Joule Thief

[PowerJunkie]

Hello everybody,

I made my first Joule Thief yesterday and having a bit of trouble. I made it according to the guide on YouTube by the Make Podcast (http://www.youtube.com/watch?v=gTAqGKt64WM) as it looked pretty simple! I've made a 1/2" ferrite toroid with about 24 loops of thin copper wire. I am using a 2N3904 transistor. I tried out a AAA and AA (separately) battery and it worked great! I read the comments and saw that Colin Mitchell from TalkingElectronics explained how to improve upon it. I connected the feedback winding lead (that used to be connected to the end of the resistor, as shown in the YouTube video) directly into the Base [Middle Lead] of the Transistor and connected the resistor between the "Feedback winding" lead and the other lead that acts as the positive supply. I have used both a 1,000ohm and 20ohm resistor as experimentation. Here's the schematic of the "improvements" I did, so you understand what I did: http://www.instructables.com/files/deriv/F2I/ZRXQ/FR0ZHOS5/F2IZRXQFR0ZHOS5.MEDIUM.jpg

I tried it and it worked great! It was now twice as bright than it was when I first made it according to the video. I have tried out both a 2.1V Green LED and 3.6V Super Bright White LED and they're bright as heck when connected to a AAA or AA battery! Now, here come's the problem! I'm making this to use as an "idiot light" for a couple of engine sensors in my engine compartment. I've tried connecting my Joule Thief to multiple sensors that puts out around 2.0 V and 2.5 V. My problem is that the darn LED doesn't light up! Nothing at all. Now, if I remove the resistor completely that's bridged between the "Feedback winding" lead, then it lights up so darn DIM that you'll have to put your eyeball up to it in a pitch black moonless night to see a hint of light glowing from within. This is while using the 2.1V Green LED OR the 3.6V Super Bright White LED. Yet, take it off and connect it to a AA battery (with OR without the resistor bridged, it doesn't seem to matter with a battery!) then it works beautifully - the white LED is so bright that it blinds you!

Can anyone give me any idea's why it's not working with the vehicle, but works with a AA battery that's 1V less? I can even use a nearly-dead AA battery that's putting out 0.9V and it's 5,000 times brighter than it is on the vehicle. I have ensured that it's completely grounded in the vehicle, as well. I've also tried connecting a 22N capacitor from the feedback winding lead to the negative lead, but it doesn't seem to change a thing. One thing to note is that I connected the raw leads of the 2.1V Green LED (just the LED only, no Joule Thief or anything) to the engine sensors and the LED lit up just fine. It wasn't as bright as it is on a Joule Thief with a AA battery, but it definitely lit up!

I'm ready to chuck this damn thing in the trash bin since I've spent around MORE than 15 hours in the last 3 days fooling around with this thing trying to figure it out! This is COMPLETELY foreign to me (I've never done any electronics before) but I'm a quick learner!

I really need to get this to work, so ANY help, drawings or general ideas at all would be HIGHLY appreciated!

Thanks so much!

[jadaro2600]

Well, it appears as if we can post our own topics in this forums.  Why not do so.

Take everyone's different winding techniques for example?  ...or setups using multiple toroids?

Or fluorescents?

Or High voltage?

or General questions?

Or the JTC Bedini or JTC pulsemotors, etc.

Start your own related thread.  ...Maybe at the 500th page, the thread should be locked for referencing purposes only.

[Pirate88179]

@ Jim:

TheNop raises a good issue I did not think about.  If we shift to 15 posts per page, or 5, or whatever, it will no longer be page 500.  Maybe we need to think about this or, as Jadaro says, if someone wants to make an index page, maybe they can start another topic?  I don't really know but, this is why I suggested running it by the good folks on here.  If we all put our minds together, I am sure we can come up with something workable.

Hey, I just had an idea Jim, if you make an index, I can insert it into the first post on the diagram topic.  I can erase what I posted on the first post and put in the index.  Maybe this is a better way to go?

Bill

[jadaro2600]

Hello everybody,

I made my first Joule Thief yesterday and having a bit of trouble. I made it according to the guide on YouTube by the Make Podcast (http://www.youtube.com/watch?v=gTAqGKt64WM) as it looked pretty simple! I've made a 1/2" ferrite toroid with about 24 loops of thin copper wire. I am using a 2N3904 transistor. I tried out a AAA and AA (separately) battery and it worked great! I read the comments and saw that Colin Mitchell from TalkingElectronics explained how to improve upon it. I connected the feedback winding lead (that used to be connected to the end of the resistor, as shown in the YouTube video) directly into the Base [Middle Lead] of the Transistor and connected the resistor between the "Feedback winding" lead and the other lead that acts as the positive supply. I have used both a 1,000ohm and 20ohm resistor as experimentation.

I tried it and it worked great! It was now twice as bright than it was when I first made it according to the video. I have tried out both a 2.1V Green LED and 3.6V Super Bright White LED and they're bright as heck when connected to a AAA or AA battery! Now, here come's the problem! I'm making this to use as an "idiot light" for a couple of engine sensors in my engine compartment. I've tried connecting my Joule Thief to multiple sensors that puts out around 2.0 V and 2.5 V. My problem is that the darn LED doesn't light up! Nothing at all. Now, if I remove the resistor completely that's bridged between the "Feedback winding" lead, then it lights up so darn DIM that you'll have to put your eyeball up to it in a pitch black moonless night to see a hint of light glowing from within. This is while using the 2.1V Green LED OR the 3.6V Super Bright White LED. Yet, take it off and connect it to a AA battery (with OR without the resistor bridged, it doesn't seem to matter with a battery!) then it works beautifully - the white LED is so bright that it blinds you!

Can anyone give me any idea's why it's not working with the vehicle, but works with a AA battery that's 1V less? I can even use a nearly-dead AA battery that's putting out 0.9V and it's 5,000 times brighter than it is on the vehicle. I have ensured that it's completely grounded in the vehicle, as well. I've also tried connecting a 22N capacitor from the feedback winding lead to the negative lead, but it doesn't seem to change a thing. One thing to note is that I connected the raw leads of the 2.1V Green LED (just the LED only, no Joule Thief or anything) to the engine sensors and the LED lit up just fine. It wasn't as bright as it is on a Joule Thief with a AA battery, but it definitely lit up!

I'm ready to chuck this damn thing in the trash bin since I've spent around MORE than 15 hours in the last 3 days fooling around with this thing trying to figure it out! This is COMPLETELY foreign to me (I've never done any electronics before) but I'm a quick learner!

I really need to get this to work, so ANY help, drawings or general ideas at all would be HIGHLY appreciated!

Thanks so much!

Well, there are basically three things to make sure of:

The shorter winding goes to the base, and can be resisted at the base, or at the positive terminal.

The windings should be opposite flowing ..this can be a tough spot for some people.  If you were to wind them the same way around the mass of the toroid, then they would essentially flow the same way if they were connected ....

these coils need to be put in the circuit so that the flow of one opposes the flow of another.  A toroid isn't always the best example of how to wind a transformer.  consider a bar, and say you were to wrap two wires around it at the same time, and when you start, you have a yellow and a green wire on the inside, and when you finish you have yellow and green on the outside ....green is on path yellow is another.

putting the green path on the inside connecting it to the positive terminal and the green on the outside connected to the collector.  now, the yellow on the outside must now connect to the resistor which is connected to the positive terminal and the yellow on the inside must connect to the base of the transistor.

there must be a capacitor connector from the emitter to the end of the resistor where the yellow coil starts.

- - - - -
All that you need is a twisted pair of wires, you do not need a toroid.  simply get a twisted pair, connecting one wire from start end to positive, and its other end to collector, now at the end of the twisted pair, connect the free wire to the resistor and the other end to the base.  Here is an image of this, here is a schematic.

The third schematic is both npn and pnp, the one on the bottom is the normal mode, the dots on the coils represent the opposite directions that the coil have to be put in.

[TheNOP]

@PowerJunkie
hi
and welcome

what are the sensors you are talking about ?
i know what engine sensors are, but just to make shure we are talking of the same thing.
they might not be what you think they are.

can they provide at least 10 miliamps ?

you say they provide 2 volts, is that AC, DC  or plused DC  ?

i would not recommand to anyone to connect a jt to any car engine sensors.
it would be the best way to create unexpected problems.
but that depends on what exactly you are calling sensors.