to be available on ebay for those who want to experiment with this and not wait a long time getting parts or scavenging for parts. I'd say let's all experiment someday one of us would have that "Aha" moment and the world is changed forever for the good I hope. :)
What do you mean by dropping the voltage? What are you using to measure it? Where in the circuit? You'd need an oscilloscope to see the voltage. A digital meter with numerical display on the DC or AC scales won't work since the voltage is spikes with low voltage in between the spikes. What are you trying to power, an LED?
i wired a little speaker to the circuit just a minute ago and it gives of the same tone only a bit louder so i assume the noise is correlating to the frequency of the joule thief :) thanks for the quick response!
Thanks. It's around 20,000 to 30,000 hertz. You can control it by replacing the fixed resistor with a variable resistor or potentiometer. See my latest video "Fun with Joule Thief Powering a CFL" where I show the waveforms on the oscilloscope and also using the potentiometer and its effect. There's a link to the video in the description below this one. It's also the most recent video on my channel page.
The resistor is there to protect the transistor along the base to emitter path from too much current. Resistors reduce current flowing through them. These coils don't really serve the purpose of a normal step-up or step-down transformer but the primary is considered to be the red coil in the video, the one going through the collector and emitter path and to the LED. The secondary is the green coil, the one going through the base and emitter path.
Mine was only 26 AWG, so that's fairly thin. But I didn't think about what you're saying and my red wire was even thinner, 30 AWG. Keep in mind, when the red coil dumps into the LED, the collapsing magnetic field also induces current into the green coil, which shuts down the gate faster.
Can you tell me how long the battery will last ?? Can using two batteries of the same voltage really increase the voltage avalible for a bank of LEDs ???
I haven''t measured how long the battery will last so I can't say. This is a fairly inefficient circuit though but at least it allows a battery that's at too low a voltage to power the LED with a normal circuit to work.
I don't know what the maximum voltage would be but a lot of people run compact fluorescent light bulbs off of them and they require high voltage. Their ferrite cores are usually larger and they use higher power transistors.
Thanks Dennis. Happy to hear you enjoy them. -Steve
What do you mean by "doesn't seem to work very well". What's it doing? Is it intermittent, or just dimmer, or not lighting at all? How many turns did you have before on each coil and how many do you have this time?
There are lots of variations but this is the basic one. You can see it working and how I put it together step-by-step in my "Make a Joule Thief for Zombie Batteries" video. There's a link to it in the description below this video or you can find it on my channel page. If you watch that you might get some tips on how to get yours to work.
I recall having the battery voltage at the LED at one time too. I don't recall what it turned out to be but it wasn't a bad transistor. It might have been that had the connections to the coils wrong. If you look at them closely you'll see that they're supposed to be crossed in a way. Maybe check that.
That depends in large part on the resistance of the resistor but at one point I measured a single cycle taking 40 microseconds, so 25,000 times a second. You can see this measurement on my oscilloscope in my "Make a Joule Thief for Zombie Batteries" video. There's a link to it in the description below this video.
I very much appreciated this video and the time you took to animate the concept step by step.
Very nice, complete explanation of the Joule Thief Circuit, RimstarOrg !
i gotta keep watching these videos. electronics looks like so much fun but is real complicated to me.
I just listened to it a bit again and didn't see that. But thanks for your feedback anyway, those are things I look out for.
Very nice video. It would be great if most people who view it read all of the comments that relate to saturation. There are only 20 or so, but enough to help the viewer know what is really going on. In many other online videos and written explanations of how a Joule Thief works, core saturation a common explanation and it really does not happen here, as the comments clearly state. For fun, as a Christmas project, I built a Joule Thief using a styrofoam torus (outer major diameter of 1 foot) wound with a bit more than 900 turns for both coils. That results in inductances of about 2mH. It works fine, but the pulses are a bit short because I used AWG 26 wire so the resistance is larger than it really should be. I wound 15 turns on a ferrite core with an inductance factor of about 11uH which worked almost the same except the pulses are longer due to lower losses. I also simulated both circuits with LT-Spice and linear inductors (no nonlinear core material) and everything is in excellent agreement. In all three cases, you can see that transistor saturation is what causes the cycling of the circuit. Keep up the good work and have fun with the many, many comments. BTW, I am a professor of electrical engineering and use the Joule Thief in my classes. Students love it.
Hi, and I'm glad you like what I do. I'm guessing your LED is one that can turn on at 1.5 volts or less (if you're battery is fully charged then it's likely over 1.5 volts.) Do you have any packaging with your LED that tells you what voltage it needs? The LEDs I use require 1.85 volts, and that's why I need a joule thief.
Thanks, good to hear it! Not only that, 25% the render time and 25% the upload time of a live video of the same length! :)
I don't have any plans for overunity/free energy generators, only some rough ideas on vacuum engineering that are likely wrong. See my rimstar.org website for that. Meanwhile, see the description below this video for links to my other videos on how to make joule thiefs, one for lighting an LED and another for a CFL if you need details. And I'm glad to hear this video helped. Thanks for watching!
Hi Amelia. Oh wow! Great to hear you find it useful in that way. Thanks for letting me know! -Steve
Cool! How many turns do your coils have?
Wow. This video explains it perfectly! Thanks for that nice explanation. Also the transistor visual is great!
what is wonderful explanation.. no such video exist on youtube... even in 2017
I agree! I'm trying to make one now that'll light a compact fluorescent lightbulb, something quite popular to do.
The first thing is go back and check all you connections to see if they're good and if they're right. That's especially the case for the coils since they have to be connected backwards from what you'd expect. Another thing is to try an LED with a higher mcd rating. The higher the mcd, the brighter it lights up. Of course it's a trade off with the LED's voltage requirements. I find 1,400 mcd works great. Also, LEDs don't always emit light in all directions so look at it from various directions.
Yeah, there are three things that I know of that end the first step in what goes on, and leads to the transistor shutting off and the whole process reversing - if that's what you mean by the current being limited. Due to time restrictions and not wanting to bore people to death by going over all three, I decided to go with just the saturation reason. That's why I said "one a few things that can cause this process to reverse." I'm glad you liked the video despite it's limitations.
Connecting the LED between collector and + terminal makes the circuit even more efficient! Only the 'spikes' generated in the coil are used to power the LED. Works 24/7 for about a month on a single battery! Brightness is also ratherr consistent since oscillating frequence increases when battery voltage drops.
If I recall correctly, yes, lower voltage gives lower frequency.
If the induction coil is continuously feeding power to the LED then it won't be the same. The joule thief builds up energy over time in the coils/core and then releases it in a burst at high voltage and current. Then it builds up again and releases in a burst again. With continuous feeding to the LED, the energy will be too low at all times.
3:55 absolutely incorrect explanation. When transistor gate is open red wire induces opposite voltage on green wire through the coil, and transistor is closing, and the rest of the magnetic energy goes to LED, then cycle repeats.
I'm not sure if it's using the power more efficiently. It's hard to say if the total power it's using by flashing on and off is less than the total power it would use without the circuit by staying on all the time. It's still possible that during those 'on' times it's using double or triple the normal amount of power. The peak voltage is way above what the LED requires. I measured 24 volts in my other video. But it is making use of otherwise dead batteries, and that's good.
Its the low impedance coil & high inductance ferrite toroid. Low impedance windings inducts high current and generates large flux in the ferite core, so when the field collapses the high flux translates to voltage potential. It just adds a series voltage pulse on top to the battery voltage.
The physics gets more complicated, but this is a good start.
BTW the opposing polarity of the 2 coils, the larger coil chokes the smaller coil as soon as the NPN opens, and in turn shuts the NPN.
I'm just going by what my scope showed me. If you look at my Make a Joule Thief for Zombie Batteries video at 0:37 you'll see the waveform for the voltage. There may just not be much current in the reverse direction. I don't see why there would be.
Oh, sorry to hear you had difficulty. The anode/positive/long lead is connected to the collector of the transistor which is also connected to the red wire going to the red coil. The cathode/negative/short lead is connected to the emitter and battery negative.
Maybe your confusion is because I drew the long lead connected directly to the transistor's collector without any intermediate wire. Maybe that made you think those weren't the leads and that they were missing?
I agree, in this case it's not because the core is saturated. In the video I said there were a few possible ways the cycle could reverse. I should have explained them all, and wish I hadn't chosen not to. Too late. With this small a battery it's more likely it reverses for the reason you say. If it were a larger battery and a ferrite core then core saturation is a possible reason.
With some changes, like a bigger battery and more turns on the primary and a higher power transistor, you can power the tubes of a compact fluorescent lightbulb.
Did you use an oscilloscope to measure it? If you look at the oscilloscope output in my Make a Joule Thief for Zombie Batteries video you'll see it's not something a DMM is designed to handle as either AC or DC.
Yes, it's the same type of toroid, just different coils/wires wrapped around it. But it's easy to remove the wires and wrap your own around it. I removed my toroid from an old power supply, removed the wires and then wrapped my own. You can see me wrapping them in my other joule thief video "Make a Joule Thief for Zombie Batteries" which you can find a link to in the description below this video. And I agree, it is amazing and beautiful and delightful when you see a circuit you made working.
Great Video! Excellent explanation of electronic theory and explanation of how this circuit operates!
Pretty much. It's a fun circuit to play with and try all sorts of things.
RimstarOrg, My analysis was wrong. I was working without a scope. When I used a 1.5v and removed the Transistor from the circuit,the LED turned off. When I used a 3.7v and remove the Transistor from the circuit, the LED stayed on. I thought this was because, the circuit did no vibrate. I Was wrong.
Thank you for responding. You videos are excelent!
This vid was really easy to understand, thanks! Really wanted to know how these worked.
Thanks. Glad you like it. One thing I should have added was more of the possible ways in which the transformer could shut down besides a saturated core. Oh well.
The resistor is for limiting the current to the transistor so that the transistor doesn't get damaged. And thanks! Glad to hear you like the video.
The resistor protect the base, not the led. How come the inductor high voltage does not blow the led?
This is a great explanation . Very well thought out .
The noise is normal. If you watch a lot of joule thief videos you'll hear it in many, sometimes very loud. My understanding is that it's the coils and/or core vibrating that's causing it. I don't know offhand how to change it to get rid of it.
It powers the LED with batteries whose voltage is so low that they'd normally be considered dead and thrown out. I guess another is that you can power the tubes of a compact fluorescent light bulb when its circuitry dies by replacing that circuitry with a joule thief, and run it on batteries. And for those so inclined, they're fun circuits to toy with.
The one in my Make a Joule Thief for Zombie Batteries video was oscillating at 46 microseconds per cycle or 21,739 times a second. If you watch that video you can see this in the oscilloscope clip at 0:36 into the video. Each horizontal division on the scope screen is set to 10 microseconds.