Joule Thief Operation

How I think a joule thief works

[@logandihel]

That was one of the best explanations I've heard about the operation of the joule thief. I like how you envisioned yourself as a positive charge trying to flow through the circuit with only one way to go

[@Amar7talks]

From india❤❤ Excellent explained...No one could made me understand but you.. Thank a lot sir❤❤

[@muruhappanchidambaram9489]

The best explanation for a joule thief

[@onyinyeobinwa4022]

Nice Circuit analysis keep up the good 👍

[@to4698]

Thank you so much! The best ❤ explanation in youtube.

[@siliconsys]

Nice video ,i think in the same way, many people think that this goods produce free energy. Thats put in clear.

[@DwiNoviantoUntidar]

Can u tell me how to calculate the voltage spike? So i can estimate how many times should i twist. thanks at first.

[@MongrelShark]

Thank you. You videos are pretty good too :) To see what I am describing, you will have to try a few different winds, in combination with transistor of different Hfe. I found a microwave oven transformer makes a very intresting study case. As do toroids with 10:1 up to 17.5:1 ratios. Did one with 37:1 ratio (zener diode tester), but it behaved pretty much as the 17.5:1 wind. So no need to over do it. I normally have 10 turns on the 1 side.

[@rva1945]

I built a small JT flashlight more than 10 years now, the batt may be already dead with less than 1V, and the LED brights stringly as always.

[@JustFun-iz9rf]

That was well explained thank you 👍🏼

[@incxxxx]

What is the inductance of the coils???

[@MongrelShark]

So the tiny current in the primary (collector) coil actually pushes the voltage up on the base, allowing the transistor to open. Once it opens there is more current on primary, but there is a path of lesser resistance this way too. The hfe of the transistor will determine how long this happens for (normally nano seconds or less) as will inductance and wind ratio. At some point, the transistor is on so much, that all the current goes through the colector, and the base voltage drops. cont...

[@HeilmanHackatronics]

Once I fix my oscilloscope I will analyze the circuit again, nice videos by the way.

[@caroleheilman3992]

Does energy get stored in the magnetic field in the coil (stage 1), and then the collapsing field (stage 2) induces a higher voltage (stage 3) than that created it in the load? Is this the same a blocking oscillator?

[@charlesdickens6706]

......is the LED in correct orientation here ?

[@MongrelShark]

When the base current drops the transistor switches off, HARD. This causes the emf spike, which goes high on collector, and LOW on base (try LED cathode on base and anode on emitter or collector) Keeping the transistor off. Bigger inductors will do this for longer, and genrally take longer to switch off too. Once the emf has finished, the primary and secondary winds to start to go back to pos terminal voltage, which causes magnetic amplification. On the base wind, starting it over.

[@peacebewu]

wait I'm kinda confused now...in a video by rimsstar org, he mentions that the coil actually initially induces voltage to the other coil positively, therefore saturating the bjt. Now in this video

[@sFeral]

I'm fairly sure that, as u said, initially both coils negate each others inductances (oversimplified since current change rates are different between the coils) hence the current through the base coil rises quicker to then be stifled by the same Force that initially enabled it, and if the stifling lasts (if collector current is still rising)for any amount of time past 0 and base current starts flowing the other way, it shortly thereafter creates the base spike which isn't desirable... so the point would be to tune the system until only the collector coil spike remains to be harvested or in other words IF I'm right, the C current has to reach max at the same moment the base current ceases.

[@Traderhood]

Very good. Thanks.

[@vongacoc]

Thank you very much

[@MongrelShark]

So I tested that 1980 thing here, and now I have to watch the video all over again. LMAO.

[@WTF_BBQ]

damn, I hate it when people use the + as the direction of the electron flow. It makes it confusing. Electrons are negative which means the electrons are coming from the negative side of the battery and that's how the REAL flow of current is suppose to be flowing from.

[@brettcitro8961]

Most Electrical Engineers use conventional current flow, (+) to (-).

[@SamaritanElad]

@@brettcitro8961 N0 they don't

[@Zp5Entertainment]

Zp5 (Indonesian language) Faktor dasar yg dapat memperbesar tegangan output itu apa ?

[@michelg3000]

My joule thief works fine when I use a small 1.5v battery. However,When I use a larger voltage say for instance 2.7, the joule thief drains the current directly from the battery. I does not oscillate. anybody knows why? Does the JT only work with voltages within the range of 1.5v?

[@HeilmanHackatronics]

ocult3000 0.8v should work okay.

[@michelg3000]

It seems to work with low voltages. 4 volts would not work. I don't know why. Can someone explain why?

[@michelg3000]

***** I did not mention 4 volts in my post. Your post may intend to reach someone else.

[@HomoInsanus]

If you are using a LED then higher voltage "can get through" it. But if you are using lower voltage the LED (diode) is closed(not enough voltage to open it) and the current has to find another way through the primary coil->base->.... and so on.

[@charlesdickens6706]

.....so if you connect two LEDs in series it then should work again I'm guessing .

[@patty1991]

Can you Charge your 1,5v battery With the 3v Side ? *win*

[@sailingcapedissappointment2012]

I think I might be keeping the batteries up as I have built a joule thief circuit with a slightly higher voltage to handle the drag of more components and I am running a mechanical flasher that has a considerable higher draw than an LED . Also I have another joule thief in the circuit that I wanted to experiment with that uses the same toroid that I wound with a center tap so I can adjust it with a potentiometer and switch back an forth with in and out of the circuit. I began constructing this so that I could test mosfets in an inverter I have that has quit working that way I can test the mosfets to see if they heat up or whatever and when I looked up the spec sheets I found out they were SCR's, that is how old this inverter is apparently. When I wound the toroid I used a ferrite magnet and I have placed it on two larger ferrite magnets and I belive they have a lot of power. The batteries are three AA Duracells that I recharged a few times, they are older and I thought they were dead and was going to just suck the life out of them and throw them away. After putting them in this circuit I have not had to charge them back up again and it seems to me like it was after adding the two large magnets to the transformer. Three LEDs and a mechanical flasher and it's all still point to point wiring and the three LEDs are blinding, I don't run it continuously because I am worried I might burn up the LED's but I have run it every everyday, for a couple months now. Also I tried to take a picture of this spagehtie mess with my phone and I think the HF fields have caused the camera in the phone to behave strangely .. The picture I took has a couple of things wrong with it and the first thing I noticed is it has created a background in the picture with some lines running across it and there is clock in the picture that is backwards, also there is a light with a handle on it and the handle is now on the other side of it, so some of the things in the picture have somehow been reversed, very strange and all this from three AA Duracells. I imagine these old batteries will eventually run down and I have yet to hook this up to the scope but perhaps our host here would be more interested in analyzing this situation ....

[@MongrelShark]

Not a bad basic explanation. You missed a couple of advanced points. The hfe and inductance values play a critical role. There is also magnetic amplification at play. Silicon transistors can be started from 0.4v, with no resistor. Even though the transistor needs.7v to turn on. when you connect power to centertap, the collector end of coil must rise to battery voltage, even if base disconected. This means some current is in the coil before it starts. cont...

[@davidprice2861]

Pretty good analysis of joule thief operation, I'd been looking at my scope trying to work it out, the discharge of secondary coil turning off the transistor base is the key to it all. My circuit is the same as yours except I put a 100 Ohm resistor between emitter and ground, (more economical) I have a total current 6mA, 1mA thru led. Still quite bright! Thanks, you are a good thinker. Some of the comments you got are from morons, ignore them.

[@MongrelShark]

There are videos on my channel showing reverse Joule Thiefs where the neg base spike is used to light the led. Putting the emf current back into the battery. There are examples of these around KZbin (including the famous and slightly misunderstood "Dr Jones" version) That can run from a 0.5v-0.7v AA for months or years. Due to the bemf stimulating the chemical reaction in the battery (wont run long on a cap). I also have a video of a germanium transistor (0.175v base) JT starting from 0,06v

[@lexclock]

mmm prefer to think that is magic