Joule Thief

[electricme]

Gary:
I agree with most of what you are saying, but the most important thing to watch for is to get the phasing right when you connect two or more transformer secondary output coils in series (same with the primary as well)

If you look at the setup which has 4 MOT transformers it will show you what I mean.
BTW, the circuit is not drawn wrong, you can see there are 2 lines drawn (black) from the center of 2 transformers (inner transformers) to the iron lamination's of the outer transformers.
In the case of MOTs the start winding is secured to the lamination's by a rivet.

Looking again at the two inner transformers, the GREEN line represents a wire connecting both the lamination's which is part of the circuit, notice the Earth connection.

So in the case of 4 MOT transformers, they must be isolated from each other, and you must never touch the iron core.
To fix this live core problem you remove the "pin" and sleeve the wire and anchor it securely by using appropriate HV insulating material, then threadding a cotton strip around the transformer, to anchor the terminal assembly and aralditing it. There may be other methods that I am not aware of.

But I do not accept responsibility if someone does this and hurts themselves.
Search all over the internet and look for those posts modifying MOTs to see if there is a better method, I only use what works well for myself.

I like your idea on using a switch to connect power to the second HV transformer, you could switch the second TF on or off as a test setup to explore the differences in the outputs.

I read the transistor on the flash PCB is a fairly robust device and can cope with a few amps where ordinary transistors will let out the smoke.

I think we could solder two of these same transistors in parallel to double the switching current to the transformer primaries, can't see any problems using this method.


Has anyone used a transistor from the camera boards to drive the Joule Thief?
   

[resonanceman]

Gary:
I agree with most of what you are saying, but the most important thing to watch for is to get the phasing right when you connect two or more transformer secondary output coils in series (same with the primary as well)

If you look at the setup which has 4 MOT transformers it will show you what I mean.
BTW, the circuit is not drawn wrong, you can see there are 2 lines drawn (black) from the center of 2 transformers (inner transformers) to the iron lamination's of the outer transformers.
In the case of MOTs the start winding is secured to the lamination's by a rivet.

Looking again at the two inner transformers, the GREEN line represents a wire connecting both the lamination's which is part of the circuit, notice the Earth connection.

So in the case of 4 MOT transformers, they must be isolated from each other, and you must never touch the iron core.
To fix this live core problem you remove the "pin" and sleeve the wire and anchor it securely by using appropriate HV insulating material, then threadding a cotton strip around the transformer, to anchor the terminal assembly and aralditing it. There may be other methods that I am not aware of.

But I do not accept responsibility if someone does this and hurts themselves.
Search all over the internet and look for those posts modifying MOTs to see if there is a better method, I only use what works well for myself.

I like your idea on using a switch to connect power to the second HV transformer, you could switch the second TF on or off as a test setup to explore the differences in the outputs.

I read the transistor on the flash PCB is a fairly robust device and can cope with a few amps where ordinary transistors will let out the smoke.

I think we could solder two of these same transistors in parallel to double the switching current to the transformer primaries, can't see any problems using this method.


Has anyone used a transistor from the camera boards to drive the Joule Thief?
   

Jim

I can see you have been studying this for a while.
Are you planning on actually using MOTs?
If so  have you thought of using a IGBT ( Insulated gate bipolar transistor )
They are expensive but they can handle some power.
I learned about them reading about how to make a solid state spark gap.

I do understand the problem of phase can  create with AC circuits .
i have never really worried about it...... I just experiment.
I connect another inductor and either the circuit gets stronger or it gets weaker

I played with feedback and balancing loads  for months a while back.
Most of my inductors were JT coils but I imagine that at least the basics apply to larger coils like MOTs


I have a different way of driving MOTs on my to do list.
It is similar to some of what IST was doing.
I was planning on making a small JT that would be used just for switching a IGBT on and off,
The voltage used for the MOT could be anything your IGBT could handle.
I got a couple IGBTs that can  handle 900V so I am thinking 250 or 300V might  be a safe maximum for input voltage....... assuming I never get careless and fire it up with no load......with no load I am guessing it would be somewhere around 2 KV and it would have a few amps behind it too




I am not sure  how many CFLs it  will  be  able to light.......I am guessing a few dozen'


I am just not ready to play with anything that lethal yet

gary

[electricme]

Gary:

No I am not going to use a MOT on my camera circuit to drive a CFL.
I needed to explain what I was doing by adding another HV transformer into the camera circuit, as there were no information available in the JT forum or elseware, I had to go look for it.

I knew from my searches a couple of years ago where someone had successfully married up 2 MOTs, somewhere I have also seen on the net someone has done the same using 2 car ignition coils, they are simply high voltage transformers, they put out 15KV each, ha ha, now you can see where we might be able to do by combining the JT with the Camera bits.

All I will be doing is to use the small tiny HV transformer that comes with the camera boards, they need to be identical, because I will run into electrical mismatch with loading, resistances, capacitance's, in other words if it works one transformer will have to take more of the load and burn out or the transistor firing off the primary will over heat and burn out.
So there is lots to think about.
 
I read someone had placed a microwave HV capacitor in series with the MOT output, I watched a video yesterday showing this thing was making some arcs that were out of this world, they were able to arc a couple feet long, just by adding the HV caps.

This fellow held a insulated rod which had a insulated wire going back to the earth of the circuit, but he was taking it very slow and safe.

I won't be expecting anything like this to happen, in fact a 1mm spark gap represents 1000 volts, as the series transformer will put out 700volts, I will not even be in the ball park, but I expect the neon would go phutt, but the flash tube should light like a light bulb, ha ha.

We all know a single flash from a flashing tube looks like, it is very intense and hurts the eyes, imagine if it was going off at 20 cycles a second, it should look like a powerful search light, especially if focused by a 6 volt lantern torch reflector, take the 6v bulb out and replace it with the flash tube vertically in the bulb holder. That keeps it in the focal plane of the mirror.
Now if I put a much smaller HV capacitor in series with the HV output, I could expect some real energy to be there.

I made a special circuit several years ago doing just this, it was fed from the HV output from the hand wound JT secondary, and it could give a real punch if you accidentally touched the ends.

I'm getting too far and head of myself now, but it's something to think about for a project down the road.

IGBTs need to be turned hard ON and OFF very rapidly, if they aren't they will destruct, I don't know enough of the camera circuit triggering waveforms to see if they can do this.
I know the sharper knee in the wave form will give the very best HV output from the transformer, this will be the stuff to trigger the transformer to give a better juicer spark.


Bill:
Hows the bees today, whats the tally so far, you got any stings? Hows the air space there 

jim

[Pirate88179]

Jim:

The bees are missing 10 of their airmen.  Here is a photo I got off of the net of one of them...the ones here are more yellow but the size is about the same.  I did not have my 1,500 volt stun swatter when I went out today and had to resort to hand to hand combat.  I smacked one of them out of the air with my hand and he hit the fence hard and fell to the ground.  I then stepped on him and....when I removed my foot...he took off again and appeared to be somewhat angry.  That swatter does the job and they never get up after a hit from that.  It is basically  JT circuit.

These things are almost the size of small birds, ha ha.

Bill

[nievesoliveras]

A schematic and photo of it assembled.
Found at http://www.instructables.com

Jesus